revert predicate change

microsoft · Oct 31, 2023 · ec113c0 · ec113c0
1 parent bc15c38
commit ec113c0
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -18313,7 +18313,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         return constraint && (isGenericObjectType(constraint) || isGenericIndexType(constraint)) ? cloneTypeParameter(p) : p;
     }
 
-    function isSimpleTupleType(node: TypeNode): node is TupleTypeNode {
+    function isSimpleTupleType(node: TypeNode): boolean {
         return isTupleTypeNode(node) && length(node.elements) > 0 &&
             !some(node.elements, e => isOptionalTypeNode(e) || isRestTypeNode(e) || isNamedTupleMember(e) && !!(e.questionToken || e.dotDotDotToken));
     }
@@ -18350,7 +18350,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             // conditional type when any tuple elements are generic. This is such that non-distributable conditional
             // types can be written `[X] extends [Y] ? ...` and be deferred similarly to `X extends Y ? ...`.
             const checkTuples = isSimpleTupleType(checkTypeNode) && isSimpleTupleType(extendsTypeNode) &&
-                length(checkTypeNode.elements) === length(extendsTypeNode.elements);
+                length((checkTypeNode as TupleTypeNode).elements) === length((extendsTypeNode as TupleTypeNode).elements);
             const checkTypeDeferred = isDeferredType(checkType, checkTuples);
             let combinedMapper: TypeMapper | undefined;
             if (root.inferTypeParameters) {