From fb01ab28ec90c59e54e6e7e1209a46ea5933cc4e Mon Sep 17 00:00:00 2001
From: ripatel-fd <ripatel+git@jumptrading.com>
Date: Fri, 15 Mar 2024 21:59:41 +0100
Subject: [PATCH] Use static memory layout for all sysvars (#249)

Co-authored-by: Richard Patel <ripatel@jumptrading.com>
---
 sdk/program/src/epoch_rewards.rs  | 2 ++
 sdk/program/src/fee_calculator.rs | 1 +
 sdk/program/src/stake_history.rs  | 1 +
 3 files changed, 4 insertions(+)

diff --git a/sdk/program/src/epoch_rewards.rs b/sdk/program/src/epoch_rewards.rs
index 525caf5f1..e3229486e 100644
--- a/sdk/program/src/epoch_rewards.rs
+++ b/sdk/program/src/epoch_rewards.rs
@@ -7,6 +7,8 @@
 //! [`sysvar::epoch_rewards`]: crate::sysvar::epoch_rewards
 
 use std::ops::AddAssign;
+
+#[repr(C)]
 #[derive(Debug, Serialize, Deserialize, PartialEq, Eq, Default, Clone, Copy, AbiExample)]
 pub struct EpochRewards {
     /// total rewards for the current epoch, in lamports
diff --git a/sdk/program/src/fee_calculator.rs b/sdk/program/src/fee_calculator.rs
index ef29ec2e2..c4dcb572c 100644
--- a/sdk/program/src/fee_calculator.rs
+++ b/sdk/program/src/fee_calculator.rs
@@ -6,6 +6,7 @@ use {
     log::*,
 };
 
+#[repr(C)]
 #[derive(Serialize, Deserialize, Default, PartialEq, Eq, Clone, Copy, Debug, AbiExample)]
 #[serde(rename_all = "camelCase")]
 pub struct FeeCalculator {
diff --git a/sdk/program/src/stake_history.rs b/sdk/program/src/stake_history.rs
index 331803e5f..0441482fd 100644
--- a/sdk/program/src/stake_history.rs
+++ b/sdk/program/src/stake_history.rs
@@ -11,6 +11,7 @@ use std::ops::Deref;
 
 pub const MAX_ENTRIES: usize = 512; // it should never take as many as 512 epochs to warm up or cool down
 
+#[repr(C)]
 #[derive(Debug, Serialize, Deserialize, PartialEq, Eq, Default, Clone, AbiExample)]
 pub struct StakeHistoryEntry {
     pub effective: u64,    // effective stake at this epoch