From f68c79554f0f1a82ea916097a554f72a7d488acc Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Wed, 21 Oct 2020 01:05:00 +0100
Subject: [PATCH 01/11] Add <variant> header to files that will need it

---
 src/chainparams.cpp                               | 1 +
 src/consensus/params.h                            | 2 ++
 src/gtest/test_keys.cpp                           | 2 ++
 src/gtest/test_miner.cpp                          | 2 ++
 src/key_io.cpp                                    | 1 +
 src/main.cpp                                      | 1 +
 src/miner.h                                       | 1 +
 src/primitives/transaction.h                      | 1 +
 src/proof_verifier.cpp                            | 2 ++
 src/rpc/mining.cpp                                | 1 +
 src/rpc/misc.cpp                                  | 1 +
 src/rpc/rawtransaction.cpp                        | 1 +
 src/script/standard.h                             | 1 +
 src/test/key_tests.cpp                            | 1 +
 src/test/script_standard_tests.cpp                | 2 ++
 src/wallet/asyncrpcoperation_mergetoaddress.cpp   | 1 +
 src/wallet/asyncrpcoperation_saplingmigration.cpp | 2 ++
 src/wallet/asyncrpcoperation_sendmany.cpp         | 1 +
 src/wallet/asyncrpcoperation_shieldcoinbase.cpp   | 1 +
 src/wallet/rpcdump.cpp                            | 1 +
 src/wallet/rpcwallet.cpp                          | 1 +
 src/wallet/test/rpc_wallet_tests.cpp              | 1 +
 src/wallet/wallet.cpp                             | 1 +
 src/zcash/Address.hpp                             | 2 +-
 src/zcash/Proof.hpp                               | 2 +-
 25 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index d8bebb862..85c38b4e6 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -13,6 +13,7 @@
 #include "utilstrencodings.h"
 
 #include <assert.h>
+#include <variant>
 
 #include <boost/assign/list_of.hpp>
 
diff --git a/src/consensus/params.h b/src/consensus/params.h
index eb4874710..01a6edb0c 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -11,6 +11,8 @@
 #include "key_constants.h"
 #include <zcash/address/sapling.hpp>
 
+#include <variant>
+
 #include <boost/optional.hpp>
 #include <boost/variant.hpp>
 
diff --git a/src/gtest/test_keys.cpp b/src/gtest/test_keys.cpp
index eb2735a28..c61b50073 100644
--- a/src/gtest/test_keys.cpp
+++ b/src/gtest/test_keys.cpp
@@ -4,6 +4,8 @@
 
 #include "utiltest.h"
 
+#include <variant>
+
 #include <gtest/gtest.h>
 
 TEST(Keys, EncodeAndDecodeSapling)
diff --git a/src/gtest/test_miner.cpp b/src/gtest/test_miner.cpp
index c648a6750..e73f77a43 100644
--- a/src/gtest/test_miner.cpp
+++ b/src/gtest/test_miner.cpp
@@ -7,6 +7,8 @@
 #include "miner.h"
 #include "util.h"
 
+#include <variant>
+
 
 TEST(Miner, GetMinerAddress) {
     SelectParams(CBaseChainParams::MAIN);
diff --git a/src/key_io.cpp b/src/key_io.cpp
index 27a1b8a2e..f739f5437 100644
--- a/src/key_io.cpp
+++ b/src/key_io.cpp
@@ -16,6 +16,7 @@
 #include <assert.h>
 #include <string.h>
 #include <algorithm>
+#include <variant>
 
 namespace
 {
diff --git a/src/main.cpp b/src/main.cpp
index 1415c2da7..9a9346a16 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -39,6 +39,7 @@
 #include <algorithm>
 #include <atomic>
 #include <sstream>
+#include <variant>
 
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/math/distributions/poisson.hpp>
diff --git a/src/miner.h b/src/miner.h
index 080d29195..2cee74fbc 100644
--- a/src/miner.h
+++ b/src/miner.h
@@ -11,6 +11,7 @@
 #include <boost/optional.hpp>
 #include <boost/shared_ptr.hpp>
 #include <stdint.h>
+#include <variant>
 
 class CBlockIndex;
 class CChainParams;
diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index cff19b0e3..553fa5ede 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -15,6 +15,7 @@
 #include "consensus/consensus.h"
 
 #include <array>
+#include <variant>
 
 #include <boost/variant.hpp>
 
diff --git a/src/proof_verifier.cpp b/src/proof_verifier.cpp
index a99690609..58099c0bd 100644
--- a/src/proof_verifier.cpp
+++ b/src/proof_verifier.cpp
@@ -6,6 +6,8 @@
 
 #include <zcash/JoinSplit.hpp>
 
+#include <variant>
+
 #include <boost/variant.hpp>
 #include <librustzcash.h>
 
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index cdcaa4407..f79e98c04 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -28,6 +28,7 @@
 #endif
 
 #include <stdint.h>
+#include <variant>
 
 #include <boost/assign/list_of.hpp>
 #include <boost/shared_ptr.hpp>
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 9c12d954b..89b46b68d 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -19,6 +19,7 @@
 #endif
 
 #include <stdint.h>
+#include <variant>
 
 #include <boost/assign/list_of.hpp>
 
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index bdffd3573..4d6580518 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -26,6 +26,7 @@
 #endif
 
 #include <stdint.h>
+#include <variant>
 
 #include <boost/assign/list_of.hpp>
 
diff --git a/src/script/standard.h b/src/script/standard.h
index 97df161f5..4a3706738 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -12,6 +12,7 @@
 #include <boost/variant.hpp>
 
 #include <stdint.h>
+#include <variant>
 
 static const bool DEFAULT_ACCEPT_DATACARRIER = true;
 
diff --git a/src/test/key_tests.cpp b/src/test/key_tests.cpp
index d87470b23..25b285c85 100644
--- a/src/test/key_tests.cpp
+++ b/src/test/key_tests.cpp
@@ -16,6 +16,7 @@
 #include "zcash/Address.hpp"
 
 #include <string>
+#include <variant>
 #include <vector>
 
 #include <boost/test/unit_test.hpp>
diff --git a/src/test/script_standard_tests.cpp b/src/test/script_standard_tests.cpp
index 90a77e366..c7948a550 100644
--- a/src/test/script_standard_tests.cpp
+++ b/src/test/script_standard_tests.cpp
@@ -10,6 +10,8 @@
 #include "script/standard.h"
 #include "test/test_bitcoin.h"
 
+#include <variant>
+
 #include <boost/test/unit_test.hpp>
 
 
diff --git a/src/wallet/asyncrpcoperation_mergetoaddress.cpp b/src/wallet/asyncrpcoperation_mergetoaddress.cpp
index 7fdeea97a..fd6b62187 100644
--- a/src/wallet/asyncrpcoperation_mergetoaddress.cpp
+++ b/src/wallet/asyncrpcoperation_mergetoaddress.cpp
@@ -32,6 +32,7 @@
 #include <iostream>
 #include <string>
 #include <thread>
+#include <variant>
 
 #include <rust/ed25519.h>
 
diff --git a/src/wallet/asyncrpcoperation_saplingmigration.cpp b/src/wallet/asyncrpcoperation_saplingmigration.cpp
index 45845720d..8be4b6af7 100644
--- a/src/wallet/asyncrpcoperation_saplingmigration.cpp
+++ b/src/wallet/asyncrpcoperation_saplingmigration.cpp
@@ -12,6 +12,8 @@
 #include "utilmoneystr.h"
 #include "wallet.h"
 
+#include <variant>
+
 const CAmount FEE = 10000;
 const int MIGRATION_EXPIRY_DELTA = 450;
 
diff --git a/src/wallet/asyncrpcoperation_sendmany.cpp b/src/wallet/asyncrpcoperation_sendmany.cpp
index bb9f4e0ff..cc6061a24 100644
--- a/src/wallet/asyncrpcoperation_sendmany.cpp
+++ b/src/wallet/asyncrpcoperation_sendmany.cpp
@@ -34,6 +34,7 @@
 #include <chrono>
 #include <thread>
 #include <string>
+#include <variant>
 
 #include <rust/ed25519.h>
 
diff --git a/src/wallet/asyncrpcoperation_shieldcoinbase.cpp b/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
index 3407466b7..495e925f4 100644
--- a/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
+++ b/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
@@ -34,6 +34,7 @@
 #include <chrono>
 #include <thread>
 #include <string>
+#include <variant>
 
 #include <rust/ed25519.h>
 
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index f6aa3488e..ebf9037e5 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -16,6 +16,7 @@
 
 #include <fstream>
 #include <stdint.h>
+#include <variant>
 
 #include <boost/algorithm/string.hpp>
 #include <boost/date_time/posix_time/posix_time.hpp>
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 4f051a785..06faa9bb0 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -42,6 +42,7 @@
 #include <univalue.h>
 
 #include <numeric>
+#include <variant>
 
 #include <rust/ed25519.h>
 
diff --git a/src/wallet/test/rpc_wallet_tests.cpp b/src/wallet/test/rpc_wallet_tests.cpp
index 3e2989356..fb4ef3030 100644
--- a/src/wallet/test/rpc_wallet_tests.cpp
+++ b/src/wallet/test/rpc_wallet_tests.cpp
@@ -29,6 +29,7 @@
 #include <array>
 #include <chrono>
 #include <thread>
+#include <variant>
 
 #include <fstream>
 #include <unordered_set>
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 0f5288983..e5a3228f2 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -31,6 +31,7 @@
 
 #include <algorithm>
 #include <assert.h>
+#include <variant>
 
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/thread.hpp>
diff --git a/src/zcash/Address.hpp b/src/zcash/Address.hpp
index a4700fbbc..4dc65d6fc 100644
--- a/src/zcash/Address.hpp
+++ b/src/zcash/Address.hpp
@@ -5,7 +5,7 @@
 #include "zcash/address/sprout.hpp"
 #include "zcash/address/zip32.h"
 
-#include <boost/variant.hpp>
+#include <variant>
 
 namespace libzcash {
 class InvalidEncoding {
diff --git a/src/zcash/Proof.hpp b/src/zcash/Proof.hpp
index 0b9855f63..1bb55c413 100644
--- a/src/zcash/Proof.hpp
+++ b/src/zcash/Proof.hpp
@@ -4,7 +4,7 @@
 #include "serialize.h"
 #include "uint256.h"
 
-#include <boost/variant.hpp>
+#include <variant>
 
 namespace libzcash {
 

From b521cb89321f6ded1a5a69e8846e3a8b875accc2 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Wed, 21 Oct 2020 01:07:14 +0100
Subject: [PATCH 02/11] scripted-diff: Migrate from boost::variant to
 std::variant

-BEGIN VERIFY SCRIPT-
sed -i 's/boost::variant/std::variant/' ./src/*.h ./src/*.cpp ./src/*/*.h* ./src/*/*.cpp ;
sed -i 's/boost::get<\(.*\)>(&/std::get_if<\1>(\&/' ./src/*.h ./src/*.cpp ./src/*/*.h ./src/*/*.cpp ./src/*/*/*.cpp ;
sed -i 's/boost::get</std::get</' ./src/*.h ./src/*.cpp ./src/*/*.h ./src/*/*.cpp ./src/*/*/*.cpp ;
sed -i 's/boost::apply_visitor(/std::visit(/' ./src/*.h ./src/*.cpp ./src/*/*.h ./src/*/*.cpp ;
sed -i 's/class \(.*\)\b \?: public boost::static_visitor<.*>/class \1/' ./src/*.h ./src/*.cpp ./src/*/*.h* ./src/*/*.cpp ;
sed -i ':a;N;$!ba;s/#include <boost\/variant\(\/.*\)\?.hpp>\n//' ./src/*.h ./src/*.cpp ./src/*/*.h ./src/*/*.cpp ;
sed -i ':a;N;$!ba;s/#include "boost\/variant\/.*.hpp"\n//' ./src/*/*.cpp ;
-END VERIFY SCRIPT-
---
 src/chainparams.cpp                           |  2 +-
 src/consensus/funding.h                       |  1 -
 src/consensus/params.cpp                      |  8 ++--
 src/consensus/params.h                        |  5 +-
 src/gtest/test_joinsplit.cpp                  |  1 -
 src/gtest/test_keys.cpp                       | 12 ++---
 src/gtest/test_miner.cpp                      | 14 +++---
 src/init.cpp                                  |  6 +--
 src/key_io.cpp                                | 18 ++++----
 src/keystore.h                                |  1 -
 src/main.cpp                                  |  4 +-
 src/miner.cpp                                 | 18 ++++----
 src/miner.h                                   |  6 +--
 src/primitives/transaction.h                  |  5 +-
 src/proof_verifier.cpp                        |  5 +-
 src/rpc/mining.cpp                            | 14 +++---
 src/rpc/misc.cpp                              | 16 +++----
 src/rpc/rawtransaction.cpp                    |  2 +-
 src/script/standard.cpp                       |  4 +-
 src/script/standard.h                         |  3 +-
 src/test/key_tests.cpp                        | 16 +++----
 src/test/script_standard_tests.cpp            | 32 ++++++-------
 src/transaction_builder.cpp                   |  1 -
 .../asyncrpcoperation_mergetoaddress.cpp      |  6 +--
 .../asyncrpcoperation_saplingmigration.cpp    |  3 +-
 src/wallet/asyncrpcoperation_sendmany.cpp     | 22 ++++-----
 .../asyncrpcoperation_shieldcoinbase.cpp      |  2 +-
 src/wallet/asyncrpcoperation_shieldcoinbase.h |  2 +-
 src/wallet/rpcdump.cpp                        | 16 +++----
 src/wallet/rpcwallet.cpp                      | 46 +++++++++----------
 src/wallet/test/rpc_wallet_tests.cpp          |  6 +--
 src/wallet/wallet.cpp                         | 12 ++---
 src/wallet/wallet.h                           | 12 ++---
 src/zcash/Address.hpp                         | 10 ++--
 src/zcash/Proof.hpp                           |  2 +-
 35 files changed, 161 insertions(+), 172 deletions(-)

diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 85c38b4e6..0353ae1d2 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -813,7 +813,7 @@ CScript CChainParams::GetFoundersRewardScriptAtHeight(int nHeight) const {
     CTxDestination address = keyIO.DecodeDestination(GetFoundersRewardAddressAtHeight(nHeight).c_str());
     assert(IsValidDestination(address));
     assert(IsScriptDestination(address));
-    CScriptID scriptID = boost::get<CScriptID>(address); // address is a boost variant
+    CScriptID scriptID = std::get<CScriptID>(address); // address is a boost variant
     CScript script = CScript() << OP_HASH160 << ToByteVector(scriptID) << OP_EQUAL;
     return script;
 }
diff --git a/src/consensus/funding.h b/src/consensus/funding.h
index b2dc1cd6c..91230db2b 100644
--- a/src/consensus/funding.h
+++ b/src/consensus/funding.h
@@ -8,7 +8,6 @@
 #include <amount.h>
 #include <consensus/params.h>
 
-#include <boost/variant.hpp>
 
 namespace Consensus
 {
diff --git a/src/consensus/params.cpp b/src/consensus/params.cpp
index a6525f4b7..cc519337b 100644
--- a/src/consensus/params.cpp
+++ b/src/consensus/params.cpp
@@ -102,7 +102,7 @@ namespace Consensus {
         return (nHeight - fundingStreamStartHeight + startPeriodOffset) / nFundingPeriodLength;
     }
 
-    boost::variant<FundingStream, FundingStreamError> FundingStream::ValidateFundingStream(
+    std::variant<FundingStream, FundingStreamError> FundingStream::ValidateFundingStream(
         const Consensus::Params& params,
         const int startHeight,
         const int endHeight,
@@ -123,7 +123,7 @@ namespace Consensus {
         return FundingStream(startHeight, endHeight, addresses);
     };
 
-    class GetFundingStreamOrThrow: public boost::static_visitor<FundingStream> {
+    class GetFundingStreamOrThrow {
     public:
         FundingStream operator()(const FundingStream& fs) const {
             return fs;
@@ -163,12 +163,12 @@ namespace Consensus {
                 // If the string is not a valid transparent or Sapling address, we will
                 // throw here.
 
-                addresses.push_back(boost::get<libzcash::SaplingPaymentAddress>(zaddr));
+                addresses.push_back(std::get<libzcash::SaplingPaymentAddress>(zaddr));
             }
         }
 
         auto validationResult = FundingStream::ValidateFundingStream(params, startHeight, endHeight, addresses);
-        return boost::apply_visitor(GetFundingStreamOrThrow(), validationResult);
+        return std::visit(GetFundingStreamOrThrow(), validationResult);
     };
 
     void Params::AddZIP207FundingStream(
diff --git a/src/consensus/params.h b/src/consensus/params.h
index 01a6edb0c..f5830855d 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -14,7 +14,6 @@
 #include <variant>
 
 #include <boost/optional.hpp>
-#include <boost/variant.hpp>
 
 namespace Consensus {
 
@@ -84,7 +83,7 @@ struct NetworkUpgrade {
     boost::optional<uint256> hashActivationBlock;
 };
 
-typedef boost::variant<libzcash::SaplingPaymentAddress, CScript> FundingStreamAddress;
+typedef std::variant<libzcash::SaplingPaymentAddress, CScript> FundingStreamAddress;
 
 /**
  * Index into Params.vFundingStreams.
@@ -118,7 +117,7 @@ public:
     FundingStream(const FundingStream& fs):
         startHeight(fs.startHeight), endHeight(fs.endHeight), addresses(fs.addresses) { }
 
-    static boost::variant<FundingStream, FundingStreamError> ValidateFundingStream(
+    static std::variant<FundingStream, FundingStreamError> ValidateFundingStream(
         const Consensus::Params& params,
         const int startHeight,
         const int endHeight,
diff --git a/src/gtest/test_joinsplit.cpp b/src/gtest/test_joinsplit.cpp
index 65c452102..b89c3d6ad 100644
--- a/src/gtest/test_joinsplit.cpp
+++ b/src/gtest/test_joinsplit.cpp
@@ -2,7 +2,6 @@
 
 #include "utilstrencodings.h"
 
-#include <boost/variant/get.hpp>
 
 #include "zcash/prf.h"
 #include "util.h"
diff --git a/src/gtest/test_keys.cpp b/src/gtest/test_keys.cpp
index c61b50073..e31b6796a 100644
--- a/src/gtest/test_keys.cpp
+++ b/src/gtest/test_keys.cpp
@@ -26,8 +26,8 @@ TEST(Keys, EncodeAndDecodeSapling)
             auto spendingkey2 = keyIO.DecodeSpendingKey(sk_string);
             EXPECT_TRUE(IsValidSpendingKey(spendingkey2));
 
-            ASSERT_TRUE(boost::get<libzcash::SaplingExtendedSpendingKey>(&spendingkey2) != nullptr);
-            auto sk2 = boost::get<libzcash::SaplingExtendedSpendingKey>(spendingkey2);
+            ASSERT_TRUE(std::get_if<libzcash::SaplingExtendedSpendingKey>(&spendingkey2) != nullptr);
+            auto sk2 = std::get<libzcash::SaplingExtendedSpendingKey>(spendingkey2);
             EXPECT_EQ(sk, sk2);
         }
         {
@@ -40,8 +40,8 @@ TEST(Keys, EncodeAndDecodeSapling)
             auto viewingkey2 = keyIO.DecodeViewingKey(vk_string);
             EXPECT_TRUE(IsValidViewingKey(viewingkey2));
 
-            ASSERT_TRUE(boost::get<libzcash::SaplingExtendedFullViewingKey>(&viewingkey2) != nullptr);
-            auto extfvk2 = boost::get<libzcash::SaplingExtendedFullViewingKey>(viewingkey2);
+            ASSERT_TRUE(std::get_if<libzcash::SaplingExtendedFullViewingKey>(&viewingkey2) != nullptr);
+            auto extfvk2 = std::get<libzcash::SaplingExtendedFullViewingKey>(viewingkey2);
             EXPECT_EQ(extfvk, extfvk2);
         }
         {
@@ -55,8 +55,8 @@ TEST(Keys, EncodeAndDecodeSapling)
             auto paymentaddr2 = keyIO.DecodePaymentAddress(addr_string);
             EXPECT_TRUE(IsValidPaymentAddress(paymentaddr2));
 
-            ASSERT_TRUE(boost::get<libzcash::SaplingPaymentAddress>(&paymentaddr2) != nullptr);
-            auto addr2 = boost::get<libzcash::SaplingPaymentAddress>(paymentaddr2);
+            ASSERT_TRUE(std::get_if<libzcash::SaplingPaymentAddress>(&paymentaddr2) != nullptr);
+            auto addr2 = std::get<libzcash::SaplingPaymentAddress>(paymentaddr2);
             EXPECT_EQ(addr, addr2);
         }
     }
diff --git a/src/gtest/test_miner.cpp b/src/gtest/test_miner.cpp
index e73f77a43..61d454407 100644
--- a/src/gtest/test_miner.cpp
+++ b/src/gtest/test_miner.cpp
@@ -54,8 +54,8 @@ TEST(Miner, GetMinerAddress) {
         MinerAddress minerAddress;
         GetMinerAddress(minerAddress);
         EXPECT_TRUE(IsValidMinerAddress(minerAddress));
-        EXPECT_TRUE(boost::get<boost::shared_ptr<CReserveScript>>(&minerAddress) != nullptr);
-        auto coinbaseScript = boost::get<boost::shared_ptr<CReserveScript>>(minerAddress);
+        EXPECT_TRUE(std::get_if<boost::shared_ptr<CReserveScript>>(&minerAddress) != nullptr);
+        auto coinbaseScript = std::get<boost::shared_ptr<CReserveScript>>(minerAddress);
         EXPECT_EQ(expectedCoinbaseScript, coinbaseScript->reserveScript);
     }
 
@@ -65,8 +65,8 @@ TEST(Miner, GetMinerAddress) {
         MinerAddress minerAddress;
         GetMinerAddress(minerAddress);
         EXPECT_TRUE(IsValidMinerAddress(minerAddress));
-        EXPECT_TRUE(boost::get<boost::shared_ptr<CReserveScript>>(&minerAddress) != nullptr);
-        auto coinbaseScript = boost::get<boost::shared_ptr<CReserveScript>>(minerAddress);
+        EXPECT_TRUE(std::get_if<boost::shared_ptr<CReserveScript>>(&minerAddress) != nullptr);
+        auto coinbaseScript = std::get<boost::shared_ptr<CReserveScript>>(minerAddress);
         EXPECT_EQ(expectedCoinbaseScript, coinbaseScript->reserveScript);
     }
 
@@ -76,8 +76,8 @@ TEST(Miner, GetMinerAddress) {
         MinerAddress minerAddress;
         GetMinerAddress(minerAddress);
         EXPECT_TRUE(IsValidMinerAddress(minerAddress));
-        EXPECT_TRUE(boost::get<boost::shared_ptr<CReserveScript>>(&minerAddress) != nullptr);
-        auto coinbaseScript = boost::get<boost::shared_ptr<CReserveScript>>(minerAddress);
+        EXPECT_TRUE(std::get_if<boost::shared_ptr<CReserveScript>>(&minerAddress) != nullptr);
+        auto coinbaseScript = std::get<boost::shared_ptr<CReserveScript>>(minerAddress);
         EXPECT_EQ(expectedCoinbaseScript, coinbaseScript->reserveScript);
     }
 
@@ -103,7 +103,7 @@ TEST(Miner, GetMinerAddress) {
         MinerAddress minerAddress;
         GetMinerAddress(minerAddress);
         EXPECT_TRUE(IsValidMinerAddress(minerAddress));
-        EXPECT_TRUE(boost::get<libzcash::SaplingPaymentAddress>(&minerAddress) != nullptr);
+        EXPECT_TRUE(std::get_if<libzcash::SaplingPaymentAddress>(&minerAddress) != nullptr);
     }
 
     // Valid Sapling address with leading whitespace
diff --git a/src/init.cpp b/src/init.cpp
index ab46a51e7..473692646 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1054,7 +1054,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
             // Try a Sapling address
             auto zaddr = keyIO.DecodePaymentAddress(mapArgs["-mineraddress"]);
             if (!IsValidPaymentAddress(zaddr) ||
-                boost::get<libzcash::SaplingPaymentAddress>(&zaddr) == nullptr)
+                std::get_if<libzcash::SaplingPaymentAddress>(&zaddr) == nullptr)
             {
                 return InitError(strprintf(
                     _("Invalid address for -mineraddress=<addr>: '%s' (must be a Sapling or transparent address)"),
@@ -1575,11 +1575,11 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
         if (pwalletMain) {
             CTxDestination addr = keyIO.DecodeDestination(mapArgs["-mineraddress"]);
             if (IsValidDestination(addr)) {
-                CKeyID keyID = boost::get<CKeyID>(addr);
+                CKeyID keyID = std::get<CKeyID>(addr);
                 minerAddressInLocalWallet = pwalletMain->HaveKey(keyID);
             } else {
                 auto zaddr = keyIO.DecodePaymentAddress(mapArgs["-mineraddress"]);
-                minerAddressInLocalWallet = boost::apply_visitor(
+                minerAddressInLocalWallet = std::visit(
                     HaveSpendingKeyForPaymentAddress(pwalletMain), zaddr);
             }
         }
diff --git a/src/key_io.cpp b/src/key_io.cpp
index f739f5437..8e049d874 100644
--- a/src/key_io.cpp
+++ b/src/key_io.cpp
@@ -10,8 +10,6 @@
 #include <script/script.h>
 #include <utilstrencodings.h>
 
-#include <boost/variant/apply_visitor.hpp>
-#include <boost/variant/static_visitor.hpp>
 
 #include <assert.h>
 #include <string.h>
@@ -20,7 +18,7 @@
 
 namespace
 {
-class DestinationEncoder : public boost::static_visitor<std::string>
+class DestinationEncoder
 {
 private:
     const KeyConstants& keyConstants;
@@ -45,7 +43,7 @@ public:
     std::string operator()(const CNoDestination& no) const { return {}; }
 };
 
-class PaymentAddressEncoder : public boost::static_visitor<std::string>
+class PaymentAddressEncoder
 {
 private:
     const KeyConstants& keyConstants;
@@ -78,7 +76,7 @@ public:
     std::string operator()(const libzcash::InvalidEncoding& no) const { return {}; }
 };
 
-class ViewingKeyEncoder : public boost::static_visitor<std::string>
+class ViewingKeyEncoder
 {
 private:
     const KeyConstants& keyConstants;
@@ -116,7 +114,7 @@ public:
     std::string operator()(const libzcash::InvalidEncoding& no) const { return {}; }
 };
 
-class SpendingKeyEncoder : public boost::static_visitor<std::string>
+class SpendingKeyEncoder
 {
 private:
     const KeyConstants& keyConstants;
@@ -265,7 +263,7 @@ std::string KeyIO::EncodeExtKey(const CExtKey& key)
 
 std::string KeyIO::EncodeDestination(const CTxDestination& dest)
 {
-    return boost::apply_visitor(DestinationEncoder(keyConstants), dest);
+    return std::visit(DestinationEncoder(keyConstants), dest);
 }
 
 bool KeyIO::IsValidDestinationString(const std::string& str)
@@ -275,7 +273,7 @@ bool KeyIO::IsValidDestinationString(const std::string& str)
 
 std::string KeyIO::EncodePaymentAddress(const libzcash::PaymentAddress& zaddr)
 {
-    return boost::apply_visitor(PaymentAddressEncoder(keyConstants), zaddr);
+    return std::visit(PaymentAddressEncoder(keyConstants), zaddr);
 }
 
 template<typename T1, typename T2, typename T3>
@@ -337,7 +335,7 @@ bool KeyIO::IsValidPaymentAddressString(const std::string& str) {
 
 std::string KeyIO::EncodeViewingKey(const libzcash::ViewingKey& vk)
 {
-    return boost::apply_visitor(ViewingKeyEncoder(keyConstants), vk);
+    return std::visit(ViewingKeyEncoder(keyConstants), vk);
 }
 
 libzcash::ViewingKey KeyIO::DecodeViewingKey(const std::string& str)
@@ -354,7 +352,7 @@ libzcash::ViewingKey KeyIO::DecodeViewingKey(const std::string& str)
 
 std::string KeyIO::EncodeSpendingKey(const libzcash::SpendingKey& zkey)
 {
-    return boost::apply_visitor(SpendingKeyEncoder(keyConstants), zkey);
+    return std::visit(SpendingKeyEncoder(keyConstants), zkey);
 }
 
 libzcash::SpendingKey KeyIO::DecodeSpendingKey(const std::string& str)
diff --git a/src/keystore.h b/src/keystore.h
index fd5c8996b..69baf26e8 100644
--- a/src/keystore.h
+++ b/src/keystore.h
@@ -15,7 +15,6 @@
 #include "zcash/NoteEncryption.hpp"
 
 #include <boost/signals2/signal.hpp>
-#include <boost/variant.hpp>
 
 /** A virtual base class for key stores */
 class CKeyStore
diff --git a/src/main.cpp b/src/main.cpp
index 9a9346a16..e2fcecb6a 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -963,7 +963,7 @@ bool ContextualCheckTransaction(
                 if (canopyActive) {
                     libzcash::SaplingPaymentAddress zaddr(encPlaintext->d, outPlaintext->pk_d);
                     for (auto it = fundingStreamElements.begin(); it != fundingStreamElements.end(); ++it) {
-                        const libzcash::SaplingPaymentAddress* streamAddr = boost::get<libzcash::SaplingPaymentAddress>(&(it->first));
+                        const libzcash::SaplingPaymentAddress* streamAddr = std::get_if<libzcash::SaplingPaymentAddress>(&(it->first));
                         if (streamAddr && zaddr == *streamAddr && encPlaintext->value() == it->second) {
                             fundingStreamElements.erase(it);
                             break;
@@ -1013,7 +1013,7 @@ bool ContextualCheckTransaction(
             // Detect transparent funding streams.
             for (const CTxOut& output : tx.vout) {
                 for (auto it = fundingStreamElements.begin(); it != fundingStreamElements.end(); ++it) {
-                    const CScript* taddr = boost::get<CScript>(&(it->first));
+                    const CScript* taddr = std::get_if<CScript>(&(it->first));
                     if (taddr && output.scriptPubKey == *taddr && output.nValue == it->second) {
                         fundingStreamElements.erase(it);
                         break;
diff --git a/src/miner.cpp b/src/miner.cpp
index b3bdabc20..4d1e9835f 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -122,7 +122,7 @@ bool IsShieldedMinerAddress(const MinerAddress& minerAddr) {
         minerAddr.type() == typeid(boost::shared_ptr<CReserveScript>));
 }
 
-class AddFundingStreamValueToTx : public boost::static_visitor<bool>
+class AddFundingStreamValueToTx
 {
 private:
     CMutableTransaction &mtx;
@@ -158,7 +158,7 @@ public:
 };
 
 
-class AddOutputsToCoinbaseTxAndSign : public boost::static_visitor<>
+class AddOutputsToCoinbaseTxAndSign
 {
 private:
     CMutableTransaction &mtx;
@@ -194,7 +194,7 @@ public:
 
                 for (Consensus::FundingStreamElement fselem : fundingStreamElements) {
                     miner_reward -= fselem.second;
-                    bool added = boost::apply_visitor(AddFundingStreamValueToTx(mtx, ctx, fselem.second, GetZip212Flag()), fselem.first);
+                    bool added = std::visit(AddFundingStreamValueToTx(mtx, ctx, fselem.second, GetZip212Flag()), fselem.first);
                     if (!added) {
                         librustzcash_sapling_proving_ctx_free(ctx);
                         throw new std::runtime_error("Failed to add funding stream output.");
@@ -297,7 +297,7 @@ CMutableTransaction CreateCoinbaseTransaction(const CChainParams& chainparams, C
         mtx.nExpiryHeight = 0;
 
         // Add outputs and sign
-        boost::apply_visitor(
+        std::visit(
             AddOutputsToCoinbaseTxAndSign(mtx, chainparams, nHeight, nFees),
             minerAddress);
 
@@ -667,7 +667,7 @@ void GetMinerAddress(MinerAddress &minerAddress)
     CTxDestination addr = keyIO.DecodeDestination(mAddrArg);
     if (IsValidDestination(addr)) {
         boost::shared_ptr<MinerAddressScript> mAddr(new MinerAddressScript());
-        CKeyID keyID = boost::get<CKeyID>(addr);
+        CKeyID keyID = std::get<CKeyID>(addr);
 
         mAddr->reserveScript = CScript() << OP_DUP << OP_HASH160 << ToByteVector(keyID) << OP_EQUALVERIFY << OP_CHECKSIG;
         minerAddress = mAddr;
@@ -675,8 +675,8 @@ void GetMinerAddress(MinerAddress &minerAddress)
         // Try a Sapling address
         auto zaddr = keyIO.DecodePaymentAddress(mAddrArg);
         if (IsValidPaymentAddress(zaddr)) {
-            if (boost::get<libzcash::SaplingPaymentAddress>(&zaddr) != nullptr) {
-                minerAddress = boost::get<libzcash::SaplingPaymentAddress>(zaddr);
+            if (std::get_if<libzcash::SaplingPaymentAddress>(&zaddr) != nullptr) {
+                minerAddress = std::get<libzcash::SaplingPaymentAddress>(zaddr);
             }
         }
     }
@@ -757,7 +757,7 @@ void static BitcoinMiner(const CChainParams& chainparams)
 
     try {
         // Throw an error if no address valid for mining was provided.
-        if (!boost::apply_visitor(IsValidMinerAddress(), minerAddress)) {
+        if (!std::visit(IsValidMinerAddress(), minerAddress)) {
             throw std::runtime_error("No miner address available (mining requires a wallet or -mineraddress)");
         }
 
@@ -852,7 +852,7 @@ void static BitcoinMiner(const CChainParams& chainparams)
                         cancelSolver = false;
                     }
                     SetThreadPriority(THREAD_PRIORITY_LOWEST);
-                    boost::apply_visitor(KeepMinerAddress(), minerAddress);
+                    std::visit(KeepMinerAddress(), minerAddress);
 
                     // In regression test mode, stop mining after a block is found.
                     if (chainparams.MineBlocksOnDemand()) {
diff --git a/src/miner.h b/src/miner.h
index 2cee74fbc..d9c4947b2 100644
--- a/src/miner.h
+++ b/src/miner.h
@@ -29,9 +29,9 @@ public:
     friend bool operator<(const InvalidMinerAddress &a, const InvalidMinerAddress &b) { return true; }
 };
 
-typedef boost::variant<InvalidMinerAddress, libzcash::SaplingPaymentAddress, boost::shared_ptr<CReserveScript>> MinerAddress;
+typedef std::variant<InvalidMinerAddress, libzcash::SaplingPaymentAddress, boost::shared_ptr<CReserveScript>> MinerAddress;
 
-class KeepMinerAddress : public boost::static_visitor<>
+class KeepMinerAddress
 {
 public:
     KeepMinerAddress() {}
@@ -45,7 +45,7 @@ public:
 
 bool IsShieldedMinerAddress(const MinerAddress& minerAddr);
 
-class IsValidMinerAddress : public boost::static_visitor<bool>
+class IsValidMinerAddress
 {
 public:
     IsValidMinerAddress() {}
diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index 553fa5ede..9981bc7dd 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -17,7 +17,6 @@
 #include <array>
 #include <variant>
 
-#include <boost/variant.hpp>
 
 #include "zcash/NoteEncryption.hpp"
 #include "zcash/Zcash.h"
@@ -141,7 +140,7 @@ public:
 };
 
 template <typename Stream>
-class SproutProofSerializer : public boost::static_visitor<>
+class SproutProofSerializer
 {
     Stream& s;
     bool useGroth;
@@ -170,7 +169,7 @@ template<typename Stream, typename T>
 inline void SerReadWriteSproutProof(Stream& s, const T& proof, bool useGroth, CSerActionSerialize ser_action)
 {
     auto ps = SproutProofSerializer<Stream>(s, useGroth);
-    boost::apply_visitor(ps, proof);
+    std::visit(ps, proof);
 }
 
 template<typename Stream, typename T>
diff --git a/src/proof_verifier.cpp b/src/proof_verifier.cpp
index 58099c0bd..92a620cba 100644
--- a/src/proof_verifier.cpp
+++ b/src/proof_verifier.cpp
@@ -8,10 +8,9 @@
 
 #include <variant>
 
-#include <boost/variant.hpp>
 #include <librustzcash.h>
 
-class SproutProofVerifier : public boost::static_visitor<bool>
+class SproutProofVerifier
 {
     ProofVerifier& verifier;
     const Ed25519VerificationKey& joinSplitPubKey;
@@ -68,5 +67,5 @@ bool ProofVerifier::VerifySprout(
     }
 
     auto pv = SproutProofVerifier(*this, joinSplitPubKey, jsdesc);
-    return boost::apply_visitor(pv, jsdesc.proof);
+    return std::visit(pv, jsdesc.proof);
 }
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index f79e98c04..03be2a6d3 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -190,13 +190,13 @@ UniValue generate(const UniValue& params, bool fHelp)
     GetMainSignals().AddressForMining(minerAddress);
 
     // If the keypool is exhausted, no script is returned at all.  Catch this.
-    auto resv = boost::get<boost::shared_ptr<CReserveScript>>(&minerAddress);
+    auto resv = std::get_if<boost::shared_ptr<CReserveScript>>(&minerAddress);
     if (resv && !resv->get()) {
         throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
     }
 
     // Throw an error if no address valid for mining was provided.
-    if (!boost::apply_visitor(IsValidMinerAddress(), minerAddress)) {
+    if (!std::visit(IsValidMinerAddress(), minerAddress)) {
         throw JSONRPCError(RPC_INTERNAL_ERROR, "No miner address available (mining requires a wallet or -mineraddress)");
     }
 
@@ -263,7 +263,7 @@ endloop:
         blockHashes.push_back(pblock->GetHash().GetHex());
 
         //mark miner address as important because it was used at least for one coinbase output
-        boost::apply_visitor(KeepMinerAddress(), minerAddress);
+        std::visit(KeepMinerAddress(), minerAddress);
     }
     return blockHashes;
 }
@@ -671,7 +671,7 @@ UniValue getblocktemplate(const UniValue& params, bool fHelp)
         }
 
         // Throw an error if no address valid for mining was provided.
-        if (!boost::apply_visitor(IsValidMinerAddress(), minerAddress)) {
+        if (!std::visit(IsValidMinerAddress(), minerAddress)) {
             throw JSONRPCError(RPC_INTERNAL_ERROR, "No miner address available (mining requires a wallet or -mineraddress)");
         }
 
@@ -680,7 +680,7 @@ UniValue getblocktemplate(const UniValue& params, bool fHelp)
             throw JSONRPCError(RPC_OUT_OF_MEMORY, "Out of memory");
 
         // Mark script as important because it was used at least for one coinbase output
-        boost::apply_visitor(KeepMinerAddress(), minerAddress);
+        std::visit(KeepMinerAddress(), minerAddress);
 
         // Need to update only after we know CreateNewBlock succeeded
         pindexPrev = pindexPrevNew;
@@ -983,7 +983,7 @@ UniValue getblocksubsidy(const UniValue& params, bool fHelp)
             auto fs = consensus.vFundingStreams[idx];
             auto address = fs.get().RecipientAddress(consensus, nHeight);
 
-            CScript* outpoint = boost::get<CScript>(&address);
+            CScript* outpoint = std::get_if<CScript>(&address);
             std::string addressStr;
 
             if (outpoint != nullptr) {
@@ -993,7 +993,7 @@ UniValue getblocksubsidy(const UniValue& params, bool fHelp)
                 addressStr = find_value(pubkey, "addresses").get_array()[0].get_str();
 
