From 8da8730dca4fa43edf0cca37963f475c108fdbf3 Mon Sep 17 00:00:00 2001
From: Michael Sproul <michael@sigmaprime.io>
Date: Tue, 2 Apr 2019 10:22:19 +1100
Subject: [PATCH] spec: check ProposalSlashing epochs, not slots

As per v0.5.{0,1} of the spec, we only need to check that the epochs of two proposal slashings are
equal, not their slots.
---
 eth2/state_processing/src/per_block_processing/errors.rs     | 4 ++--
 .../src/per_block_processing/verify_proposer_slashing.rs     | 5 +++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/eth2/state_processing/src/per_block_processing/errors.rs b/eth2/state_processing/src/per_block_processing/errors.rs
index 6614f6f608..9c36e0238b 100644
--- a/eth2/state_processing/src/per_block_processing/errors.rs
+++ b/eth2/state_processing/src/per_block_processing/errors.rs
@@ -271,10 +271,10 @@ pub enum ProposerSlashingValidationError {
 pub enum ProposerSlashingInvalid {
     /// The proposer index is not a known validator.
     ProposerUnknown(u64),
-    /// The two proposal have different slots.
+    /// The two proposal have different epochs.
     ///
     /// (proposal_1_slot, proposal_2_slot)
-    ProposalSlotMismatch(Slot, Slot),
+    ProposalEpochMismatch(Slot, Slot),
     /// The proposals are identical and therefore not slashable.
     ProposalsIdentical,
     /// The specified proposer has already been slashed.
diff --git a/eth2/state_processing/src/per_block_processing/verify_proposer_slashing.rs b/eth2/state_processing/src/per_block_processing/verify_proposer_slashing.rs
index 8e0a70f963..b5113863e1 100644
--- a/eth2/state_processing/src/per_block_processing/verify_proposer_slashing.rs
+++ b/eth2/state_processing/src/per_block_processing/verify_proposer_slashing.rs
@@ -21,8 +21,9 @@ pub fn verify_proposer_slashing(
         })?;
 
     verify!(
-        proposer_slashing.header_1.slot == proposer_slashing.header_2.slot,
-        Invalid::ProposalSlotMismatch(
+        proposer_slashing.header_1.slot.epoch(spec.slots_per_epoch)
+            == proposer_slashing.header_2.slot.epoch(spec.slots_per_epoch),
+        Invalid::ProposalEpochMismatch(
             proposer_slashing.header_1.slot,
             proposer_slashing.header_2.slot
         )