From 9a20ecb9e46817bea17637193ca866d976ff952b Mon Sep 17 00:00:00 2001
From: vbuterin <v@buterin.com>
Date: Tue, 27 Nov 2018 12:07:30 -0500
Subject: [PATCH] Added handling for withdrawn validators

---
 specs/core/0_beacon-chain.md | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 9376b95b3..01b3687c6 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -760,11 +760,7 @@ def add_validator(state: State,
                      msg=hash(signed_message),
                      sig=proof_of_possession,
                      domain=get_domain(state, current_slot, DOMAIN_DEPOSIT))
-    # Pubkey uniqueness
-    validator_pubkeys = [v.pubkey for v in state.validators]
-    if pubkey not in validator_pubkeys:
-        assert deposit_size == DEPOSIT_SIZE
-        rec = ValidatorRecord(
+    rec = ValidatorRecord(
             pubkey=pubkey,
             withdrawal_credentials=withdrawal_credentials,
             randao_commitment=randao_commitment,
@@ -773,7 +769,12 @@ def add_validator(state: State,
             status=status,
             last_status_change_slot=current_slot,
             exit_seq=0
-        )
+    )
+    # Pubkey uniqueness
+    validator_pubkeys = [v.pubkey for v in state.validators]
+    if pubkey not in validator_pubkeys:
+        assert deposit_size == DEPOSIT_SIZE
+
         index = min_empty_validator(state.validators)
         if index is None:
             state.validators.append(rec)
@@ -787,6 +788,9 @@ def add_validator(state: State,
         assert val.withdrawal_credentials == withdrawal_credentials
         assert deposit_size >= MIN_TOPUP_SIZE
         val.balance += deposit_size
+        # If the validator is withdrawn, overwrite it with the new validator data
+        if val.status == WITHDRAWN:
+            state.validators[index] = rec
         return index
 ```