             } else {
-                libzcash::SaplingPaymentAddress* zaddr = boost::get<libzcash::SaplingPaymentAddress>(&address);
+                libzcash::SaplingPaymentAddress* zaddr = std::get_if<libzcash::SaplingPaymentAddress>(&address);
                 if (zaddr != nullptr) {
                     // For shielded funding stream addresses
                     addressStr = keyIO.EncodePaymentAddress(*zaddr);
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 89b46b68d..eb4d02c4e 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -115,7 +115,7 @@ UniValue getinfo(const UniValue& params, bool fHelp)
 }
 
 #ifdef ENABLE_WALLET
-class DescribeAddressVisitor : public boost::static_visitor<UniValue>
+class DescribeAddressVisitor
 {
 public:
     UniValue operator()(const CNoDestination &dest) const { return UniValue(UniValue::VOBJ); }
@@ -204,7 +204,7 @@ UniValue validateaddress(const UniValue& params, bool fHelp)
         isminetype mine = pwalletMain ? IsMine(*pwalletMain, dest) : ISMINE_NO;
         ret.pushKV("ismine", (mine & ISMINE_SPENDABLE) ? true : false);
         ret.pushKV("iswatchonly", (mine & ISMINE_WATCH_ONLY) ? true: false);
-        UniValue detail = boost::apply_visitor(DescribeAddressVisitor(), dest);
+        UniValue detail = std::visit(DescribeAddressVisitor(), dest);
         ret.pushKVs(detail);
         if (pwalletMain && pwalletMain->mapAddressBook.count(dest))
             ret.pushKV("account", pwalletMain->mapAddressBook[dest].name);
@@ -214,7 +214,7 @@ UniValue validateaddress(const UniValue& params, bool fHelp)
 }
 
 
-class DescribePaymentAddressVisitor : public boost::static_visitor<UniValue>
+class DescribePaymentAddressVisitor
 {
 public:
     UniValue operator()(const libzcash::InvalidEncoding &zaddr) const { return UniValue(UniValue::VOBJ); }
@@ -288,7 +288,7 @@ UniValue z_validateaddress(const UniValue& params, bool fHelp)
     if (isValid)
     {
         ret.pushKV("address", strAddress);
-        UniValue detail = boost::apply_visitor(DescribePaymentAddressVisitor(), address);
+        UniValue detail = std::visit(DescribePaymentAddressVisitor(), address);
         ret.pushKVs(detail);
     }
     return ret;
@@ -324,7 +324,7 @@ CScript _createmultisig_redeemScript(const UniValue& params)
         // Case 1: Bitcoin address and we have full public key:
         CTxDestination dest = keyIO.DecodeDestination(ks);
         if (pwalletMain && IsValidDestination(dest)) {
-            const CKeyID *keyID = boost::get<CKeyID>(&dest);
+            const CKeyID *keyID = std::get_if<CKeyID>(&dest);
             if (!keyID) {
                 throw std::runtime_error(strprintf("%s does not refer to a key", ks));
             }
@@ -439,7 +439,7 @@ UniValue verifymessage(const UniValue& params, bool fHelp)
         throw JSONRPCError(RPC_TYPE_ERROR, "Invalid address");
     }
 
-    const CKeyID *keyID = boost::get<CKeyID>(&destination);
+    const CKeyID *keyID = std::get_if<CKeyID>(&destination);
     if (!keyID) {
         throw JSONRPCError(RPC_TYPE_ERROR, "Address does not refer to key");
     }
@@ -539,13 +539,13 @@ static bool getIndexKey(
         return false;
     }
     if (IsKeyDestination(dest)) {
-        auto x = boost::get<CKeyID>(&dest);
+        auto x = std::get_if<CKeyID>(&dest);
         memcpy(&hashBytes, x->begin(), 20);
         type = CScript::P2PKH;
         return true;
     }
     if (IsScriptDestination(dest)) {
-        auto x = boost::get<CScriptID>(&dest);
+        auto x = std::get_if<CScriptID>(&dest);
         memcpy(&hashBytes, x->begin(), 20);
         type = CScript::P2SH;
         return true;
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 4d6580518..814123b62 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -104,7 +104,7 @@ UniValue TxJoinSplitToJSON(const CTransaction& tx) {
 
         CDataStream ssProof(SER_NETWORK, PROTOCOL_VERSION);
         auto ps = SproutProofSerializer<CDataStream>(ssProof, useGroth);
-        boost::apply_visitor(ps, jsdescription.proof);
+        std::visit(ps, jsdescription.proof);
         joinsplit.pushKV("proof", HexStr(ssProof.begin(), ssProof.end()));
 
         {
diff --git a/src/script/standard.cpp b/src/script/standard.cpp
index acf5f5615..567ee7bda 100644
--- a/src/script/standard.cpp
+++ b/src/script/standard.cpp
@@ -225,7 +225,7 @@ bool ExtractDestinations(const CScript& scriptPubKey, txnouttype& typeRet, vecto
 
 namespace
 {
-class CScriptVisitor : public boost::static_visitor<bool>
+class CScriptVisitor
 {
 private:
     CScript *script;
@@ -255,7 +255,7 @@ CScript GetScriptForDestination(const CTxDestination& dest)
 {
     CScript script;
 
-    boost::apply_visitor(CScriptVisitor(&script), dest);
+    std::visit(CScriptVisitor(&script), dest);
     return script;
 }
 
diff --git a/src/script/standard.h b/src/script/standard.h
index 4a3706738..fc6903e37 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -9,7 +9,6 @@
 #include "script/interpreter.h"
 #include "uint256.h"
 
-#include <boost/variant.hpp>
 
 #include <stdint.h>
 #include <variant>
@@ -77,7 +76,7 @@ public:
  *  * CScriptID: TX_SCRIPTHASH destination
  *  A CTxDestination is the internal data type encoded in a bitcoin address
  */
-typedef boost::variant<CNoDestination, CKeyID, CScriptID> CTxDestination;
+typedef std::variant<CNoDestination, CKeyID, CScriptID> CTxDestination;
 
 /** Check whether a CTxDestination is a CNoDestination. */
 bool IsValidDestination(const CTxDestination& dest);
diff --git a/src/test/key_tests.cpp b/src/test/key_tests.cpp
index 25b285c85..959bb25da 100644
--- a/src/test/key_tests.cpp
+++ b/src/test/key_tests.cpp
@@ -203,8 +203,8 @@ BOOST_AUTO_TEST_CASE(zc_address_test)
 
             auto spendingkey2 = keyIO.DecodeSpendingKey(sk_string);
             BOOST_CHECK(IsValidSpendingKey(spendingkey2));
-            BOOST_ASSERT(boost::get<SproutSpendingKey>(&spendingkey2) != nullptr);
-            auto sk2 = boost::get<SproutSpendingKey>(spendingkey2);
+            BOOST_ASSERT(std::get_if<SproutSpendingKey>(&spendingkey2) != nullptr);
+            auto sk2 = std::get<SproutSpendingKey>(spendingkey2);
             BOOST_CHECK(sk.inner() == sk2.inner());
         }
         {
@@ -218,8 +218,8 @@ BOOST_AUTO_TEST_CASE(zc_address_test)
             auto paymentaddr2 = keyIO.DecodePaymentAddress(addr_string);
             BOOST_ASSERT(IsValidPaymentAddress(paymentaddr2));
 
-            BOOST_ASSERT(boost::get<SproutPaymentAddress>(&paymentaddr2) != nullptr);
-            auto addr2 = boost::get<SproutPaymentAddress>(paymentaddr2);
+            BOOST_ASSERT(std::get_if<SproutPaymentAddress>(&paymentaddr2) != nullptr);
+            auto addr2 = std::get<SproutPaymentAddress>(paymentaddr2);
             BOOST_CHECK(addr.a_pk == addr2.a_pk);
             BOOST_CHECK(addr.pk_enc == addr2.pk_enc);
         }
@@ -242,8 +242,8 @@ BOOST_AUTO_TEST_CASE(zs_address_test)
             auto spendingkey2 = keyIO.DecodeSpendingKey(sk_string);
             BOOST_CHECK(IsValidSpendingKey(spendingkey2));
 
-            BOOST_ASSERT(boost::get<SaplingExtendedSpendingKey>(&spendingkey2) != nullptr);
-            auto sk2 = boost::get<SaplingExtendedSpendingKey>(spendingkey2);
+            BOOST_ASSERT(std::get_if<SaplingExtendedSpendingKey>(&spendingkey2) != nullptr);
+            auto sk2 = std::get<SaplingExtendedSpendingKey>(spendingkey2);
             BOOST_CHECK(sk == sk2);
         }
         {
@@ -255,8 +255,8 @@ BOOST_AUTO_TEST_CASE(zs_address_test)
             auto paymentaddr2 = keyIO.DecodePaymentAddress(addr_string);
             BOOST_CHECK(IsValidPaymentAddress(paymentaddr2));
 
-            BOOST_ASSERT(boost::get<SaplingPaymentAddress>(&paymentaddr2) != nullptr);
-            auto addr2 = boost::get<SaplingPaymentAddress>(paymentaddr2);
+            BOOST_ASSERT(std::get_if<SaplingPaymentAddress>(&paymentaddr2) != nullptr);
+            auto addr2 = std::get<SaplingPaymentAddress>(paymentaddr2);
             BOOST_CHECK(addr == addr2);
         }
     }
diff --git a/src/test/script_standard_tests.cpp b/src/test/script_standard_tests.cpp
index c7948a550..569f47a8b 100644
--- a/src/test/script_standard_tests.cpp
+++ b/src/test/script_standard_tests.cpp
@@ -177,23 +177,23 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestination)
     s.clear();
     s << ToByteVector(pubkey) << OP_CHECKSIG;
     BOOST_CHECK(ExtractDestination(s, address));
-    BOOST_CHECK(boost::get<CKeyID>(&address) &&
-                *boost::get<CKeyID>(&address) == pubkey.GetID());
+    BOOST_CHECK(std::get_if<CKeyID>(&address) &&
+                *std::get_if<CKeyID>(&address) == pubkey.GetID());
 
     // TX_PUBKEYHASH
     s.clear();
     s << OP_DUP << OP_HASH160 << ToByteVector(pubkey.GetID()) << OP_EQUALVERIFY << OP_CHECKSIG;
     BOOST_CHECK(ExtractDestination(s, address));
-    BOOST_CHECK(boost::get<CKeyID>(&address) &&
-                *boost::get<CKeyID>(&address) == pubkey.GetID());
+    BOOST_CHECK(std::get_if<CKeyID>(&address) &&
+                *std::get_if<CKeyID>(&address) == pubkey.GetID());
 
     // TX_SCRIPTHASH
     CScript redeemScript(s); // initialize with leftover P2PKH script
     s.clear();
     s << OP_HASH160 << ToByteVector(CScriptID(redeemScript)) << OP_EQUAL;
     BOOST_CHECK(ExtractDestination(s, address));
-    BOOST_CHECK(boost::get<CScriptID>(&address) &&
-                *boost::get<CScriptID>(&address) == CScriptID(redeemScript));
+    BOOST_CHECK(std::get_if<CScriptID>(&address) &&
+                *std::get_if<CScriptID>(&address) == CScriptID(redeemScript));
 
     // TX_MULTISIG
     s.clear();
@@ -237,8 +237,8 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestinations)
     BOOST_CHECK_EQUAL(whichType, TX_PUBKEY);
     BOOST_CHECK_EQUAL(addresses.size(), 1);
     BOOST_CHECK_EQUAL(nRequired, 1);
-    BOOST_CHECK(boost::get<CKeyID>(&addresses[0]) &&
-                *boost::get<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
+    BOOST_CHECK(std::get_if<CKeyID>(&addresses[0]) &&
+                *std::get_if<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
 
     // TX_PUBKEYHASH
     s.clear();
@@ -247,8 +247,8 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestinations)
     BOOST_CHECK_EQUAL(whichType, TX_PUBKEYHASH);
     BOOST_CHECK_EQUAL(addresses.size(), 1);
     BOOST_CHECK_EQUAL(nRequired, 1);
-    BOOST_CHECK(boost::get<CKeyID>(&addresses[0]) &&
-                *boost::get<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
+    BOOST_CHECK(std::get_if<CKeyID>(&addresses[0]) &&
+                *std::get_if<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
 
     // TX_SCRIPTHASH
     CScript redeemScript(s); // initialize with leftover P2PKH script
@@ -258,8 +258,8 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestinations)
     BOOST_CHECK_EQUAL(whichType, TX_SCRIPTHASH);
     BOOST_CHECK_EQUAL(addresses.size(), 1);
     BOOST_CHECK_EQUAL(nRequired, 1);
-    BOOST_CHECK(boost::get<CScriptID>(&addresses[0]) &&
-                *boost::get<CScriptID>(&addresses[0]) == CScriptID(redeemScript));
+    BOOST_CHECK(std::get_if<CScriptID>(&addresses[0]) &&
+                *std::get_if<CScriptID>(&addresses[0]) == CScriptID(redeemScript));
 
     // TX_MULTISIG
     s.clear();
@@ -271,10 +271,10 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestinations)
     BOOST_CHECK_EQUAL(whichType, TX_MULTISIG);
     BOOST_CHECK_EQUAL(addresses.size(), 2);
     BOOST_CHECK_EQUAL(nRequired, 2);
-    BOOST_CHECK(boost::get<CKeyID>(&addresses[0]) &&
-                *boost::get<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
-    BOOST_CHECK(boost::get<CKeyID>(&addresses[1]) &&
-                *boost::get<CKeyID>(&addresses[1]) == pubkeys[1].GetID());
+    BOOST_CHECK(std::get_if<CKeyID>(&addresses[0]) &&
+                *std::get_if<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
+    BOOST_CHECK(std::get_if<CKeyID>(&addresses[1]) &&
+                *std::get_if<CKeyID>(&addresses[1]) == pubkeys[1].GetID());
 
     // TX_NULL_DATA
     s.clear();
diff --git a/src/transaction_builder.cpp b/src/transaction_builder.cpp
index 334ac08ed..469a66fa2 100644
--- a/src/transaction_builder.cpp
+++ b/src/transaction_builder.cpp
@@ -12,7 +12,6 @@
 #include "utilmoneystr.h"
 #include "zcash/Note.hpp"
 
-#include <boost/variant.hpp>
 #include <librustzcash.h>
 #include <rust/ed25519.h>
 
diff --git a/src/wallet/asyncrpcoperation_mergetoaddress.cpp b/src/wallet/asyncrpcoperation_mergetoaddress.cpp
index fd6b62187..20d848def 100644
--- a/src/wallet/asyncrpcoperation_mergetoaddress.cpp
+++ b/src/wallet/asyncrpcoperation_mergetoaddress.cpp
@@ -333,7 +333,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
             std::string zaddr = std::get<0>(recipient_);
             std::string memo = std::get<1>(recipient_);
             std::array<unsigned char, ZC_MEMO_SIZE> hexMemo = get_memo_from_hex_string(memo);
-            auto saplingPaymentAddress = boost::get<libzcash::SaplingPaymentAddress>(&toPaymentAddress_);
+            auto saplingPaymentAddress = std::get_if<libzcash::SaplingPaymentAddress>(&toPaymentAddress_);
             if (saplingPaymentAddress == nullptr) {
                 // This should never happen as we have already determined that the payment is to sapling
                 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Could not get Sapling payment address.");
@@ -406,7 +406,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
         info.vpub_old = sendAmount;
         info.vpub_new = 0;
 
-        JSOutput jso = JSOutput(boost::get<libzcash::SproutPaymentAddress>(toPaymentAddress_), sendAmount);
+        JSOutput jso = JSOutput(std::get<libzcash::SproutPaymentAddress>(toPaymentAddress_), sendAmount);
         if (hexMemo.size() > 0) {
             jso.memo = get_memo_from_hex_string(hexMemo);
         }
@@ -690,7 +690,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
             // If this is the final output, set the target and memo
             if (isToZaddr_ && vpubNewProcessed) {
                 outputType = "target";
-                jso.addr = boost::get<libzcash::SproutPaymentAddress>(toPaymentAddress_);
+                jso.addr = std::get<libzcash::SproutPaymentAddress>(toPaymentAddress_);
                 if (!hexMemo.empty()) {
                     jso.memo = get_memo_from_hex_string(hexMemo);
                 }
diff --git a/src/wallet/asyncrpcoperation_saplingmigration.cpp b/src/wallet/asyncrpcoperation_saplingmigration.cpp
index 8be4b6af7..e76d0b072 100644
--- a/src/wallet/asyncrpcoperation_saplingmigration.cpp
+++ b/src/wallet/asyncrpcoperation_saplingmigration.cpp
@@ -1,5 +1,4 @@
 #include "assert.h"
-#include "boost/variant/static_visitor.hpp"
 #include "asyncrpcoperation_saplingmigration.h"
 #include "init.h"
 #include "key_io.h"
@@ -198,7 +197,7 @@ libzcash::SaplingPaymentAddress AsyncRPCOperation_saplingmigration::getMigration
     if (mapArgs.count("-migrationdestaddress")) {
         std::string migrationDestAddress = mapArgs["-migrationdestaddress"];
         auto address = keyIO.DecodePaymentAddress(migrationDestAddress);
-        auto saplingAddress = boost::get<libzcash::SaplingPaymentAddress>(&address);
+        auto saplingAddress = std::get_if<libzcash::SaplingPaymentAddress>(&address);
         assert(saplingAddress != nullptr); // This is checked in init.cpp
         return *saplingAddress;
     }
diff --git a/src/wallet/asyncrpcoperation_sendmany.cpp b/src/wallet/asyncrpcoperation_sendmany.cpp
index cc6061a24..d26d50a8e 100644
--- a/src/wallet/asyncrpcoperation_sendmany.cpp
+++ b/src/wallet/asyncrpcoperation_sendmany.cpp
@@ -99,13 +99,13 @@ AsyncRPCOperation_sendmany::AsyncRPCOperation_sendmany(
         auto address = keyIO.DecodePaymentAddress(fromAddress);
         if (IsValidPaymentAddress(address)) {
             // We don't need to lock on the wallet as spending key related methods are thread-safe
-            if (!boost::apply_visitor(HaveSpendingKeyForPaymentAddress(pwalletMain), address)) {
+            if (!std::visit(HaveSpendingKeyForPaymentAddress(pwalletMain), address)) {
                 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid from address, no spending key found for zaddr");
             }
 
             isfromzaddr_ = true;
             frompaymentaddress_ = address;
-            spendingkey_ = boost::apply_visitor(GetSpendingKeyForPaymentAddress(pwalletMain), address).get();
+            spendingkey_ = std::visit(GetSpendingKeyForPaymentAddress(pwalletMain), address).get();
         } else {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid from address");
         }
@@ -306,7 +306,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
         SaplingExpandedSpendingKey expsk;
         uint256 ovk;
         if (isfromzaddr_) {
-            auto sk = boost::get<libzcash::SaplingExtendedSpendingKey>(spendingkey_);
+            auto sk = std::get<libzcash::SaplingExtendedSpendingKey>(spendingkey_);
             expsk = sk.expsk;
             ovk = expsk.full_viewing_key().ovk;
         } else {
@@ -374,8 +374,8 @@ bool AsyncRPCOperation_sendmany::main_impl() {
             auto hexMemo = r.memo;
 
             auto addr = keyIO.DecodePaymentAddress(address);
-            assert(boost::get<libzcash::SaplingPaymentAddress>(&addr) != nullptr);
-            auto to = boost::get<libzcash::SaplingPaymentAddress>(addr);
+            assert(std::get_if<libzcash::SaplingPaymentAddress>(&addr) != nullptr);
+            auto to = std::get<libzcash::SaplingPaymentAddress>(addr);
 
             auto memo = get_memo_from_hex_string(hexMemo);
 
@@ -533,7 +533,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
                 zOutputsDeque.pop_front();
 
                 PaymentAddress pa = keyIO.DecodePaymentAddress(address);
-                JSOutput jso = JSOutput(boost::get<libzcash::SproutPaymentAddress>(pa), value);
+                JSOutput jso = JSOutput(std::get<libzcash::SproutPaymentAddress>(pa), value);
                 if (hexMemo.size() > 0) {
                     jso.memo = get_memo_from_hex_string(hexMemo);
                 }
@@ -636,7 +636,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
             intermediates.insert(std::make_pair(tree.root(), tree));    // chained js are interstitial (found in between block boundaries)
 
             // Decrypt the change note's ciphertext to retrieve some data we need
-            ZCNoteDecryption decryptor(boost::get<libzcash::SproutSpendingKey>(spendingkey_).receiving_key());
+            ZCNoteDecryption decryptor(std::get<libzcash::SproutSpendingKey>(spendingkey_).receiving_key());
             auto hSig = prevJoinSplit.h_sig(tx_.joinSplitPubKey);
             try {
                 SproutNotePlaintext plaintext = SproutNotePlaintext::decrypt(
@@ -646,7 +646,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
                         hSig,
                         (unsigned char) changeOutputIndex);
 
-                SproutNote note = plaintext.note(boost::get<libzcash::SproutPaymentAddress>(frompaymentaddress_));
+                SproutNote note = plaintext.note(std::get<libzcash::SproutPaymentAddress>(frompaymentaddress_));
                 info.notes.push_back(note);
 
                 jsInputValue += plaintext.value();
@@ -796,7 +796,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
         } else {
             PaymentAddress pa = keyIO.DecodePaymentAddress(address);
             // If we are here, we know we have no Sapling outputs.
-            JSOutput jso = JSOutput(boost::get<libzcash::SproutPaymentAddress>(pa), value);
+            JSOutput jso = JSOutput(std::get<libzcash::SproutPaymentAddress>(pa), value);
             if (hexMemo.size() > 0) {
                 jso.memo = get_memo_from_hex_string(hexMemo);
             }
@@ -805,7 +805,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
 
         // create output for any change
         if (jsChange>0) {
-            info.vjsout.push_back(JSOutput(boost::get<libzcash::SproutPaymentAddress>(frompaymentaddress_), jsChange));
+            info.vjsout.push_back(JSOutput(std::get<libzcash::SproutPaymentAddress>(frompaymentaddress_), jsChange));
 
             LogPrint("zrpcunsafe", "%s: generating note for change (amount=%s)\n",
                     getId(),
@@ -1011,7 +1011,7 @@ UniValue AsyncRPCOperation_sendmany::perform_joinsplit(
         if (!witnesses[i]) {
             throw runtime_error("joinsplit input could not be found in tree");
         }
-        info.vjsin.push_back(JSInput(*witnesses[i], info.notes[i], boost::get<libzcash::SproutSpendingKey>(spendingkey_)));
+        info.vjsin.push_back(JSInput(*witnesses[i], info.notes[i], std::get<libzcash::SproutSpendingKey>(spendingkey_)));
     }
 
     // Make sure there are two inputs and two outputs
diff --git a/src/wallet/asyncrpcoperation_shieldcoinbase.cpp b/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
index 495e925f4..f8ad942b9 100644
--- a/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
+++ b/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
@@ -197,7 +197,7 @@ bool AsyncRPCOperation_shieldcoinbase::main_impl() {
     LogPrint("zrpc", "%s: spending %s to shield %s with fee %s\n",
             getId(), FormatMoney(targetAmount), FormatMoney(sendAmount), FormatMoney(minersFee));
 
-    return boost::apply_visitor(ShieldToAddress(this, sendAmount), tozaddr_);
+    return std::visit(ShieldToAddress(this, sendAmount), tozaddr_);
 }
 
 bool ShieldToAddress::operator()(const libzcash::SproutPaymentAddress &zaddr) const {
diff --git a/src/wallet/asyncrpcoperation_shieldcoinbase.h b/src/wallet/asyncrpcoperation_shieldcoinbase.h
index 5d9abba8a..22b624ec2 100644
--- a/src/wallet/asyncrpcoperation_shieldcoinbase.h
+++ b/src/wallet/asyncrpcoperation_shieldcoinbase.h
@@ -97,7 +97,7 @@ private:
     std::vector<PaymentDisclosureKeyInfo> paymentDisclosureData_;
 };
 
-class ShieldToAddress : public boost::static_visitor<bool>
+class ShieldToAddress
 {
 private:
     AsyncRPCOperation_shieldcoinbase *m_op;
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index ebf9037e5..4127992d5 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -400,7 +400,7 @@ UniValue importwallet_impl(const UniValue& params, bool fImportZKeys)
             boost::optional<std::string> hdKeypath = (vstr.size() > 3) ? boost::optional<std::string>(vstr[2]) : boost::none;
             boost::optional<std::string> seedFpStr = (vstr.size() > 3) ? boost::optional<std::string>(vstr[3]) : boost::none;
             if (IsValidSpendingKey(spendingkey)) {
-                auto addResult = boost::apply_visitor(
+                auto addResult = std::visit(
                     AddSpendingKeyToWallet(pwalletMain, Params().GetConsensus(), nTime, hdKeypath, seedFpStr, true), spendingkey);
                 if (addResult == KeyAlreadyExists){
                     LogPrint("zrpc", "Skipping import of zaddr (key already present)\n");
@@ -502,7 +502,7 @@ UniValue dumpprivkey(const UniValue& params, bool fHelp)
     if (!IsValidDestination(dest)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid Zcash address");
     }
-    const CKeyID *keyID = boost::get<CKeyID>(&dest);
+    const CKeyID *keyID = std::get_if<CKeyID>(&dest);
     if (!keyID) {
         throw JSONRPCError(RPC_TYPE_ERROR, "Address does not refer to a key");
     }
@@ -754,13 +754,13 @@ UniValue z_importkey(const UniValue& params, bool fHelp)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid spending key");
     }
 
-    auto addrInfo = boost::apply_visitor(libzcash::AddressInfoFromSpendingKey{}, spendingkey);
+    auto addrInfo = std::visit(libzcash::AddressInfoFromSpendingKey{}, spendingkey);
     UniValue result(UniValue::VOBJ);
     result.pushKV("type", addrInfo.first);
     result.pushKV("address", keyIO.EncodePaymentAddress(addrInfo.second));
 
     // Sapling support
-    auto addResult = boost::apply_visitor(AddSpendingKeyToWallet(pwalletMain, Params().GetConsensus()), spendingkey);
+    auto addResult = std::visit(AddSpendingKeyToWallet(pwalletMain, Params().GetConsensus()), spendingkey);
     if (addResult == KeyAlreadyExists && fIgnoreExistingKey) {
         return result;
     }
@@ -849,13 +849,13 @@ UniValue z_importviewingkey(const UniValue& params, bool fHelp)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid viewing key");
     }
 
-    auto addrInfo = boost::apply_visitor(libzcash::AddressInfoFromViewingKey{}, viewingkey);
+    auto addrInfo = std::visit(libzcash::AddressInfoFromViewingKey{}, viewingkey);
     UniValue result(UniValue::VOBJ);
     const string strAddress = keyIO.EncodePaymentAddress(addrInfo.second);
     result.pushKV("type", addrInfo.first);
     result.pushKV("address", strAddress);
 
-    auto addResult = boost::apply_visitor(AddViewingKeyToWallet(pwalletMain), viewingkey);
+    auto addResult = std::visit(AddViewingKeyToWallet(pwalletMain), viewingkey);
     if (addResult == SpendingKeyExists) {
         throw JSONRPCError(
             RPC_WALLET_ERROR,
@@ -909,7 +909,7 @@ UniValue z_exportkey(const UniValue& params, bool fHelp)
     }
 
     // Sapling support
-    auto sk = boost::apply_visitor(GetSpendingKeyForPaymentAddress(pwalletMain), address);
+    auto sk = std::visit(GetSpendingKeyForPaymentAddress(pwalletMain), address);
     if (!sk) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet does not hold private zkey for this zaddr");
     }
@@ -947,7 +947,7 @@ UniValue z_exportviewingkey(const UniValue& params, bool fHelp)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid zaddr");
     }
 
-    auto vk = boost::apply_visitor(GetViewingKeyForPaymentAddress(pwalletMain), address);
+    auto vk = std::visit(GetViewingKeyForPaymentAddress(pwalletMain), address);
     if (vk) {
         return keyIO.EncodeViewingKey(vk.get());
     } else {
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 06faa9bb0..6ae938159 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -590,7 +590,7 @@ UniValue signmessage(const UniValue& params, bool fHelp)
         throw JSONRPCError(RPC_TYPE_ERROR, "Invalid address");
     }
 
-    const CKeyID *keyID = boost::get<CKeyID>(&dest);
+    const CKeyID *keyID = std::get_if<CKeyID>(&dest);
     if (!keyID) {
         throw JSONRPCError(RPC_TYPE_ERROR, "Address does not refer to key");
     }
@@ -2515,7 +2515,7 @@ UniValue listunspent(const UniValue& params, bool fHelp)
                 entry.pushKV("account", pwalletMain->mapAddressBook[address].name);
 
             if (scriptPubKey.IsPayToScriptHash()) {
-                const CScriptID& hash = boost::get<CScriptID>(address);
+                const CScriptID& hash = std::get<CScriptID>(address);
                 CScript redeemScript;
                 if (pwalletMain->GetCScript(hash, redeemScript))
                     entry.pushKV("redeemScript", HexStr(redeemScript.begin(), redeemScript.end()));
@@ -2627,7 +2627,7 @@ UniValue z_listunspent(const UniValue& params, bool fHelp)
             if (!IsValidPaymentAddress(zaddr)) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, string("Invalid parameter, address is not a valid zaddr: ") + address);
             }
-            auto hasSpendingKey = boost::apply_visitor(HaveSpendingKeyForPaymentAddress(pwalletMain), zaddr);
+            auto hasSpendingKey = std::visit(HaveSpendingKeyForPaymentAddress(pwalletMain), zaddr);
             if (!fIncludeWatchonly && !hasSpendingKey) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, string("Invalid parameter, spending key for address does not belong to wallet: ") + address);
             }
@@ -2951,10 +2951,10 @@ UniValue zc_raw_receive(const UniValue& params, bool fHelp)
     if (!IsValidSpendingKey(spendingkey)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid spending key");
     }
-    if (boost::get<libzcash::SproutSpendingKey>(&spendingkey) == nullptr) {
+    if (std::get_if<libzcash::SproutSpendingKey>(&spendingkey) == nullptr) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Only works with Sprout spending keys");
     }
-    SproutSpendingKey k = boost::get<libzcash::SproutSpendingKey>(spendingkey);
+    SproutSpendingKey k = std::get<libzcash::SproutSpendingKey>(spendingkey);
 
     uint256 epk;
     unsigned char nonce;
@@ -3077,10 +3077,10 @@ UniValue zc_raw_joinsplit(const UniValue& params, bool fHelp)
         if (!IsValidSpendingKey(spendingkey)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid spending key");
         }
-        if (boost::get<libzcash::SproutSpendingKey>(&spendingkey) == nullptr) {
+        if (std::get_if<libzcash::SproutSpendingKey>(&spendingkey) == nullptr) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Only works with Sprout spending keys");
         }
-        SproutSpendingKey k = boost::get<libzcash::SproutSpendingKey>(spendingkey);
+        SproutSpendingKey k = std::get<libzcash::SproutSpendingKey>(spendingkey);
 
         keys.push_back(k);
 
@@ -3125,12 +3125,12 @@ UniValue zc_raw_joinsplit(const UniValue& params, bool fHelp)
         if (!IsValidPaymentAddress(addrTo)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid recipient address.");
         }
-        if (boost::get<libzcash::SproutPaymentAddress>(&addrTo) == nullptr) {
+        if (std::get_if<libzcash::SproutPaymentAddress>(&addrTo) == nullptr) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Only works with Sprout payment addresses");
         }
         CAmount nAmount = AmountFromValue(outputs[name_]);
 
-        vjsout.push_back(JSOutput(boost::get<libzcash::SproutPaymentAddress>(addrTo), nAmount));
+        vjsout.push_back(JSOutput(std::get<libzcash::SproutPaymentAddress>(addrTo), nAmount));
     }
 
     while (vjsout.size() < ZC_NUM_JS_OUTPUTS) {
@@ -3479,7 +3479,7 @@ UniValue z_listreceivedbyaddress(const UniValue& params, bool fHelp)
     }
 
     // Visitor to support Sprout and Sapling addrs
-    if (!boost::apply_visitor(PaymentAddressBelongsToWallet(pwalletMain), zaddr)) {
+    if (!std::visit(PaymentAddressBelongsToWallet(pwalletMain), zaddr)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "From address does not belong to this node, zaddr spending key or viewing key not found.");
     }
 
@@ -3489,12 +3489,12 @@ UniValue z_listreceivedbyaddress(const UniValue& params, bool fHelp)
     pwalletMain->GetFilteredNotes(sproutEntries, saplingEntries, fromaddress, nMinDepth, false, false);
 
     std::set<std::pair<PaymentAddress, uint256>> nullifierSet;
-    auto hasSpendingKey = boost::apply_visitor(HaveSpendingKeyForPaymentAddress(pwalletMain), zaddr);
+    auto hasSpendingKey = std::visit(HaveSpendingKeyForPaymentAddress(pwalletMain), zaddr);
     if (hasSpendingKey) {
         nullifierSet = pwalletMain->GetNullifiersForAddresses({zaddr});
     }
 
-    if (boost::get<libzcash::SproutPaymentAddress>(&zaddr) != nullptr) {
+    if (std::get_if<libzcash::SproutPaymentAddress>(&zaddr) != nullptr) {
         for (SproutNoteEntry & entry : sproutEntries) {
             UniValue obj(UniValue::VOBJ);
             obj.pushKV("txid", entry.jsop.hash.ToString());
@@ -3516,7 +3516,7 @@ UniValue z_listreceivedbyaddress(const UniValue& params, bool fHelp)
             }
             result.push_back(obj);
         }
-    } else if (boost::get<libzcash::SaplingPaymentAddress>(&zaddr) != nullptr) {
+    } else if (std::get_if<libzcash::SaplingPaymentAddress>(&zaddr) != nullptr) {
         for (SaplingNoteEntry & entry : saplingEntries) {
             UniValue obj(UniValue::VOBJ);
             obj.pushKV("txid", entry.op.hash.ToString());
@@ -3587,7 +3587,7 @@ UniValue z_getbalance(const UniValue& params, bool fHelp)
         if (!IsValidPaymentAddress(res)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid from address, should be a taddr or zaddr.");
         }
-        if (!boost::apply_visitor(PaymentAddressBelongsToWallet(pwalletMain), res)) {
+        if (!std::visit(PaymentAddressBelongsToWallet(pwalletMain), res)) {
              throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "From address does not belong to this node, spending key or viewing key not found.");
         }
     }
@@ -4073,12 +4073,12 @@ UniValue z_sendmany(const UniValue& params, bool fHelp)
             }
 
             // Check that we have the spending key
-            if (!boost::apply_visitor(HaveSpendingKeyForPaymentAddress(pwalletMain), res)) {
+            if (!std::visit(HaveSpendingKeyForPaymentAddress(pwalletMain), res)) {
                 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "From address does not belong to this node, zaddr spending key not found.");
             }
 
             // Remember whether this is a Sprout or Sapling address
-            fromSapling = boost::get<libzcash::SaplingPaymentAddress>(&res) != nullptr;
+            fromSapling = std::get_if<libzcash::SaplingPaymentAddress>(&res) != nullptr;
         }
     }
     // This logic will need to be updated if we add a new shielded pool
@@ -4122,7 +4122,7 @@ UniValue z_sendmany(const UniValue& params, bool fHelp)
             if (IsValidPaymentAddress(res)) {
                 isZaddr = true;
 
-                bool toSapling = boost::get<libzcash::SaplingPaymentAddress>(&res) != nullptr;
+                bool toSapling = std::get_if<libzcash::SaplingPaymentAddress>(&res) != nullptr;
                 bool toSprout = !toSapling;
                 noSproutAddrs = noSproutAddrs && toSapling;
 
@@ -4221,7 +4221,7 @@ UniValue z_sendmany(const UniValue& params, bool fHelp)
     for (int i = 0; i < zaddrRecipients.size(); i++) {
         auto address = zaddrRecipients[i].address;
         auto res = keyIO.DecodePaymentAddress(address);
-        bool toSapling = boost::get<libzcash::SaplingPaymentAddress>(&res) != nullptr;
+        bool toSapling = std::get_if<libzcash::SaplingPaymentAddress>(&res) != nullptr;
         if (toSapling) {
             mtx.vShieldedOutput.push_back(OutputDescription());
         } else {
@@ -4521,7 +4521,7 @@ UniValue z_shieldcoinbase(const UniValue& params, bool fHelp)
 
     if (canopyActive) {
         auto decodeAddr = keyIO.DecodePaymentAddress(destaddress);
-        bool isToSproutZaddr = (boost::get<libzcash::SproutPaymentAddress>(&decodeAddr) != nullptr);
+        bool isToSproutZaddr = (std::get_if<libzcash::SproutPaymentAddress>(&decodeAddr) != nullptr);
 
         if (isToSproutZaddr) {
             throw JSONRPCError(RPC_VERIFY_REJECTED, "Sprout shielding is not supported after Canopy activation");
@@ -4601,7 +4601,7 @@ UniValue z_shieldcoinbase(const UniValue& params, bool fHelp)
         CAmount nValue = out.tx->vout[out.i].nValue;
 
         if (!maxedOutFlag) {
-            size_t increase = (boost::get<CScriptID>(&address) != nullptr) ? CTXIN_SPEND_P2SH_SIZE : CTXIN_SPEND_DUST_SIZE;
+            size_t increase = (std::get_if<CScriptID>(&address) != nullptr) ? CTXIN_SPEND_P2SH_SIZE : CTXIN_SPEND_DUST_SIZE;
             if (estimatedTxSize + increase >= max_tx_size ||
                 (mempoolLimit > 0 && utxoCounter > mempoolLimit))
             {
@@ -4776,7 +4776,7 @@ UniValue z_mergetoaddress(const UniValue& params, bool fHelp)
                 auto zaddr = keyIO.DecodePaymentAddress(address);
                 if (IsValidPaymentAddress(zaddr)) {
                     zaddrs.insert(zaddr);
-                    if (boost::get<libzcash::SaplingPaymentAddress>(&zaddr) != nullptr) {
+                    if (std::get_if<libzcash::SaplingPaymentAddress>(&zaddr) != nullptr) {
                         isFromNonSprout = true;
                     }
                 } else {
@@ -4810,7 +4810,7 @@ UniValue z_mergetoaddress(const UniValue& params, bool fHelp)
     if (!IsValidDestination(taddr)) {
         auto decodeAddr = keyIO.DecodePaymentAddress(destaddress);
         if (IsValidPaymentAddress(decodeAddr)) {
-            if (boost::get<libzcash::SaplingPaymentAddress>(&decodeAddr) != nullptr) {
+            if (std::get_if<libzcash::SaplingPaymentAddress>(&decodeAddr) != nullptr) {
                 isToSaplingZaddr = true;
                 // If Sapling is not active, do not allow sending to a sapling addresses.
                 if (!saplingActive) {
@@ -4921,7 +4921,7 @@ UniValue z_mergetoaddress(const UniValue& params, bool fHelp)
             CAmount nValue = out.tx->vout[out.i].nValue;
 
             if (!maxedOutUTXOsFlag) {
-                size_t increase = (boost::get<CScriptID>(&address) != nullptr) ? CTXIN_SPEND_P2SH_SIZE : CTXIN_SPEND_DUST_SIZE;
+                size_t increase = (std::get_if<CScriptID>(&address) != nullptr) ? CTXIN_SPEND_P2SH_SIZE : CTXIN_SPEND_DUST_SIZE;
                 if (estimatedTxSize + increase >= max_tx_size ||
                     (mempoolLimit > 0 && utxoCounter > mempoolLimit))
                 {
diff --git a/src/wallet/test/rpc_wallet_tests.cpp b/src/wallet/test/rpc_wallet_tests.cpp
index fb4ef3030..de269349c 100644
--- a/src/wallet/test/rpc_wallet_tests.cpp
+++ b/src/wallet/test/rpc_wallet_tests.cpp
@@ -645,8 +645,8 @@ BOOST_AUTO_TEST_CASE(rpc_wallet_z_importwallet)
     // check that we have the spending key for the address
     auto address = keyIO.DecodePaymentAddress(testAddr);
     BOOST_CHECK(IsValidPaymentAddress(address));
-    BOOST_ASSERT(boost::get<libzcash::SproutPaymentAddress>(&address) != nullptr);
-    auto addr = boost::get<libzcash::SproutPaymentAddress>(address);
+    BOOST_ASSERT(std::get_if<libzcash::SproutPaymentAddress>(&address) != nullptr);
+    auto addr = std::get<libzcash::SproutPaymentAddress>(address);
     BOOST_CHECK(pwalletMain->HaveSproutSpendingKey(addr));
 
