Use CompareExchange

jcouv · Jan 14, 2022 · 27d7a4b · 27d7a4b
1 parent c63cb79
commit 27d7a4b
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/src/Compilers/CSharp/Portable/Symbols/Tuples/TupleTypeSymbol.cs b/src/Compilers/CSharp/Portable/Symbols/Tuples/TupleTypeSymbol.cs
@@ -1051,7 +1051,11 @@ internal SmallDictionary<Symbol, Symbol> UnderlyingDefinitionToMemberMap
             {
                 get
                 {
-                    return _lazyUnderlyingDefinitionToMemberMap ??= computeDefinitionToMemberMap();
+                    if (_lazyUnderlyingDefinitionToMemberMap is null)
+                    {
+                        Interlocked.CompareExchange(ref _lazyUnderlyingDefinitionToMemberMap, computeDefinitionToMemberMap(), null);
+                    }
+                    return _lazyUnderlyingDefinitionToMemberMap;
 
                     SmallDictionary<Symbol, Symbol> computeDefinitionToMemberMap()
                     {