From bc334427e3619b4c1e5aec15477f67debad1ceeb Mon Sep 17 00:00:00 2001
From: "mergify[bot]" <37929162+mergify[bot]@users.noreply.github.com>
Date: Sat, 21 Nov 2020 05:41:53 +0000
Subject: [PATCH] stake: Don't pay out rewards for epochs where inflation was
 not enabled (#13745)

(cherry picked from commit 13aa38d307875dbf4f0fa31866979e72103f0c27)

Co-authored-by: Trent Nelson <trent@solana.com>
---
 programs/stake/src/stake_state.rs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/programs/stake/src/stake_state.rs b/programs/stake/src/stake_state.rs
index 49dada59d3..e2725612ee 100644
--- a/programs/stake/src/stake_state.rs
+++ b/programs/stake/src/stake_state.rs
@@ -621,6 +621,11 @@ impl Stake {
             fix_stake_deactivate,
         );
 
+        // Drive credits_observed forward unconditionally when rewards are disabled
+        if point_value.rewards == 0 && fix_stake_deactivate {
+            return Some((0, 0, credits_observed));
+        }
+
         if points == 0 || point_value.points == 0 {
             return None;
         }
@@ -3083,6 +3088,23 @@ mod tests {
                 true,
             )
         );
+
+        // now one with inflation disabled. no one gets paid, but we still need
+        // to advance the stake state's observed_credits field to prevent back-
+        // paying rewards when inflation is turned on.
+        assert_eq!(
+            Some((0, 0, 4)),
+            stake.calculate_rewards(
+                &PointValue {
+                    rewards: 0,
+                    points: 4
+                },
+                &vote_state,
+                None,
+                &mut null_tracer(),
+                true,
+            )
+        );
     }
 
     #[test]