     // Verify the spending key is the same as the test data
@@ -759,7 +759,7 @@ template <typename ADDR_TYPE>
 void CheckHaveAddr(const libzcash::PaymentAddress& addr) {
 
     BOOST_CHECK(IsValidPaymentAddress(addr));
-    auto addr_of_type = boost::get<ADDR_TYPE>(&addr);
+    auto addr_of_type = std::get_if<ADDR_TYPE>(&addr);
     BOOST_ASSERT(addr_of_type != nullptr);
 
     HaveSpendingKeyForPaymentAddress test(pwalletMain);
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index e5a3228f2..e32ce956b 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -691,7 +691,7 @@ std::set<std::pair<libzcash::PaymentAddress, uint256>> CWallet::GetNullifiersFor
     // (There may be more than one diversified address for a given ivk.)
     std::map<libzcash::SaplingIncomingViewingKey, std::vector<libzcash::SaplingPaymentAddress>> ivkMap;
     for (const auto & addr : addresses) {
-        auto saplingAddr = boost::get<libzcash::SaplingPaymentAddress>(&addr);
+        auto saplingAddr = std::get_if<libzcash::SaplingPaymentAddress>(&addr);
         if (saplingAddr != nullptr) {
             libzcash::SaplingIncomingViewingKey ivk;
             this->GetSaplingIncomingViewingKey(*saplingAddr, ivk);
@@ -3712,7 +3712,7 @@ bool CWallet::CreateTransaction(const vector<CRecipient>& vecSend, CWalletTx& wt
                     CScript scriptChange;
 
                     // coin control: send change to custom address
-                    if (coinControl && !boost::get<CNoDestination>(&coinControl->destChange))
+                    if (coinControl && !std::get_if<CNoDestination>(&coinControl->destChange))
                         scriptChange = GetScriptForDestination(coinControl->destChange);
 
                     // no coin control: send change to newly generated address
@@ -4534,7 +4534,7 @@ std::vector<SaplingOutPoint> CWallet::ListLockedSaplingNotes()
 
 /** @} */ // end of Actions
 
-class CAffectedKeysVisitor : public boost::static_visitor<void> {
+class CAffectedKeysVisitor {
 private:
     const CKeyStore &keystore;
     std::vector<CKeyID> &vKeys;
@@ -4548,7 +4548,7 @@ public:
         int nRequired;
         if (ExtractDestinations(script, type, vDest, nRequired)) {
             for (const CTxDestination &dest : vDest)
-                boost::apply_visitor(*this, dest);
+                std::visit(*this, dest);
         }
     }
 
@@ -4622,7 +4622,7 @@ void CWallet::GetKeyBirthTimes(std::map<CKeyID, int64_t> &mapKeyBirth) const {
 
 bool CWallet::AddDestData(const CTxDestination &dest, const std::string &key, const std::string &value)
 {
-    if (boost::get<CNoDestination>(&dest))
+    if (std::get_if<CNoDestination>(&dest))
         return false;
 
     mapAddressBook[dest].destdata.insert(std::make_pair(key, value));
@@ -4913,7 +4913,7 @@ bool CWallet::ParameterInteraction()
     if (mapArgs.count("-migrationdestaddress")) {
         std::string migrationDestAddress = mapArgs["-migrationdestaddress"];
         libzcash::PaymentAddress address = keyIO.DecodePaymentAddress(migrationDestAddress);
-        if (boost::get<libzcash::SaplingPaymentAddress>(&address) == nullptr) {
+        if (std::get_if<libzcash::SaplingPaymentAddress>(&address) == nullptr) {
             return UIError(_("-migrationdestaddress must be a valid Sapling address."));
         }
     }
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 8ec41d9dc..f9d4e7e15 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -1467,7 +1467,7 @@ public:
 // Shielded key and address generalizations
 //
 
-class PaymentAddressBelongsToWallet : public boost::static_visitor<bool>
+class PaymentAddressBelongsToWallet
 {
 private:
     CWallet *m_wallet;
@@ -1479,7 +1479,7 @@ public:
     bool operator()(const libzcash::InvalidEncoding& no) const;
 };
 
-class GetViewingKeyForPaymentAddress : public boost::static_visitor<boost::optional<libzcash::ViewingKey>>
+class GetViewingKeyForPaymentAddress
 {
 private:
     CWallet *m_wallet;
@@ -1491,7 +1491,7 @@ public:
     boost::optional<libzcash::ViewingKey> operator()(const libzcash::InvalidEncoding& no) const;
 };
 
-class HaveSpendingKeyForPaymentAddress : public boost::static_visitor<bool>
+class HaveSpendingKeyForPaymentAddress
 {
 private:
     CWallet *m_wallet;
@@ -1503,7 +1503,7 @@ public:
     bool operator()(const libzcash::InvalidEncoding& no) const;
 };
 
-class GetSpendingKeyForPaymentAddress : public boost::static_visitor<boost::optional<libzcash::SpendingKey>>
+class GetSpendingKeyForPaymentAddress
 {
 private:
     CWallet *m_wallet;
@@ -1522,7 +1522,7 @@ enum KeyAddResult {
     KeyNotAdded,
 };
 
-class AddViewingKeyToWallet : public boost::static_visitor<KeyAddResult>
+class AddViewingKeyToWallet
 {
 private:
     CWallet *m_wallet;
@@ -1534,7 +1534,7 @@ public:
     KeyAddResult operator()(const libzcash::InvalidEncoding& no) const;
 };
 
-class AddSpendingKeyToWallet : public boost::static_visitor<KeyAddResult>
+class AddSpendingKeyToWallet
 {
 private:
     CWallet *m_wallet;
diff --git a/src/zcash/Address.hpp b/src/zcash/Address.hpp
index 4dc65d6fc..a8fbacac9 100644
--- a/src/zcash/Address.hpp
+++ b/src/zcash/Address.hpp
@@ -14,18 +14,18 @@ public:
     friend bool operator<(const InvalidEncoding &a, const InvalidEncoding &b) { return true; }
 };
 
-typedef boost::variant<InvalidEncoding, SproutPaymentAddress, SaplingPaymentAddress> PaymentAddress;
-typedef boost::variant<InvalidEncoding, SproutViewingKey, SaplingExtendedFullViewingKey> ViewingKey;
-typedef boost::variant<InvalidEncoding, SproutSpendingKey, SaplingExtendedSpendingKey> SpendingKey;
+typedef std::variant<InvalidEncoding, SproutPaymentAddress, SaplingPaymentAddress> PaymentAddress;
+typedef std::variant<InvalidEncoding, SproutViewingKey, SaplingExtendedFullViewingKey> ViewingKey;
+typedef std::variant<InvalidEncoding, SproutSpendingKey, SaplingExtendedSpendingKey> SpendingKey;
 
-class AddressInfoFromSpendingKey : public boost::static_visitor<std::pair<std::string, PaymentAddress>> {
+class AddressInfoFromSpendingKey {
 public:
     std::pair<std::string, PaymentAddress> operator()(const SproutSpendingKey&) const;
     std::pair<std::string, PaymentAddress> operator()(const struct SaplingExtendedSpendingKey&) const;
     std::pair<std::string, PaymentAddress> operator()(const InvalidEncoding&) const;
 };
 
-class AddressInfoFromViewingKey : public boost::static_visitor<std::pair<std::string, PaymentAddress>> {
+class AddressInfoFromViewingKey {
 public:
     std::pair<std::string, PaymentAddress> operator()(const SproutViewingKey&) const;
     std::pair<std::string, PaymentAddress> operator()(const struct SaplingExtendedFullViewingKey&) const;
diff --git a/src/zcash/Proof.hpp b/src/zcash/Proof.hpp
index 1bb55c413..fa6069581 100644
--- a/src/zcash/Proof.hpp
+++ b/src/zcash/Proof.hpp
@@ -211,7 +211,7 @@ typedef std::array<unsigned char, GROTH_PROOF_SIZE> GrothProof;
 // TODO: Because PHGRProof is listed first, using the default
 // constructor for JSDescription() will create a JSDescription
 // with a PHGRProof. The default however should be GrothProof.
-typedef boost::variant<PHGRProof, GrothProof> SproutProof;
+typedef std::variant<PHGRProof, GrothProof> SproutProof;
 
 }
 

From ae4551004aac3b40f315b8b613a4d5bff2b377e2 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Wed, 21 Oct 2020 01:19:55 +0100
Subject: [PATCH 03/11] Finish migrating to std::variant

---
 src/chainparams.cpp                |  2 +-
 src/miner.cpp                      |  4 ++--
 src/script/standard.cpp            |  6 +++---
 src/script/standard.h              |  1 +
 src/test/script_standard_tests.cpp | 16 ++++++++--------
 src/zcash/Address.cpp              |  6 +++---
 6 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 0353ae1d2..359a6f59b 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -813,7 +813,7 @@ CScript CChainParams::GetFoundersRewardScriptAtHeight(int nHeight) const {
     CTxDestination address = keyIO.DecodeDestination(GetFoundersRewardAddressAtHeight(nHeight).c_str());
     assert(IsValidDestination(address));
     assert(IsScriptDestination(address));
-    CScriptID scriptID = std::get<CScriptID>(address); // address is a boost variant
+    CScriptID scriptID = std::get<CScriptID>(address); // address is a variant
     CScript script = CScript() << OP_HASH160 << ToByteVector(scriptID) << OP_EQUAL;
     return script;
 }
diff --git a/src/miner.cpp b/src/miner.cpp
index 4d1e9835f..72a97358d 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -118,8 +118,8 @@ void UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams,
 
 bool IsShieldedMinerAddress(const MinerAddress& minerAddr) {
     return !(
-        minerAddr.type() == typeid(InvalidMinerAddress) ||
-        minerAddr.type() == typeid(boost::shared_ptr<CReserveScript>));
+        std::holds_alternative<InvalidMinerAddress>(minerAddr) ||
+        std::holds_alternative<boost::shared_ptr<CReserveScript>>(minerAddr));
 }
 
 class AddFundingStreamValueToTx
diff --git a/src/script/standard.cpp b/src/script/standard.cpp
index 567ee7bda..853ffe957 100644
--- a/src/script/standard.cpp
+++ b/src/script/standard.cpp
@@ -276,15 +276,15 @@ CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys)
 }
 
 bool IsValidDestination(const CTxDestination& dest) {
-    return dest.which() != 0;
+    return !std::holds_alternative<CNoDestination>(dest);
 }
 
 bool IsKeyDestination(const CTxDestination& dest) {
-    return dest.which() == 1;
+    return std::holds_alternative<CKeyID>(dest);
 }
 
 bool IsScriptDestination(const CTxDestination& dest) {
-    return dest.which() == 2;
+    return std::holds_alternative<CScriptID>(dest);
 }
 
 // insightexplorer
diff --git a/src/script/standard.h b/src/script/standard.h
index fc6903e37..09a23368f 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -66,6 +66,7 @@ enum txnouttype
 class CNoDestination {
 public:
     friend bool operator==(const CNoDestination &a, const CNoDestination &b) { return true; }
+    friend bool operator!=(const CNoDestination &a, const CNoDestination &b) { return false; }
     friend bool operator<(const CNoDestination &a, const CNoDestination &b) { return true; }
 };
 
diff --git a/src/test/script_standard_tests.cpp b/src/test/script_standard_tests.cpp
index 569f47a8b..e77f20230 100644
--- a/src/test/script_standard_tests.cpp
+++ b/src/test/script_standard_tests.cpp
@@ -178,14 +178,14 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestination)
     s << ToByteVector(pubkey) << OP_CHECKSIG;
     BOOST_CHECK(ExtractDestination(s, address));
     BOOST_CHECK(std::get_if<CKeyID>(&address) &&
-                *std::get_if<CKeyID>(&address) == pubkey.GetID());
+                std::get<CKeyID>(address) == pubkey.GetID());
 
     // TX_PUBKEYHASH
     s.clear();
     s << OP_DUP << OP_HASH160 << ToByteVector(pubkey.GetID()) << OP_EQUALVERIFY << OP_CHECKSIG;
     BOOST_CHECK(ExtractDestination(s, address));
     BOOST_CHECK(std::get_if<CKeyID>(&address) &&
-                *std::get_if<CKeyID>(&address) == pubkey.GetID());
+                std::get<CKeyID>(address) == pubkey.GetID());
 
     // TX_SCRIPTHASH
     CScript redeemScript(s); // initialize with leftover P2PKH script
@@ -193,7 +193,7 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestination)
     s << OP_HASH160 << ToByteVector(CScriptID(redeemScript)) << OP_EQUAL;
     BOOST_CHECK(ExtractDestination(s, address));
     BOOST_CHECK(std::get_if<CScriptID>(&address) &&
-                *std::get_if<CScriptID>(&address) == CScriptID(redeemScript));
+                std::get<CScriptID>(address) == CScriptID(redeemScript));
 
     // TX_MULTISIG
     s.clear();
@@ -238,7 +238,7 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestinations)
     BOOST_CHECK_EQUAL(addresses.size(), 1);
     BOOST_CHECK_EQUAL(nRequired, 1);
     BOOST_CHECK(std::get_if<CKeyID>(&addresses[0]) &&
-                *std::get_if<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
+                std::get<CKeyID>(addresses[0]) == pubkeys[0].GetID());
 
     // TX_PUBKEYHASH
     s.clear();
@@ -248,7 +248,7 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestinations)
     BOOST_CHECK_EQUAL(addresses.size(), 1);
     BOOST_CHECK_EQUAL(nRequired, 1);
     BOOST_CHECK(std::get_if<CKeyID>(&addresses[0]) &&
-                *std::get_if<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
+                std::get<CKeyID>(addresses[0]) == pubkeys[0].GetID());
 
     // TX_SCRIPTHASH
     CScript redeemScript(s); // initialize with leftover P2PKH script
@@ -259,7 +259,7 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestinations)
     BOOST_CHECK_EQUAL(addresses.size(), 1);
     BOOST_CHECK_EQUAL(nRequired, 1);
     BOOST_CHECK(std::get_if<CScriptID>(&addresses[0]) &&
-                *std::get_if<CScriptID>(&addresses[0]) == CScriptID(redeemScript));
+                std::get<CScriptID>(addresses[0]) == CScriptID(redeemScript));
 
     // TX_MULTISIG
     s.clear();
@@ -272,9 +272,9 @@ BOOST_AUTO_TEST_CASE(script_standard_ExtractDestinations)
     BOOST_CHECK_EQUAL(addresses.size(), 2);
     BOOST_CHECK_EQUAL(nRequired, 2);
     BOOST_CHECK(std::get_if<CKeyID>(&addresses[0]) &&
-                *std::get_if<CKeyID>(&addresses[0]) == pubkeys[0].GetID());
+                std::get<CKeyID>(addresses[0]) == pubkeys[0].GetID());
     BOOST_CHECK(std::get_if<CKeyID>(&addresses[1]) &&
-                *std::get_if<CKeyID>(&addresses[1]) == pubkeys[1].GetID());
+                std::get<CKeyID>(addresses[1]) == pubkeys[1].GetID());
 
     // TX_NULL_DATA
     s.clear();
diff --git a/src/zcash/Address.cpp b/src/zcash/Address.cpp
index f4134e1a1..4c1fad1c7 100644
--- a/src/zcash/Address.cpp
+++ b/src/zcash/Address.cpp
@@ -25,13 +25,13 @@ std::pair<std::string, PaymentAddress> AddressInfoFromViewingKey::operator()(con
 }
 
 bool IsValidPaymentAddress(const libzcash::PaymentAddress& zaddr) {
-    return zaddr.which() != 0;
+    return !std::holds_alternative<libzcash::InvalidEncoding>(zaddr);
 }
 
 bool IsValidViewingKey(const libzcash::ViewingKey& vk) {
-    return vk.which() != 0;
+    return !std::holds_alternative<libzcash::InvalidEncoding>(vk);
 }
 
 bool IsValidSpendingKey(const libzcash::SpendingKey& zkey) {
-    return zkey.which() != 0;
+    return !std::holds_alternative<libzcash::InvalidEncoding>(zkey);
 }

From d9928926f38cfa84989ba1641851644836bb842c Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Wed, 21 Oct 2020 00:39:23 +0100
Subject: [PATCH 04/11] Migrate from boost::optional::get to
 boost::optional::value

std::optional only has std::optional::value.
---
 src/consensus/funding.cpp                     |  6 +--
 src/consensus/upgrades.cpp                    |  2 +-
 src/gtest/test_checktransaction.cpp           |  4 +-
 src/gtest/test_foundersreward.cpp             |  4 +-
 src/gtest/test_mempoollimit.cpp               |  2 +-
 src/gtest/test_noteencryption.cpp             | 32 +++++++-------
 src/gtest/test_pow.cpp                        |  2 +-
 src/gtest/test_sapling_note.cpp               |  2 +-
 src/gtest/test_validation.cpp                 | 10 ++---
 src/gtest/test_zip32.cpp                      |  2 +-
 src/init.cpp                                  |  2 +-
 src/main.cpp                                  | 10 ++---
 src/metrics.cpp                               |  2 +-
 src/miner.cpp                                 |  4 +-
 src/net.cpp                                   |  2 +-
 src/pow.cpp                                   |  2 +-
 src/rpc/mining.cpp                            |  2 +-
 src/transaction_builder.cpp                   | 14 +++----
 src/txmempool.cpp                             |  2 +-
 src/utiltest.cpp                              |  2 +-
 .../asyncrpcoperation_mergetoaddress.cpp      | 10 ++---
 .../asyncrpcoperation_saplingmigration.cpp    |  4 +-
 src/wallet/asyncrpcoperation_sendmany.cpp     | 10 ++---
 src/wallet/gtest/test_wallet.cpp              | 32 +++++++-------
 src/wallet/gtest/test_wallet_zkeys.cpp        |  6 +--
 src/wallet/rpcdump.cpp                        |  4 +-
 src/wallet/rpcwallet.cpp                      |  2 +-
 src/wallet/wallet.cpp                         | 42 +++++++++----------
 src/zcash/Note.cpp                            | 12 +++---
 src/zcash/address/zip32.cpp                   |  2 +-
 src/zcbenchmarks.cpp                          |  6 +--
 31 files changed, 119 insertions(+), 119 deletions(-)

diff --git a/src/consensus/funding.cpp b/src/consensus/funding.cpp
index 918deae8d..7cec13080 100644
--- a/src/consensus/funding.cpp
+++ b/src/consensus/funding.cpp
@@ -61,9 +61,9 @@ std::set<FundingStreamElement> GetActiveFundingStreamElements(
             // in the definition of vFundingStreams.
             auto fs = params.vFundingStreams[idx];
             // Funding period is [startHeight, endHeight)
-            if (fs && nHeight >= fs.get().GetStartHeight() && nHeight < fs.get().GetEndHeight()) {
+            if (fs && nHeight >= fs.value().GetStartHeight() && nHeight < fs.value().GetEndHeight()) {
                 requiredElements.insert(std::make_pair(
-                    fs.get().RecipientAddress(params, nHeight),
+                    fs.value().RecipientAddress(params, nHeight),
                     FundingStreamInfo[idx].Value(blockSubsidy)));
             }
         }
@@ -82,7 +82,7 @@ std::vector<FSInfo> GetActiveFundingStreams(
     if (params.NetworkUpgradeActive(nHeight, Consensus::UPGRADE_CANOPY)) {
         for (uint32_t idx = Consensus::FIRST_FUNDING_STREAM; idx < Consensus::MAX_FUNDING_STREAMS; idx++) {
             auto fs = params.vFundingStreams[idx];
-            if (fs && nHeight >= fs.get().GetStartHeight() && nHeight < fs.get().GetEndHeight()) {
+            if (fs && nHeight >= fs.value().GetStartHeight() && nHeight < fs.value().GetEndHeight()) {
                 activeStreams.push_back(FundingStreamInfo[idx]);
             }
         }
diff --git a/src/consensus/upgrades.cpp b/src/consensus/upgrades.cpp
index 1825e9f8a..07003907b 100644
--- a/src/consensus/upgrades.cpp
+++ b/src/consensus/upgrades.cpp
@@ -161,7 +161,7 @@ boost::optional<int> NextActivationHeight(
 {
     auto idx = NextEpoch(nHeight, params);
     if (idx) {
-        return params.vUpgrades[idx.get()].nActivationHeight;
+        return params.vUpgrades[idx.value()].nActivationHeight;
     }
     return boost::none;
 }
diff --git a/src/gtest/test_checktransaction.cpp b/src/gtest/test_checktransaction.cpp
index 402a93864..4f79e9261 100644
--- a/src/gtest/test_checktransaction.cpp
+++ b/src/gtest/test_checktransaction.cpp
@@ -1134,7 +1134,7 @@ TEST(ChecktransactionTests, HeartwoodAcceptsShieldedCoinbase) {
     auto output = OutputDescriptionInfo(ovk, note, {{0xF6}});
 
     auto ctx = librustzcash_sapling_proving_ctx_init();
-    auto odesc = output.Build(ctx).get();
+    auto odesc = output.Build(ctx).value();
     librustzcash_sapling_proving_ctx_free(ctx);
 
     CMutableTransaction mtx = GetValidTransaction();
@@ -1240,7 +1240,7 @@ TEST(ChecktransactionTests, HeartwoodEnforcesSaplingRulesOnShieldedCoinbase) {
 
     // Add a Sapling output.
     auto ctx = librustzcash_sapling_proving_ctx_init();
-    auto odesc = output.Build(ctx).get();
+    auto odesc = output.Build(ctx).value();
     librustzcash_sapling_proving_ctx_free(ctx);
     mtx.vShieldedOutput.push_back(odesc);
 
diff --git a/src/gtest/test_foundersreward.cpp b/src/gtest/test_foundersreward.cpp
index 2f526d79c..9f2e1d721 100644
--- a/src/gtest/test_foundersreward.cpp
+++ b/src/gtest/test_foundersreward.cpp
@@ -105,8 +105,8 @@ void checkNumberOfUniqueAddresses(int nUnique) {
 int GetMaxFundingStreamHeight(const Consensus::Params& params) {
     int result = 0;
     for (auto fs : params.vFundingStreams) {
-        if (fs && result < fs.get().GetEndHeight() - 1) {
-            result = fs.get().GetEndHeight() - 1;
+        if (fs && result < fs.value().GetEndHeight() - 1) {
+            result = fs.value().GetEndHeight() - 1;
         }
     }
 
diff --git a/src/gtest/test_mempoollimit.cpp b/src/gtest/test_mempoollimit.cpp
index 380bb3097..5d9d01739 100644
--- a/src/gtest/test_mempoollimit.cpp
+++ b/src/gtest/test_mempoollimit.cpp
@@ -100,7 +100,7 @@ TEST(MempoolLimitTests, WeightedTxTreeCheckSizeAfterDropping)
         EXPECT_EQ(12000 + LOW_FEE_PENALTY, tree.getTotalWeight().evictionWeight);
         boost::optional<uint256> drop = tree.maybeDropRandom();
         ASSERT_TRUE(drop.is_initialized());
-        uint256 txid = drop.get();
+        uint256 txid = drop.value();
         testedDropping.insert(txid);
         // Do not continue to test if a particular trial fails
         ASSERT_EQ(8000, tree.getTotalWeight().cost);
diff --git a/src/gtest/test_noteencryption.cpp b/src/gtest/test_noteencryption.cpp
index 6dae057af..a4b3d9229 100644
--- a/src/gtest/test_noteencryption.cpp
+++ b/src/gtest/test_noteencryption.cpp
@@ -50,7 +50,7 @@ TEST(NoteEncryption, NotePlaintext)
         if (!cmu_opt) {
             FAIL();
         }
-        uint256 cmu = cmu_opt.get();
+        uint256 cmu = cmu_opt.value();
         SaplingNotePlaintext pt(note, memo);
 
         auto res = pt.encrypt(addr.pk_d);
@@ -58,7 +58,7 @@ TEST(NoteEncryption, NotePlaintext)
             FAIL();
         }
 
-        auto enc = res.get();
+        auto enc = res.value();
 
         auto ct = enc.first;
         auto encryptor = enc.second;
@@ -88,7 +88,7 @@ TEST(NoteEncryption, NotePlaintext)
             FAIL();
         }
 
-        auto bar = foo.get();
+        auto bar = foo.value();
 
         ASSERT_TRUE(bar.value() == pt.value());
         ASSERT_TRUE(bar.memo() == pt.memo());
@@ -101,7 +101,7 @@ TEST(NoteEncryption, NotePlaintext)
             FAIL();
         }
 
-        auto new_note = foobar.get();
+        auto new_note = foobar.value();
 
         ASSERT_TRUE(note.value() == new_note.value());
         ASSERT_TRUE(note.d == new_note.d);
@@ -136,7 +136,7 @@ TEST(NoteEncryption, NotePlaintext)
             FAIL();
         }
 
-        auto decrypted_out_ct_unwrapped = decrypted_out_ct.get();
+        auto decrypted_out_ct_unwrapped = decrypted_out_ct.value();
 
         ASSERT_TRUE(decrypted_out_ct_unwrapped.pk_d == out_pt.pk_d);
         ASSERT_TRUE(decrypted_out_ct_unwrapped.esk == out_pt.esk);
@@ -169,7 +169,7 @@ TEST(NoteEncryption, NotePlaintext)
             FAIL();
         }
 
-        bar = foo.get();
+        bar = foo.value();
 
         ASSERT_TRUE(bar.value() == pt.value());
         ASSERT_TRUE(bar.memo() == pt.memo());
@@ -210,7 +210,7 @@ TEST(NoteEncryption, RejectsInvalidNoteZip212Enabled)
         if (!cmu_opt) {
             FAIL();
         }
-        uint256 cmu = cmu_opt.get();
+        uint256 cmu = cmu_opt.value();
         SaplingNotePlaintext pt(note, memo);
 
         auto res = pt.encrypt(addr.pk_d);
@@ -218,7 +218,7 @@ TEST(NoteEncryption, RejectsInvalidNoteZip212Enabled)
             FAIL();
         }
 
-        auto enc = res.get();
+        auto enc = res.value();
 
         auto ct = enc.first;
         auto encryptor = enc.second;
@@ -241,7 +241,7 @@ TEST(NoteEncryption, RejectsInvalidNoteZip212Enabled)
         if (!cmu_opt) {
             FAIL();
         }
-        uint256 cmu = cmu_opt.get();
+        uint256 cmu = cmu_opt.value();
         SaplingNotePlaintext pt(note, memo);
 
         auto res = pt.encrypt(addr.pk_d);
@@ -249,7 +249,7 @@ TEST(NoteEncryption, RejectsInvalidNoteZip212Enabled)
             FAIL();
         }
 
-        auto enc = res.get();
+        auto enc = res.value();
 
         auto ct = enc.first;
         auto encryptor = enc.second;
@@ -301,7 +301,7 @@ TEST(NoteEncryption, AcceptsValidNoteZip212Enabled)
         if (!cmu_opt) {
             FAIL();
         }
-        uint256 cmu = cmu_opt.get();
+        uint256 cmu = cmu_opt.value();
         SaplingNotePlaintext pt(note, memo);
 
         auto res = pt.encrypt(addr.pk_d);
@@ -309,7 +309,7 @@ TEST(NoteEncryption, AcceptsValidNoteZip212Enabled)
             FAIL();
         }
 
-        auto enc = res.get();
+        auto enc = res.value();
 
         auto ct = enc.first;
         auto encryptor = enc.second;
@@ -343,7 +343,7 @@ TEST(NoteEncryption, AcceptsValidNoteZip212Enabled)
                 if (!cmu_opt) {
                     FAIL();
                 }
-                uint256 cmu = cmu_opt.get();
+                uint256 cmu = cmu_opt.value();
                 SaplingNotePlaintext pt(note, memo);
 
                 auto res = pt.encrypt(addr.pk_d);
@@ -351,7 +351,7 @@ TEST(NoteEncryption, AcceptsValidNoteZip212Enabled)
                     FAIL();
                 }
 
-                auto enc = res.get();
+                auto enc = res.value();
 
                 auto ct = enc.first;
                 auto encryptor = enc.second;
@@ -380,7 +380,7 @@ TEST(NoteEncryption, AcceptsValidNoteZip212Enabled)
         if (!cmu_opt) {
             FAIL();
         }
-        uint256 cmu = cmu_opt.get();
+        uint256 cmu = cmu_opt.value();
         SaplingNotePlaintext pt(note, memo);
 
         auto res = pt.encrypt(addr.pk_d);
@@ -388,7 +388,7 @@ TEST(NoteEncryption, AcceptsValidNoteZip212Enabled)
             FAIL();
         }
 
-        auto enc = res.get();
+        auto enc = res.value();
 
         auto ct = enc.first;
         auto encryptor = enc.second;
diff --git a/src/gtest/test_pow.cpp b/src/gtest/test_pow.cpp
index 709296f78..ba5e05607 100644
--- a/src/gtest/test_pow.cpp
+++ b/src/gtest/test_pow.cpp
@@ -93,7 +93,7 @@ TEST(PoW, MinDifficultyRules) {
     std::vector<CBlockIndex> blocks(lastBlk+1);
     for (int i = 0; i <= lastBlk; i++) {
         blocks[i].pprev = i ? &blocks[i - 1] : nullptr;
-        blocks[i].nHeight = params.nPowAllowMinDifficultyBlocksAfterHeight.get() + i;
+        blocks[i].nHeight = params.nPowAllowMinDifficultyBlocksAfterHeight.value() + i;
         blocks[i].nTime = i ? blocks[i - 1].nTime + params.PoWTargetSpacing(i) : 1269211443;
         blocks[i].nBits = 0x1e7fffff; /* target 0x007fffff000... */
         blocks[i].nChainWork = i ? blocks[i - 1].nChainWork + GetBlockProof(blocks[i - 1]) : arith_uint256(0);
diff --git a/src/gtest/test_sapling_note.cpp b/src/gtest/test_sapling_note.cpp
index ca1fece7c..5eeb2fa83 100644
--- a/src/gtest/test_sapling_note.cpp
+++ b/src/gtest/test_sapling_note.cpp
@@ -45,7 +45,7 @@ TEST(SaplingNote, TestVectors)
 
     // Test commitment
     SaplingNote note = SaplingNote(diversifier, pk_d, v, r, Zip212Enabled::BeforeZip212);
-    ASSERT_EQ(note.cmu().get(), cm);
+    ASSERT_EQ(note.cmu().value(), cm);
 
     // Test nullifier
     SaplingSpendingKey spendingKey(sk);
diff --git a/src/gtest/test_validation.cpp b/src/gtest/test_validation.cpp
index a411bfc2d..dec997196 100644
--- a/src/gtest/test_validation.cpp
+++ b/src/gtest/test_validation.cpp
@@ -43,11 +43,11 @@ public:
     }
 
     bool GetCoins(const uint256 &txid, CCoins &coins) const {
-        if (coin && txid == coin.get().first.second) {
+        if (coin && txid == coin.value().first.second) {
             CCoins newCoins;
             newCoins.vout.resize(2);
-            newCoins.vout[0] = coin.get().second.first;
-            newCoins.nHeight = coin.get().second.second;
+            newCoins.vout[0] = coin.value().second.first;
+            newCoins.nHeight = coin.value().second.second;
             coins.swap(newCoins);
             return true;
         } else {
@@ -56,7 +56,7 @@ public:
     }
 
     bool HaveCoins(const uint256 &txid) const {
-        if (coin && txid == coin.get().first.second) {
+        if (coin && txid == coin.value().first.second) {
             return true;
         } else {
             return false;
@@ -65,7 +65,7 @@ public:
 
     uint256 GetBestBlock() const {
         if (coin) {
-            return coin.get().first.first;
+            return coin.value().first.first;
         } else {
             uint256 a;
             return a;
diff --git a/src/gtest/test_zip32.cpp b/src/gtest/test_zip32.cpp
index e7715fd03..c8ee5a335 100644
--- a/src/gtest/test_zip32.cpp
+++ b/src/gtest/test_zip32.cpp
@@ -109,7 +109,7 @@ TEST(ZIP32, TestVectors) {
     auto maybe_m_1_2hv_3 = m_1_2hv.Derive(3);
     EXPECT_TRUE(maybe_m_1_2hv_3);
 
-    auto m_1_2hv_3 = maybe_m_1_2hv_3.get();
+    auto m_1_2hv_3 = maybe_m_1_2hv_3.value();
     EXPECT_EQ(m_1_2hv_3.depth, 3);
     EXPECT_EQ(m_1_2hv_3.parentFVKTag, 0x7583c148);
     EXPECT_EQ(m_1_2hv_3.childIndex, 3);
diff --git a/src/init.cpp b/src/init.cpp
index 473692646..1b8a9cdde 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -900,7 +900,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     // Set this early so that experimental features are correctly enabled/disabled
     auto err = InitExperimentalMode();
     if (err) {
-        return InitError(err.get());
+        return InitError(err.value());
     }
 
     // Make sure enough file descriptors are available
diff --git a/src/main.cpp b/src/main.cpp
index e2fcecb6a..137256d46 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1966,7 +1966,7 @@ bool IsInitialBlockDownload(const CChainParams& chainParams)
             // If an upgrade is active, we must be past its activation height.
             assert(chainActive[upgrade.nActivationHeight]);
 
-            if (chainActive[upgrade.nActivationHeight]->GetBlockHash() != upgrade.hashActivationBlock.get()) {
+            if (chainActive[upgrade.nActivationHeight]->GetBlockHash() != upgrade.hashActivationBlock.value()) {
                 AbortNode(
                     strprintf(
                         "%s: We are on a chain with sufficient work, but the activation block hash for the %s network upgrade is not as expected.\n"
@@ -1978,7 +1978,7 @@ bool IsInitialBlockDownload(const CChainParams& chainParams)
                         chainParams.GetConsensus().nMinimumChainWork.GetHex(),
                         chainActive.Height(),
                         upgrade.nActivationHeight,
-                        upgrade.hashActivationBlock.get().GetHex(),
+                        upgrade.hashActivationBlock.value().GetHex(),
                         chainActive[upgrade.nActivationHeight]->GetBlockHash().GetHex()),
                     _("We are on a chain with sufficient work, but the network upgrade checkpoints do not match. Your node may be under attack! Shutting down for safety."));
                 return true;
@@ -2575,7 +2575,7 @@ static DisconnectResult DisconnectBlock(const CBlock& block, CValidationState& s
 
     // This is guaranteed to be filled by LoadBlockIndex.
     assert(pindex->nCachedBranchId);
-    auto consensusBranchId = pindex->nCachedBranchId.get();
+    auto consensusBranchId = pindex->nCachedBranchId.value();
 
     if (chainparams.GetConsensus().NetworkUpgradeActive(pindex->nHeight, Consensus::UPGRADE_HEARTWOOD)) {
         view.PopHistoryNode(consensusBranchId);
@@ -6982,7 +6982,7 @@ CMutableTransaction CreateNewContextualCMutableTransaction(const Consensus::Para
 
         bool blossomActive = consensusParams.NetworkUpgradeActive(nHeight, Consensus::UPGRADE_BLOSSOM);
         unsigned int defaultExpiryDelta = blossomActive ? DEFAULT_POST_BLOSSOM_TX_EXPIRY_DELTA : DEFAULT_PRE_BLOSSOM_TX_EXPIRY_DELTA;
-        mtx.nExpiryHeight = nHeight + (expiryDeltaArg ? expiryDeltaArg.get() : defaultExpiryDelta);
+        mtx.nExpiryHeight = nHeight + (expiryDeltaArg ? expiryDeltaArg.value() : defaultExpiryDelta);
 
         // mtx.nExpiryHeight == 0 is valid for coinbase transactions
         if (mtx.nExpiryHeight <= 0 || mtx.nExpiryHeight >= TX_EXPIRY_HEIGHT_THRESHOLD) {
@@ -6994,7 +6994,7 @@ CMutableTransaction CreateNewContextualCMutableTransaction(const Consensus::Para
         // TX_EXPIRING_SOON_THRESHOLD (3) blocks (for DoS mitigation) based on the current height.
         auto nextActivationHeight = NextActivationHeight(nHeight, consensusParams);
         if (nextActivationHeight) {
-            mtx.nExpiryHeight = std::min(mtx.nExpiryHeight, static_cast<uint32_t>(nextActivationHeight.get()) - 1);
+            mtx.nExpiryHeight = std::min(mtx.nExpiryHeight, static_cast<uint32_t>(nextActivationHeight.value()) - 1);
         }
     }
     return mtx;
diff --git a/src/metrics.cpp b/src/metrics.cpp
index 944e13da1..a688b4019 100644
--- a/src/metrics.cpp
+++ b/src/metrics.cpp
@@ -279,7 +279,7 @@ boost::optional<int64_t> SecondsLeftToNextEpoch(const Consensus::Params& params,
 {
     auto nextHeight = NextActivationHeight(currentHeight, params);
     if (nextHeight) {
-        return (nextHeight.get() - currentHeight) * params.PoWTargetSpacing(nextHeight.get() - 1);
+        return (nextHeight.value() - currentHeight) * params.PoWTargetSpacing(nextHeight.value() - 1);
     } else {
         return boost::none;
     }
diff --git a/src/miner.cpp b/src/miner.cpp
index 72a97358d..fbfa3fe3c 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -143,7 +143,7 @@ public:
 
         auto odesc = output.Build(ctx);
         if (odesc) {
-            mtx.vShieldedOutput.push_back(odesc.get());
+            mtx.vShieldedOutput.push_back(odesc.value());
             mtx.valueBalance -= fundingStreamValue;
             return true;
         } else {
@@ -260,7 +260,7 @@ public:
             librustzcash_sapling_proving_ctx_free(ctx);
             throw new std::runtime_error("Failed to create shielded output for miner");
         }
-        mtx.vShieldedOutput.push_back(odesc.get());
+        mtx.vShieldedOutput.push_back(odesc.value());
 
