keyof return string directly if one entry

luau-lang · Sep 8, 2024 · c8ebe3e · c8ebe3e
1 parent d9536ce
commit c8ebe3e
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/Analysis/src/TypeFunction.cpp b/Analysis/src/TypeFunction.cpp
@@ -2041,6 +2041,12 @@ TypeFunctionReductionResult<TypeId> keyofFunctionImpl(
     for (std::string key : keys)
         singletons.push_back(ctx->arena->addType(SingletonType{StringSingleton{key}}));
 
+    // If there's only one entry, we don't need a UnionType.
+    // We can take straight take it from the first entry
+    // because it was added into the type arena already.
+    if (singletons.size() == 1)
+        return {singletons.front(), false, {}, {}};
+
     return {ctx->arena->addType(UnionType{singletons}), false, {}, {}};
 }