Exclude mapped types with optionality modifiers and 'as' clauses

microsoft · Mar 15, 2022 · 1d08203 · 1d08203
1 parent 3f63804
commit 1d08203
Showing 1 changed file with 5 additions and 2 deletions.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -12219,8 +12219,11 @@ namespace ts {
         }
 
         function isMappedTypeGenericIndexedAccess(type: Type) {
-            return type.flags & TypeFlags.IndexedAccess && getObjectFlags((type as IndexedAccessType).objectType) & ObjectFlags.Mapped &&
-                !isGenericMappedType((type as IndexedAccessType).objectType) && isGenericIndexType((type as IndexedAccessType).indexType);
+            let objectType;
+            return !!(type.flags & TypeFlags.IndexedAccess && getObjectFlags(objectType = (type as IndexedAccessType).objectType) & ObjectFlags.Mapped &&
+                !isGenericMappedType(objectType) && isGenericIndexType((type as IndexedAccessType).indexType) &&
+                !(getMappedTypeModifiers(objectType as MappedType) & (MappedTypeModifiers.IncludeOptional | MappedTypeModifiers.ExcludeOptional)) &&
+                !(getNameTypeFromMappedType(objectType as MappedType)));
         }
 
         /**