         ComputeBindingSig(ctx);
 
diff --git a/src/net.cpp b/src/net.cpp
index 7e7b97339..f7a0a7ded 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -823,7 +823,7 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) {
     const Consensus::Params& params = Params().GetConsensus();
     auto nextEpoch = NextEpoch(height, params);
     if (nextEpoch) {
-        auto idx = nextEpoch.get();
+        auto idx = nextEpoch.value();
         int nActivationHeight = params.vUpgrades[idx].nActivationHeight;
 
         if (nActivationHeight > 0 &&
diff --git a/src/pow.cpp b/src/pow.cpp
index 8cb9826c5..181e9d710 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -31,7 +31,7 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
         // Comparing to pindexLast->nHeight with >= because this function
         // returns the work required for the block after pindexLast.
         if (params.nPowAllowMinDifficultyBlocksAfterHeight != boost::none &&
-            pindexLast->nHeight >= params.nPowAllowMinDifficultyBlocksAfterHeight.get())
+            pindexLast->nHeight >= params.nPowAllowMinDifficultyBlocksAfterHeight.value())
         {
             // Special difficulty rule for testnet:
             // If the new block's timestamp is more than 6 * block interval minutes
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 03be2a6d3..34aabe86f 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -981,7 +981,7 @@ UniValue getblocksubsidy(const UniValue& params, bool fHelp)
             fsobj.pushKV("valueZat", nStreamAmount);
 
             auto fs = consensus.vFundingStreams[idx];
-            auto address = fs.get().RecipientAddress(consensus, nHeight);
+            auto address = fs.value().RecipientAddress(consensus, nHeight);
 
             CScript* outpoint = std::get_if<CScript>(&address);
             std::string addressStr;
diff --git a/src/transaction_builder.cpp b/src/transaction_builder.cpp
index 469a66fa2..7dc93c8c6 100644
--- a/src/transaction_builder.cpp
+++ b/src/transaction_builder.cpp
@@ -36,7 +36,7 @@ boost::optional<OutputDescription> OutputDescriptionInfo::Build(void* ctx) {
     if (!res) {
         return boost::none;
     }
-    auto enc = res.get();
+    auto enc = res.value();
     auto encryptor = enc.second;
 
     libzcash::SaplingPaymentAddress address(this->note.d, this->note.pk_d);
@@ -81,7 +81,7 @@ bool TransactionBuilderResult::IsError() { return maybeError != boost::none; }
 
 CTransaction TransactionBuilderResult::GetTxOrThrow() {
     if (maybeTx) {
-        return maybeTx.get();
+        return maybeTx.value();
     } else {
         throw JSONRPCError(RPC_WALLET_ERROR, "Failed to build transaction: " + GetError());
     }
@@ -89,7 +89,7 @@ CTransaction TransactionBuilderResult::GetTxOrThrow() {
 
 std::string TransactionBuilderResult::GetError() {
     if (maybeError) {
-        return maybeError.get();
+        return maybeError.value();
     } else {
         // This can only happen if isTx() is true in which case we should not call getError()
         throw std::runtime_error("getError() was called in TransactionBuilderResult, but the result was not initialized as an error.");
@@ -285,7 +285,7 @@ TransactionBuilderResult TransactionBuilder::Build()
         if (saplingChangeAddr) {
             AddSaplingOutput(saplingChangeAddr->first, saplingChangeAddr->second, change);
         } else if (sproutChangeAddr) {
-            AddSproutOutput(sproutChangeAddr.get(), change);
+            AddSproutOutput(sproutChangeAddr.value(), change);
         } else if (tChangeAddr) {
             // tChangeAddr has already been validated.
             AddTransparentOutput(tChangeAddr.value(), change);
@@ -360,7 +360,7 @@ TransactionBuilderResult TransactionBuilder::Build()
             return TransactionBuilderResult("Failed to create output description");
         }
 
-        mtx.vShieldedOutput.push_back(odesc.get());
+        mtx.vShieldedOutput.push_back(odesc.value());
     }
 
     //
@@ -574,7 +574,7 @@ void TransactionBuilder::CreateJSDescriptions()
                 if (!changeWitness && changeOutputIndex == n++) {
                     changeWitness = tree.witness();
                 } else if (changeWitness) {
-                    changeWitness.get().append(commitment);
+                    changeWitness.value().append(commitment);
                 }
             }
             assert(changeWitness.has_value());
@@ -593,7 +593,7 @@ void TransactionBuilder::CreateJSDescriptions()
                     (unsigned char)changeOutputIndex);
 
                 auto note = plaintext.note(changeAddress);
-                vjsin[0] = libzcash::JSInput(changeWitness.get(), note, changeKey);
+                vjsin[0] = libzcash::JSInput(changeWitness.value(), note, changeKey);
 
                 jsInputValue += plaintext.value();
 
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 60b376918..b3ceb860c 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -841,7 +841,7 @@ void CTxMemPool::EnsureSizeLimit() {
     AssertLockHeld(cs);
     boost::optional<uint256> maybeDropTxId;
     while ((maybeDropTxId = weightedTxTree->maybeDropRandom()).is_initialized()) {
-        uint256 txId = maybeDropTxId.get();
+        uint256 txId = maybeDropTxId.value();
         recentlyEvicted->add(txId);
         std::list<CTransaction> removed;
         remove(mapTx.find(txId)->GetTx(), removed, true);
diff --git a/src/utiltest.cpp b/src/utiltest.cpp
index 9d7984ce5..9592e273c 100644
--- a/src/utiltest.cpp
+++ b/src/utiltest.cpp
@@ -290,7 +290,7 @@ CKey AddTestCKeyToKeyStore(CBasicKeyStore& keyStore) {
 TestSaplingNote GetTestSaplingNote(const libzcash::SaplingPaymentAddress& pa, CAmount value) {
     // Generate dummy Sapling note
     libzcash::SaplingNote note(pa, value, libzcash::Zip212Enabled::BeforeZip212);
-    uint256 cm = note.cmu().get();
+    uint256 cm = note.cmu().value();
     SaplingMerkleTree tree;
     tree.append(cm);
     return { note, tree };
diff --git a/src/wallet/asyncrpcoperation_mergetoaddress.cpp b/src/wallet/asyncrpcoperation_mergetoaddress.cpp
index 20d848def..201db5b0b 100644
--- a/src/wallet/asyncrpcoperation_mergetoaddress.cpp
+++ b/src/wallet/asyncrpcoperation_mergetoaddress.cpp
@@ -91,7 +91,7 @@ AsyncRPCOperation_mergetoaddress::AsyncRPCOperation_mergetoaddress(
     isUsingBuilder_ = false;
     if (builder) {
         isUsingBuilder_ = true;
-        builder_ = builder.get();
+        builder_ = builder.value();
     }
 
     KeyIO keyIO(Params());
@@ -324,7 +324,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
             if (!witnesses[i]) {
                 throw JSONRPCError(RPC_WALLET_ERROR, "Missing witness for Sapling note");
             }
-            builder_.AddSaplingSpend(expsks[i], saplingNotes[i], anchor, witnesses[i].get());
+            builder_.AddSaplingSpend(expsks[i], saplingNotes[i], anchor, witnesses[i].value());
         }
 
         if (isToTaddr_) {
@@ -349,7 +349,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
             if (!ovk) {
                 throw JSONRPCError(RPC_WALLET_ERROR, "Sending to a Sapling address requires an ovk.");
             }
-            builder_.AddSaplingOutput(ovk.get(), *saplingPaymentAddress, sendAmount, hexMemo);
+            builder_.AddSaplingOutput(ovk.value(), *saplingPaymentAddress, sendAmount, hexMemo);
         }
 
         // Build the transaction
@@ -541,7 +541,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
                 if (!changeWitness && changeOutputIndex == n++) {
                     changeWitness = tree.witness();
                 } else if (changeWitness) {
-                    changeWitness.get().append(commitment);
+                    changeWitness.value().append(commitment);
                 }
             }
             if (changeWitness) {
@@ -640,7 +640,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
                 if (!optionalWitness) {
                     throw JSONRPCError(RPC_WALLET_ERROR, "Witness for note commitment is null");
                 }
-                SproutWitness w = *optionalWitness; // could use .get();
+                SproutWitness w = *optionalWitness; // could use .value();
                 if (jsChange > 0) {
                     for (const uint256& commitment : previousCommitments) {
                         w.append(commitment);
diff --git a/src/wallet/asyncrpcoperation_saplingmigration.cpp b/src/wallet/asyncrpcoperation_saplingmigration.cpp
index e76d0b072..94cf972fc 100644
--- a/src/wallet/asyncrpcoperation_saplingmigration.cpp
+++ b/src/wallet/asyncrpcoperation_saplingmigration.cpp
@@ -72,7 +72,7 @@ bool AsyncRPCOperation_saplingmigration::main_impl() {
     LogPrint("zrpcunsafe", "%s: Beginning AsyncRPCOperation_saplingmigration.\n", getId());
     const Consensus::Params& consensusParams = Params().GetConsensus();
     auto nextActivationHeight = NextActivationHeight(targetHeight_, consensusParams);
-    if (nextActivationHeight && targetHeight_ + MIGRATION_EXPIRY_DELTA >= nextActivationHeight.get()) {
+    if (nextActivationHeight && targetHeight_ + MIGRATION_EXPIRY_DELTA >= nextActivationHeight.value()) {
         LogPrint("zrpcunsafe", "%s: Migration txs would be created before a NU activation but may expire after. Skipping this round.\n", getId());
         setMigrationResult(0, 0, std::vector<std::string>());
         return true;
@@ -141,7 +141,7 @@ bool AsyncRPCOperation_saplingmigration::main_impl() {
             uint256 inputAnchor;
             std::vector<boost::optional<SproutWitness>> vInputWitnesses;
             pwalletMain->GetSproutNoteWitnesses(vOutPoints, vInputWitnesses, inputAnchor);
-            builder.AddSproutInput(sproutSk, sproutEntry.note, vInputWitnesses[0].get());
+            builder.AddSproutInput(sproutSk, sproutEntry.note, vInputWitnesses[0].value());
         }
         // The amount chosen *includes* the 0.0001 ZEC fee for this transaction, i.e.
         // the value of the Sapling output will be 0.0001 ZEC less.
diff --git a/src/wallet/asyncrpcoperation_sendmany.cpp b/src/wallet/asyncrpcoperation_sendmany.cpp
index d26d50a8e..bd55bf456 100644
--- a/src/wallet/asyncrpcoperation_sendmany.cpp
+++ b/src/wallet/asyncrpcoperation_sendmany.cpp
@@ -85,7 +85,7 @@ AsyncRPCOperation_sendmany::AsyncRPCOperation_sendmany(
     isUsingBuilder_ = false;
     if (builder) {
         isUsingBuilder_ = true;
-        builder_ = builder.get();
+        builder_ = builder.value();
     }
 
     KeyIO keyIO(Params());
@@ -105,7 +105,7 @@ AsyncRPCOperation_sendmany::AsyncRPCOperation_sendmany(
 
             isfromzaddr_ = true;
             frompaymentaddress_ = address;
-            spendingkey_ = std::visit(GetSpendingKeyForPaymentAddress(pwalletMain), address).get();
+            spendingkey_ = std::visit(GetSpendingKeyForPaymentAddress(pwalletMain), address).value();
         } else {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid from address");
         }
@@ -364,7 +364,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
             if (!witnesses[i]) {
                 throw JSONRPCError(RPC_WALLET_ERROR, "Missing witness for Sapling note");
             }
-            builder_.AddSaplingSpend(expsk, notes[i], anchor, witnesses[i].get());
+            builder_.AddSaplingSpend(expsk, notes[i], anchor, witnesses[i].value());
         }
 
         // Add Sapling outputs
@@ -626,7 +626,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
                 if (!changeWitness && changeOutputIndex == n++) {
                     changeWitness = tree.witness();
                 } else if (changeWitness) {
-                    changeWitness.get().append(commitment);
+                    changeWitness.value().append(commitment);
                 }
             }
             if (changeWitness) {
@@ -724,7 +724,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
                 if (!optionalWitness) {
                     throw JSONRPCError(RPC_WALLET_ERROR, "Witness for note commitment is null");
                 }
-                SproutWitness w = *optionalWitness; // could use .get();
+                SproutWitness w = *optionalWitness; // could use .value();
                 if (jsChange > 0) {
                     for (const uint256& commitment : previousCommitments) {
                         w.append(commitment);
diff --git a/src/wallet/gtest/test_wallet.cpp b/src/wallet/gtest/test_wallet.cpp
index f451e8275..97ecd8bc3 100644
--- a/src/wallet/gtest/test_wallet.cpp
+++ b/src/wallet/gtest/test_wallet.cpp
@@ -360,7 +360,7 @@ TEST(WalletTests, SetSaplingNoteAddrsInCWalletTx) {
         auto pk = sk.DefaultAddress();
 
         libzcash::SaplingNote note(pk, 50000, zip_212_enabled[ver]);
-        auto cm = note.cmu().get();
+        auto cm = note.cmu().value();
         SaplingMerkleTree tree;
         tree.append(cm);
         auto anchor = tree.root();
@@ -368,7 +368,7 @@ TEST(WalletTests, SetSaplingNoteAddrsInCWalletTx) {
 
         auto nf = note.nullifier(fvk, witness.position());
         ASSERT_TRUE(nf);
-        uint256 nullifier = nf.get();
+        uint256 nullifier = nf.value();
 
         auto builder = TransactionBuilder(consensusParams, 1);
         builder.AddSaplingSpend(expsk, note, anchor, witness);
@@ -634,7 +634,7 @@ TEST(WalletTests, GetConflictedSaplingNotes) {
 
         // Generate note A
         libzcash::SaplingNote note(pk, 50000, zip_212_enabled[ver]);
-        auto cm = note.cmu().get();
+        auto cm = note.cmu().value();
         SaplingMerkleTree saplingTree;
         saplingTree.append(cm);
         auto anchor = saplingTree.root();
@@ -684,15 +684,15 @@ TEST(WalletTests, GetConflictedSaplingNotes) {
                 wtx.vShieldedOutput[0].ephemeralKey,
                 wtx.vShieldedOutput[0].cmu);
         ASSERT_EQ(static_cast<bool>(maybe_pt), true);
-        auto maybe_note = maybe_pt.get().note(ivk);
+        auto maybe_note = maybe_pt.value().note(ivk);
         ASSERT_EQ(static_cast<bool>(maybe_note), true);
-        auto note2 = maybe_note.get();
+        auto note2 = maybe_note.value();
 
         SaplingOutPoint sop0(wtx.GetHash(), 0);
         auto spend_note_witness =  wtx.mapSaplingNoteData[sop0].witnesses.front();
         auto maybe_nf = note2.nullifier(extfvk.fvk, spend_note_witness.position());
         ASSERT_EQ(static_cast<bool>(maybe_nf), true);
-        auto nullifier2 = maybe_nf.get();
+        auto nullifier2 = maybe_nf.value();
 
         anchor = saplingTree.root();
 
@@ -804,7 +804,7 @@ TEST(WalletTests, SaplingNullifierIsSpent) {
     // Manually compute the nullifier based on the known position
     auto nf = testNote.note.nullifier(extfvk.fvk, testNote.tree.witness().position());
     ASSERT_TRUE(nf);
-    uint256 nullifier = nf.get();
+    uint256 nullifier = nf.value();
 
     // Verify note has not been spent
     EXPECT_FALSE(wallet.IsSaplingSpent(nullifier));
@@ -889,7 +889,7 @@ TEST(WalletTests, NavigateFromSaplingNullifierToNote) {
     // Manually compute the nullifier based on the expected position
     auto nf = testNote.note.nullifier(extfvk.fvk, testNote.tree.witness().position());
     ASSERT_TRUE(nf);
-    uint256 nullifier = nf.get();
+    uint256 nullifier = nf.value();
 
     // Verify dummy note is unspent
     EXPECT_FALSE(wallet.IsSaplingSpent(nullifier));
@@ -941,7 +941,7 @@ TEST(WalletTests, NavigateFromSaplingNullifierToNote) {
         EXPECT_EQ(hash, op.hash);
         EXPECT_EQ(1, nd.witnesses.size());
         ASSERT_TRUE(nd.nullifier);
-        auto nf = nd.nullifier.get();
+        auto nf = nd.nullifier.value();
         EXPECT_EQ(1, wallet.mapSaplingNullifiersToNotes.count(nf));
         EXPECT_EQ(op.hash, wallet.mapSaplingNullifiersToNotes[nf].hash);
         EXPECT_EQ(op.n, wallet.mapSaplingNullifiersToNotes[nf].n);
@@ -1007,7 +1007,7 @@ TEST(WalletTests, SpentSaplingNoteIsFromMe) {
 
         // Generate Sapling note A
         libzcash::SaplingNote note(pk, 50000, zip_212_enabled[ver]);
-        auto cm = note.cmu().get();
+        auto cm = note.cmu().value();
         SaplingMerkleTree saplingTree;
         saplingTree.append(cm);
         auto anchor = saplingTree.root();
@@ -1059,7 +1059,7 @@ TEST(WalletTests, SpentSaplingNoteIsFromMe) {
         // Manually compute the nullifier and check map entry does not exist
         auto nf = note.nullifier(extfvk.fvk, witness.position());
         ASSERT_TRUE(nf);
-        ASSERT_FALSE(wallet.mapSaplingNullifiersToNotes.count(nf.get()));
+        ASSERT_FALSE(wallet.mapSaplingNullifiersToNotes.count(nf.value()));
 
         // Decrypt note B
         auto maybe_pt = libzcash::SaplingNotePlaintext::decrypt(
@@ -1070,16 +1070,16 @@ TEST(WalletTests, SpentSaplingNoteIsFromMe) {
             wtx.vShieldedOutput[0].ephemeralKey,
             wtx.vShieldedOutput[0].cmu);
         ASSERT_EQ(static_cast<bool>(maybe_pt), true);
-        auto maybe_note = maybe_pt.get().note(ivk);
+        auto maybe_note = maybe_pt.value().note(ivk);
         ASSERT_EQ(static_cast<bool>(maybe_note), true);
-        auto note2 = maybe_note.get();
+        auto note2 = maybe_note.value();
 
         // Get witness to retrieve position of note B we want to spend
         SaplingOutPoint sop0(wtx.GetHash(), 0);
         auto spend_note_witness =  wtx.mapSaplingNoteData[sop0].witnesses.front();
         auto maybe_nf = note2.nullifier(extfvk.fvk, spend_note_witness.position());
         ASSERT_EQ(static_cast<bool>(maybe_nf), true);
-        auto nullifier2 = maybe_nf.get();
+        auto nullifier2 = maybe_nf.value();
 
         // NOTE: Not updating the anchor results in a core dump.  Shouldn't builder just return error?
         // *** Error in `./zcash-gtest': double free or corruption (out): 0x00007ffd8755d990 ***
@@ -1997,9 +1997,9 @@ TEST(WalletTests, MarkAffectedSaplingTransactionsDirty) {
     // Prepare to spend the note that was just created
     auto maybe_pt = libzcash::SaplingNotePlaintext::decrypt(consensusParams, fakeIndex.nHeight, tx1.vShieldedOutput[0].encCiphertext, ivk, tx1.vShieldedOutput[0].ephemeralKey, tx1.vShieldedOutput[0].cmu);
     ASSERT_EQ(static_cast<bool>(maybe_pt), true);
-    auto maybe_note = maybe_pt.get().note(ivk);
+    auto maybe_note = maybe_pt.value().note(ivk);
     ASSERT_EQ(static_cast<bool>(maybe_note), true);
-    auto note = maybe_note.get();
+    auto note = maybe_note.value();
     auto anchor = saplingTree.root();
     auto witness = saplingTree.witness();
 
diff --git a/src/wallet/gtest/test_wallet_zkeys.cpp b/src/wallet/gtest/test_wallet_zkeys.cpp
index 1cc5752b0..5cd7c4888 100644
--- a/src/wallet/gtest/test_wallet_zkeys.cpp
+++ b/src/wallet/gtest/test_wallet_zkeys.cpp
@@ -70,7 +70,7 @@ TEST(WalletZkeysTest, StoreAndLoadSaplingZkeys) {
     // If we can't get an early diversified address, we are very unlucky
     blob88 diversifier;
     diversifier.begin()[0] = 10;
-    auto dpa = sk.ToXFVK().Address(diversifier).get().second;
+    auto dpa = sk.ToXFVK().Address(diversifier).value().second;
 
     // verify wallet only has the default address
     EXPECT_TRUE(wallet.HaveSaplingIncomingViewingKey(sk.DefaultAddress()));
@@ -98,7 +98,7 @@ TEST(WalletZkeysTest, StoreAndLoadSaplingZkeys) {
     ASSERT_EQ(wallet.mapSaplingZKeyMetadata[ivk2].nCreateTime, now);
 
     // Load a diversified address for the third key into the wallet
-    auto dpa2 = sk2.ToXFVK().Address(diversifier).get().second;
+    auto dpa2 = sk2.ToXFVK().Address(diversifier).value().second;
     EXPECT_TRUE(wallet.HaveSaplingIncomingViewingKey(sk2.DefaultAddress()));
     EXPECT_FALSE(wallet.HaveSaplingIncomingViewingKey(dpa2));
     EXPECT_TRUE(wallet.LoadSaplingPaymentAddress(dpa2, ivk2));
@@ -449,7 +449,7 @@ TEST(wallet_zkeys_tests, WriteCryptedSaplingZkeyDirectToDb) {
     EXPECT_TRUE(wallet.GetSaplingExtendedSpendingKey(address, extsk));
     blob88 diversifier;
     diversifier.begin()[0] = 10;
-    auto dpa = extsk.ToXFVK().Address(diversifier).get().second;
+    auto dpa = extsk.ToXFVK().Address(diversifier).value().second;
 
     // Add diversified address to the wallet
     auto ivk = extsk.expsk.full_viewing_key().in_viewing_key();
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 4127992d5..a2c0937a1 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -913,7 +913,7 @@ UniValue z_exportkey(const UniValue& params, bool fHelp)
     if (!sk) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet does not hold private zkey for this zaddr");
     }
-    return keyIO.EncodeSpendingKey(sk.get());
+    return keyIO.EncodeSpendingKey(sk.value());
 }
 
 UniValue z_exportviewingkey(const UniValue& params, bool fHelp)
@@ -949,7 +949,7 @@ UniValue z_exportviewingkey(const UniValue& params, bool fHelp)
 
     auto vk = std::visit(GetViewingKeyForPaymentAddress(pwalletMain), address);
     if (vk) {
-        return keyIO.EncodeViewingKey(vk.get());
+        return keyIO.EncodeViewingKey(vk.value());
     } else {
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet does not hold private key or viewing key for this zaddr");
     }
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 6ae938159..7847f6d65 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -3829,7 +3829,7 @@ UniValue z_viewtransaction(const UniValue& params, bool fHelp)
         // means the plaintext leadbyte was valid at the block height
         // where the note was received.
         // https://zips.z.cash/zip-0212#changes-to-the-process-of-receiving-sapling-notes
-        auto decrypted = wtxPrev.DecryptSaplingNoteWithoutLeadByteCheck(op).get();
+        auto decrypted = wtxPrev.DecryptSaplingNoteWithoutLeadByteCheck(op).value();
         auto notePt = decrypted.first;
         auto pa = decrypted.second;
 
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index e32ce956b..93fe8f320 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -705,7 +705,7 @@ std::set<std::pair<libzcash::PaymentAddress, uint256>> CWallet::GetNullifiersFor
             auto & nullifier = noteData.nullifier;
             auto & address = noteData.address;
             if (nullifier && addresses.count(address)) {
-                nullifierSet.insert(std::make_pair(address, nullifier.get()));
+                nullifierSet.insert(std::make_pair(address, nullifier.value()));
             }
         }
         // Sapling
@@ -715,7 +715,7 @@ std::set<std::pair<libzcash::PaymentAddress, uint256>> CWallet::GetNullifiersFor
             auto & ivk = noteData.ivk;
             if (nullifier && ivkMap.count(ivk)) {
                 for (const auto & addr : ivkMap[ivk]) {
-                    nullifierSet.insert(std::make_pair(addr, nullifier.get()));
+                    nullifierSet.insert(std::make_pair(addr, nullifier.value()));
                 }
             }
         }
@@ -1523,7 +1523,7 @@ void CWallet::UpdateSaplingNullifierNoteMapWithTx(CWalletTx& wtx) {
         if (nd.witnesses.empty()) {
             // If there are no witnesses, erase the nullifier and associated mapping.
             if (item.second.nullifier) {
-                mapSaplingNullifiersToNotes.erase(item.second.nullifier.get());
+                mapSaplingNullifiersToNotes.erase(item.second.nullifier.value());
             }
             item.second.nullifier = boost::none;
         }
@@ -1544,13 +1544,13 @@ void CWallet::UpdateSaplingNullifierNoteMapWithTx(CWalletTx& wtx) {
             // otherwise the item would not exist in the first place.
             assert(optPlaintext != boost::none);
 
-            auto optNote = optPlaintext.get().note(nd.ivk);
+            auto optNote = optPlaintext.value().note(nd.ivk);
             assert(optNote != boost::none);
 
-            auto optNullifier = optNote.get().nullifier(extfvk.fvk, position);
+            auto optNullifier = optNote.value().nullifier(extfvk.fvk, position);
             // This should not happen.  If it does, maybe the position has been corrupted or miscalculated?
             assert(optNullifier != boost::none);
-            uint256 nullifier = optNullifier.get();
+            uint256 nullifier = optNullifier.value();
             mapSaplingNullifiersToNotes[nullifier] = op;
             item.second.nullifier = nullifier;
         }
@@ -1946,9 +1946,9 @@ std::pair<mapSaplingNoteData_t, SaplingIncomingViewingKeyMap> CWallet::FindMySap
             if (!result) {
                 continue;
             }
-            auto address = ivk.address(result.get().d);
-            if (address && mapSaplingIncomingViewingKeys.count(address.get()) == 0) {
-                viewingKeysToAdd[address.get()] = ivk;
+            auto address = ivk.address(result.value().d);
+            if (address && mapSaplingIncomingViewingKeys.count(address.value()) == 0) {
+                viewingKeysToAdd[address.value()] = ivk;
             }
             // We don't cache the nullifier here as computing it requires knowledge of the note position
             // in the commitment tree, which can only be determined when the transaction has been mined.
@@ -2360,11 +2360,11 @@ boost::optional<std::pair<
         output.ephemeralKey,
         output.cmu);
     assert(maybe_pt != boost::none);
-    auto notePt = maybe_pt.get();
+    auto notePt = maybe_pt.value();
 
     auto maybe_pa = nd.ivk.address(notePt.d);
     assert(maybe_pa != boost::none);
-    auto pa = maybe_pa.get();
+    auto pa = maybe_pa.value();
 
     return std::make_pair(notePt, pa);
 }
@@ -2393,11 +2393,11 @@ boost::optional<std::pair<
         output.ephemeralKey,
         output.cmu);
     assert(maybe_pt != boost::none);
-    auto notePt = maybe_pt.get();
+    auto notePt = maybe_pt.value();
 
     auto maybe_pa = nd.ivk.address(notePt.d);
     assert(static_cast<bool>(maybe_pa));
-    auto pa = maybe_pa.get();
+    auto pa = maybe_pa.value();
 
     return std::make_pair(notePt, pa);
 }
@@ -2429,7 +2429,7 @@ boost::optional<std::pair<
             outPt->pk_d,
             output.cmu);
         assert(static_cast<bool>(maybe_pt));
-        auto notePt = maybe_pt.get();
+        auto notePt = maybe_pt.value();
 
         return std::make_pair(notePt, SaplingPaymentAddress(notePt.d, outPt->pk_d));
     }
@@ -2469,7 +2469,7 @@ boost::optional<std::pair<
             outPt->pk_d,
             output.cmu);
         assert(static_cast<bool>(maybe_pt));
-        auto notePt = maybe_pt.get();
+        auto notePt = maybe_pt.value();
 
         return std::make_pair(notePt, SaplingPaymentAddress(notePt.d, outPt->pk_d));
     }
@@ -3884,7 +3884,7 @@ bool CWallet::CommitTransaction(CWalletTx& wtxNew, boost::optional<CReserveKey&>
 
             if (reservekey) {
                 // Take key pair from key pool so it won't be used again
-                reservekey.get().KeepKey();
+                reservekey.value().KeepKey();
             }
 
             // Add tx to wallet, because if it has change it's also ours,
@@ -5132,10 +5132,10 @@ void CWallet::GetFilteredNotes(
             // its plaintext had been successfully decrypted previously.
             assert(optDeserialized != boost::none);
 
-            auto notePt = optDeserialized.get();
+            auto notePt = optDeserialized.value();
             auto maybe_pa = nd.ivk.address(notePt.d);
             assert(static_cast<bool>(maybe_pa));
-            auto pa = maybe_pa.get();
+            auto pa = maybe_pa.value();
 
             // skip notes which belong to a different payment address in the wallet
             if (!(filterAddresses.empty() || filterAddresses.count(pa))) {
@@ -5156,7 +5156,7 @@ void CWallet::GetFilteredNotes(
                 continue;
             }
 
-            auto note = notePt.note(nd.ivk).get();
+            auto note = notePt.note(nd.ivk).value();
             saplingEntries.push_back(SaplingNoteEntry {
                 op, pa, note, notePt.memo(), wtx.GetDepthInMainChain() });
         }
@@ -5343,11 +5343,11 @@ KeyAddResult AddSpendingKeyToWallet::operator()(const libzcash::SaplingExtendedS
                 m_wallet->mapSaplingZKeyMetadata[ivk].nCreateTime = std::max((int64_t) 154051200, nTime);
             }
             if (hdKeypath) {
-                m_wallet->mapSaplingZKeyMetadata[ivk].hdKeypath = hdKeypath.get();
+                m_wallet->mapSaplingZKeyMetadata[ivk].hdKeypath = hdKeypath.value();
             }
             if (seedFpStr) {
                 uint256 seedFp;
-                seedFp.SetHex(seedFpStr.get());
+                seedFp.SetHex(seedFpStr.value());
                 m_wallet->mapSaplingZKeyMetadata[ivk].seedFp = seedFp;
             }
             return KeyAdded;
diff --git a/src/zcash/Note.cpp b/src/zcash/Note.cpp
index b4cdc64f0..abbfae0bc 100644
--- a/src/zcash/Note.cpp
+++ b/src/zcash/Note.cpp
@@ -176,7 +176,7 @@ boost::optional<SaplingNote> SaplingNotePlaintext::note(const SaplingIncomingVie
             assert(leadbyte == 0x02);
             zip_212_enabled = Zip212Enabled::AfterZip212;
         };
-        auto tmp = SaplingNote(d, addr.get().pk_d, value_, rseed, zip_212_enabled);
+        auto tmp = SaplingNote(d, addr.value().pk_d, value_, rseed, zip_212_enabled);
         return tmp;
     } else {
         return boost::none;
@@ -199,7 +199,7 @@ boost::optional<SaplingOutgoingPlaintext> SaplingOutgoingPlaintext::decrypt(
     // Deserialize from the plaintext
     try {
         CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
-        ss << pt.get();
+        ss << pt.value();
         SaplingOutgoingPlaintext ret;
         ss >> ret;
         assert(ss.size() == 0);
@@ -254,7 +254,7 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_
     SaplingNotePlaintext ret;
     try {
         CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
-        ss << encPlaintext.get();
+        ss << encPlaintext.value();
         ss >> ret;
         assert(ss.size() == 0);
         return ret;
@@ -356,7 +356,7 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_
     SaplingNotePlaintext ret;
     try {
         CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
-        ss << encPlaintext.get();
+        ss << encPlaintext.value();
         ss >> ret;
         assert(ss.size() == 0);
         return ret;
@@ -421,7 +421,7 @@ boost::optional<SaplingNotePlaintextEncryptionResult> SaplingNotePlaintext::encr
     if (!sne) {
         return boost::none;
     }
-    auto enc = sne.get();
+    auto enc = sne.value();
 
     // Create the plaintext
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
@@ -435,7 +435,7 @@ boost::optional<SaplingNotePlaintextEncryptionResult> SaplingNotePlaintext::encr
     if (!encciphertext) {
         return boost::none;
     }
-    return SaplingNotePlaintextEncryptionResult(encciphertext.get(), enc);
+    return SaplingNotePlaintextEncryptionResult(encciphertext.value(), enc);
 }
 
 
diff --git a/src/zcash/address/zip32.cpp b/src/zcash/address/zip32.cpp
index 188a33e84..6104da568 100644
--- a/src/zcash/address/zip32.cpp
+++ b/src/zcash/address/zip32.cpp
@@ -105,7 +105,7 @@ libzcash::SaplingPaymentAddress SaplingExtendedFullViewingKey::DefaultAddress()
     if (!addr) {
         throw std::runtime_error("SaplingExtendedFullViewingKey::DefaultAddress(): No valid diversifiers out of 2^88!");
     }
-    return addr.get().second;
+    return addr.value().second;
 }
 
 SaplingExtendedSpendingKey SaplingExtendedSpendingKey::Master(const HDSeed& seed)
diff --git a/src/zcbenchmarks.cpp b/src/zcbenchmarks.cpp
index 7f87b9817..3573ca0b5 100644
--- a/src/zcbenchmarks.cpp
+++ b/src/zcbenchmarks.cpp
@@ -374,7 +374,7 @@ CWalletTx CreateSaplingTxWithNoteData(const Consensus::Params& consensusParams,
     auto wtx = GetValidSaplingReceive(consensusParams, keyStore, sk, 10);
     auto testNote = GetTestSaplingNote(sk.DefaultAddress(), 10);
     auto fvk = sk.expsk.full_viewing_key();
-    auto nullifier = testNote.note.nullifier(fvk, testNote.tree.witness().position()).get();
+    auto nullifier = testNote.note.nullifier(fvk, testNote.tree.witness().position()).value();
 
     mapSaplingNoteData_t noteDataMap;
     SaplingOutPoint outPoint {wtx.GetHash(), 0};
@@ -595,7 +595,7 @@ double benchmark_create_sapling_spend()
     SaplingNote note(address, GetRand(MAX_MONEY), libzcash::Zip212Enabled::BeforeZip212);
     SaplingMerkleTree tree;
     auto maybe_cmu = note.cmu();
-    tree.append(maybe_cmu.get());
+    tree.append(maybe_cmu.value());
     auto anchor = tree.root();
     auto witness = tree.witness();
     auto maybe_nf = note.nullifier(expsk.full_viewing_key(), witness.position());
@@ -653,7 +653,7 @@ double benchmark_create_sapling_output()
         throw JSONRPCError(RPC_INTERNAL_ERROR, "SaplingNotePlaintext::encrypt() failed");
     }
 
-    auto enc = res.get();
+    auto enc = res.value();
     auto encryptor = enc.second;
 
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);

From 521eb81a95e87c630bef19e704f7f3612dc39d53 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Wed, 21 Oct 2020 01:39:13 +0100
Subject: [PATCH 05/11] Add <optional> header to files that will need it

---
 src/chain.h                                       | 1 +
 src/chainparams.cpp                               | 1 +
 src/consensus/params.h                            | 1 +
 src/consensus/upgrades.h                          | 1 +
 src/crypto/equihash.cpp                           | 2 ++
 src/experimental_features.h                       | 1 +
 src/gtest/test_noteencryption.cpp                 | 1 +
 src/gtest/test_upgrades.cpp                       | 1 +
 src/gtest/test_validation.cpp                     | 2 ++
 src/main.h                                        | 1 +
 src/mempool_limit.h                               | 1 +
 src/metrics.cpp                                   | 2 ++
 src/metrics.h                                     | 1 +
 src/rpc/blockchain.cpp                            | 1 +
 src/serialize.h                                   | 1 +
 src/test/serialize_tests.cpp                      | 1 +
 src/transaction_builder.h                         | 1 +
 src/txmempool.cpp                                 | 2 ++
 src/validationinterface.h                         | 2 ++
 src/wallet/asyncrpcoperation_common.h             | 2 ++
 src/wallet/asyncrpcoperation_mergetoaddress.h     | 1 +
 src/wallet/asyncrpcoperation_saplingmigration.cpp | 1 +
 src/wallet/asyncrpcoperation_sendmany.h           | 1 +
 src/wallet/asyncrpcoperation_shieldcoinbase.cpp   | 1 +
 src/wallet/gtest/test_wallet.cpp                  | 2 ++
 src/wallet/rpcdump.cpp                            | 1 +
 src/wallet/rpcwallet.cpp                          | 1 +
 src/wallet/test/rpc_wallet_tests.cpp              | 1 +
 src/wallet/wallet.h                               | 1 +
 src/zcash/IncrementalMerkleTree.hpp               | 1 +
 src/zcash/Note.hpp                                | 1 +
 src/zcash/NoteEncryption.hpp                      | 1 +
 src/zcash/address/sapling.hpp                     | 2 ++
 src/zcash/address/zip32.h                         | 1 +
 34 files changed, 42 insertions(+)

diff --git a/src/chain.h b/src/chain.h
index bedad61ee..2458d9690 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -12,6 +12,7 @@
 #include "tinyformat.h"
 #include "uint256.h"
 
+#include <optional>
 #include <vector>
 
 static const int SPROUT_VALUE_VERSION = 1001400;
diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 359a6f59b..774a3f064 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -13,6 +13,7 @@
 #include "utilstrencodings.h"
 
 #include <assert.h>
+#include <optional>
 #include <variant>
 
 #include <boost/assign/list_of.hpp>
diff --git a/src/consensus/params.h b/src/consensus/params.h
index f5830855d..51e36c209 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -11,6 +11,7 @@
 #include "key_constants.h"
 #include <zcash/address/sapling.hpp>
 
+#include <optional>
 #include <variant>
 
 #include <boost/optional.hpp>
diff --git a/src/consensus/upgrades.h b/src/consensus/upgrades.h
index e8ed40daa..b06d34542 100644
--- a/src/consensus/upgrades.h
+++ b/src/consensus/upgrades.h
@@ -7,6 +7,7 @@
 
 #include "consensus/params.h"
 
+#include <optional>
 #include <boost/optional.hpp>
 
 enum UpgradeState {
diff --git a/src/crypto/equihash.cpp b/src/crypto/equihash.cpp
index d63d0f9d3..ffe293b2d 100644
--- a/src/crypto/equihash.cpp
+++ b/src/crypto/equihash.cpp
@@ -20,6 +20,8 @@
 #include "crypto/equihash.h"
 #include "util.h"
 
+#include <optional>
+
 #ifdef ENABLE_MINING
 void eh_HashState::Update(const unsigned char *input, size_t inputLen)
 {
diff --git a/src/experimental_features.h b/src/experimental_features.h
index 35333fbd4..48d916492 100644
--- a/src/experimental_features.h
+++ b/src/experimental_features.h
@@ -5,6 +5,7 @@
 #ifndef ZCASH_EXPERIMENTAL_FEATURES_H
 #define ZCASH_EXPERIMENTAL_FEATURES_H
 
+#include <optional>
 #include <string>
 #include <vector>
 #include <boost/optional.hpp>
diff --git a/src/gtest/test_noteencryption.cpp b/src/gtest/test_noteencryption.cpp
index a4b3d9229..d59afd485 100644
--- a/src/gtest/test_noteencryption.cpp
+++ b/src/gtest/test_noteencryption.cpp
@@ -2,6 +2,7 @@
 #include "sodium.h"
 
 #include <array>
+#include <optional>
 #include <stdexcept>
 
 #include "zcash/Note.hpp"
diff --git a/src/gtest/test_upgrades.cpp b/src/gtest/test_upgrades.cpp
index b33317288..71a0e3256 100644
--- a/src/gtest/test_upgrades.cpp
+++ b/src/gtest/test_upgrades.cpp
@@ -3,6 +3,7 @@
 #include "chainparams.h"
 #include "consensus/upgrades.h"
 
+#include <optional>
 #include <boost/optional.hpp>
 
 class UpgradesTest : public ::testing::Test {
diff --git a/src/gtest/test_validation.cpp b/src/gtest/test_validation.cpp
index dec997196..4d195f2ce 100644
--- a/src/gtest/test_validation.cpp
+++ b/src/gtest/test_validation.cpp
@@ -7,6 +7,8 @@
 #include "transaction_builder.h"
 #include "utiltest.h"
 
