genesis: create EpochRewards at epoch 0 (#6125)

Author: 2501babe

programs/stake/src/config.rs

@@ -45,9 +45,9 @@ pub fn create_account(lamports: u64, config: &Config) -> AccountSharedData {
 #[allow(deprecated)]
 pub fn add_genesis_account(genesis_config: &mut GenesisConfig) -> u64 {
     let mut account = create_config_account(vec![], &Config::default(), 0);
-    let lamports = genesis_config.rent.minimum_balance(account.data().len());
+    let lamports = std::cmp::max(genesis_config.rent.minimum_balance(account.data().len()), 1);
 
-    account.set_lamports(lamports.max(1));
+    account.set_lamports(lamports);
 
     genesis_config.add_account(solana_stake_interface::config::id(), account);
 

programs/stake/src/epoch_rewards.rs

@@ -0,0 +1,21 @@
+//! Creates the initial empty EpochRewards sysvar
+use {
+    solana_account::{AccountSharedData, WritableAccount},
+    solana_genesis_config::GenesisConfig,
+    solana_sdk_ids::sysvar,
+    solana_sysvar::{
+        epoch_rewards::{self, EpochRewards},
+        Sysvar,
+    },
+};
+
+pub fn add_genesis_account(genesis_config: &mut GenesisConfig) -> u64 {
+    let data = vec![0; EpochRewards::size_of()];
+    let lamports = std::cmp::max(genesis_config.rent.minimum_balance(data.len()), 1);
+
+    let account = AccountSharedData::create(lamports, data, sysvar::id(), false, u64::MAX);
+
+    genesis_config.add_account(epoch_rewards::id(), account);
+
+    lamports
+}

programs/stake/src/lib.rs

@@ -8,13 +8,16 @@ pub use solana_sdk_ids::stake::{check_id, id};
 use {solana_genesis_config::GenesisConfig, solana_native_token::LAMPORTS_PER_SOL};
 
 pub mod config;
+pub mod epoch_rewards;
 #[deprecated(since = "2.2.0")]
 pub mod points;
 pub mod stake_instruction;
 pub mod stake_state;
 
 pub fn add_genesis_accounts(genesis_config: &mut GenesisConfig) -> u64 {
-    config::add_genesis_account(genesis_config)
+    let config_lamports = config::add_genesis_account(genesis_config);
+    let rewards_lamports = epoch_rewards::add_genesis_account(genesis_config);
+    config_lamports.saturating_add(rewards_lamports)
 }
 
 /// The minimum stake amount that can be delegated, in lamports.

runtime/src/bank/partitioned_epoch_rewards/mod.rs

@@ -611,13 +611,7 @@ mod tests {
                 );
 
                 assert!(curr_bank.is_calculated());
-
-                if slot == SLOTS_PER_EPOCH {
-                    // cap should increase because of new epoch rewards
-                    assert!(post_cap > pre_cap);
-                } else {
-                    assert_eq!(post_cap, pre_cap);
-                }
+                assert_eq!(post_cap, pre_cap);
             } else if slot == SLOTS_PER_EPOCH + 1 {
                 // 1. when curr_slot == SLOTS_PER_EPOCH + 1, the 2nd block of
                 // epoch 1, reward distribution should happen in this block.
@@ -694,9 +688,6 @@ mod tests {
 
                 // calculation block, state should be calculated.
                 assert!(curr_bank.is_calculated());
-
-                // cap should increase because of new epoch rewards
-                assert!(post_cap > pre_cap);
             } else if slot == SLOTS_PER_EPOCH + 1 {
                 // When curr_slot == SLOTS_PER_EPOCH + 1, the 2nd block of
                 // epoch 1, reward distribution should happen in this block. The