zcash_client_backend: Pass `Proposal` values by reference.

zcash_client_backend/CHANGELOG.md

@@ -47,6 +47,8 @@ and this library adheres to Rust's notion of
     `TransactionBalance`.
   - `wallet::create_spend_to_address` now takes an additional
     `change_memo` argument.
+  - `wallet::create_proposed_transaction` now takes its `proposal` argument
+      by reference instead of as an owned value.
 - `zcash_client_backend::fees::ChangeValue::Sapling` is now a structured variant.
   In addition to the existing change value, it now also carries an optional memo
   to be associated with the change output.

zcash_client_backend/src/data_api/wallet.rs

@@ -237,7 +237,7 @@ where
         prover,
         usk,
         ovk_policy,
-        proposal,
+        &proposal,
         min_confirmations,
     )
 }
@@ -338,7 +338,7 @@ where
         prover,
         usk,
         ovk_policy,
-        proposal,
+        &proposal,
         min_confirmations,
     )
 }
@@ -494,7 +494,7 @@ pub fn create_proposed_transaction<DbT, ParamsT, InputsErrT, FeeRuleT>(
     prover: impl SaplingProver,
     usk: &UnifiedSpendingKey,
     ovk_policy: OvkPolicy,
-    proposal: Proposal<FeeRuleT, DbT::NoteRef>,
+    proposal: &Proposal<FeeRuleT, DbT::NoteRef>,
     min_confirmations: NonZeroU32,
 ) -> Result<
     TxId,
@@ -821,7 +821,7 @@ where
         prover,
         usk,
         OvkPolicy::Sender,
-        proposal,
+        &proposal,
         min_confirmations,
     )
 }

zcash_client_sqlite/src/testing.rs

@@ -621,7 +621,7 @@ impl<Cache> TestState<Cache> {
             test_prover(),
             usk,
             ovk_policy,
-            proposal,
+            &proposal,
             min_confirmations,
         )
     }