+#include <optional>
+
 extern bool ReceivedBlockTransactions(
     const CBlock &block,
     CValidationState& state,
diff --git a/src/main.h b/src/main.h
index c029fd68f..a4b176905 100644
--- a/src/main.h
+++ b/src/main.h
@@ -35,6 +35,7 @@
 #include <algorithm>
 #include <exception>
 #include <map>
+#include <optional>
 #include <set>
 #include <stdint.h>
 #include <string>
diff --git a/src/mempool_limit.h b/src/mempool_limit.h
index f6b011474..c00f94384 100644
--- a/src/mempool_limit.h
+++ b/src/mempool_limit.h
@@ -6,6 +6,7 @@
 #define ZCASH_MEMPOOL_LIMIT_H
 
 #include <map>
+#include <optional>
 #include <set>
 #include <vector>
 
diff --git a/src/metrics.cpp b/src/metrics.cpp
index a688b4019..68fff8122 100644
--- a/src/metrics.cpp
+++ b/src/metrics.cpp
@@ -18,6 +18,8 @@
 #include <boost/range/irange.hpp>
 #include <boost/thread.hpp>
 #include <boost/thread/synchronized_value.hpp>
+
+#include <optional>
 #include <string>
 #ifdef WIN32
 #include <io.h>
diff --git a/src/metrics.h b/src/metrics.h
index da1ffd00c..a3f2f67d0 100644
--- a/src/metrics.h
+++ b/src/metrics.h
@@ -10,6 +10,7 @@
 
 #include <atomic>
 #include <mutex>
+#include <optional>
 #include <string>
 
 struct AtomicCounter {
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index d3695051e..1cc1e4598 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -22,6 +22,7 @@
 
 #include <univalue.h>
 
+#include <optional>
 #include <regex>
 
 using namespace std;
diff --git a/src/serialize.h b/src/serialize.h
index b19344af4..29d35900b 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -16,6 +16,7 @@
 #include <list>
 #include <map>
 #include <memory>
+#include <optional>
 #include <set>
 #include <stdint.h>
 #include <string>
diff --git a/src/test/serialize_tests.cpp b/src/test/serialize_tests.cpp
index bed934000..ac79ef82d 100644
--- a/src/test/serialize_tests.cpp
+++ b/src/test/serialize_tests.cpp
@@ -9,6 +9,7 @@
 #include "utilstrencodings.h"
 
 #include <array>
+#include <optional>
 #include <stdint.h>
 
 #include <boost/test/unit_test.hpp>
diff --git a/src/transaction_builder.h b/src/transaction_builder.h
index 7c8523049..36bc5ba6d 100644
--- a/src/transaction_builder.h
+++ b/src/transaction_builder.h
@@ -18,6 +18,7 @@
 #include "zcash/Note.hpp"
 #include "zcash/NoteEncryption.hpp"
 
+#include <optional>
 #include <boost/optional.hpp>
 
 #define NO_MEMO {{0xF6}}
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index b3ceb860c..3f889c2b5 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -17,6 +17,8 @@
 #include "validationinterface.h"
 #include "version.h"
 
+#include <optional>
+
 using namespace std;
 
 CTxMemPoolEntry::CTxMemPoolEntry():
diff --git a/src/validationinterface.h b/src/validationinterface.h
index 127848947..ec1568183 100644
--- a/src/validationinterface.h
+++ b/src/validationinterface.h
@@ -6,6 +6,8 @@
 #ifndef BITCOIN_VALIDATIONINTERFACE_H
 #define BITCOIN_VALIDATIONINTERFACE_H
 
+#include <optional>
+
 #include <boost/signals2/signal.hpp>
 #include <boost/shared_ptr.hpp>
 
diff --git a/src/wallet/asyncrpcoperation_common.h b/src/wallet/asyncrpcoperation_common.h
index d63f5821e..d7448eb3d 100644
--- a/src/wallet/asyncrpcoperation_common.h
+++ b/src/wallet/asyncrpcoperation_common.h
@@ -9,6 +9,8 @@
 #include "univalue.h"
 #include "wallet.h"
 
+#include <optional>
+
 /**
  * Sends a given transaction.
  * 
diff --git a/src/wallet/asyncrpcoperation_mergetoaddress.h b/src/wallet/asyncrpcoperation_mergetoaddress.h
index d0b8b177f..d00733753 100644
--- a/src/wallet/asyncrpcoperation_mergetoaddress.h
+++ b/src/wallet/asyncrpcoperation_mergetoaddress.h
@@ -15,6 +15,7 @@
 #include "zcash/JoinSplit.hpp"
 
 #include <array>
+#include <optional>
 #include <tuple>
 #include <unordered_map>
 
diff --git a/src/wallet/asyncrpcoperation_saplingmigration.cpp b/src/wallet/asyncrpcoperation_saplingmigration.cpp
index 94cf972fc..fbad5f956 100644
--- a/src/wallet/asyncrpcoperation_saplingmigration.cpp
+++ b/src/wallet/asyncrpcoperation_saplingmigration.cpp
@@ -11,6 +11,7 @@
 #include "utilmoneystr.h"
 #include "wallet.h"
 
+#include <optional>
 #include <variant>
 
 const CAmount FEE = 10000;
diff --git a/src/wallet/asyncrpcoperation_sendmany.h b/src/wallet/asyncrpcoperation_sendmany.h
index cc0a941fa..7fd33ce79 100644
--- a/src/wallet/asyncrpcoperation_sendmany.h
+++ b/src/wallet/asyncrpcoperation_sendmany.h
@@ -15,6 +15,7 @@
 #include "wallet/paymentdisclosure.h"
 
 #include <array>
+#include <optional>
 #include <unordered_map>
 #include <tuple>
 
diff --git a/src/wallet/asyncrpcoperation_shieldcoinbase.cpp b/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
index f8ad942b9..8e9a0c48c 100644
--- a/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
+++ b/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
@@ -32,6 +32,7 @@
 #include <array>
 #include <iostream>
 #include <chrono>
+#include <optional>
 #include <thread>
 #include <string>
 #include <variant>
diff --git a/src/wallet/gtest/test_wallet.cpp b/src/wallet/gtest/test_wallet.cpp
index 97ecd8bc3..4b4b1686c 100644
--- a/src/wallet/gtest/test_wallet.cpp
+++ b/src/wallet/gtest/test_wallet.cpp
@@ -14,6 +14,8 @@
 #include "zcash/Note.hpp"
 #include "zcash/NoteEncryption.hpp"
 
+#include <optional>
+
 using ::testing::Return;
 
 ACTION(ThrowLogicError) {
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index a2c0937a1..8b90280ef 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -15,6 +15,7 @@
 #include "wallet.h"
 
 #include <fstream>
+#include <optional>
 #include <stdint.h>
 #include <variant>
 
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 7847f6d65..27b3329fd 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -42,6 +42,7 @@
 #include <univalue.h>
 
 #include <numeric>
+#include <optional>
 #include <variant>
 
 #include <rust/ed25519.h>
diff --git a/src/wallet/test/rpc_wallet_tests.cpp b/src/wallet/test/rpc_wallet_tests.cpp
index de269349c..9634fce0e 100644
--- a/src/wallet/test/rpc_wallet_tests.cpp
+++ b/src/wallet/test/rpc_wallet_tests.cpp
@@ -28,6 +28,7 @@
 
 #include <array>
 #include <chrono>
+#include <optional>
 #include <thread>
 #include <variant>
 
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index f9d4e7e15..b6c413850 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -28,6 +28,7 @@
 
 #include <algorithm>
 #include <map>
+#include <optional>
 #include <set>
 #include <stdexcept>
 #include <stdint.h>
diff --git a/src/zcash/IncrementalMerkleTree.hpp b/src/zcash/IncrementalMerkleTree.hpp
index 805f456eb..80f7e846d 100644
--- a/src/zcash/IncrementalMerkleTree.hpp
+++ b/src/zcash/IncrementalMerkleTree.hpp
@@ -3,6 +3,7 @@
 
 #include <array>
 #include <deque>
+#include <optional>
 #include <boost/optional.hpp>
 
 #include "uint256.h"
diff --git a/src/zcash/Note.hpp b/src/zcash/Note.hpp
index 34eaafb7d..d2ab36145 100644
--- a/src/zcash/Note.hpp
+++ b/src/zcash/Note.hpp
@@ -9,6 +9,7 @@
 #include "consensus/consensus.h"
 
 #include <array>
+#include <optional>
 #include <boost/optional.hpp>
 
 namespace libzcash {
diff --git a/src/zcash/NoteEncryption.hpp b/src/zcash/NoteEncryption.hpp
index 308d81dc1..b3c029cad 100644
--- a/src/zcash/NoteEncryption.hpp
+++ b/src/zcash/NoteEncryption.hpp
@@ -13,6 +13,7 @@ https://github.com/zcash/zips/blob/master/protocol/protocol.pdf
 #include "zcash/Address.hpp"
 
 #include <array>
+#include <optional>
 
 namespace libzcash {
 
diff --git a/src/zcash/address/sapling.hpp b/src/zcash/address/sapling.hpp
index 477474126..11d0cc196 100644
--- a/src/zcash/address/sapling.hpp
+++ b/src/zcash/address/sapling.hpp
@@ -9,6 +9,8 @@
 #include "uint256.h"
 #include "zcash/Zcash.h"
 
+#include <optional>
+
 namespace libzcash {
 
 const size_t SerializedSaplingPaymentAddressSize = 43;
diff --git a/src/zcash/address/zip32.h b/src/zcash/address/zip32.h
index 8ce2c9ba3..5aef0babb 100644
--- a/src/zcash/address/zip32.h
+++ b/src/zcash/address/zip32.h
@@ -10,6 +10,7 @@
 #include "uint256.h"
 #include "zcash/address/sapling.hpp"
 
+#include <optional>
 #include <boost/optional.hpp>
 
 const uint32_t ZIP32_HARDENED_KEY_LIMIT = 0x80000000;

From d8d0918951acd0fbab197f7eb46e38da53169ed6 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Wed, 21 Oct 2020 01:44:15 +0100
Subject: [PATCH 06/11] scripted-diff: Migrate from boost::optional to
 std::optional

-BEGIN VERIFY SCRIPT-
sed -i 's/boost::none/std::nullopt/g' ./src/*.h ./src/*.cpp ./src/*/*.h* ./src/*/*.cpp ./src/*/*/*.h* ./src/*/*/*.cpp ;
sed -i 's/boost::optional/std::optional/g' ./src/*.h ./src/*.cpp ./src/*/*.h* ./src/*/*.cpp ./src/*/*/*.h* ./src/*/*/*.cpp ;
sed -i 's/std::optional<\(.*\)&>/std::optional<std::reference_wrapper<\1>>/' ./src/*/*.h ./src/*/*.cpp ;
sed -i 's/is_initialized()/has_value()/' ./src/*.cpp ./src/*/*.cpp ;
sed -i ':a;N;$!ba;s/#include <boost\/optional.hpp>\n//' ./src/*.h ./src/*.cpp ./src/*/*.h* ./src/*/*.cpp ./src/*/*/*.h ./src/*/*/*.cpp ;
sed -i ':a;N;$!ba;s/#include "boost\/optional.hpp"\n//' ./src/*.h ;
-END VERIFY SCRIPT-
---
 src/chain.h                                   | 26 +++---
 src/chainparams.cpp                           |  2 +-
 src/consensus/params.h                        |  7 +-
 src/consensus/upgrades.cpp                    | 10 +--
 src/consensus/upgrades.h                      |  9 +-
 src/crypto/equihash.cpp                       |  7 +-
 src/experimental_features.cpp                 |  4 +-
 src/experimental_features.h                   |  3 +-
 src/gtest/test_mempoollimit.cpp               |  6 +-
 src/gtest/test_noteencryption.cpp             |  2 +-
 src/gtest/test_upgrades.cpp                   | 49 ++++++-----
 src/gtest/test_validation.cpp                 |  4 +-
 src/main.cpp                                  | 22 ++---
 src/main.h                                    |  2 +-
 src/mempool_limit.cpp                         |  4 +-
 src/mempool_limit.h                           |  3 +-
 src/metrics.cpp                               |  7 +-
 src/metrics.h                                 |  2 +-
 src/miner.cpp                                 |  4 +-
 src/miner.h                                   |  1 -
 src/pow.cpp                                   |  2 +-
 src/rpc/blockchain.cpp                        |  8 +-
 src/serialize.h                               | 11 ++-
 src/test/serialize_tests.cpp                  |  9 +-
 src/transaction_builder.cpp                   | 26 +++---
 src/transaction_builder.h                     | 13 ++-
 src/txmempool.cpp                             |  4 +-
 src/validationinterface.cpp                   |  2 +-
 src/validationinterface.h                     |  4 +-
 src/wallet/asyncrpcoperation_common.cpp       |  4 +-
 src/wallet/asyncrpcoperation_common.h         |  4 +-
 .../asyncrpcoperation_mergetoaddress.cpp      | 28 +++----
 src/wallet/asyncrpcoperation_mergetoaddress.h |  8 +-
 .../asyncrpcoperation_saplingmigration.cpp    |  2 +-
 src/wallet/asyncrpcoperation_sendmany.cpp     | 20 ++---
 src/wallet/asyncrpcoperation_sendmany.h       |  8 +-
 .../asyncrpcoperation_shieldcoinbase.cpp      |  4 +-
 src/wallet/gtest/test_wallet.cpp              | 36 ++++----
 src/wallet/paymentdisclosuredb.h              |  1 -
 src/wallet/rpcdump.cpp                        |  4 +-
 src/wallet/rpcwallet.cpp                      |  8 +-
 src/wallet/test/rpc_wallet_tests.cpp          | 49 ++++++-----
 src/wallet/wallet.cpp                         | 82 +++++++++----------
 src/wallet/wallet.h                           | 46 +++++------
 src/zcash/IncrementalMerkleTree.cpp           | 16 ++--
 src/zcash/IncrementalMerkleTree.hpp           |  9 +-
 src/zcash/JoinSplit.cpp                       |  1 -
 src/zcash/Note.cpp                            | 72 ++++++++--------
 src/zcash/Note.hpp                            | 23 +++---
 src/zcash/NoteEncryption.cpp                  | 24 +++---
 src/zcash/NoteEncryption.hpp                  | 10 +--
 src/zcash/address/sapling.cpp                 |  6 +-
 src/zcash/address/sapling.hpp                 |  2 +-
 src/zcash/address/zip32.cpp                   |  8 +-
 src/zcash/address/zip32.h                     |  5 +-
 55 files changed, 358 insertions(+), 375 deletions(-)

diff --git a/src/chain.h b/src/chain.h
index 2458d9690..01204fdc8 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -229,7 +229,7 @@ public:
     //! Branch ID corresponding to the consensus rules used to validate this block.
     //! Only cached if block validity is BLOCK_VALID_CONSENSUS.
     //! Persisted at each activation height, memory-only for intervening blocks.
-    boost::optional<uint32_t> nCachedBranchId;
+    std::optional<uint32_t> nCachedBranchId;
 
     //! The anchor for the tree state up to the start of this block
     uint256 hashSproutAnchor;
@@ -238,22 +238,22 @@ public:
     uint256 hashFinalSproutRoot;
 
     //! Change in value held by the Sprout circuit over this block.
-    //! Will be boost::none for older blocks on old nodes until a reindex has taken place.
-    boost::optional<CAmount> nSproutValue;
+    //! Will be std::nullopt for older blocks on old nodes until a reindex has taken place.
+    std::optional<CAmount> nSproutValue;
 
     //! (memory only) Total value held by the Sprout circuit up to and including this block.
-    //! Will be boost::none for on old nodes until a reindex has taken place.
-    //! Will be boost::none if nChainTx is zero.
-    boost::optional<CAmount> nChainSproutValue;
+    //! Will be std::nullopt for on old nodes until a reindex has taken place.
+    //! Will be std::nullopt if nChainTx is zero.
+    std::optional<CAmount> nChainSproutValue;
 
     //! Change in value held by the Sapling circuit over this block.
-    //! Not a boost::optional because this was added before Sapling activated, so we can
+    //! Not a std::optional because this was added before Sapling activated, so we can
     //! rely on the invariant that every block before this was added had nSaplingValue = 0.
     CAmount nSaplingValue;
 
     //! (memory only) Total value held by the Sapling circuit up to and including this block.
-    //! Will be boost::none if nChainTx is zero.
-    boost::optional<CAmount> nChainSaplingValue;
+    //! Will be std::nullopt if nChainTx is zero.
+    std::optional<CAmount> nChainSaplingValue;
 
     //! Root of the Sapling commitment tree as of the end of this block.
     //!
@@ -296,14 +296,14 @@ public:
         nTx = 0;
         nChainTx = 0;
         nStatus = 0;
-        nCachedBranchId = boost::none;
+        nCachedBranchId = std::nullopt;
         hashSproutAnchor = uint256();
         hashFinalSproutRoot = uint256();
         nSequenceId = 0;
-        nSproutValue = boost::none;
-        nChainSproutValue = boost::none;
+        nSproutValue = std::nullopt;
+        nChainSproutValue = std::nullopt;
         nSaplingValue = 0;
-        nChainSaplingValue = boost::none;
+        nChainSaplingValue = std::nullopt;
 
         nVersion       = 0;
         hashMerkleRoot = uint256();
diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 774a3f064..4f4b81130 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -105,7 +105,7 @@ public:
         consensus.nPowMaxAdjustUp = 16; // 16% adjustment up
         consensus.nPreBlossomPowTargetSpacing = Consensus::PRE_BLOSSOM_POW_TARGET_SPACING;
         consensus.nPostBlossomPowTargetSpacing = Consensus::POST_BLOSSOM_POW_TARGET_SPACING;
-        consensus.nPowAllowMinDifficultyBlocksAfterHeight = boost::none;
+        consensus.nPowAllowMinDifficultyBlocksAfterHeight = std::nullopt;
         consensus.fPowNoRetargeting = false;
         consensus.vUpgrades[Consensus::BASE_SPROUT].nProtocolVersion = 170002;
         consensus.vUpgrades[Consensus::BASE_SPROUT].nActivationHeight =
diff --git a/src/consensus/params.h b/src/consensus/params.h
index 51e36c209..464ca0347 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -14,7 +14,6 @@
 #include <optional>
 #include <variant>
 
-#include <boost/optional.hpp>
 
 namespace Consensus {
 
@@ -81,7 +80,7 @@ struct NetworkUpgrade {
      * scrutiny than regular releases. nMinimumChainWork MUST be set to at least the chain
      * work of this block, otherwise this detection will have false positives.
      */
-    boost::optional<uint256> hashActivationBlock;
+    std::optional<uint256> hashActivationBlock;
 };
 
 typedef std::variant<libzcash::SaplingPaymentAddress, CScript> FundingStreamAddress;
@@ -212,7 +211,7 @@ struct Params {
     NetworkUpgrade vUpgrades[MAX_NETWORK_UPGRADES];
 
     int nFundingPeriodLength;
-    boost::optional<FundingStream> vFundingStreams[MAX_FUNDING_STREAMS];
+    std::optional<FundingStream> vFundingStreams[MAX_FUNDING_STREAMS];
     void AddZIP207FundingStream(
         const KeyConstants& keyConstants,
         FundingStreamIndex idx,
@@ -264,7 +263,7 @@ struct Params {
     unsigned int nEquihashN = 0;
     unsigned int nEquihashK = 0;
     uint256 powLimit;
-    boost::optional<uint32_t> nPowAllowMinDifficultyBlocksAfterHeight;
+    std::optional<uint32_t> nPowAllowMinDifficultyBlocksAfterHeight;
     bool fPowNoRetargeting;
     int64_t nPowAveragingWindow;
     int64_t nPowMaxAdjustDown;
diff --git a/src/consensus/upgrades.cpp b/src/consensus/upgrades.cpp
index 07003907b..29f8acce7 100644
--- a/src/consensus/upgrades.cpp
+++ b/src/consensus/upgrades.cpp
@@ -140,9 +140,9 @@ bool IsActivationHeightForAnyUpgrade(
     return false;
 }
 
-boost::optional<int> NextEpoch(int nHeight, const Consensus::Params& params) {
+std::optional<int> NextEpoch(int nHeight, const Consensus::Params& params) {
     if (nHeight < 0) {
-        return boost::none;
+        return std::nullopt;
     }
 
     // Sprout is never pending
@@ -152,10 +152,10 @@ boost::optional<int> NextEpoch(int nHeight, const Consensus::Params& params) {
         }
     }
 
-    return boost::none;
+    return std::nullopt;
 }
 
-boost::optional<int> NextActivationHeight(
+std::optional<int> NextActivationHeight(
     int nHeight,
     const Consensus::Params& params)
 {
@@ -163,5 +163,5 @@ boost::optional<int> NextActivationHeight(
     if (idx) {
         return params.vUpgrades[idx.value()].nActivationHeight;
     }
-    return boost::none;
+    return std::nullopt;
 }
diff --git a/src/consensus/upgrades.h b/src/consensus/upgrades.h
index b06d34542..812c0ad18 100644
--- a/src/consensus/upgrades.h
+++ b/src/consensus/upgrades.h
@@ -8,7 +8,6 @@
 #include "consensus/params.h"
 
 #include <optional>
-#include <boost/optional.hpp>
 
 enum UpgradeState {
     UPGRADE_DISABLED,
@@ -84,15 +83,15 @@ bool IsActivationHeightForAnyUpgrade(
 
 /**
  * Returns the index of the next upgrade after the given block height, or
- * boost::none if there are no more known upgrades.
+ * std::nullopt if there are no more known upgrades.
  */
-boost::optional<int> NextEpoch(int nHeight, const Consensus::Params& params);
+std::optional<int> NextEpoch(int nHeight, const Consensus::Params& params);
 
 /**
  * Returns the activation height for the next upgrade after the given block height,
- * or boost::none if there are no more known upgrades.
+ * or std::nullopt if there are no more known upgrades.
  */
-boost::optional<int> NextActivationHeight(
+std::optional<int> NextActivationHeight(
     int nHeight,
     const Consensus::Params& params);
 
diff --git a/src/crypto/equihash.cpp b/src/crypto/equihash.cpp
index ffe293b2d..ad64a37fc 100644
--- a/src/crypto/equihash.cpp
+++ b/src/crypto/equihash.cpp
@@ -151,7 +151,6 @@ std::vector<unsigned char> GetMinimalFromIndices(std::vector<eh_index> indices,
 #include <iostream>
 #include <stdexcept>
 
-#include <boost/optional.hpp>
 
 static EhSolverCancelledException solver_cancelled;
 
@@ -648,7 +647,7 @@ bool Equihash<N,K>::OptimisedSolve(const eh_HashState& base_state,
         size_t hashLen;
         size_t lenIndices;
         unsigned char tmpHash[HashOutput];
-        std::vector<boost::optional<std::vector<FullStepRow<FinalFullWidth>>>> X;
+        std::vector<std::optional<std::vector<FullStepRow<FinalFullWidth>>>> X;
         X.reserve(K+1);
 
         // 3) Repeat steps 1 and 2 for each partial index
@@ -666,7 +665,7 @@ bool Equihash<N,K>::OptimisedSolve(const eh_HashState& base_state,
                                  N/8, HashLength, CollisionBitLength, newIndex);
                 if (cancelled(PartialGeneration)) throw solver_cancelled;
             }
-            boost::optional<std::vector<FullStepRow<FinalFullWidth>>> ic = icv;
+            std::optional<std::vector<FullStepRow<FinalFullWidth>>> ic = icv;
 
             // 2a) For each pair of lists:
             hashLen = HashLength;
@@ -691,7 +690,7 @@ bool Equihash<N,K>::OptimisedSolve(const eh_HashState& base_state,
                         if (ic->size() == 0)
                             goto invalidsolution;
 
-                        X[r] = boost::none;
+                        X[r] = std::nullopt;
                         hashLen -= CollisionByteLength;
                         lenIndices *= 2;
                         rti = lti;
diff --git a/src/experimental_features.cpp b/src/experimental_features.cpp
index 93a4fd2ed..67afbf7fc 100644
--- a/src/experimental_features.cpp
+++ b/src/experimental_features.cpp
@@ -12,7 +12,7 @@ bool fExperimentalPaymentDisclosure = false;
 bool fExperimentalInsightExplorer = false;
 bool fExperimentalLightWalletd = false;
 
-boost::optional<std::string> InitExperimentalMode()
+std::optional<std::string> InitExperimentalMode()
 {
     auto fExperimentalMode = GetBoolArg("-experimentalfeatures", false);
     fExperimentalDeveloperEncryptWallet = GetBoolArg("-developerencryptwallet", false);
@@ -35,7 +35,7 @@ boost::optional<std::string> InitExperimentalMode()
             return _("Light Walletd requires -experimentalfeatures.");
         }
     }
-    return boost::none;
+    return std::nullopt;
 }
 
 std::vector<std::string> GetExperimentalFeatures()
diff --git a/src/experimental_features.h b/src/experimental_features.h
index 48d916492..d607f1d53 100644
--- a/src/experimental_features.h
+++ b/src/experimental_features.h
@@ -8,7 +8,6 @@
 #include <optional>
 #include <string>
 #include <vector>
-#include <boost/optional.hpp>
 
 extern bool fExperimentalDeveloperEncryptWallet;
 extern bool fExperimentalDeveloperSetPoolSizeZero;
@@ -16,7 +15,7 @@ extern bool fExperimentalPaymentDisclosure;
 extern bool fExperimentalInsightExplorer;
 extern bool fExperimentalLightWalletd;
 
-boost::optional<std::string> InitExperimentalMode();
+std::optional<std::string> InitExperimentalMode();
 std::vector<std::string> GetExperimentalFeatures();
 
 #endif // ZCASH_EXPERIMENTAL_FEATURES_H
diff --git a/src/gtest/test_mempoollimit.cpp b/src/gtest/test_mempoollimit.cpp
index 5d9d01739..8869b27d7 100644
--- a/src/gtest/test_mempoollimit.cpp
+++ b/src/gtest/test_mempoollimit.cpp
@@ -94,12 +94,12 @@ TEST(MempoolLimitTests, WeightedTxTreeCheckSizeAfterDropping)
         tree.add(WeightedTxInfo(TX_ID2, TxWeight(MIN_TX_COST, MIN_TX_COST)));
         EXPECT_EQ(8000, tree.getTotalWeight().cost);
         EXPECT_EQ(8000, tree.getTotalWeight().evictionWeight);
-        EXPECT_FALSE(tree.maybeDropRandom().is_initialized());
+        EXPECT_FALSE(tree.maybeDropRandom().has_value());
         tree.add(WeightedTxInfo(TX_ID3, TxWeight(MIN_TX_COST, MIN_TX_COST + LOW_FEE_PENALTY)));
         EXPECT_EQ(12000, tree.getTotalWeight().cost);
         EXPECT_EQ(12000 + LOW_FEE_PENALTY, tree.getTotalWeight().evictionWeight);
-        boost::optional<uint256> drop = tree.maybeDropRandom();
-        ASSERT_TRUE(drop.is_initialized());
+        std::optional<uint256> drop = tree.maybeDropRandom();
+        ASSERT_TRUE(drop.has_value());
         uint256 txid = drop.value();
         testedDropping.insert(txid);
         // Do not continue to test if a particular trial fails
diff --git a/src/gtest/test_noteencryption.cpp b/src/gtest/test_noteencryption.cpp
index d59afd485..640dd64d6 100644
--- a/src/gtest/test_noteencryption.cpp
+++ b/src/gtest/test_noteencryption.cpp
@@ -443,7 +443,7 @@ TEST(NoteEncryption, SaplingApi)
     librustzcash_sapling_generate_r(esk.begin());
 
     // Invalid diversifier
-    ASSERT_EQ(boost::none, SaplingNoteEncryption::FromDiversifier({1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, esk));
+    ASSERT_EQ(std::nullopt, SaplingNoteEncryption::FromDiversifier({1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, esk));
 
     // Encrypt to pk_1
     auto enc = *SaplingNoteEncryption::FromDiversifier(pk_1.d, esk);
diff --git a/src/gtest/test_upgrades.cpp b/src/gtest/test_upgrades.cpp
index 71a0e3256..d7ff0d791 100644
--- a/src/gtest/test_upgrades.cpp
+++ b/src/gtest/test_upgrades.cpp
@@ -4,7 +4,6 @@
 #include "consensus/upgrades.h"
 
 #include <optional>
-#include <boost/optional.hpp>
 
 class UpgradesTest : public ::testing::Test {
 protected:
@@ -149,28 +148,28 @@ TEST_F(UpgradesTest, NextEpoch) {
     const Consensus::Params& params = Params().GetConsensus();
 
     // Consensus::NetworkUpgrade::NO_ACTIVATION_HEIGHT
-    EXPECT_EQ(NextEpoch(-1, params), boost::none);
-    EXPECT_EQ(NextEpoch(0, params), boost::none);
-    EXPECT_EQ(NextEpoch(1, params), boost::none);
-    EXPECT_EQ(NextEpoch(1000000, params), boost::none);
+    EXPECT_EQ(NextEpoch(-1, params), std::nullopt);
+    EXPECT_EQ(NextEpoch(0, params), std::nullopt);
+    EXPECT_EQ(NextEpoch(1, params), std::nullopt);
+    EXPECT_EQ(NextEpoch(1000000, params), std::nullopt);
 
     UpdateNetworkUpgradeParameters(Consensus::UPGRADE_TESTDUMMY, Consensus::NetworkUpgrade::ALWAYS_ACTIVE);
 
-    EXPECT_EQ(NextEpoch(-1, params), boost::none);
-    EXPECT_EQ(NextEpoch(0, params), boost::none);
-    EXPECT_EQ(NextEpoch(1, params), boost::none);
-    EXPECT_EQ(NextEpoch(1000000, params), boost::none);
+    EXPECT_EQ(NextEpoch(-1, params), std::nullopt);
+    EXPECT_EQ(NextEpoch(0, params), std::nullopt);
+    EXPECT_EQ(NextEpoch(1, params), std::nullopt);
+    EXPECT_EQ(NextEpoch(1000000, params), std::nullopt);
 
     int nActivationHeight = 100;
     UpdateNetworkUpgradeParameters(Consensus::UPGRADE_TESTDUMMY, nActivationHeight);
 
-    EXPECT_EQ(NextEpoch(-1, params), boost::none);
+    EXPECT_EQ(NextEpoch(-1, params), std::nullopt);
     EXPECT_EQ(NextEpoch(0, params), static_cast<int>(Consensus::UPGRADE_TESTDUMMY));
     EXPECT_EQ(NextEpoch(1, params), static_cast<int>(Consensus::UPGRADE_TESTDUMMY));
     EXPECT_EQ(NextEpoch(nActivationHeight - 1, params), static_cast<int>(Consensus::UPGRADE_TESTDUMMY));
-    EXPECT_EQ(NextEpoch(nActivationHeight, params), boost::none);
-    EXPECT_EQ(NextEpoch(nActivationHeight + 1, params), boost::none);
-    EXPECT_EQ(NextEpoch(1000000, params), boost::none);
+    EXPECT_EQ(NextEpoch(nActivationHeight, params), std::nullopt);
+    EXPECT_EQ(NextEpoch(nActivationHeight + 1, params), std::nullopt);
+    EXPECT_EQ(NextEpoch(1000000, params), std::nullopt);
 }
 
 TEST_F(UpgradesTest, NextActivationHeight) {
@@ -178,26 +177,26 @@ TEST_F(UpgradesTest, NextActivationHeight) {
     const Consensus::Params& params = Params().GetConsensus();
 
     // Consensus::NetworkUpgrade::NO_ACTIVATION_HEIGHT
-    EXPECT_EQ(NextActivationHeight(-1, params), boost::none);
-    EXPECT_EQ(NextActivationHeight(0, params), boost::none);
-    EXPECT_EQ(NextActivationHeight(1, params), boost::none);
-    EXPECT_EQ(NextActivationHeight(1000000, params), boost::none);
+    EXPECT_EQ(NextActivationHeight(-1, params), std::nullopt);
+    EXPECT_EQ(NextActivationHeight(0, params), std::nullopt);
+    EXPECT_EQ(NextActivationHeight(1, params), std::nullopt);
+    EXPECT_EQ(NextActivationHeight(1000000, params), std::nullopt);
 
     UpdateNetworkUpgradeParameters(Consensus::UPGRADE_TESTDUMMY, Consensus::NetworkUpgrade::ALWAYS_ACTIVE);
 
-    EXPECT_EQ(NextActivationHeight(-1, params), boost::none);
-    EXPECT_EQ(NextActivationHeight(0, params), boost::none);
-    EXPECT_EQ(NextActivationHeight(1, params), boost::none);
-    EXPECT_EQ(NextActivationHeight(1000000, params), boost::none);
+    EXPECT_EQ(NextActivationHeight(-1, params), std::nullopt);
+    EXPECT_EQ(NextActivationHeight(0, params), std::nullopt);
+    EXPECT_EQ(NextActivationHeight(1, params), std::nullopt);
+    EXPECT_EQ(NextActivationHeight(1000000, params), std::nullopt);
 
     int nActivationHeight = 100;
     UpdateNetworkUpgradeParameters(Consensus::UPGRADE_TESTDUMMY, nActivationHeight);
 
-    EXPECT_EQ(NextActivationHeight(-1, params), boost::none);
+    EXPECT_EQ(NextActivationHeight(-1, params), std::nullopt);
     EXPECT_EQ(NextActivationHeight(0, params), nActivationHeight);
     EXPECT_EQ(NextActivationHeight(1, params), nActivationHeight);
     EXPECT_EQ(NextActivationHeight(nActivationHeight - 1, params), nActivationHeight);
-    EXPECT_EQ(NextActivationHeight(nActivationHeight, params), boost::none);
-    EXPECT_EQ(NextActivationHeight(nActivationHeight + 1, params), boost::none);
-    EXPECT_EQ(NextActivationHeight(1000000, params), boost::none);
+    EXPECT_EQ(NextActivationHeight(nActivationHeight, params), std::nullopt);
+    EXPECT_EQ(NextActivationHeight(nActivationHeight + 1, params), std::nullopt);
+    EXPECT_EQ(NextActivationHeight(1000000, params), std::nullopt);
 }
diff --git a/src/gtest/test_validation.cpp b/src/gtest/test_validation.cpp
index 4d195f2ce..0710ae30d 100644
--- a/src/gtest/test_validation.cpp
+++ b/src/gtest/test_validation.cpp
@@ -16,7 +16,7 @@ extern bool ReceivedBlockTransactions(
     CBlockIndex *pindexNew,
     const CDiskBlockPos& pos);
 
-void ExpectOptionalAmount(CAmount expected, boost::optional<CAmount> actual) {
+void ExpectOptionalAmount(CAmount expected, std::optional<CAmount> actual) {
     EXPECT_TRUE((bool)actual);
     if (actual) {
         EXPECT_EQ(expected, *actual);
@@ -26,7 +26,7 @@ void ExpectOptionalAmount(CAmount expected, boost::optional<CAmount> actual) {
 // Fake a view that optionally contains a single coin.
 class ValidationFakeCoinsViewDB : public CCoinsView {
 public:
-    boost::optional<std::pair<std::pair<uint256, uint256>, std::pair<CTxOut, int>>> coin;
+    std::optional<std::pair<std::pair<uint256, uint256>, std::pair<CTxOut, int>>> coin;
 
     ValidationFakeCoinsViewDB() {}
     ValidationFakeCoinsViewDB(uint256 blockHash, uint256 txid, CTxOut txOut, int nHeight) :
diff --git a/src/main.cpp b/src/main.cpp
index 137256d46..67326de8e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -86,7 +86,7 @@ uint64_t nPruneTarget = 0;
 bool fAlerts = DEFAULT_ALERTS;
 int64_t nMaxTipAge = DEFAULT_MAX_TIP_AGE;
 
-boost::optional<unsigned int> expiryDeltaArg = boost::none;
+std::optional<unsigned int> expiryDeltaArg = std::nullopt;
 
 CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
 CAmount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
@@ -2793,7 +2793,7 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
         // Sapling
         //
         // If we've reached ConnectBlock, we have all transactions of
-        // parents and can expect nChainSaplingValue not to be boost::none.
+        // parents and can expect nChainSaplingValue not to be std::nullopt.
         // However, the miner and mining RPCs may not have populated this
         // value and will call `TestBlockValidity`. So, we act
         // conditionally.
@@ -3853,7 +3853,7 @@ void FallbackSproutValuePoolBalance(
                 assert(*pindex->nChainSproutValue == chainparams.SproutValuePoolCheckpointBalance());
                 // And we should expect non-none for the delta stored in the block index here,
                 // or the checkpoint is too early.
-                assert(pindex->nSproutValue != boost::none);
+                assert(pindex->nSproutValue != std::nullopt);
             }
         } else {
             LogPrintf(
@@ -3889,9 +3889,9 @@ bool ReceivedBlockTransactions(
         }
     }
     pindexNew->nSproutValue = sproutValue;
-    pindexNew->nChainSproutValue = boost::none;
+    pindexNew->nChainSproutValue = std::nullopt;
     pindexNew->nSaplingValue = saplingValue;
-    pindexNew->nChainSaplingValue = boost::none;
+    pindexNew->nChainSaplingValue = std::nullopt;
     pindexNew->nFile = pos.nFile;
     pindexNew->nDataPos = pos.nPos;
     pindexNew->nUndoPos = 0;
@@ -3913,12 +3913,12 @@ bool ReceivedBlockTransactions(
                 if (pindex->pprev->nChainSproutValue && pindex->nSproutValue) {
                     pindex->nChainSproutValue = *pindex->pprev->nChainSproutValue + *pindex->nSproutValue;
                 } else {
-                    pindex->nChainSproutValue = boost::none;
+                    pindex->nChainSproutValue = std::nullopt;
                 }
                 if (pindex->pprev->nChainSaplingValue) {
                     pindex->nChainSaplingValue = *pindex->pprev->nChainSaplingValue + pindex->nSaplingValue;
                 } else {
-                    pindex->nChainSaplingValue = boost::none;
+                    pindex->nChainSaplingValue = std::nullopt;
                 }
             } else {
                 pindex->nChainSproutValue = pindex->nSproutValue;
@@ -4659,17 +4659,17 @@ bool static LoadBlockIndexDB()
                     if (pindex->pprev->nChainSproutValue && pindex->nSproutValue) {
                         pindex->nChainSproutValue = *pindex->pprev->nChainSproutValue + *pindex->nSproutValue;
                     } else {
-                        pindex->nChainSproutValue = boost::none;
+                        pindex->nChainSproutValue = std::nullopt;
                     }
                     if (pindex->pprev->nChainSaplingValue) {
                         pindex->nChainSaplingValue = *pindex->pprev->nChainSaplingValue + pindex->nSaplingValue;
                     } else {
-                        pindex->nChainSaplingValue = boost::none;
+                        pindex->nChainSaplingValue = std::nullopt;
                     }
                 } else {
                     pindex->nChainTx = 0;
-                    pindex->nChainSproutValue = boost::none;
-                    pindex->nChainSaplingValue = boost::none;
+                    pindex->nChainSproutValue = std::nullopt;
+                    pindex->nChainSaplingValue = std::nullopt;
                     mapBlocksUnlinked.insert(std::make_pair(pindex->pprev, pindex));
                 }
             } else {
diff --git a/src/main.h b/src/main.h
index a4b176905..b04354967 100644
--- a/src/main.h
+++ b/src/main.h
@@ -134,7 +134,7 @@ struct BlockHasher
     size_t operator()(const uint256& hash) const { return hash.GetCheapHash(); }
 };
 
