From 2762a6b3b58c319e0d1a6ceca5a49df3ea84823c Mon Sep 17 00:00:00 2001
From: Ian Leitch <ian@leitch.io>
Date: Mon, 3 Jan 2022 17:38:35 +0000
Subject: [PATCH] Fix concurrent mutation crash while indexing. Closes #450 &
 #451 (#452)

---
 CHANGELOG.md                                    | 2 +-
 Sources/PeripheryKit/Indexer/SwiftIndexer.swift | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index fc4245652..a2958ca54 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,7 +10,7 @@
 
 ##### Bug Fixes
 
-- None.
+- Fix a crash while indexing.
 
 ## 2.8.4 (2021-12-30)
 
diff --git a/Sources/PeripheryKit/Indexer/SwiftIndexer.swift b/Sources/PeripheryKit/Indexer/SwiftIndexer.swift
index 67612c195..0b3e3bd26 100644
--- a/Sources/PeripheryKit/Indexer/SwiftIndexer.swift
+++ b/Sources/PeripheryKit/Indexer/SwiftIndexer.swift
@@ -285,8 +285,10 @@ public final class SwiftIndexer {
                     continue
                 }
 
-                for ref in refs {
-                    associateUnsafe(ref, with: decl)
+                graph.mutating {
+                    for ref in refs {
+                        associateUnsafe(ref, with: decl)
+                    }
                 }
             }
         }