-extern boost::optional<unsigned int> expiryDeltaArg;
+extern std::optional<unsigned int> expiryDeltaArg;
 extern CScript COINBASE_FLAGS;
 extern CCriticalSection cs_main;
 extern CTxMemPool mempool;
diff --git a/src/mempool_limit.cpp b/src/mempool_limit.cpp
index efa15a8c5..78c6e7320 100644
--- a/src/mempool_limit.cpp
+++ b/src/mempool_limit.cpp
@@ -118,11 +118,11 @@ void WeightedTxTree::remove(const uint256& txId)
     childWeights.pop_back();
 }
 
-boost::optional<uint256> WeightedTxTree::maybeDropRandom()
+std::optional<uint256> WeightedTxTree::maybeDropRandom()
 {
     TxWeight totalTxWeight = getTotalWeight();
     if (totalTxWeight.cost <= capacity) {
-        return boost::none;
+        return std::nullopt;
     }
     LogPrint("mempool", "Mempool cost limit exceeded (cost=%d, limit=%d)\n", totalTxWeight.cost, capacity);
     int randomWeight = GetRand(totalTxWeight.evictionWeight);
diff --git a/src/mempool_limit.h b/src/mempool_limit.h
index c00f94384..9d8ef3f44 100644
--- a/src/mempool_limit.h
+++ b/src/mempool_limit.h
@@ -10,7 +10,6 @@
 #include <set>
 #include <vector>
 
-#include "boost/optional.hpp"
 #include "primitives/transaction.h"
 #include "uint256.h"
 
@@ -123,7 +122,7 @@ public:
 
     // If the total cost limit is exceeded, pick a random number based on the total cost
     // of the collection and remove the associated transaction.
-    boost::optional<uint256> maybeDropRandom();
+    std::optional<uint256> maybeDropRandom();
 };
 
 
diff --git a/src/metrics.cpp b/src/metrics.cpp
index 68fff8122..c921da15e 100644
--- a/src/metrics.cpp
+++ b/src/metrics.cpp
@@ -14,7 +14,6 @@
 #include "utilmoneystr.h"
 #include "utilstrencodings.h"
 
-#include <boost/optional.hpp>
 #include <boost/range/irange.hpp>
 #include <boost/thread.hpp>
 #include <boost/thread/synchronized_value.hpp>
@@ -277,13 +276,13 @@ std::string DisplayHashRate(double value)
     return strprintf(_("%.3f TSol/s"), value / coef);
 }
 
-boost::optional<int64_t> SecondsLeftToNextEpoch(const Consensus::Params& params, int currentHeight)
+std::optional<int64_t> SecondsLeftToNextEpoch(const Consensus::Params& params, int currentHeight)
 {
     auto nextHeight = NextActivationHeight(currentHeight, params);
     if (nextHeight) {
         return (nextHeight.value() - currentHeight) * params.PoWTargetSpacing(nextHeight.value() - 1);
     } else {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
@@ -643,7 +642,7 @@ void ThreadShowMetricsScreen()
         }
 
         // Lock and fetch stats before erasing the screen, in case we block.
-        boost::optional<MetricsStats> metricsStats;
+        std::optional<MetricsStats> metricsStats;
         if (loaded) {
             metricsStats = loadStats();
         }
diff --git a/src/metrics.h b/src/metrics.h
index a3f2f67d0..e20473287 100644
--- a/src/metrics.h
+++ b/src/metrics.h
@@ -76,7 +76,7 @@ void TrackMinedBlock(uint256 hash);
 void MarkStartTime();
 double GetLocalSolPS();
 int EstimateNetHeight(const Consensus::Params& params, int currentBlockHeight, int64_t currentBlockTime);
-boost::optional<int64_t> SecondsLeftToNextEpoch(const Consensus::Params& params, int currentHeight);
+std::optional<int64_t> SecondsLeftToNextEpoch(const Consensus::Params& params, int currentHeight);
 std::string DisplayDuration(int64_t time, DurationFormat format);
 std::string DisplaySize(size_t value);
 std::string DisplayHashRate(double value);
diff --git a/src/miner.cpp b/src/miner.cpp
index fbfa3fe3c..9465352bb 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -111,7 +111,7 @@ void UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams,
     pblock->nTime = nTime;
 
     // Updating time can change work required on testnet:
-    if (consensusParams.nPowAllowMinDifficultyBlocksAfterHeight != boost::none) {
+    if (consensusParams.nPowAllowMinDifficultyBlocksAfterHeight != std::nullopt) {
         pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, consensusParams);
     }
 }
@@ -931,7 +931,7 @@ void static BitcoinMiner(const CChainParams& chainparams)
                 // Update nNonce and nTime
                 pblock->nNonce = ArithToUint256(UintToArith256(pblock->nNonce) + 1);
                 UpdateTime(pblock, chainparams.GetConsensus(), pindexPrev);
-                if (chainparams.GetConsensus().nPowAllowMinDifficultyBlocksAfterHeight != boost::none)
+                if (chainparams.GetConsensus().nPowAllowMinDifficultyBlocksAfterHeight != std::nullopt)
                 {
                     // Changing pblock->nTime can change work required on testnet:
                     hashTarget.SetCompact(pblock->nBits);
diff --git a/src/miner.h b/src/miner.h
index d9c4947b2..9f3eacecf 100644
--- a/src/miner.h
+++ b/src/miner.h
@@ -8,7 +8,6 @@
 
 #include "primitives/block.h"
 
-#include <boost/optional.hpp>
 #include <boost/shared_ptr.hpp>
 #include <stdint.h>
 #include <variant>
diff --git a/src/pow.cpp b/src/pow.cpp
index 181e9d710..28b8f2bf4 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -30,7 +30,7 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
     {
         // Comparing to pindexLast->nHeight with >= because this function
         // returns the work required for the block after pindexLast.
-        if (params.nPowAllowMinDifficultyBlocksAfterHeight != boost::none &&
+        if (params.nPowAllowMinDifficultyBlocksAfterHeight != std::nullopt &&
             pindexLast->nHeight >= params.nPowAllowMinDifficultyBlocksAfterHeight.value())
         {
             // Special difficulty rule for testnet:
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 1cc1e4598..7e5bf469c 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -84,8 +84,8 @@ double GetNetworkDifficulty(const CBlockIndex* blockindex)
 
 static UniValue ValuePoolDesc(
     const std::string &name,
-    const boost::optional<CAmount> chainValue,
-    const boost::optional<CAmount> valueDelta)
+    const std::optional<CAmount> chainValue,
+    const std::optional<CAmount> valueDelta)
 {
     UniValue rv(UniValue::VOBJ);
     rv.pushKV("id", name);
@@ -1060,8 +1060,8 @@ UniValue getblockchaininfo(const UniValue& params, bool fHelp)
 
     CBlockIndex* tip = chainActive.Tip();
     UniValue valuePools(UniValue::VARR);
-    valuePools.push_back(ValuePoolDesc("sprout", tip->nChainSproutValue, boost::none));
-    valuePools.push_back(ValuePoolDesc("sapling", tip->nChainSaplingValue, boost::none));
+    valuePools.push_back(ValuePoolDesc("sprout", tip->nChainSproutValue, std::nullopt));
+    valuePools.push_back(ValuePoolDesc("sapling", tip->nChainSaplingValue, std::nullopt));
     obj.pushKV("valuePools",            valuePools);
 
     const Consensus::Params& consensusParams = Params().GetConsensus();
diff --git a/src/serialize.h b/src/serialize.h
index 29d35900b..2c933bc0f 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -24,7 +24,6 @@
 #include <utility>
 #include <vector>
 
-#include <boost/optional.hpp>
 
 #include <rust/ed25519/types.h>
 
@@ -539,8 +538,8 @@ template<typename Stream, typename T, typename A> inline void Unserialize(Stream
 /**
  * optional
  */
-template<typename Stream, typename T> void Serialize(Stream& os, const boost::optional<T>& item);
-template<typename Stream, typename T> void Unserialize(Stream& is, boost::optional<T>& item);
+template<typename Stream, typename T> void Serialize(Stream& os, const std::optional<T>& item);
+template<typename Stream, typename T> void Unserialize(Stream& is, std::optional<T>& item);
 
 /**
  * array
@@ -785,7 +784,7 @@ inline void Unserialize(Stream& is, std::vector<T, A>& v)
  * optional
  */
 template<typename Stream, typename T>
-void Serialize(Stream& os, const boost::optional<T>& item)
+void Serialize(Stream& os, const std::optional<T>& item)
 {
     // If the value is there, put 0x01 and then serialize the value.
     // If it's not, put 0x00.
@@ -800,13 +799,13 @@ void Serialize(Stream& os, const boost::optional<T>& item)
 }
 
 template<typename Stream, typename T>
-void Unserialize(Stream& is, boost::optional<T>& item)
+void Unserialize(Stream& is, std::optional<T>& item)
 {
     unsigned char discriminant = 0x00;
     Unserialize(is, discriminant);
 
     if (discriminant == 0x00) {
-        item = boost::none;
+        item = std::nullopt;
     } else if (discriminant == 0x01) {
         T object;
         Unserialize(is, object);
diff --git a/src/test/serialize_tests.cpp b/src/test/serialize_tests.cpp
index ac79ef82d..b00fa69a4 100644
--- a/src/test/serialize_tests.cpp
+++ b/src/test/serialize_tests.cpp
@@ -13,7 +13,6 @@
 #include <stdint.h>
 
 #include <boost/test/unit_test.hpp>
-#include <boost/optional.hpp>
 
 using namespace std;
 
@@ -84,15 +83,15 @@ public:
 
 BOOST_AUTO_TEST_CASE(boost_optional)
 {
-    check_ser_rep<boost::optional<unsigned char>>(0xff, {0x01, 0xff});
-    check_ser_rep<boost::optional<unsigned char>>(boost::none, {0x00});
-    check_ser_rep<boost::optional<std::string>>(std::string("Test"), {0x01, 0x04, 'T', 'e', 's', 't'});
+    check_ser_rep<std::optional<unsigned char>>(0xff, {0x01, 0xff});
+    check_ser_rep<std::optional<unsigned char>>(std::nullopt, {0x00});
+    check_ser_rep<std::optional<std::string>>(std::string("Test"), {0x01, 0x04, 'T', 'e', 's', 't'});
 
     {
         // Ensure that canonical optional discriminant is used
         CDataStream ss(SER_DISK, 0);
         ss.write("\x02\x04Test", 6);
-        boost::optional<std::string> into;
+        std::optional<std::string> into;
 
         BOOST_CHECK_THROW(ss >> into, std::ios_base::failure);
     }
diff --git a/src/transaction_builder.cpp b/src/transaction_builder.cpp
index 7dc93c8c6..9660d23c8 100644
--- a/src/transaction_builder.cpp
+++ b/src/transaction_builder.cpp
@@ -24,17 +24,17 @@ SpendDescriptionInfo::SpendDescriptionInfo(
     librustzcash_sapling_generate_r(alpha.begin());
 }
 
-boost::optional<OutputDescription> OutputDescriptionInfo::Build(void* ctx) {
+std::optional<OutputDescription> OutputDescriptionInfo::Build(void* ctx) {
     auto cmu = this->note.cmu();
     if (!cmu) {
-        return boost::none;
+        return std::nullopt;
     }
 
     libzcash::SaplingNotePlaintext notePlaintext(this->note, this->memo);
 
     auto res = notePlaintext.encrypt(this->note.pk_d);
     if (!res) {
-        return boost::none;
+        return std::nullopt;
     }
     auto enc = res.value();
     auto encryptor = enc.second;
@@ -54,7 +54,7 @@ boost::optional<OutputDescription> OutputDescriptionInfo::Build(void* ctx) {
             this->note.value(),
             odesc.cv.begin(),
             odesc.zkproof.begin())) {
-        return boost::none;
+        return std::nullopt;
     }
 
     odesc.cmu = *cmu;
@@ -75,9 +75,9 @@ TransactionBuilderResult::TransactionBuilderResult(const CTransaction& tx) : may
 
 TransactionBuilderResult::TransactionBuilderResult(const std::string& error) : maybeError(error) {}
 
-bool TransactionBuilderResult::IsTx() { return maybeTx != boost::none; }
+bool TransactionBuilderResult::IsTx() { return maybeTx != std::nullopt; }
 
-bool TransactionBuilderResult::IsError() { return maybeError != boost::none; }
+bool TransactionBuilderResult::IsError() { return maybeError != std::nullopt; }
 
 CTransaction TransactionBuilderResult::GetTxOrThrow() {
     if (maybeTx) {
@@ -227,15 +227,15 @@ void TransactionBuilder::SetFee(CAmount fee)
 void TransactionBuilder::SendChangeTo(libzcash::SaplingPaymentAddress changeAddr, uint256 ovk)
 {
     saplingChangeAddr = std::make_pair(ovk, changeAddr);
-    sproutChangeAddr = boost::none;
-    tChangeAddr = boost::none;
+    sproutChangeAddr = std::nullopt;
+    tChangeAddr = std::nullopt;
 }
 
 void TransactionBuilder::SendChangeTo(libzcash::SproutPaymentAddress changeAddr)
 {
     sproutChangeAddr = changeAddr;
-    saplingChangeAddr = boost::none;
-    tChangeAddr = boost::none;
+    saplingChangeAddr = std::nullopt;
+    tChangeAddr = std::nullopt;
 }
 
 void TransactionBuilder::SendChangeTo(CTxDestination& changeAddr)
@@ -245,8 +245,8 @@ void TransactionBuilder::SendChangeTo(CTxDestination& changeAddr)
     }
 
     tChangeAddr = changeAddr;
-    saplingChangeAddr = boost::none;
-    sproutChangeAddr = boost::none;
+    saplingChangeAddr = std::nullopt;
+    sproutChangeAddr = std::nullopt;
 }
 
 TransactionBuilderResult TransactionBuilder::Build()
@@ -566,7 +566,7 @@ void TransactionBuilder::CreateJSDescriptions()
 
             assert(changeOutputIndex != -1);
             assert(changeOutputIndex < prevJoinSplit.commitments.size());
-            boost::optional<SproutWitness> changeWitness;
+            std::optional<SproutWitness> changeWitness;
             int n = 0;
             for (const uint256& commitment : prevJoinSplit.commitments) {
                 tree.append(commitment);
diff --git a/src/transaction_builder.h b/src/transaction_builder.h
index 36bc5ba6d..69198f234 100644
--- a/src/transaction_builder.h
+++ b/src/transaction_builder.h
@@ -19,7 +19,6 @@
 #include "zcash/NoteEncryption.hpp"
 
 #include <optional>
-#include <boost/optional.hpp>
 
 #define NO_MEMO {{0xF6}}
 
@@ -47,7 +46,7 @@ struct OutputDescriptionInfo {
         libzcash::SaplingNote note,
         std::array<unsigned char, ZC_MEMO_SIZE> memo) : ovk(ovk), note(note), memo(memo) {}
 
-    boost::optional<OutputDescription> Build(void* ctx);
+    std::optional<OutputDescription> Build(void* ctx);
 };
 
 struct TransparentInputInfo {
@@ -61,8 +60,8 @@ struct TransparentInputInfo {
 
 class TransactionBuilderResult {
 private:
-    boost::optional<CTransaction> maybeTx;
-    boost::optional<std::string> maybeError;
+    std::optional<CTransaction> maybeTx;
+    std::optional<std::string> maybeError;
 public:
     TransactionBuilderResult() = delete;
     TransactionBuilderResult(const CTransaction& tx);
@@ -90,9 +89,9 @@ private:
     std::vector<libzcash::JSOutput> jsOutputs;
     std::vector<TransparentInputInfo> tIns;
 
-    boost::optional<std::pair<uint256, libzcash::SaplingPaymentAddress>> saplingChangeAddr;
-    boost::optional<libzcash::SproutPaymentAddress> sproutChangeAddr;
-    boost::optional<CTxDestination> tChangeAddr;
+    std::optional<std::pair<uint256, libzcash::SaplingPaymentAddress>> saplingChangeAddr;
+    std::optional<libzcash::SproutPaymentAddress> sproutChangeAddr;
+    std::optional<CTxDestination> tChangeAddr;
 
 public:
     TransactionBuilder() {}
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 3f889c2b5..72a7a7c0d 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -841,8 +841,8 @@ bool CTxMemPool::IsRecentlyEvicted(const uint256& txId) {
 
 void CTxMemPool::EnsureSizeLimit() {
     AssertLockHeld(cs);
-    boost::optional<uint256> maybeDropTxId;
-    while ((maybeDropTxId = weightedTxTree->maybeDropRandom()).is_initialized()) {
+    std::optional<uint256> maybeDropTxId;
+    while ((maybeDropTxId = weightedTxTree->maybeDropRandom()).has_value()) {
         uint256 txId = maybeDropTxId.value();
         recentlyEvicted->add(txId);
         std::list<CTransaction> removed;
diff --git a/src/validationinterface.cpp b/src/validationinterface.cpp
index d0cc6a264..016f37d39 100644
--- a/src/validationinterface.cpp
+++ b/src/validationinterface.cpp
@@ -189,7 +189,7 @@ void ThreadNotifyWallets(CBlockIndex *pindexLastTip)
                 SyncWithWallets(tx, NULL, pindexLastTip->nHeight);
             }
             // Update cached incremental witnesses
-            GetMainSignals().ChainTip(pindexLastTip, &block, boost::none);
+            GetMainSignals().ChainTip(pindexLastTip, &block, std::nullopt);
 
             // On to the next block!
             pindexLastTip = pindexLastTip->pprev;
diff --git a/src/validationinterface.h b/src/validationinterface.h
index ec1568183..ae129c179 100644
--- a/src/validationinterface.h
+++ b/src/validationinterface.h
@@ -37,7 +37,7 @@ protected:
     virtual void UpdatedBlockTip(const CBlockIndex *pindex) {}
     virtual void SyncTransaction(const CTransaction &tx, const CBlock *pblock, const int nHeight) {}
     virtual void EraseFromWallet(const uint256 &hash) {}
-    virtual void ChainTip(const CBlockIndex *pindex, const CBlock *pblock, boost::optional<std::pair<SproutMerkleTree, SaplingMerkleTree>> added) {}
+    virtual void ChainTip(const CBlockIndex *pindex, const CBlock *pblock, std::optional<std::pair<SproutMerkleTree, SaplingMerkleTree>> added) {}
     virtual void UpdatedTransaction(const uint256 &hash) {}
     virtual void Inventory(const uint256 &hash) {}
     virtual void ResendWalletTransactions(int64_t nBestBlockTime) {}
@@ -59,7 +59,7 @@ struct CMainSignals {
     /** Notifies listeners of an updated transaction without new data (for now: a coinbase potentially becoming visible). */
     boost::signals2::signal<void (const uint256 &)> UpdatedTransaction;
     /** Notifies listeners of a change to the tip of the active block chain. */
-    boost::signals2::signal<void (const CBlockIndex *, const CBlock *, boost::optional<std::pair<SproutMerkleTree, SaplingMerkleTree>>)> ChainTip;
+    boost::signals2::signal<void (const CBlockIndex *, const CBlock *, std::optional<std::pair<SproutMerkleTree, SaplingMerkleTree>>)> ChainTip;
     /** Notifies listeners about an inventory item being seen on the network. */
     boost::signals2::signal<void (const uint256 &)> Inventory;
     /** Tells listeners to broadcast their data. */
diff --git a/src/wallet/asyncrpcoperation_common.cpp b/src/wallet/asyncrpcoperation_common.cpp
index d3c911f84..97f697a4e 100644
--- a/src/wallet/asyncrpcoperation_common.cpp
+++ b/src/wallet/asyncrpcoperation_common.cpp
@@ -6,7 +6,7 @@
 
 extern UniValue signrawtransaction(const UniValue& params, bool fHelp);
 
-UniValue SendTransaction(CTransaction& tx, boost::optional<CReserveKey&> reservekey, bool testmode) {
+UniValue SendTransaction(CTransaction& tx, std::optional<std::reference_wrapper<CReserveKey>> reservekey, bool testmode) {
     UniValue o(UniValue::VOBJ);
     // Send the transaction
     if (!testmode) {
@@ -25,7 +25,7 @@ UniValue SendTransaction(CTransaction& tx, boost::optional<CReserveKey&> reserve
     return o;
 }
 
-std::pair<CTransaction, UniValue> SignSendRawTransaction(UniValue obj, boost::optional<CReserveKey&> reservekey, bool testmode) {
+std::pair<CTransaction, UniValue> SignSendRawTransaction(UniValue obj, std::optional<std::reference_wrapper<CReserveKey>> reservekey, bool testmode) {
     // Sign the raw transaction
     UniValue rawtxnValue = find_value(obj, "rawtxn");
     if (rawtxnValue.isNull()) {
diff --git a/src/wallet/asyncrpcoperation_common.h b/src/wallet/asyncrpcoperation_common.h
index d7448eb3d..e7054aa33 100644
--- a/src/wallet/asyncrpcoperation_common.h
+++ b/src/wallet/asyncrpcoperation_common.h
@@ -20,7 +20,7 @@
  * If testmode is true, do not commit the transaction,
  * return {"test": 1, "txid": tx.GetHash().ToString(), "hex": EncodeHexTx(tx)}
  */
-UniValue SendTransaction(CTransaction& tx, boost::optional<CReserveKey&> reservekey, bool testmode);
+UniValue SendTransaction(CTransaction& tx, std::optional<std::reference_wrapper<CReserveKey>> reservekey, bool testmode);
 
 /**
  * Sign and send a raw transaction.
@@ -28,6 +28,6 @@ UniValue SendTransaction(CTransaction& tx, boost::optional<CReserveKey&> reserve
  * 
  * Returns a pair of (the parsed transaction, and the result of sending)
  */
-std::pair<CTransaction, UniValue> SignSendRawTransaction(UniValue obj, boost::optional<CReserveKey&> reservekey, bool testmode);
+std::pair<CTransaction, UniValue> SignSendRawTransaction(UniValue obj, std::optional<std::reference_wrapper<CReserveKey>> reservekey, bool testmode);
 
 #endif // ZCASH_WALLET_ASYNCRPCOPERATION_COMMON_H
diff --git a/src/wallet/asyncrpcoperation_mergetoaddress.cpp b/src/wallet/asyncrpcoperation_mergetoaddress.cpp
index 201db5b0b..e72f2f154 100644
--- a/src/wallet/asyncrpcoperation_mergetoaddress.cpp
+++ b/src/wallet/asyncrpcoperation_mergetoaddress.cpp
@@ -57,7 +57,7 @@ int mta_find_output(UniValue obj, int n)
 }
 
 AsyncRPCOperation_mergetoaddress::AsyncRPCOperation_mergetoaddress(
-    boost::optional<TransactionBuilder> builder,
+    std::optional<TransactionBuilder> builder,
     CMutableTransaction contextualTx,
     std::vector<MergeToAddressInputUTXO> utxoInputs,
     std::vector<MergeToAddressInputSproutNote> sproutNoteInputs,
@@ -296,7 +296,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
             builder_.AddTransparentInput(outPoint, scriptPubKey, amount);
         }
 
-        boost::optional<uint256> ovk;
+        std::optional<uint256> ovk;
         // Select Sapling notes
         std::vector<SaplingOutPoint> saplingOPs;
         std::vector<SaplingNote> saplingNotes;
@@ -313,7 +313,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
 
         // Fetch Sapling anchor and witnesses
         uint256 anchor;
-        std::vector<boost::optional<SaplingWitness>> witnesses;
+        std::vector<std::optional<SaplingWitness>> witnesses;
         {
             LOCK2(cs_main, pwalletMain->cs_wallet);
             pwalletMain->GetSaplingNoteWitnesses(saplingOPs, witnesses, anchor);
@@ -355,7 +355,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
         // Build the transaction
         tx_ = builder_.Build().GetTxOrThrow();
 
-        UniValue sendResult = SendTransaction(tx_, boost::none, testmode);
+        UniValue sendResult = SendTransaction(tx_, std::nullopt, testmode);
         set_result(sendResult);
 
         return true;
@@ -375,7 +375,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
     if (isPureTaddrOnlyTx) {
         UniValue obj(UniValue::VOBJ);
         obj.pushKV("rawtxn", EncodeHexTx(tx_));
-        auto txAndResult = SignSendRawTransaction(obj, boost::none, testmode);
+        auto txAndResult = SignSendRawTransaction(obj, std::nullopt, testmode);
         tx_ = txAndResult.first;
         set_result(txAndResult.second);
         return true;
@@ -413,7 +413,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
         info.vjsout.push_back(jso);
 
         UniValue obj = perform_joinsplit(info);
-        auto txAndResult = SignSendRawTransaction(obj, boost::none, testmode);
+        auto txAndResult = SignSendRawTransaction(obj, std::nullopt, testmode);
         tx_ = txAndResult.first;
         set_result(txAndResult.second);
         return true;
@@ -438,7 +438,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
             JSOutPoint jso = std::get<0>(t);
             std::vector<JSOutPoint> vOutPoints = {jso};
             uint256 inputAnchor;
-            std::vector<boost::optional<SproutWitness>> vInputWitnesses;
+            std::vector<std::optional<SproutWitness>> vInputWitnesses;
             pwalletMain->GetSproutNoteWitnesses(vOutPoints, vInputWitnesses, inputAnchor);
             jsopWitnessAnchorMap[jso.ToString()] = MergeToAddressWitnessAnchorData{vInputWitnesses[0], inputAnchor};
         }
@@ -502,7 +502,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
 
         CAmount jsInputValue = 0;
         uint256 jsAnchor;
-        std::vector<boost::optional<SproutWitness>> witnesses;
+        std::vector<std::optional<SproutWitness>> witnesses;
 
         JSDescription prevJoinSplit;
 
@@ -533,7 +533,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
             }
 
             assert(changeOutputIndex != -1);
-            boost::optional<SproutWitness> changeWitness;
+            std::optional<SproutWitness> changeWitness;
             int n = 0;
             for (const uint256& commitment : prevJoinSplit.commitments) {
                 tree.append(commitment);
@@ -583,7 +583,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
         std::vector<SproutNote> vInputNotes;
         std::vector<SproutSpendingKey> vInputZKeys;
         std::vector<JSOutPoint> vOutPoints;
-        std::vector<boost::optional<SproutWitness>> vInputWitnesses;
+        std::vector<std::optional<SproutWitness>> vInputWitnesses;
         uint256 inputAnchor;
         int numInputsNeeded = (jsChange > 0) ? 1 : 0;
         while (numInputsNeeded++ < ZC_NUM_JS_INPUTS && zInputsDeque.size() > 0) {
@@ -714,7 +714,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
     assert(zInputsDeque.size() == 0);
     assert(vpubNewProcessed);
 
-    auto txAndResult = SignSendRawTransaction(obj, boost::none, testmode);
+    auto txAndResult = SignSendRawTransaction(obj, std::nullopt, testmode);
     tx_ = txAndResult.first;
     set_result(txAndResult.second);
     return true;
@@ -723,7 +723,7 @@ bool AsyncRPCOperation_mergetoaddress::main_impl()
 
 UniValue AsyncRPCOperation_mergetoaddress::perform_joinsplit(MergeToAddressJSInfo& info)
 {
-    std::vector<boost::optional<SproutWitness>> witnesses;
+    std::vector<std::optional<SproutWitness>> witnesses;
     uint256 anchor;
     {
         LOCK(cs_main);
@@ -735,7 +735,7 @@ UniValue AsyncRPCOperation_mergetoaddress::perform_joinsplit(MergeToAddressJSInf
 
 UniValue AsyncRPCOperation_mergetoaddress::perform_joinsplit(MergeToAddressJSInfo& info, std::vector<JSOutPoint>& outPoints)
 {
-    std::vector<boost::optional<SproutWitness>> witnesses;
+    std::vector<std::optional<SproutWitness>> witnesses;
     uint256 anchor;
     {
         LOCK(cs_main);
@@ -746,7 +746,7 @@ UniValue AsyncRPCOperation_mergetoaddress::perform_joinsplit(MergeToAddressJSInf
 
 UniValue AsyncRPCOperation_mergetoaddress::perform_joinsplit(
     MergeToAddressJSInfo& info,
-    std::vector<boost::optional<SproutWitness>> witnesses,
+    std::vector<std::optional<SproutWitness>> witnesses,
     uint256 anchor)
 {
     if (anchor.IsNull()) {
diff --git a/src/wallet/asyncrpcoperation_mergetoaddress.h b/src/wallet/asyncrpcoperation_mergetoaddress.h
index d00733753..745346b98 100644
--- a/src/wallet/asyncrpcoperation_mergetoaddress.h
+++ b/src/wallet/asyncrpcoperation_mergetoaddress.h
@@ -51,7 +51,7 @@ struct MergeToAddressJSInfo {
 
 // A struct to help us track the witness and anchor for a given JSOutPoint
 struct MergeToAddressWitnessAnchorData {
-    boost::optional<SproutWitness> witness;
+    std::optional<SproutWitness> witness;
     uint256 anchor;
 };
 
@@ -59,7 +59,7 @@ class AsyncRPCOperation_mergetoaddress : public AsyncRPCOperation
 {
 public:
     AsyncRPCOperation_mergetoaddress(
-        boost::optional<TransactionBuilder> builder,
+        std::optional<TransactionBuilder> builder,
         CMutableTransaction contextualTx,
         std::vector<MergeToAddressInputUTXO> utxoInputs,
         std::vector<MergeToAddressInputSproutNote> sproutNoteInputs,
@@ -123,7 +123,7 @@ private:
     // JoinSplit where you have the witnesses and anchor
     UniValue perform_joinsplit(
         MergeToAddressJSInfo& info,
-        std::vector<boost::optional<SproutWitness>> witnesses,
+        std::vector<std::optional<SproutWitness>> witnesses,
         uint256 anchor);
 
     void lock_utxos();
@@ -181,7 +181,7 @@ public:
 
     UniValue perform_joinsplit(
         MergeToAddressJSInfo& info,
-        std::vector<boost::optional<SproutWitness>> witnesses,
+        std::vector<std::optional<SproutWitness>> witnesses,
         uint256 anchor)
     {
         return delegate->perform_joinsplit(info, witnesses, anchor);
diff --git a/src/wallet/asyncrpcoperation_saplingmigration.cpp b/src/wallet/asyncrpcoperation_saplingmigration.cpp
index fbad5f956..89fa03cc6 100644
--- a/src/wallet/asyncrpcoperation_saplingmigration.cpp
+++ b/src/wallet/asyncrpcoperation_saplingmigration.cpp
@@ -140,7 +140,7 @@ bool AsyncRPCOperation_saplingmigration::main_impl() {
             // for each Sprout JoinSplit description
             // TODO: the above functionality (in comment) is not implemented in zcashd
             uint256 inputAnchor;
-            std::vector<boost::optional<SproutWitness>> vInputWitnesses;
+            std::vector<std::optional<SproutWitness>> vInputWitnesses;
             pwalletMain->GetSproutNoteWitnesses(vOutPoints, vInputWitnesses, inputAnchor);
             builder.AddSproutInput(sproutSk, sproutEntry.note, vInputWitnesses[0].value());
         }
diff --git a/src/wallet/asyncrpcoperation_sendmany.cpp b/src/wallet/asyncrpcoperation_sendmany.cpp
index bd55bf456..55a6ec2c1 100644
--- a/src/wallet/asyncrpcoperation_sendmany.cpp
+++ b/src/wallet/asyncrpcoperation_sendmany.cpp
@@ -58,7 +58,7 @@ int find_output(UniValue obj, int n) {
 }
 
 AsyncRPCOperation_sendmany::AsyncRPCOperation_sendmany(
-        boost::optional<TransactionBuilder> builder,
+        std::optional<TransactionBuilder> builder,
         CMutableTransaction contextualTx,
         std::string fromAddress,
         std::vector<SendManyRecipient> tOutputs,
@@ -353,7 +353,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
 
         // Fetch Sapling anchor and witnesses
         uint256 anchor;
-        std::vector<boost::optional<SaplingWitness>> witnesses;
+        std::vector<std::optional<SaplingWitness>> witnesses;
         {
             LOCK2(cs_main, pwalletMain->cs_wallet);
             pwalletMain->GetSaplingNoteWitnesses(ops, witnesses, anchor);
@@ -476,7 +476,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
             JSOutPoint jso = t.point;
             std::vector<JSOutPoint> vOutPoints = { jso };
             uint256 inputAnchor;
-            std::vector<boost::optional<SproutWitness>> vInputWitnesses;
+            std::vector<std::optional<SproutWitness>> vInputWitnesses;
             pwalletMain->GetSproutNoteWitnesses(vOutPoints, vInputWitnesses, inputAnchor);
             jsopWitnessAnchorMap[ jso.ToString() ] = WitnessAnchorData{ vInputWitnesses[0], inputAnchor };
         }
@@ -587,7 +587,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
 
         CAmount jsInputValue = 0;
         uint256 jsAnchor;
-        std::vector<boost::optional<SproutWitness>> witnesses;
+        std::vector<std::optional<SproutWitness>> witnesses;
 
         JSDescription prevJoinSplit;
 
@@ -618,7 +618,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
             }
 
             assert(changeOutputIndex != -1);
-            boost::optional<SproutWitness> changeWitness;
+            std::optional<SproutWitness> changeWitness;
             int n = 0;
             for (const uint256& commitment : prevJoinSplit.commitments) {
                 tree.append(commitment);
@@ -667,7 +667,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
         //
         std::vector<SproutNote> vInputNotes;
         std::vector<JSOutPoint> vOutPoints;
-        std::vector<boost::optional<SproutWitness>> vInputWitnesses;
+        std::vector<std::optional<SproutWitness>> vInputWitnesses;
         uint256 inputAnchor;
         int numInputsNeeded = (jsChange>0) ? 1 : 0;
         while (numInputsNeeded++ < ZC_NUM_JS_INPUTS && zInputsDeque.size() > 0) {
@@ -825,7 +825,7 @@ bool AsyncRPCOperation_sendmany::main_impl() {
     assert(zOutputsDeque.size() == 0);
     assert(vpubNewProcessed);
 
-    auto txAndResult = SignSendRawTransaction(obj, boost::none, testmode);
+    auto txAndResult = SignSendRawTransaction(obj, std::nullopt, testmode);
     tx_ = txAndResult.first;
     set_result(txAndResult.second);
     return true;
@@ -974,7 +974,7 @@ bool AsyncRPCOperation_sendmany::find_unspent_notes() {
 }
 
 UniValue AsyncRPCOperation_sendmany::perform_joinsplit(AsyncJoinSplitInfo & info) {
-    std::vector<boost::optional < SproutWitness>> witnesses;
+    std::vector<std::optional < SproutWitness>> witnesses;
     uint256 anchor;
     {
         LOCK(cs_main);
@@ -985,7 +985,7 @@ UniValue AsyncRPCOperation_sendmany::perform_joinsplit(AsyncJoinSplitInfo & info
 
 
 UniValue AsyncRPCOperation_sendmany::perform_joinsplit(AsyncJoinSplitInfo & info, std::vector<JSOutPoint> & outPoints) {
-    std::vector<boost::optional < SproutWitness>> witnesses;
+    std::vector<std::optional < SproutWitness>> witnesses;
     uint256 anchor;
     {
         LOCK(cs_main);
@@ -996,7 +996,7 @@ UniValue AsyncRPCOperation_sendmany::perform_joinsplit(AsyncJoinSplitInfo & info
 
 UniValue AsyncRPCOperation_sendmany::perform_joinsplit(
         AsyncJoinSplitInfo & info,
-        std::vector<boost::optional < SproutWitness>> witnesses,
+        std::vector<std::optional < SproutWitness>> witnesses,
         uint256 anchor)
 {
     if (anchor.IsNull()) {
diff --git a/src/wallet/asyncrpcoperation_sendmany.h b/src/wallet/asyncrpcoperation_sendmany.h
index 7fd33ce79..ba578e276 100644
--- a/src/wallet/asyncrpcoperation_sendmany.h
+++ b/src/wallet/asyncrpcoperation_sendmany.h
@@ -61,14 +61,14 @@ struct AsyncJoinSplitInfo
 
 // A struct to help us track the witness and anchor for a given JSOutPoint
 struct WitnessAnchorData {
-	boost::optional<SproutWitness> witness;
+	std::optional<SproutWitness> witness;
 	uint256 anchor;
 };
 
 class AsyncRPCOperation_sendmany : public AsyncRPCOperation {
 public:
     AsyncRPCOperation_sendmany(
-        boost::optional<TransactionBuilder> builder,
+        std::optional<TransactionBuilder> builder,
         CMutableTransaction contextualTx,
         std::string fromAddress,
         std::vector<SendManyRecipient> tOutputs,
@@ -142,7 +142,7 @@ private:
     // JoinSplit where you have the witnesses and anchor
     UniValue perform_joinsplit(
         AsyncJoinSplitInfo & info,
-        std::vector<boost::optional < SproutWitness>> witnesses,
+        std::vector<std::optional < SproutWitness>> witnesses,
         uint256 anchor);
 
     // payment disclosure!
@@ -197,7 +197,7 @@ public:
 
     UniValue perform_joinsplit(
         AsyncJoinSplitInfo & info,
-        std::vector<boost::optional < SproutWitness>> witnesses,
+        std::vector<std::optional < SproutWitness>> witnesses,
         uint256 anchor)
     {
         return delegate->perform_joinsplit(info, witnesses, anchor);
diff --git a/src/wallet/asyncrpcoperation_shieldcoinbase.cpp b/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
index 8e9a0c48c..c1203b7b6 100644
--- a/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
+++ b/src/wallet/asyncrpcoperation_shieldcoinbase.cpp
@@ -224,7 +224,7 @@ bool ShieldToAddress::operator()(const libzcash::SproutPaymentAddress &zaddr) co
     info.vjsout.push_back(jso);
     UniValue obj = m_op->perform_joinsplit(info);
 
-    auto txAndResult = SignSendRawTransaction(obj, boost::none, m_op->testmode);
+    auto txAndResult = SignSendRawTransaction(obj, std::nullopt, m_op->testmode);
     m_op->tx_ = txAndResult.first;
     m_op->set_result(txAndResult.second);
     return true;
@@ -252,7 +252,7 @@ bool ShieldToAddress::operator()(const libzcash::SaplingPaymentAddress &zaddr) c
     // Build the transaction
     m_op->tx_ = m_op->builder_.Build().GetTxOrThrow();
 
-    UniValue sendResult = SendTransaction(m_op->tx_, boost::none, m_op->testmode);
+    UniValue sendResult = SendTransaction(m_op->tx_, std::nullopt, m_op->testmode);
     m_op->set_result(sendResult);
 
     return true;
diff --git a/src/wallet/gtest/test_wallet.cpp b/src/wallet/gtest/test_wallet.cpp
index 4b4b1686c..e0abbe7fd 100644
--- a/src/wallet/gtest/test_wallet.cpp
+++ b/src/wallet/gtest/test_wallet.cpp
@@ -105,8 +105,8 @@ std::pair<JSOutPoint, SaplingOutPoint> CreateValidBlock(TestWallet& wallet,
 std::pair<uint256, uint256> GetWitnessesAndAnchors(TestWallet& wallet,
                                 std::vector<JSOutPoint>& sproutNotes,
                                 std::vector<SaplingOutPoint>& saplingNotes,
-                                std::vector<boost::optional<SproutWitness>>& sproutWitnesses,
-                                std::vector<boost::optional<SaplingWitness>>& saplingWitnesses) {
+                                std::vector<std::optional<SproutWitness>>& sproutWitnesses,
+                                std::vector<std::optional<SaplingWitness>>& saplingWitnesses) {
     sproutWitnesses.clear();
     saplingWitnesses.clear();
     uint256 sproutAnchor;
@@ -1161,8 +1161,8 @@ TEST(WalletTests, CachedWitnessesEmptyChain) {
     std::vector<JSOutPoint> sproutNotes {jsoutpt, jsoutpt2};
     std::vector<SaplingOutPoint> saplingNotes = SetSaplingNoteData(wtx);
 
-    std::vector<boost::optional<SproutWitness>> sproutWitnesses;
-    std::vector<boost::optional<SaplingWitness>> saplingWitnesses;
+    std::vector<std::optional<SproutWitness>> sproutWitnesses;
+    std::vector<std::optional<SaplingWitness>> saplingWitnesses;
 
     ::GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, sproutWitnesses, saplingWitnesses);
 
@@ -1216,8 +1216,8 @@ TEST(WalletTests, CachedWitnessesChainTip) {
         // Called to fetch anchor
         std::vector<JSOutPoint> sproutNotes {outpts.first};
         std::vector<SaplingOutPoint> saplingNotes {outpts.second};
-        std::vector<boost::optional<SproutWitness>> sproutWitnesses;
-        std::vector<boost::optional<SaplingWitness>> saplingWitnesses;
+        std::vector<std::optional<SproutWitness>> sproutWitnesses;
+        std::vector<std::optional<SaplingWitness>> saplingWitnesses;
 
         anchors1 = GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, sproutWitnesses, saplingWitnesses);
         EXPECT_NE(anchors1.first, anchors1.second);
@@ -1238,8 +1238,8 @@ TEST(WalletTests, CachedWitnessesChainTip) {
         wallet.AddToWallet(wtx, true, NULL);
 
         std::vector<JSOutPoint> sproutNotes {jsoutpt};
-        std::vector<boost::optional<SproutWitness>> sproutWitnesses;
-        std::vector<boost::optional<SaplingWitness>> saplingWitnesses;
+        std::vector<std::optional<SproutWitness>> sproutWitnesses;
+        std::vector<std::optional<SaplingWitness>> saplingWitnesses;
 
         GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, sproutWitnesses, saplingWitnesses);
 
@@ -1286,8 +1286,8 @@ TEST(WalletTests, CachedWitnessesChainTip) {
 
         // Incrementing with the same block again should not change the cache
         wallet.IncrementNoteWitnesses(&index2, &block2, sproutTree, saplingTree);
-        std::vector<boost::optional<SproutWitness>> sproutWitnesses5;
-        std::vector<boost::optional<SaplingWitness>> saplingWitnesses5;
+        std::vector<std::optional<SproutWitness>> sproutWitnesses5;
+        std::vector<std::optional<SaplingWitness>> saplingWitnesses5;
 
         auto anchors5 = GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, sproutWitnesses5, saplingWitnesses5);
         EXPECT_NE(anchors5.first, anchors5.second);
@@ -1328,8 +1328,8 @@ TEST(WalletTests, CachedWitnessesDecrementFirst) {
         // Called to fetch anchor
         std::vector<JSOutPoint> sproutNotes {outpts.first};
         std::vector<SaplingOutPoint> saplingNotes {outpts.second};
-        std::vector<boost::optional<SproutWitness>> sproutWitnesses;
-        std::vector<boost::optional<SaplingWitness>> saplingWitnesses;
+        std::vector<std::optional<SproutWitness>> sproutWitnesses;
+        std::vector<std::optional<SaplingWitness>> saplingWitnesses;
         anchors2 = GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, sproutWitnesses, saplingWitnesses);
     }
 
@@ -1348,8 +1348,8 @@ TEST(WalletTests, CachedWitnessesDecrementFirst) {
         wallet.AddToWallet(wtx, true, NULL);
 
         std::vector<JSOutPoint> sproutNotes {jsoutpt};
-        std::vector<boost::optional<SproutWitness>> sproutWitnesses;
-        std::vector<boost::optional<SaplingWitness>> saplingWitnesses;
+        std::vector<std::optional<SproutWitness>> sproutWitnesses;
+        std::vector<std::optional<SaplingWitness>> saplingWitnesses;
 
         auto anchors3 = GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, sproutWitnesses, saplingWitnesses);
 
@@ -1393,8 +1393,8 @@ TEST(WalletTests, CachedWitnessesCleanIndex) {
     SproutMerkleTree sproutRiTree = sproutTree;
     SaplingMerkleTree saplingTree;
     SaplingMerkleTree saplingRiTree = saplingTree;
-    std::vector<boost::optional<SproutWitness>> sproutWitnesses;
-    std::vector<boost::optional<SaplingWitness>> saplingWitnesses;
+    std::vector<std::optional<SproutWitness>> sproutWitnesses;
+    std::vector<std::optional<SaplingWitness>> saplingWitnesses;
 
     auto sk = libzcash::SproutSpendingKey::random();
     wallet.AddSproutSpendingKey(sk);
@@ -1510,8 +1510,8 @@ TEST(WalletTests, ClearNoteWitnessCache) {
     saplingNotes.emplace_back(wtx.GetHash(), 1);
     ASSERT_EQ(saplingNotes.size(), 2);
 
-    std::vector<boost::optional<SproutWitness>> sproutWitnesses;
-    std::vector<boost::optional<SaplingWitness>> saplingWitnesses;
+    std::vector<std::optional<SproutWitness>> sproutWitnesses;
+    std::vector<std::optional<SaplingWitness>> saplingWitnesses;
 
     // Before clearing, we should have a witness for one note
     GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, sproutWitnesses, saplingWitnesses);
diff --git a/src/wallet/paymentdisclosuredb.h b/src/wallet/paymentdisclosuredb.h
index 703e97a92..8f93f1f73 100644
--- a/src/wallet/paymentdisclosuredb.h
+++ b/src/wallet/paymentdisclosuredb.h
@@ -13,7 +13,6 @@
 #include <future>
 #include <memory>
 
-#include <boost/optional.hpp>
 
 #include <leveldb/db.h>
 
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 8b90280ef..d6c3130b0 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -398,8 +398,8 @@ UniValue importwallet_impl(const UniValue& params, bool fImportZKeys)
             auto spendingkey = keyIO.DecodeSpendingKey(vstr[0]);
             int64_t nTime = DecodeDumpTime(vstr[1]);
             // Only include hdKeypath and seedFpStr if we have both
-            boost::optional<std::string> hdKeypath = (vstr.size() > 3) ? boost::optional<std::string>(vstr[2]) : boost::none;
-            boost::optional<std::string> seedFpStr = (vstr.size() > 3) ? boost::optional<std::string>(vstr[3]) : boost::none;
+            std::optional<std::string> hdKeypath = (vstr.size() > 3) ? std::optional<std::string>(vstr[2]) : std::nullopt;
+            std::optional<std::string> seedFpStr = (vstr.size() > 3) ? std::optional<std::string>(vstr[3]) : std::nullopt;
             if (IsValidSpendingKey(spendingkey)) {
                 auto addResult = std::visit(
                     AddSpendingKeyToWallet(pwalletMain, Params().GetConsensus(), nTime, hdKeypath, seedFpStr, true), spendingkey);
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 27b3329fd..c70241777 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2989,7 +2989,7 @@ UniValue zc_raw_receive(const UniValue& params, bool fHelp)
     SproutNote decrypted_note = npt.note(payment_addr);
 
     assert(pwalletMain != NULL);
-    std::vector<boost::optional<SproutWitness>> witnesses;
+    std::vector<std::optional<SproutWitness>> witnesses;
     uint256 anchor;
     uint256 commitment = decrypted_note.cm();
     pwalletMain->WitnessNoteCommitment(
@@ -3099,7 +3099,7 @@ UniValue zc_raw_joinsplit(const UniValue& params, bool fHelp)
     }
 
     uint256 anchor;
-    std::vector<boost::optional<SproutWitness>> witnesses;
+    std::vector<std::optional<SproutWitness>> witnesses;
     pwalletMain->WitnessNoteCommitment(commitments, witnesses, anchor);
 
     assert(witnesses.size() == notes.size());
@@ -4297,7 +4297,7 @@ UniValue z_sendmany(const UniValue& params, bool fHelp)
     }
 
     // Builder (used if Sapling addresses are involved)
-    boost::optional<TransactionBuilder> builder;
+    std::optional<TransactionBuilder> builder;
     if (noSproutAddrs) {
         builder = TransactionBuilder(Params().GetConsensus(), nextBlockHeight, pwalletMain);
     }
@@ -5079,7 +5079,7 @@ UniValue z_mergetoaddress(const UniValue& params, bool fHelp)
     }
 
     // Builder (used if Sapling addresses are involved)
-    boost::optional<TransactionBuilder> builder;
+    std::optional<TransactionBuilder> builder;
     if (isToSaplingZaddr || saplingNoteInputs.size() > 0) {
         builder = TransactionBuilder(Params().GetConsensus(), nextBlockHeight, pwalletMain);
     }
diff --git a/src/wallet/test/rpc_wallet_tests.cpp b/src/wallet/test/rpc_wallet_tests.cpp
index 9634fce0e..07dee957a 100644
--- a/src/wallet/test/rpc_wallet_tests.cpp
+++ b/src/wallet/test/rpc_wallet_tests.cpp
@@ -38,7 +38,6 @@
 #include <boost/algorithm/string.hpp>
 #include <boost/test/unit_test.hpp>
 #include <boost/format.hpp>
-#include <boost/optional.hpp>
 
 #include <univalue.h>
 
@@ -1124,26 +1123,26 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_parameters)
 
     // Test constructor of AsyncRPCOperation_sendmany
     try {
-        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_sendmany(boost::none, mtx, "",{}, {}, -1));
+        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_sendmany(std::nullopt, mtx, "",{}, {}, -1));
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "Minconf cannot be negative"));
     }
 
     try {
-        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_sendmany(boost::none, mtx, "",{}, {}, 1));
+        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_sendmany(std::nullopt, mtx, "",{}, {}, 1));
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "From address parameter missing"));
     }
 
     try {
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, "tmRr6yJonqGK23UVhrKuyvTpF8qxQQjKigJ", {}, {}, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, "tmRr6yJonqGK23UVhrKuyvTpF8qxQQjKigJ", {}, {}, 1) );
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "No recipients"));
     }
 
     try {
         std::vector<SendManyRecipient> recipients = { SendManyRecipient("dummy", 1*COIN, "") };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, "INVALID", recipients, {}, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, "INVALID", recipients, {}, 1) );
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "Invalid from address"));
     }
@@ -1151,7 +1150,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_parameters)
     // Testnet payment addresses begin with 'zt'.  This test detects an incorrect prefix.
     try {
         std::vector<SendManyRecipient> recipients = { SendManyRecipient("dummy", 1*COIN, "") };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, "zcMuhvq8sEkHALuSU2i4NbNQxshSAYrpCExec45ZjtivYPbuiFPwk6WHy4SvsbeZ4siy1WheuRGjtaJmoD1J8bFqNXhsG6U", recipients, {}, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, "zcMuhvq8sEkHALuSU2i4NbNQxshSAYrpCExec45ZjtivYPbuiFPwk6WHy4SvsbeZ4siy1WheuRGjtaJmoD1J8bFqNXhsG6U", recipients, {}, 1) );
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "Invalid from address"));
     }
@@ -1160,7 +1159,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_parameters)
     // invokes a method on pwalletMain, which is undefined in the google test environment.
     try {
         std::vector<SendManyRecipient> recipients = { SendManyRecipient("dummy", 1*COIN, "") };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, "ztjiDe569DPNbyTE6TSdJTaSDhoXEHLGvYoUnBU1wfVNU52TEyT6berYtySkd21njAeEoh8fFJUT42kua9r8EnhBaEKqCpP", recipients, {}, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, "ztjiDe569DPNbyTE6TSdJTaSDhoXEHLGvYoUnBU1wfVNU52TEyT6berYtySkd21njAeEoh8fFJUT42kua9r8EnhBaEKqCpP", recipients, {}, 1) );
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "no spending key found for zaddr"));
     }
@@ -1172,7 +1171,7 @@ BOOST_AUTO_TEST_CASE(asyncrpcoperation_sign_send_raw_transaction) {
     UniValue obj(UniValue::VOBJ);
     obj.pushKV("rawtxn", raw);
     // Verify test mode is returning output (since no input taddrs, signed and unsigned are the same).
-    std::pair<CTransaction, UniValue> txAndResult = SignSendRawTransaction(obj, boost::none, true);
+    std::pair<CTransaction, UniValue> txAndResult = SignSendRawTransaction(obj, std::nullopt, true);
     UniValue resultObj = txAndResult.second.get_obj();
     std::string hex = find_value(resultObj, "hex").get_str();
     BOOST_CHECK_EQUAL(hex, raw);
@@ -1207,7 +1206,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_internals)
     // there are no utxos to spend
     {
         std::vector<SendManyRecipient> recipients = { SendManyRecipient(zaddr1, 100*COIN, "DEADBEEF") };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, taddr1, {}, recipients, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, taddr1, {}, recipients, 1) );
         operation->main();
         BOOST_CHECK(operation->isFailed());
         std::string msg = operation->getErrorMessage();
@@ -1218,7 +1217,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_internals)
     {
         try {
             std::vector<SendManyRecipient> recipients = {SendManyRecipient(taddr1, 100*COIN, "DEADBEEF")};
-            std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_sendmany(boost::none, mtx, zaddr1, recipients, {}, 0));
+            std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_sendmany(std::nullopt, mtx, zaddr1, recipients, {}, 0));
             BOOST_CHECK(false); // Fail test if an exception is not thrown
         } catch (const UniValue& objError) {
             BOOST_CHECK(find_error(objError, "Minconf cannot be zero when sending from zaddr"));
@@ -1229,7 +1228,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_internals)
     // there are no unspent notes to spend
     {
         std::vector<SendManyRecipient> recipients = { SendManyRecipient(taddr1, 100*COIN, "DEADBEEF") };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, zaddr1, recipients, {}, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, zaddr1, recipients, {}, 1) );
         operation->main();
         BOOST_CHECK(operation->isFailed());
         std::string msg = operation->getErrorMessage();
@@ -1239,7 +1238,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_internals)
     // get_memo_from_hex_string())
     {
         std::vector<SendManyRecipient> recipients = { SendManyRecipient(zaddr1, 100*COIN, "DEADBEEF") };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, zaddr1, recipients, {}, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, zaddr1, recipients, {}, 1) );
         std::shared_ptr<AsyncRPCOperation_sendmany> ptr = std::dynamic_pointer_cast<AsyncRPCOperation_sendmany> (operation);
         TEST_FRIEND_AsyncRPCOperation_sendmany proxy(ptr);
 
@@ -1290,7 +1289,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_internals)
     // add_taddr_change_output_to_tx() will append a vout to a raw transaction
     {
         std::vector<SendManyRecipient> recipients = { SendManyRecipient(zaddr1, 100*COIN, "DEADBEEF") };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, zaddr1, recipients, {}, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, zaddr1, recipients, {}, 1) );
         std::shared_ptr<AsyncRPCOperation_sendmany> ptr = std::dynamic_pointer_cast<AsyncRPCOperation_sendmany> (operation);
         TEST_FRIEND_AsyncRPCOperation_sendmany proxy(ptr);
 
@@ -1320,7 +1319,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_internals)
             SendManyRecipient("tmUSbHz3vxnwLvRyNDXbwkZxjVyDodMJEhh", 456000000, ""),
             SendManyRecipient("tmYZAXYPCP56Xa5JQWWPZuK7o7bfUQW6kkd", 789000000, ""),
         };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, zaddr1, recipients, {}, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, zaddr1, recipients, {}, 1) );
         std::shared_ptr<AsyncRPCOperation_sendmany> ptr = std::dynamic_pointer_cast<AsyncRPCOperation_sendmany> (operation);
         TEST_FRIEND_AsyncRPCOperation_sendmany proxy(ptr);
 
@@ -1338,7 +1337,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_internals)
         // Dummy input so the operation object can be instantiated.
         std::vector<SendManyRecipient> recipients = { SendManyRecipient(zaddr1, 50000, "ABCD") };
 
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(boost::none, mtx, zaddr1, {}, recipients, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_sendmany(std::nullopt, mtx, zaddr1, {}, recipients, 1) );
         std::shared_ptr<AsyncRPCOperation_sendmany> ptr = std::dynamic_pointer_cast<AsyncRPCOperation_sendmany> (operation);
         TEST_FRIEND_AsyncRPCOperation_sendmany proxy(ptr);
 
@@ -1346,7 +1345,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_sendmany_internals)
         static_cast<AsyncRPCOperation_sendmany *>(operation.get())->testmode = true;
 
         AsyncJoinSplitInfo info;
-        std::vector<boost::optional < SproutWitness>> witnesses;
+        std::vector<std::optional < SproutWitness>> witnesses;
         uint256 anchor;
         try {
             proxy.perform_joinsplit(info, witnesses, anchor);
@@ -1885,14 +1884,14 @@ BOOST_AUTO_TEST_CASE(rpc_z_mergetoaddress_parameters)
         "mainnet memo");
 
     try {
-        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_mergetoaddress(boost::none,  mtx, {}, {}, {}, testnetzaddr, -1 ));
+        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_mergetoaddress(std::nullopt,  mtx, {}, {}, {}, testnetzaddr, -1 ));
         BOOST_FAIL("Should have caused an error");
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "Fee is out of range"));
     }
 
     try {
-        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_mergetoaddress(boost::none, mtx, {}, {}, {}, testnetzaddr, 1));
+        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_mergetoaddress(std::nullopt, mtx, {}, {}, {}, testnetzaddr, 1));
         BOOST_FAIL("Should have caused an error");
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "No inputs"));
@@ -1902,7 +1901,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_mergetoaddress_parameters)
 
     try {
         MergeToAddressRecipient badaddr("", "memo");
-        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_mergetoaddress(boost::none, mtx, inputs, {}, {}, badaddr, 1));
+        std::shared_ptr<AsyncRPCOperation> operation(new AsyncRPCOperation_mergetoaddress(std::nullopt, mtx, inputs, {}, {}, badaddr, 1));
         BOOST_FAIL("Should have caused an error");
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "Recipient parameter missing"));
@@ -1915,7 +1914,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_mergetoaddress_parameters)
 
     // Sprout and Sapling inputs -> throw
     try {
-        auto operation = new AsyncRPCOperation_mergetoaddress(boost::none, mtx, inputs, sproutNoteInputs, saplingNoteInputs, testnetzaddr, 1);
+        auto operation = new AsyncRPCOperation_mergetoaddress(std::nullopt, mtx, inputs, sproutNoteInputs, saplingNoteInputs, testnetzaddr, 1);
         BOOST_FAIL("Should have caused an error");
     } catch (const UniValue& objError) {
         BOOST_CHECK(find_error(objError, "Cannot send from both Sprout and Sapling addresses using z_mergetoaddress"));
@@ -1931,7 +1930,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_mergetoaddress_parameters)
     // Testnet payment addresses begin with 'zt'.  This test detects an incorrect prefix.
     try {
         std::vector<MergeToAddressInputUTXO> inputs = { MergeToAddressInputUTXO{ COutPoint{uint256(), 0}, 0, CScript()} };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_mergetoaddress(boost::none, mtx, inputs, {}, {}, mainnetzaddr, 1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_mergetoaddress(std::nullopt, mtx, inputs, {}, {}, mainnetzaddr, 1) );
         BOOST_FAIL("Should have caused an error");
     } catch (const UniValue& objError) {
         BOOST_CHECK( find_error(objError, "Invalid recipient address"));
@@ -1965,7 +1964,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_mergetoaddress_internals)
     // Insufficient funds
     {
         std::vector<MergeToAddressInputUTXO> inputs = { MergeToAddressInputUTXO{COutPoint{uint256(),0},0, CScript()} };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_mergetoaddress(boost::none, mtx, inputs, {}, {}, zaddr1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_mergetoaddress(std::nullopt, mtx, inputs, {}, {}, zaddr1) );
         operation->main();
         BOOST_CHECK(operation->isFailed());
         std::string msg = operation->getErrorMessage();
@@ -1975,7 +1974,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_mergetoaddress_internals)
     // get_memo_from_hex_string())
     {
         std::vector<MergeToAddressInputUTXO> inputs = { MergeToAddressInputUTXO{COutPoint{uint256(),0},100000, CScript()} };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_mergetoaddress(boost::none, mtx, inputs, {}, {}, zaddr1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_mergetoaddress(std::nullopt, mtx, inputs, {}, {}, zaddr1) );
         std::shared_ptr<AsyncRPCOperation_mergetoaddress> ptr = std::dynamic_pointer_cast<AsyncRPCOperation_mergetoaddress> (operation);
         TEST_FRIEND_AsyncRPCOperation_mergetoaddress proxy(ptr);
 
@@ -2029,7 +2028,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_mergetoaddress_internals)
     {
         // Dummy input so the operation object can be instantiated.
         std::vector<MergeToAddressInputUTXO> inputs = { MergeToAddressInputUTXO{COutPoint{uint256(),0},100000, CScript()} };
-        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_mergetoaddress(boost::none, mtx, inputs, {}, {}, zaddr1) );
+        std::shared_ptr<AsyncRPCOperation> operation( new AsyncRPCOperation_mergetoaddress(std::nullopt, mtx, inputs, {}, {}, zaddr1) );
         std::shared_ptr<AsyncRPCOperation_mergetoaddress> ptr = std::dynamic_pointer_cast<AsyncRPCOperation_mergetoaddress> (operation);
         TEST_FRIEND_AsyncRPCOperation_mergetoaddress proxy(ptr);
 
@@ -2037,7 +2036,7 @@ BOOST_AUTO_TEST_CASE(rpc_z_mergetoaddress_internals)
         static_cast<AsyncRPCOperation_mergetoaddress *>(operation.get())->testmode = true;
 
         MergeToAddressJSInfo info;
-        std::vector<boost::optional < SproutWitness>> witnesses;
+        std::vector<std::optional < SproutWitness>> witnesses;
         uint256 anchor;
         try {
             proxy.perform_joinsplit(info, witnesses, anchor);
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 93fe8f320..2e09e7931 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -615,7 +615,7 @@ void CWallet::ChainTipAdded(const CBlockIndex *pindex,
 
 void CWallet::ChainTip(const CBlockIndex *pindex, 
                        const CBlock *pblock,
-                       boost::optional<std::pair<SproutMerkleTree, SaplingMerkleTree>> added)
+                       std::optional<std::pair<SproutMerkleTree, SaplingMerkleTree>> added)
 {
     if (added) {
         ChainTipAdded(pindex, pblock, added->first, added->second);
@@ -666,7 +666,7 @@ void CWallet::RunSaplingMigration(int blockHeight) {
         for (const CTransaction& transaction : pendingSaplingMigrationTxs) {
             // Send the transaction
             CWalletTx wtx(this, transaction);
-            CommitTransaction(wtx, boost::none);
+            CommitTransaction(wtx, std::nullopt);
         }
         pendingSaplingMigrationTxs.clear();
     }
@@ -1525,7 +1525,7 @@ void CWallet::UpdateSaplingNullifierNoteMapWithTx(CWalletTx& wtx) {
             if (item.second.nullifier) {
                 mapSaplingNullifiersToNotes.erase(item.second.nullifier.value());
             }
-            item.second.nullifier = boost::none;
+            item.second.nullifier = std::nullopt;
         }
         else {
             uint64_t position = nd.witnesses.front().position();
@@ -1536,20 +1536,20 @@ void CWallet::UpdateSaplingNullifierNoteMapWithTx(CWalletTx& wtx) {
 
             // The transaction would not have entered the wallet unless
             // its plaintext had been successfully decrypted previously.
-            assert(optDeserialized != boost::none);
+            assert(optDeserialized != std::nullopt);
 
             auto optPlaintext = SaplingNotePlaintext::plaintext_checks_without_height(*optDeserialized, nd.ivk, output.ephemeralKey, output.cmu);
 
             // An item in mapSaplingNoteData must have already been successfully decrypted,
             // otherwise the item would not exist in the first place.
-            assert(optPlaintext != boost::none);
+            assert(optPlaintext != std::nullopt);
 
             auto optNote = optPlaintext.value().note(nd.ivk);
-            assert(optNote != boost::none);
+            assert(optNote != std::nullopt);
 
             auto optNullifier = optNote.value().nullifier(extfvk.fvk, position);
             // This should not happen.  If it does, maybe the position has been corrupted or miscalculated?
-            assert(optNullifier != boost::none);
+            assert(optNullifier != std::nullopt);
             uint256 nullifier = optNullifier.value();
             mapSaplingNullifiersToNotes[nullifier] = op;
             item.second.nullifier = nullifier;
@@ -1842,13 +1842,13 @@ void CWallet::EraseFromWallet(const uint256 &hash)
  * Returns a nullifier if the SpendingKey is available
  * Throws std::runtime_error if the decryptor doesn't match this note
  */
-boost::optional<uint256> CWallet::GetSproutNoteNullifier(const JSDescription &jsdesc,
+std::optional<uint256> CWallet::GetSproutNoteNullifier(const JSDescription &jsdesc,
                                                          const libzcash::SproutPaymentAddress &address,
                                                          const ZCNoteDecryption &dec,
                                                          const uint256 &hSig,
                                                          uint8_t n) const
 {
-    boost::optional<uint256> ret;
+    std::optional<uint256> ret;
     auto note_pt = libzcash::SproutNotePlaintext::decrypt(
         dec,
         jsdesc.ciphertexts[n],
@@ -1988,12 +1988,12 @@ bool CWallet::IsSaplingNullifierFromMe(const uint256& nullifier) const
 }
 
 void CWallet::GetSproutNoteWitnesses(std::vector<JSOutPoint> notes,
-                                     std::vector<boost::optional<SproutWitness>>& witnesses,
+                                     std::vector<std::optional<SproutWitness>>& witnesses,
                                      uint256 &final_anchor)
 {
     LOCK(cs_wallet);
     witnesses.resize(notes.size());
-    boost::optional<uint256> rt;
+    std::optional<uint256> rt;
     int i = 0;
     for (JSOutPoint note : notes) {
         if (mapWallet.count(note.hash) &&
@@ -2015,12 +2015,12 @@ void CWallet::GetSproutNoteWitnesses(std::vector<JSOutPoint> notes,
 }
 
 void CWallet::GetSaplingNoteWitnesses(std::vector<SaplingOutPoint> notes,
-                                      std::vector<boost::optional<SaplingWitness>>& witnesses,
+                                      std::vector<std::optional<SaplingWitness>>& witnesses,
                                       uint256 &final_anchor)
 {
     LOCK(cs_wallet);
     witnesses.resize(notes.size());
-    boost::optional<uint256> rt;
+    std::optional<uint256> rt;
     int i = 0;
     for (SaplingOutPoint note : notes) {
         if (mapWallet.count(note.hash) &&
@@ -2340,13 +2340,13 @@ std::pair<SproutNotePlaintext, SproutPaymentAddress> CWalletTx::DecryptSproutNot
     }
 }
 
-boost::optional<std::pair<
+std::optional<std::pair<
     SaplingNotePlaintext,
     SaplingPaymentAddress>> CWalletTx::DecryptSaplingNote(const Consensus::Params& params, int height, SaplingOutPoint op) const
 {
     // Check whether we can decrypt this SaplingOutPoint
     if (this->mapSaplingNoteData.count(op) == 0) {
-        return boost::none;
+        return std::nullopt;
     }
 
     auto output = this->vShieldedOutput[op.n];
@@ -2359,23 +2359,23 @@ boost::optional<std::pair<
         nd.ivk,
         output.ephemeralKey,
         output.cmu);
-    assert(maybe_pt != boost::none);
+    assert(maybe_pt != std::nullopt);
     auto notePt = maybe_pt.value();
 
     auto maybe_pa = nd.ivk.address(notePt.d);
-    assert(maybe_pa != boost::none);
+    assert(maybe_pa != std::nullopt);
     auto pa = maybe_pa.value();
 
     return std::make_pair(notePt, pa);
 }
 
-boost::optional<std::pair<
+std::optional<std::pair<
     SaplingNotePlaintext,
     SaplingPaymentAddress>> CWalletTx::DecryptSaplingNoteWithoutLeadByteCheck(SaplingOutPoint op) const
 {
     // Check whether we can decrypt this SaplingOutPoint
     if (this->mapSaplingNoteData.count(op) == 0) {
-        return boost::none;
+        return std::nullopt;
     }
 
     auto output = this->vShieldedOutput[op.n];
@@ -2385,14 +2385,14 @@ boost::optional<std::pair<
 
     // The transaction would not have entered the wallet unless
     // its plaintext had been successfully decrypted previously.
-    assert(optDeserialized != boost::none);
+    assert(optDeserialized != std::nullopt);
 
     auto maybe_pt = SaplingNotePlaintext::plaintext_checks_without_height(
         *optDeserialized,
         nd.ivk,
         output.ephemeralKey,
         output.cmu);
-    assert(maybe_pt != boost::none);
+    assert(maybe_pt != std::nullopt);
     auto notePt = maybe_pt.value();
 
     auto maybe_pa = nd.ivk.address(notePt.d);
@@ -2402,7 +2402,7 @@ boost::optional<std::pair<
     return std::make_pair(notePt, pa);
 }
 
-boost::optional<std::pair<
+std::optional<std::pair<
     SaplingNotePlaintext,
     SaplingPaymentAddress>> CWalletTx::RecoverSaplingNote(const Consensus::Params& params, int height, SaplingOutPoint op, std::set<uint256>& ovks) const
 {
@@ -2435,10 +2435,10 @@ boost::optional<std::pair<
     }
 
     // Couldn't recover with any of the provided OutgoingViewingKeys
-    return boost::none;
+    return std::nullopt;
 }
 
-boost::optional<std::pair<
+std::optional<std::pair<
     SaplingNotePlaintext,
     SaplingPaymentAddress>> CWalletTx::RecoverSaplingNoteWithoutLeadByteCheck(SaplingOutPoint op, std::set<uint256>& ovks) const
 {
@@ -2460,7 +2460,7 @@ boost::optional<std::pair<
 
         // The transaction would not have entered the wallet unless
         // its plaintext had been successfully decrypted previously.
-        assert(optDeserialized != boost::none);
+        assert(optDeserialized != std::nullopt);
 
         auto maybe_pt = SaplingNotePlaintext::plaintext_checks_without_height(
             *optDeserialized,
@@ -2475,7 +2475,7 @@ boost::optional<std::pair<
     }
 
     // Couldn't recover with any of the provided OutgoingViewingKeys
-    return boost::none;
+    return std::nullopt;
 }
 
 int64_t CWalletTx::GetTxTime() const
@@ -2681,7 +2681,7 @@ bool CWalletTx::WriteToDisk(CWalletDB *pwalletdb)
 }
 
 void CWallet::WitnessNoteCommitment(std::vector<uint256> commitments,
-                                    std::vector<boost::optional<SproutWitness>>& witnesses,
+                                    std::vector<std::optional<SproutWitness>>& witnesses,
                                     uint256 &final_anchor)
 {
     witnesses.resize(commitments.size());
@@ -2701,7 +2701,7 @@ void CWallet::WitnessNoteCommitment(std::vector<uint256> commitments,
                 {
                     tree.append(note_commitment);
 
-                    for (boost::optional<SproutWitness>& wit : witnesses) {
+                    for (std::optional<SproutWitness>& wit : witnesses) {
                         if (wit) {
                             wit->append(note_commitment);
                         }
@@ -2731,7 +2731,7 @@ void CWallet::WitnessNoteCommitment(std::vector<uint256> commitments,
     // TODO: #93; Select a root via some heuristic.
     final_anchor = tree.root();
 
-    for (boost::optional<SproutWitness>& wit : witnesses) {
+    for (std::optional<SproutWitness>& wit : witnesses) {
         if (wit) {
             assert(final_anchor == wit->root());
         }
@@ -3871,7 +3871,7 @@ bool CWallet::CreateTransaction(const vector<CRecipient>& vecSend, CWalletTx& wt
 /**
  * Call after CreateTransaction unless you want to abort
  */
-bool CWallet::CommitTransaction(CWalletTx& wtxNew, boost::optional<CReserveKey&> reservekey)
+bool CWallet::CommitTransaction(CWalletTx& wtxNew, std::optional<std::reference_wrapper<CReserveKey>> reservekey)
 {
     {
         LOCK2(cs_main, cs_wallet);
@@ -5130,7 +5130,7 @@ void CWallet::GetFilteredNotes(
 
             // The transaction would not have entered the wallet unless
             // its plaintext had been successfully decrypted previously.
-            assert(optDeserialized != boost::none);
+            assert(optDeserialized != std::nullopt);
 
             auto notePt = optDeserialized.value();
             auto maybe_pa = nd.ivk.address(notePt.d);
@@ -5188,21 +5188,21 @@ bool PaymentAddressBelongsToWallet::operator()(const libzcash::InvalidEncoding&
     return false;
 }
 
-boost::optional<libzcash::ViewingKey> GetViewingKeyForPaymentAddress::operator()(
+std::optional<libzcash::ViewingKey> GetViewingKeyForPaymentAddress::operator()(
     const libzcash::SproutPaymentAddress &zaddr) const
 {
     libzcash::SproutViewingKey vk;
     if (!m_wallet->GetSproutViewingKey(zaddr, vk)) {
         libzcash::SproutSpendingKey k;
         if (!m_wallet->GetSproutSpendingKey(zaddr, k)) {
-            return boost::none;
+            return std::nullopt;
         }
         vk = k.viewing_key();
     }
     return libzcash::ViewingKey(vk);
 }
 
-boost::optional<libzcash::ViewingKey> GetViewingKeyForPaymentAddress::operator()(
+std::optional<libzcash::ViewingKey> GetViewingKeyForPaymentAddress::operator()(
     const libzcash::SaplingPaymentAddress &zaddr) const
 {
     libzcash::SaplingIncomingViewingKey ivk;
@@ -5213,11 +5213,11 @@ boost::optional<libzcash::ViewingKey> GetViewingKeyForPaymentAddress::operator()
     {
         return libzcash::ViewingKey(extfvk);
     } else {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
-boost::optional<libzcash::ViewingKey> GetViewingKeyForPaymentAddress::operator()(
+std::optional<libzcash::ViewingKey> GetViewingKeyForPaymentAddress::operator()(
     const libzcash::InvalidEncoding& no) const
 {
     // Defaults to InvalidEncoding
@@ -5244,29 +5244,29 @@ bool HaveSpendingKeyForPaymentAddress::operator()(const libzcash::InvalidEncodin
     return false;
 }
 
-boost::optional<libzcash::SpendingKey> GetSpendingKeyForPaymentAddress::operator()(
+std::optional<libzcash::SpendingKey> GetSpendingKeyForPaymentAddress::operator()(
     const libzcash::SproutPaymentAddress &zaddr) const
 {
     libzcash::SproutSpendingKey k;
     if (m_wallet->GetSproutSpendingKey(zaddr, k)) {
         return libzcash::SpendingKey(k);
     } else {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
-boost::optional<libzcash::SpendingKey> GetSpendingKeyForPaymentAddress::operator()(
+std::optional<libzcash::SpendingKey> GetSpendingKeyForPaymentAddress::operator()(
     const libzcash::SaplingPaymentAddress &zaddr) const
 {
     libzcash::SaplingExtendedSpendingKey extsk;
     if (m_wallet->GetSaplingExtendedSpendingKey(zaddr, extsk)) {
         return libzcash::SpendingKey(extsk);
     } else {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
-boost::optional<libzcash::SpendingKey> GetSpendingKeyForPaymentAddress::operator()(
+std::optional<libzcash::SpendingKey> GetSpendingKeyForPaymentAddress::operator()(
     const libzcash::InvalidEncoding& no) const
 {
     // Defaults to InvalidEncoding
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index b6c413850..1accf8334 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -228,7 +228,7 @@ public:
      * transactions they are spent in. This is the same security semantics as
      * for transparent addresses.
      */
-    boost::optional<uint256> nullifier;
+    std::optional<uint256> nullifier;
 
     /**
      * Cached incremental witnesses for spendable Notes.
@@ -291,7 +291,7 @@ public:
     std::list<SaplingWitness> witnesses;
     int witnessHeight;
     libzcash::SaplingIncomingViewingKey ivk;
-    boost::optional<uint256> nullifier;
+    std::optional<uint256> nullifier;
 
     ADD_SERIALIZE_METHODS;
 
@@ -565,17 +565,17 @@ public:
 
     std::pair<libzcash::SproutNotePlaintext, libzcash::SproutPaymentAddress> DecryptSproutNote(
         JSOutPoint jsop) const;
-    boost::optional<std::pair<
+    std::optional<std::pair<
         libzcash::SaplingNotePlaintext,
         libzcash::SaplingPaymentAddress>> DecryptSaplingNote(const Consensus::Params& params, int height, SaplingOutPoint op) const;
-    boost::optional<std::pair<
+    std::optional<std::pair<
         libzcash::SaplingNotePlaintext,
         libzcash::SaplingPaymentAddress>> DecryptSaplingNoteWithoutLeadByteCheck(SaplingOutPoint op) const;
-    boost::optional<std::pair<
+    std::optional<std::pair<
         libzcash::SaplingNotePlaintext,
         libzcash::SaplingPaymentAddress>> RecoverSaplingNote(const Consensus::Params& params, int height,
             SaplingOutPoint op, std::set<uint256>& ovks) const;
-    boost::optional<std::pair<
+    std::optional<std::pair<
         libzcash::SaplingNotePlaintext,
         libzcash::SaplingPaymentAddress>> RecoverSaplingNoteWithoutLeadByteCheck(SaplingOutPoint op, std::set<uint256>& ovks) const;
 
@@ -1179,7 +1179,7 @@ public:
     void EraseFromWallet(const uint256 &hash);
     void WitnessNoteCommitment(
          std::vector<uint256> commitments,
-         std::vector<boost::optional<SproutWitness>>& witnesses,
+         std::vector<std::optional<SproutWitness>>& witnesses,
          uint256 &final_anchor);
     int ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate = false);
     void ReacceptWalletTransactions();
@@ -1204,7 +1204,7 @@ public:
      */
     bool CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletTx& wtxNew, CReserveKey& reservekey, CAmount& nFeeRet, int& nChangePosRet,
                            std::string& strFailReason, const CCoinControl *coinControl = NULL, bool sign = true);
-    bool CommitTransaction(CWalletTx& wtxNew, boost::optional<CReserveKey&> reservekey);
+    bool CommitTransaction(CWalletTx& wtxNew, std::optional<std::reference_wrapper<CReserveKey>> reservekey);
 
     static CFeeRate minTxFee;
     /**
@@ -1232,7 +1232,7 @@ public:
 
     std::set<CTxDestination> GetAccountAddresses(const std::string& strAccount) const;
 
-    boost::optional<uint256> GetSproutNoteNullifier(
+    std::optional<uint256> GetSproutNoteNullifier(
         const JSDescription& jsdesc,
         const libzcash::SproutPaymentAddress& address,
         const ZCNoteDecryption& dec,
@@ -1245,11 +1245,11 @@ public:
 
     void GetSproutNoteWitnesses(
          std::vector<JSOutPoint> notes,
-         std::vector<boost::optional<SproutWitness>>& witnesses,
+         std::vector<std::optional<SproutWitness>>& witnesses,
          uint256 &final_anchor);
     void GetSaplingNoteWitnesses(
          std::vector<SaplingOutPoint> notes,
-         std::vector<boost::optional<SaplingWitness>>& witnesses,
+         std::vector<std::optional<SaplingWitness>>& witnesses,
          uint256 &final_anchor);
 
     isminetype IsMine(const CTxIn& txin) const;
@@ -1267,7 +1267,7 @@ public:
     void ChainTip(
         const CBlockIndex *pindex,
         const CBlock *pblock,
-        boost::optional<std::pair<SproutMerkleTree, SaplingMerkleTree>> added);
+        std::optional<std::pair<SproutMerkleTree, SaplingMerkleTree>> added);
     void RunSaplingMigration(int blockHeight);
     void AddPendingSaplingMigrationTx(const CTransaction& tx);
     /** Saves witness caches and best block locator to disk. */
@@ -1487,9 +1487,9 @@ private:
 public:
     GetViewingKeyForPaymentAddress(CWallet *wallet) : m_wallet(wallet) {}
 
-    boost::optional<libzcash::ViewingKey> operator()(const libzcash::SproutPaymentAddress &zaddr) const;
-    boost::optional<libzcash::ViewingKey> operator()(const libzcash::SaplingPaymentAddress &zaddr) const;
-    boost::optional<libzcash::ViewingKey> operator()(const libzcash::InvalidEncoding& no) const;
+    std::optional<libzcash::ViewingKey> operator()(const libzcash::SproutPaymentAddress &zaddr) const;
+    std::optional<libzcash::ViewingKey> operator()(const libzcash::SaplingPaymentAddress &zaddr) const;
+    std::optional<libzcash::ViewingKey> operator()(const libzcash::InvalidEncoding& no) const;
 };
 
 class HaveSpendingKeyForPaymentAddress
@@ -1511,9 +1511,9 @@ private:
 public:
     GetSpendingKeyForPaymentAddress(CWallet *wallet) : m_wallet(wallet) {}
 
-    boost::optional<libzcash::SpendingKey> operator()(const libzcash::SproutPaymentAddress &zaddr) const;
-    boost::optional<libzcash::SpendingKey> operator()(const libzcash::SaplingPaymentAddress &zaddr) const;
-    boost::optional<libzcash::SpendingKey> operator()(const libzcash::InvalidEncoding& no) const;
+    std::optional<libzcash::SpendingKey> operator()(const libzcash::SproutPaymentAddress &zaddr) const;
+    std::optional<libzcash::SpendingKey> operator()(const libzcash::SaplingPaymentAddress &zaddr) const;
+    std::optional<libzcash::SpendingKey> operator()(const libzcash::InvalidEncoding& no) const;
 };
 
 enum KeyAddResult {
@@ -1541,18 +1541,18 @@ private:
     CWallet *m_wallet;
     const Consensus::Params &params;
     int64_t nTime;
-    boost::optional<std::string> hdKeypath; // currently sapling only
-    boost::optional<std::string> seedFpStr; // currently sapling only
+    std::optional<std::string> hdKeypath; // currently sapling only
+    std::optional<std::string> seedFpStr; // currently sapling only
     bool log;
 public: 
     AddSpendingKeyToWallet(CWallet *wallet, const Consensus::Params &params) :
-        m_wallet(wallet), params(params), nTime(1), hdKeypath(boost::none), seedFpStr(boost::none), log(false) {}
+        m_wallet(wallet), params(params), nTime(1), hdKeypath(std::nullopt), seedFpStr(std::nullopt), log(false) {}
     AddSpendingKeyToWallet(
         CWallet *wallet,
         const Consensus::Params &params,
         int64_t _nTime,
-        boost::optional<std::string> _hdKeypath,
-        boost::optional<std::string> _seedFp,
+        std::optional<std::string> _hdKeypath,
+        std::optional<std::string> _seedFp,
         bool _log
     ) : m_wallet(wallet), params(params), nTime(_nTime), hdKeypath(_hdKeypath), seedFpStr(_seedFp), log(_log) {}
 
diff --git a/src/zcash/IncrementalMerkleTree.cpp b/src/zcash/IncrementalMerkleTree.cpp
index ded814088..4f5c23635 100644
--- a/src/zcash/IncrementalMerkleTree.cpp
+++ b/src/zcash/IncrementalMerkleTree.cpp
@@ -929,17 +929,17 @@ void IncrementalMerkleTree<Depth, Hash>::append(Hash obj) {
         right = obj;
     } else {
         // Combine the leaves and propagate it up the tree
-        boost::optional<Hash> combined = Hash::combine(*left, *right, 0);
+        std::optional<Hash> combined = Hash::combine(*left, *right, 0);
 
         // Set the "left" leaf to the object and make the "right" leaf none
         left = obj;
-        right = boost::none;
+        right = std::nullopt;
 
         for (size_t i = 0; i < Depth; i++) {
             if (i < parents.size()) {
                 if (parents[i]) {
                     combined = Hash::combine(*parents[i], *combined, i+1);
-                    parents[i] = boost::none;
+                    parents[i] = std::nullopt;
                 } else {
                     parents[i] = *combined;
                     break;
@@ -965,7 +965,7 @@ bool IncrementalMerkleTree<Depth, Hash>::is_complete(size_t depth) const {
         return false;
     }
 
-    for (const boost::optional<Hash>& parent : parents) {
+    for (const std::optional<Hash>& parent : parents) {
         if (!parent) {
             return false;
         }
@@ -996,7 +996,7 @@ size_t IncrementalMerkleTree<Depth, Hash>::next_depth(size_t skip) const {
 
     size_t d = 1;
 
-    for (const boost::optional<Hash>& parent : parents) {
+    for (const std::optional<Hash>& parent : parents) {
         if (!parent) {
             if (skip) {
                 skip--;
@@ -1024,7 +1024,7 @@ Hash IncrementalMerkleTree<Depth, Hash>::root(size_t depth,
 
     size_t d = 1;
 
-    for (const boost::optional<Hash>& parent : parents) {
+    for (const std::optional<Hash>& parent : parents) {
         if (parent) {
             root = Hash::combine(*parent, root, d);
         } else {
@@ -1067,7 +1067,7 @@ MerklePath IncrementalMerkleTree<Depth, Hash>::path(std::deque<Hash> filler_hash
 
     size_t d = 1;
 
-    for (const boost::optional<Hash>& parent : parents) {
+    for (const std::optional<Hash>& parent : parents) {
         if (parent) {
             index.push_back(true);
             path.push_back(*parent);
@@ -1117,7 +1117,7 @@ void IncrementalWitness<Depth, Hash>::append(Hash obj) {
 
         if (cursor->is_complete(cursor_depth)) {
             filled.push_back(cursor->root(cursor_depth));
-            cursor = boost::none;
+            cursor = std::nullopt;
         }
     } else {
         cursor_depth = tree.next_depth(filled.size());
diff --git a/src/zcash/IncrementalMerkleTree.hpp b/src/zcash/IncrementalMerkleTree.hpp
index 80f7e846d..807e6ee2c 100644
--- a/src/zcash/IncrementalMerkleTree.hpp
+++ b/src/zcash/IncrementalMerkleTree.hpp
@@ -4,7 +4,6 @@
 #include <array>
 #include <deque>
 #include <optional>
-#include <boost/optional.hpp>
 
 #include "uint256.h"
 #include "serialize.h"
@@ -126,11 +125,11 @@ public:
 
 private:
     static EmptyMerkleRoots<Depth, Hash> emptyroots;
-    boost::optional<Hash> left;
-    boost::optional<Hash> right;
+    std::optional<Hash> left;
+    std::optional<Hash> right;
 
     // Collapsed "left" subtrees ordered toward the root of the tree.
-    std::vector<boost::optional<Hash>> parents;
+    std::vector<std::optional<Hash>> parents;
     MerklePath path(std::deque<Hash> filler_hashes = std::deque<Hash>()) const;
     Hash root(size_t depth, std::deque<Hash> filler_hashes = std::deque<Hash>()) const;
     bool is_complete(size_t depth = Depth) const;
@@ -193,7 +192,7 @@ public:
 private:
     IncrementalMerkleTree<Depth, Hash> tree;
     std::vector<Hash> filled;
-    boost::optional<IncrementalMerkleTree<Depth, Hash>> cursor;
+    std::optional<IncrementalMerkleTree<Depth, Hash>> cursor;
     size_t cursor_depth = 0;
     std::deque<Hash> partial_path() const;
     IncrementalWitness(IncrementalMerkleTree<Depth, Hash> tree) : tree(tree) {}
diff --git a/src/zcash/JoinSplit.cpp b/src/zcash/JoinSplit.cpp
index 00f86f00b..db35c6e5a 100644
--- a/src/zcash/JoinSplit.cpp
+++ b/src/zcash/JoinSplit.cpp
@@ -6,7 +6,6 @@
 #include <memory>
 
 #include <boost/format.hpp>
-#include <boost/optional.hpp>
 #include <fstream>
 #include "tinyformat.h"
 #include "sync.h"
diff --git a/src/zcash/Note.cpp b/src/zcash/Note.cpp
index abbfae0bc..e29dd91e3 100644
--- a/src/zcash/Note.cpp
+++ b/src/zcash/Note.cpp
@@ -59,7 +59,7 @@ SaplingNote::SaplingNote(
 }
 
 // Call librustzcash to compute the commitment
-boost::optional<uint256> SaplingNote::cmu() const {
+std::optional<uint256> SaplingNote::cmu() const {
     uint256 result;
     uint256 rcm_tmp = rcm();
     if (!librustzcash_sapling_compute_cmu(
@@ -70,14 +70,14 @@ boost::optional<uint256> SaplingNote::cmu() const {
             result.begin()
         ))
     {
-        return boost::none;
+        return std::nullopt;
     }
 
     return result;
 }
 
 // Call librustzcash to compute the nullifier
-boost::optional<uint256> SaplingNote::nullifier(const SaplingFullViewingKey& vk, const uint64_t position) const
+std::optional<uint256> SaplingNote::nullifier(const SaplingFullViewingKey& vk, const uint64_t position) const
 {
     auto ak = vk.ak;
     auto nk = vk.nk;
@@ -95,7 +95,7 @@ boost::optional<uint256> SaplingNote::nullifier(const SaplingFullViewingKey& vk,
             result.begin()
     ))
     {
-        return boost::none;
+        return std::nullopt;
     }
 
     return result;
@@ -167,7 +167,7 @@ SaplingNotePlaintext::SaplingNotePlaintext(
 }
 
 
-boost::optional<SaplingNote> SaplingNotePlaintext::note(const SaplingIncomingViewingKey& ivk) const
+std::optional<SaplingNote> SaplingNotePlaintext::note(const SaplingIncomingViewingKey& ivk) const
 {
     auto addr = ivk.address(d);
     if (addr) {
@@ -179,11 +179,11 @@ boost::optional<SaplingNote> SaplingNotePlaintext::note(const SaplingIncomingVie
         auto tmp = SaplingNote(d, addr.value().pk_d, value_, rseed, zip_212_enabled);
         return tmp;
     } else {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
-boost::optional<SaplingOutgoingPlaintext> SaplingOutgoingPlaintext::decrypt(
+std::optional<SaplingOutgoingPlaintext> SaplingOutgoingPlaintext::decrypt(
     const SaplingOutCiphertext &ciphertext,
     const uint256& ovk,
     const uint256& cv,
@@ -193,7 +193,7 @@ boost::optional<SaplingOutgoingPlaintext> SaplingOutgoingPlaintext::decrypt(
 {
     auto pt = AttemptSaplingOutDecryption(ciphertext, ovk, cv, cm, epk);
     if (!pt) {
-        return boost::none;
+        return std::nullopt;
     }
 
     // Deserialize from the plaintext
@@ -207,11 +207,11 @@ boost::optional<SaplingOutgoingPlaintext> SaplingOutgoingPlaintext::decrypt(
     } catch (const boost::thread_interrupted&) {
         throw;
     } catch (...) {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
-boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::decrypt(
+std::optional<SaplingNotePlaintext> SaplingNotePlaintext::decrypt(
     const Consensus::Params& params,
     int height,
     const SaplingEncCiphertext &ciphertext,
@@ -223,7 +223,7 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::decrypt(
     auto ret = attempt_sapling_enc_decryption_deserialization(ciphertext, ivk, epk);
 
     if (!ret) {
-        return boost::none;
+        return std::nullopt;
     } else {
         const SaplingNotePlaintext plaintext = *ret;
 
@@ -231,14 +231,14 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::decrypt(
         if (!plaintext_version_is_valid(params, height, plaintext.get_leadbyte())) {
             LogPrint("receiveunsafe", "Received note plaintext with invalid lead byte %d at height %d",
                      plaintext.get_leadbyte(), height);
-            return boost::none;
+            return std::nullopt;
         }
 
         return plaintext_checks_without_height(plaintext, ivk, epk, cmu);
     }
 }
 
-boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_decryption_deserialization(
+std::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_decryption_deserialization(
     const SaplingEncCiphertext &ciphertext,
     const uint256 &ivk,
     const uint256 &epk
@@ -247,7 +247,7 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_
     auto encPlaintext = AttemptSaplingEncDecryption(ciphertext, ivk, epk);
 
     if (!encPlaintext) {
-        return boost::none;
+        return std::nullopt;
     }
 
     // Deserialize from the plaintext
@@ -261,11 +261,11 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_
     } catch (const boost::thread_interrupted&) {
         throw;
     } catch (...) {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
-boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_without_height(
+std::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_without_height(
     const SaplingNotePlaintext &plaintext,
     const uint256 &ivk,
     const uint256 &epk,
@@ -274,7 +274,7 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_wit
 {
     uint256 pk_d;
     if (!librustzcash_ivk_to_pkd(ivk.begin(), plaintext.d.data(), pk_d.begin())) {
-        return boost::none;
+        return std::nullopt;
     }
 
     uint256 cmu_expected;
@@ -287,11 +287,11 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_wit
         cmu_expected.begin()
     ))
     {
-        return boost::none;
+        return std::nullopt;
     }
 
     if (cmu_expected != cmu) {
-        return boost::none;
+        return std::nullopt;
     }
 
     if (plaintext.get_leadbyte() != 0x01) {
@@ -301,17 +301,17 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_wit
         uint256 expected_epk;
         uint256 esk = plaintext.generate_or_derive_esk();
         if (!librustzcash_sapling_ka_derivepublic(plaintext.d.data(), esk.begin(), expected_epk.begin())) {
-            return boost::none;
+            return std::nullopt;
         }
         if (expected_epk != epk) {
-            return boost::none;
+            return std::nullopt;
         }
     }
 
     return plaintext;
 }
 
-boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::decrypt(
+std::optional<SaplingNotePlaintext> SaplingNotePlaintext::decrypt(
     const Consensus::Params& params,
     int height,
     const SaplingEncCiphertext &ciphertext,
@@ -324,7 +324,7 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::decrypt(
     auto ret = attempt_sapling_enc_decryption_deserialization(ciphertext, epk, esk, pk_d);
 
     if (!ret) {
-        return boost::none;
+        return std::nullopt;
     } else {
         SaplingNotePlaintext plaintext = *ret;
 
@@ -332,14 +332,14 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::decrypt(
         if (!plaintext_version_is_valid(params, height, plaintext.get_leadbyte())) {
             LogPrint("receiveunsafe", "Received note plaintext with invalid lead byte %d at height %d",
                      plaintext.get_leadbyte(), height);
-            return boost::none;
+            return std::nullopt;
         }
 
         return plaintext_checks_without_height(plaintext, epk, esk, pk_d, cmu);
     }
 }
 
-boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_decryption_deserialization(
+std::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_decryption_deserialization(
     const SaplingEncCiphertext &ciphertext,
     const uint256 &epk,
     const uint256 &esk,
@@ -349,7 +349,7 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_
     auto encPlaintext = AttemptSaplingEncDecryption(ciphertext, epk, esk, pk_d);
 
     if (!encPlaintext) {
-        return boost::none;
+        return std::nullopt;
     };
 
     // Deserialize from the plaintext
@@ -363,11 +363,11 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::attempt_sapling_enc_
     } catch (const boost::thread_interrupted&) {
         throw;
     } catch (...) {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
-boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_without_height(
+std::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_without_height(
     const SaplingNotePlaintext &plaintext,
     const uint256 &epk,
     const uint256 &esk,
@@ -380,7 +380,7 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_wit
         // ZIP 212: Additionally check that the esk provided to this function
         // is consistent with the esk we can derive
         if (esk != plaintext.generate_or_derive_esk()) {
-            return boost::none;
+            return std::nullopt;
         }
     }
 
@@ -388,10 +388,10 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_wit
     // https://zips.z.cash/zip-0212#changes-to-the-process-of-receiving-sapling-notes
     uint256 expected_epk;
     if (!librustzcash_sapling_ka_derivepublic(plaintext.d.data(), esk.begin(), expected_epk.begin())) {
-        return boost::none;
+        return std::nullopt;
     }
     if (expected_epk != epk) {
-        return boost::none;
+        return std::nullopt;
     }
 
     uint256 cmu_expected;
@@ -404,22 +404,22 @@ boost::optional<SaplingNotePlaintext> SaplingNotePlaintext::plaintext_checks_wit
         cmu_expected.begin()
     ))
     {
-        return boost::none;
+        return std::nullopt;
     }
 
     if (cmu_expected != cmu) {
-        return boost::none;
+        return std::nullopt;
     }
 
     return plaintext;
 }
 
-boost::optional<SaplingNotePlaintextEncryptionResult> SaplingNotePlaintext::encrypt(const uint256& pk_d) const
+std::optional<SaplingNotePlaintextEncryptionResult> SaplingNotePlaintext::encrypt(const uint256& pk_d) const
 {
     // Get the encryptor
     auto sne = SaplingNoteEncryption::FromDiversifier(d, generate_or_derive_esk());
     if (!sne) {
-        return boost::none;
+        return std::nullopt;
     }
     auto enc = sne.value();
 
@@ -433,7 +433,7 @@ boost::optional<SaplingNotePlaintextEncryptionResult> SaplingNotePlaintext::encr
     // Encrypt the plaintext
     auto encciphertext = enc.encrypt_to_recipient(pk_d, pt);
     if (!encciphertext) {
-        return boost::none;
+        return std::nullopt;
     }
     return SaplingNotePlaintextEncryptionResult(encciphertext.value(), enc);
 }
diff --git a/src/zcash/Note.hpp b/src/zcash/Note.hpp
index d2ab36145..ed231f411 100644
--- a/src/zcash/Note.hpp
+++ b/src/zcash/Note.hpp
@@ -10,7 +10,6 @@
 
 #include <array>
 #include <optional>
-#include <boost/optional.hpp>
 
 namespace libzcash {
 
@@ -83,8 +82,8 @@ public:
 
     virtual ~SaplingNote() {};
 
-    boost::optional<uint256> cmu() const;
-    boost::optional<uint256> nullifier(const SaplingFullViewingKey &vk, const uint64_t position) const;
+    std::optional<uint256> cmu() const;
+    std::optional<uint256> nullifier(const SaplingFullViewingKey &vk, const uint64_t position) const;
     uint256 rcm() const;
 
     Zip212Enabled get_zip_212_enabled() const {
@@ -161,7 +160,7 @@ public:
 
     SaplingNotePlaintext(const SaplingNote& note, std::array<unsigned char, ZC_MEMO_SIZE> memo);
 
-    static boost::optional<SaplingNotePlaintext> decrypt(
+    static std::optional<SaplingNotePlaintext> decrypt(
         const Consensus::Params& params,
         int height,
         const SaplingEncCiphertext &ciphertext,
@@ -170,20 +169,20 @@ public:
         const uint256 &cmu
     );
 
-    static boost::optional<SaplingNotePlaintext> plaintext_checks_without_height(
+    static std::optional<SaplingNotePlaintext> plaintext_checks_without_height(
         const SaplingNotePlaintext &plaintext,
         const uint256 &ivk,
         const uint256 &epk,
         const uint256 &cmu
     );
 
-    static boost::optional<SaplingNotePlaintext> attempt_sapling_enc_decryption_deserialization(
+    static std::optional<SaplingNotePlaintext> attempt_sapling_enc_decryption_deserialization(
         const SaplingEncCiphertext &ciphertext,
         const uint256 &ivk,
         const uint256 &epk
     );
 
-    static boost::optional<SaplingNotePlaintext> decrypt(
+    static std::optional<SaplingNotePlaintext> decrypt(
         const Consensus::Params& params,
         int height,
         const SaplingEncCiphertext &ciphertext,
@@ -193,7 +192,7 @@ public:
         const uint256 &cmu
     );
 
-    static boost::optional<SaplingNotePlaintext> plaintext_checks_without_height(
+    static std::optional<SaplingNotePlaintext> plaintext_checks_without_height(
         const SaplingNotePlaintext &plaintext,
         const uint256 &epk,
         const uint256 &esk,
@@ -201,14 +200,14 @@ public:
         const uint256 &cmu
     );
 
-    static boost::optional<SaplingNotePlaintext> attempt_sapling_enc_decryption_deserialization(
+    static std::optional<SaplingNotePlaintext> attempt_sapling_enc_decryption_deserialization(
         const SaplingEncCiphertext &ciphertext,
         const uint256 &epk,
         const uint256 &esk,
         const uint256 &pk_d
     );
 
-    boost::optional<SaplingNote> note(const SaplingIncomingViewingKey& ivk) const;
+    std::optional<SaplingNote> note(const SaplingIncomingViewingKey& ivk) const;
 
     virtual ~SaplingNotePlaintext() {}
 
@@ -228,7 +227,7 @@ public:
         READWRITE(memo_);       // 512 bytes
     }
 
-    boost::optional<SaplingNotePlaintextEncryptionResult> encrypt(const uint256& pk_d) const;
+    std::optional<SaplingNotePlaintextEncryptionResult> encrypt(const uint256& pk_d) const;
 
     uint256 rcm() const;
     uint256 generate_or_derive_esk() const;
@@ -255,7 +254,7 @@ public:
         READWRITE(esk);         // 8 bytes
     }
 
-    static boost::optional<SaplingOutgoingPlaintext> decrypt(
+    static std::optional<SaplingOutgoingPlaintext> decrypt(
         const SaplingOutCiphertext &ciphertext,
         const uint256& ovk,
         const uint256& cv,
diff --git a/src/zcash/NoteEncryption.cpp b/src/zcash/NoteEncryption.cpp
index dd0c06215..99272f9bf 100644
--- a/src/zcash/NoteEncryption.cpp
+++ b/src/zcash/NoteEncryption.cpp
@@ -90,7 +90,7 @@ void KDF(unsigned char K[NOTEENCRYPTION_CIPHER_KEYSIZE],
 
 namespace libzcash {
 
-boost::optional<SaplingNoteEncryption> SaplingNoteEncryption::FromDiversifier(
+std::optional<SaplingNoteEncryption> SaplingNoteEncryption::FromDiversifier(
     diversifier_t d,
     uint256 esk
 )
@@ -99,13 +99,13 @@ boost::optional<SaplingNoteEncryption> SaplingNoteEncryption::FromDiversifier(
 
     // Compute epk given the diversifier
     if (!librustzcash_sapling_ka_derivepublic(d.begin(), esk.begin(), epk.begin())) {
-        return boost::none;
+        return std::nullopt;
     }
 
     return SaplingNoteEncryption(epk, esk);
 }
 
-boost::optional<SaplingEncCiphertext> SaplingNoteEncryption::encrypt_to_recipient(
+std::optional<SaplingEncCiphertext> SaplingNoteEncryption::encrypt_to_recipient(
     const uint256 &pk_d,
     const SaplingEncPlaintext &message
 )
@@ -117,7 +117,7 @@ boost::optional<SaplingEncCiphertext> SaplingNoteEncryption::encrypt_to_recipien
     uint256 dhsecret;
 
     if (!librustzcash_sapling_ka_agree(pk_d.begin(), esk.begin(), dhsecret.begin())) {
-        return boost::none;
+        return std::nullopt;
     }
 
     // Construct the symmetric key
@@ -141,7 +141,7 @@ boost::optional<SaplingEncCiphertext> SaplingNoteEncryption::encrypt_to_recipien
     return ciphertext;
 }
 
-boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption(
+std::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption(
     const SaplingEncCiphertext &ciphertext,
     const uint256 &ivk,
     const uint256 &epk
@@ -150,7 +150,7 @@ boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption(
     uint256 dhsecret;
 
     if (!librustzcash_sapling_ka_agree(epk.begin(), ivk.begin(), dhsecret.begin())) {
-        return boost::none;
+        return std::nullopt;
     }
 
     // Construct the symmetric key
@@ -170,13 +170,13 @@ boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption(
         0,
         cipher_nonce, K) != 0)
     {
-        return boost::none;
+        return std::nullopt;
     }
 
     return plaintext;
 }
 
-boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption (
+std::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption (
     const SaplingEncCiphertext &ciphertext,
     const uint256 &epk,
     const uint256 &esk,
@@ -186,7 +186,7 @@ boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption (
     uint256 dhsecret;
 
     if (!librustzcash_sapling_ka_agree(pk_d.begin(), esk.begin(), dhsecret.begin())) {
-        return boost::none;
+        return std::nullopt;
     }
 
     // Construct the symmetric key
@@ -206,7 +206,7 @@ boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption (
         0,
         cipher_nonce, K) != 0)
     {
-        return boost::none;
+        return std::nullopt;
     }
 
     return plaintext;
@@ -245,7 +245,7 @@ SaplingOutCiphertext SaplingNoteEncryption::encrypt_to_ourselves(
     return ciphertext;
 }
 
-boost::optional<SaplingOutPlaintext> AttemptSaplingOutDecryption(
+std::optional<SaplingOutPlaintext> AttemptSaplingOutDecryption(
     const SaplingOutCiphertext &ciphertext,
     const uint256 &ovk,
     const uint256 &cv,
@@ -270,7 +270,7 @@ boost::optional<SaplingOutPlaintext> AttemptSaplingOutDecryption(
         0,
         cipher_nonce, K) != 0)
     {
-        return boost::none;
+        return std::nullopt;
     }
 
     return plaintext;
diff --git a/src/zcash/NoteEncryption.hpp b/src/zcash/NoteEncryption.hpp
index b3c029cad..a4484004b 100644
--- a/src/zcash/NoteEncryption.hpp
+++ b/src/zcash/NoteEncryption.hpp
@@ -43,9 +43,9 @@ protected:
 
 public:
 
-    static boost::optional<SaplingNoteEncryption> FromDiversifier(diversifier_t d, uint256 esk);
+    static std::optional<SaplingNoteEncryption> FromDiversifier(diversifier_t d, uint256 esk);
 
-    boost::optional<SaplingEncCiphertext> encrypt_to_recipient(
+    std::optional<SaplingEncCiphertext> encrypt_to_recipient(
         const uint256 &pk_d,
         const SaplingEncPlaintext &message
     );
@@ -68,7 +68,7 @@ public:
 
 // Attempts to decrypt a Sapling note. This will not check that the contents
 // of the ciphertext are correct.
-boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption(
+std::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption(
     const SaplingEncCiphertext &ciphertext,
     const uint256 &ivk,
     const uint256 &epk
@@ -76,7 +76,7 @@ boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption(
 
 // Attempts to decrypt a Sapling note using outgoing plaintext.
 // This will not check that the contents of the ciphertext are correct.
-boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption (
+std::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption (
     const SaplingEncCiphertext &ciphertext,
     const uint256 &epk,
     const uint256 &esk,
@@ -85,7 +85,7 @@ boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption (
 
 // Attempts to decrypt a Sapling note. This will not check that the contents
 // of the ciphertext are correct.
-boost::optional<SaplingOutPlaintext> AttemptSaplingOutDecryption(
+std::optional<SaplingOutPlaintext> AttemptSaplingOutDecryption(
     const SaplingOutCiphertext &ciphertext,
     const uint256 &ovk,
     const uint256 &cv,
diff --git a/src/zcash/address/sapling.cpp b/src/zcash/address/sapling.cpp
index 30aa77348..2a49f0461 100644
--- a/src/zcash/address/sapling.cpp
+++ b/src/zcash/address/sapling.cpp
@@ -23,13 +23,13 @@ uint256 SaplingPaymentAddress::GetHash() const {
     return Hash(ss.begin(), ss.end());
 }
 
-boost::optional<SaplingPaymentAddress> SaplingIncomingViewingKey::address(diversifier_t d) const {
+std::optional<SaplingPaymentAddress> SaplingIncomingViewingKey::address(diversifier_t d) const {
     uint256 pk_d;
     if (librustzcash_check_diversifier(d.data())) {
         librustzcash_ivk_to_pkd(this->begin(), d.data(), pk_d.begin());
         return SaplingPaymentAddress(d, pk_d);
     } else {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
@@ -79,7 +79,7 @@ SaplingFullViewingKey SaplingSpendingKey::full_viewing_key() const {
 SaplingPaymentAddress SaplingSpendingKey::default_address() const {
     // Iterates within default_diversifier to ensure a valid address is returned
     auto addrOpt = full_viewing_key().in_viewing_key().address(default_diversifier(*this));
-    assert(addrOpt != boost::none);
+    assert(addrOpt != std::nullopt);
     return addrOpt.value();
 }
 
diff --git a/src/zcash/address/sapling.hpp b/src/zcash/address/sapling.hpp
index 11d0cc196..b4cccd0f1 100644
--- a/src/zcash/address/sapling.hpp
+++ b/src/zcash/address/sapling.hpp
@@ -55,7 +55,7 @@ public:
     SaplingIncomingViewingKey(uint256 ivk) : uint256(ivk) { }
 
     // Can pass in diversifier for Sapling addr
-    boost::optional<SaplingPaymentAddress> address(diversifier_t d) const;
+    std::optional<SaplingPaymentAddress> address(diversifier_t d) const;
 };
 
 class SaplingFullViewingKey {
diff --git a/src/zcash/address/zip32.cpp b/src/zcash/address/zip32.cpp
index 6104da568..d36618960 100644
--- a/src/zcash/address/zip32.cpp
+++ b/src/zcash/address/zip32.cpp
@@ -54,7 +54,7 @@ uint256 ovkForShieldingFromTaddr(HDSeed& seed) {
 
 namespace libzcash {
 
-boost::optional<SaplingExtendedFullViewingKey> SaplingExtendedFullViewingKey::Derive(uint32_t i) const
+std::optional<SaplingExtendedFullViewingKey> SaplingExtendedFullViewingKey::Derive(uint32_t i) const
 {
     CDataStream ss_p(SER_NETWORK, PROTOCOL_VERSION);
     ss_p << *this;
@@ -71,11 +71,11 @@ boost::optional<SaplingExtendedFullViewingKey> SaplingExtendedFullViewingKey::De
         ss_i >> xfvk_i;
         return xfvk_i;
     } else {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
-boost::optional<std::pair<diversifier_index_t, libzcash::SaplingPaymentAddress>>
+std::optional<std::pair<diversifier_index_t, libzcash::SaplingPaymentAddress>>
     SaplingExtendedFullViewingKey::Address(diversifier_index_t j) const
 {
     CDataStream ss_xfvk(SER_NETWORK, PROTOCOL_VERSION);
@@ -93,7 +93,7 @@ boost::optional<std::pair<diversifier_index_t, libzcash::SaplingPaymentAddress>>
         ss_addr >> addr;
         return std::make_pair(j_ret, addr);
     } else {
-        return boost::none;
+        return std::nullopt;
     }
 }
 
diff --git a/src/zcash/address/zip32.h b/src/zcash/address/zip32.h
index 5aef0babb..50e5516ae 100644
--- a/src/zcash/address/zip32.h
+++ b/src/zcash/address/zip32.h
@@ -11,7 +11,6 @@
 #include "zcash/address/sapling.hpp"
 
 #include <optional>
-#include <boost/optional.hpp>
 
 const uint32_t ZIP32_HARDENED_KEY_LIMIT = 0x80000000;
 const size_t ZIP32_XFVK_SIZE = 169;
@@ -70,12 +69,12 @@ struct SaplingExtendedFullViewingKey {
         READWRITE(dk);
     }
 
-    boost::optional<SaplingExtendedFullViewingKey> Derive(uint32_t i) const;
+    std::optional<SaplingExtendedFullViewingKey> Derive(uint32_t i) const;
 
     // Returns the first index starting from j that generates a valid
     // payment address, along with the corresponding address. Returns
     // an error if the diversifier space is exhausted.
-    boost::optional<std::pair<diversifier_index_t, libzcash::SaplingPaymentAddress>>
+    std::optional<std::pair<diversifier_index_t, libzcash::SaplingPaymentAddress>>
         Address(diversifier_index_t j) const;
 
     libzcash::SaplingPaymentAddress DefaultAddress() const;

From db17aae4db157aca1752a41b39e62469a05754d0 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Fri, 4 Dec 2020 02:51:47 +0000
Subject: [PATCH 07/11] Finish migrating to std::optional

---
 src/wallet/wallet.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 2e09e7931..12c1b1e99 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3884,7 +3884,7 @@ bool CWallet::CommitTransaction(CWalletTx& wtxNew, std::optional<std::reference_
 
             if (reservekey) {
                 // Take key pair from key pool so it won't be used again
-                reservekey.value().KeepKey();
+                reservekey.value().get().KeepKey();
             }
 
             // Add tx to wallet, because if it has change it's also ours,

From 8a1803b21a802fa57052c5172e8d8db29213de3f Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Fri, 4 Dec 2020 02:52:48 +0000
Subject: [PATCH 08/11] lint: Remove boost::variant and boost::optional from
 allowed includes

---
 test/lint/lint-includes.sh | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/test/lint/lint-includes.sh b/test/lint/lint-includes.sh
index 83dd57ce6..63ffa6420 100755
--- a/test/lint/lint-includes.sh
+++ b/test/lint/lint-includes.sh
@@ -63,7 +63,6 @@ EXPECTED_BOOST_INCLUDES=(
     boost/iostreams/concepts.hpp
     boost/iostreams/stream.hpp
     boost/math/distributions/poisson.hpp
-    boost/optional.hpp
     boost/preprocessor/arithmetic/add.hpp
     boost/preprocessor/arithmetic/sub.hpp
     boost/preprocessor/cat.hpp
@@ -100,10 +99,6 @@ EXPECTED_BOOST_INCLUDES=(
     boost/uuid/uuid.hpp
     boost/uuid/uuid_generators.hpp
     boost/uuid/uuid_io.hpp
-    boost/variant.hpp
-    boost/variant/apply_visitor.hpp
-    boost/variant/get.hpp
-    boost/variant/static_visitor.hpp
     boost/version.hpp
 )
 

From f201e1e02dd8b5f730d11bddfdc9338dc95cb7f5 Mon Sep 17 00:00:00 2001
From: fanquake <fanquake@gmail.com>
Date: Wed, 18 Nov 2020 21:38:21 +0800
Subject: [PATCH 09/11] build: set minimum supported macOS to 10.14

---
 contrib/gitian-descriptors/gitian-osx.yml | 2 +-
 depends/README.md                         | 2 +-
 depends/hosts/darwin.mk                   | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/contrib/gitian-descriptors/gitian-osx.yml b/contrib/gitian-descriptors/gitian-osx.yml
index 3b030bb1a..65533d060 100644
--- a/contrib/gitian-descriptors/gitian-osx.yml
+++ b/contrib/gitian-descriptors/gitian-osx.yml
@@ -27,7 +27,7 @@ files:
 - "Xcode-11.3.1-11C505-extracted-SDK-with-libcxx-headers.tar.gz"
 script: |
   WRAP_DIR=$HOME/wrapped
-  HOSTS="x86_64-apple-darwin16"
+  HOSTS="x86_64-apple-darwin18"
   CONFIGFLAGS="--enable-reduce-exports --disable-bench GENISOIMAGE=$WRAP_DIR/genisoimage"
   FAKETIME_HOST_PROGS=""
   FAKETIME_PROGS="ar ranlib date dmg genisoimage"
diff --git a/depends/README.md b/depends/README.md
index df312aabd..cf88a425f 100644
--- a/depends/README.md
+++ b/depends/README.md
@@ -22,7 +22,7 @@ Common `host-platform-triplets` for cross compilation are:
 
 - `i686-w64-mingw32` for Win32
 - `x86_64-w64-mingw32` for Win64
-- `x86_64-apple-darwin16` for macOS
+- `x86_64-apple-darwin18` for macOS
 - `arm-linux-gnueabihf` for Linux ARM 32 bit
 - `aarch64-linux-gnu` for Linux ARM 64 bit
 - `riscv32-linux-gnu` for Linux RISC-V 32 bit
diff --git a/depends/hosts/darwin.mk b/depends/hosts/darwin.mk
index 7c0ad99df..b6a3d5fad 100644
--- a/depends/hosts/darwin.mk
+++ b/depends/hosts/darwin.mk
@@ -1,4 +1,4 @@
-OSX_MIN_VERSION=10.12
+OSX_MIN_VERSION=10.14
 OSX_SDK_VERSION=10.15.1
 XCODE_VERSION=11.3.1
 XCODE_BUILD_ID=11C505

From bce1da684bff157f39d5d947e0bd8ee3fdc7b880 Mon Sep 17 00:00:00 2001
From: Kris Nuttycombe <kris.nuttycombe@gmail.com>
Date: Wed, 16 Dec 2020 09:48:20 -0700
Subject: [PATCH 10/11] Remove vestigial OSX_SDK_VERSION from darwin build.

Upstream still uses this variable for qt builds, but as we no longer
have the GUI wallet it's unnecessary for Zcash.
---
 depends/hosts/darwin.mk | 1 -
 1 file changed, 1 deletion(-)

diff --git a/depends/hosts/darwin.mk b/depends/hosts/darwin.mk
index b6a3d5fad..f461e65d9 100644
--- a/depends/hosts/darwin.mk
+++ b/depends/hosts/darwin.mk
@@ -1,5 +1,4 @@
 OSX_MIN_VERSION=10.14
-OSX_SDK_VERSION=10.15.1
 XCODE_VERSION=11.3.1
 XCODE_BUILD_ID=11C505
 LD64_VERSION=530

From a8bcd46b8cdd7dfa4fc908dddd3d9bc968f32ad8 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Thu, 17 Dec 2020 00:42:16 +0000
Subject: [PATCH 11/11] test: Fix test_bitcoin compilation on macOS High Sierra

Co-authored-by: Daira Hopwood <daira@jacaranda.org>
---
 src/test/coins_tests.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/test/coins_tests.cpp b/src/test/coins_tests.cpp
index b53cedf4f..f35fee667 100644
--- a/src/test/coins_tests.cpp
+++ b/src/test/coins_tests.cpp
@@ -644,7 +644,7 @@ BOOST_AUTO_TEST_CASE(chained_joinsplits)
         CMutableTransaction mtx;
         mtx.vJoinSplit.push_back(js2);
 
-        BOOST_CHECK(cache.HaveShieldedRequirements(mtx) == std::optional(UnsatisfiedShieldedReq::SproutUnknownAnchor));
+        BOOST_CHECK(cache.HaveShieldedRequirements(mtx) == std::optional<UnsatisfiedShieldedReq>(UnsatisfiedShieldedReq::SproutUnknownAnchor));
     }
 
     {
@@ -654,7 +654,7 @@ BOOST_AUTO_TEST_CASE(chained_joinsplits)
         mtx.vJoinSplit.push_back(js2);
         mtx.vJoinSplit.push_back(js1);
 
-        BOOST_CHECK(cache.HaveShieldedRequirements(mtx) == std::optional(UnsatisfiedShieldedReq::SproutUnknownAnchor));
+        BOOST_CHECK(cache.HaveShieldedRequirements(mtx) == std::optional<UnsatisfiedShieldedReq>(UnsatisfiedShieldedReq::SproutUnknownAnchor));
     }
 
     {