Merge pull request #15057 from Microsoft/fixExcessPropertyCheck

Fix excess property check

Author: ahejlsberg

src/compiler/checker.ts

@@ -8345,8 +8345,11 @@ namespace ts {
                 !t.numberIndexInfo;
         }
 
-        function isEmptyObjectType(type: Type) {
-            return type.flags & TypeFlags.Object && isEmptyResolvedType(resolveStructuredTypeMembers(<ObjectType>type));
+        function isEmptyObjectType(type: Type): boolean {
+            return type.flags & TypeFlags.Object ? isEmptyResolvedType(resolveStructuredTypeMembers(<ObjectType>type)) :
+                type.flags & TypeFlags.Union ? forEach((<UnionType>type).types, isEmptyObjectType) :
+                type.flags & TypeFlags.Intersection ? !forEach((<UnionType>type).types, t => !isEmptyObjectType(t)) :
+                false;
         }
 
         function isEnumTypeRelatedTo(source: EnumType, target: EnumType, errorReporter?: ErrorReporter) {
@@ -8662,14 +8665,8 @@ namespace ts {
             function isKnownProperty(type: Type, name: string, isComparingJsxAttributes: boolean): boolean {
                 if (type.flags & TypeFlags.Object) {
                     const resolved = resolveStructuredTypeMembers(<ObjectType>type);
-                    if ((relation === assignableRelation || relation === comparableRelation) &&
-                        (type === globalObjectType || (!isComparingJsxAttributes && isEmptyObjectType(resolved)))) {
-                        return true;
-                    }
-                    else if (resolved.stringIndexInfo || (resolved.numberIndexInfo && isNumericLiteralName(name))) {
-                        return true;
-                    }
-                    else if (getPropertyOfType(type, name) || (isComparingJsxAttributes && !isUnhyphenatedJsxName(name))) {
+                    if (resolved.stringIndexInfo || resolved.numberIndexInfo && isNumericLiteralName(name) ||
+                        getPropertyOfType(type, name) || isComparingJsxAttributes && !isUnhyphenatedJsxName(name)) {
                         // For JSXAttributes, if the attribute has a hyphenated name, consider that the attribute to be known.
                         return true;
                     }
@@ -8687,6 +8684,10 @@ namespace ts {
             function hasExcessProperties(source: FreshObjectLiteralType, target: Type, reportErrors: boolean): boolean {
                 if (maybeTypeOfKind(target, TypeFlags.Object) && !(getObjectFlags(target) & ObjectFlags.ObjectLiteralPatternWithComputedProperties)) {
                     const isComparingJsxAttributes = !!(source.flags & TypeFlags.JsxAttributes);
+                    if ((relation === assignableRelation || relation === comparableRelation) &&
+                        (target === globalObjectType || (!isComparingJsxAttributes && isEmptyObjectType(target)))) {
+                        return false;
+                    }
                     for (const prop of getPropertiesOfObjectType(source)) {
                         if (!isKnownProperty(target, prop.name, isComparingJsxAttributes)) {
                             if (reportErrors) {

tests/baselines/reference/excessPropertyCheckWithEmptyObject.errors.txt

@@ -0,0 +1,36 @@
+tests/cases/compiler/excessPropertyCheckWithEmptyObject.ts(4,23): error TS2304: Cannot find name 'window'.
+tests/cases/compiler/excessPropertyCheckWithEmptyObject.ts(4,58): error TS2345: Argument of type '{ value: string; readonly: boolean; }' is not assignable to parameter of type 'PropertyDescriptor & ThisType<any>'.
+  Object literal may only specify known properties, and 'readonly' does not exist in type 'PropertyDescriptor & ThisType<any>'.
+tests/cases/compiler/excessPropertyCheckWithEmptyObject.ts(9,30): error TS2322: Type '{ y: number; }' is not assignable to type 'A & ThisType<any>'.
+  Object literal may only specify known properties, and 'y' does not exist in type 'A & ThisType<any>'.
+tests/cases/compiler/excessPropertyCheckWithEmptyObject.ts(14,34): error TS2322: Type '{ y: string; }' is not assignable to type 'Empty & { x: number; }'.
+  Object literal may only specify known properties, and 'y' does not exist in type 'Empty & { x: number; }'.
+
+
+==== tests/cases/compiler/excessPropertyCheckWithEmptyObject.ts (4 errors) ====
+    // Repro from #14910
+    
+    // Excess property error expected here
+    Object.defineProperty(window, "prop", { value: "v1.0.0", readonly: false });
+                          ~~~~~~
+!!! error TS2304: Cannot find name 'window'.
+                                                             ~~~~~~~~~~~~~~~
+!!! error TS2345: Argument of type '{ value: string; readonly: boolean; }' is not assignable to parameter of type 'PropertyDescriptor & ThisType<any>'.
+!!! error TS2345:   Object literal may only specify known properties, and 'readonly' does not exist in type 'PropertyDescriptor & ThisType<any>'.
+    
+    interface A { x?: string }
+    
+    // Excess property error expected here
+    let a: A & ThisType<any> = { y: 10 };
+                                 ~~~~~
+!!! error TS2322: Type '{ y: number; }' is not assignable to type 'A & ThisType<any>'.
+!!! error TS2322:   Object literal may only specify known properties, and 'y' does not exist in type 'A & ThisType<any>'.
+    
+    interface Empty {}
+    
+    // Excess property error expected here
+    let x: Empty & { x: number } = { y: "hello" };
+                                     ~~~~~~~~~~
+!!! error TS2322: Type '{ y: string; }' is not assignable to type 'Empty & { x: number; }'.
+!!! error TS2322:   Object literal may only specify known properties, and 'y' does not exist in type 'Empty & { x: number; }'.
+    

tests/baselines/reference/excessPropertyCheckWithEmptyObject.js

@@ -0,0 +1,25 @@
+//// [excessPropertyCheckWithEmptyObject.ts]
+// Repro from #14910
+
+// Excess property error expected here
+Object.defineProperty(window, "prop", { value: "v1.0.0", readonly: false });
+
+interface A { x?: string }
+
+// Excess property error expected here
+let a: A & ThisType<any> = { y: 10 };
+
+interface Empty {}
+
+// Excess property error expected here
+let x: Empty & { x: number } = { y: "hello" };
+
+
+//// [excessPropertyCheckWithEmptyObject.js]
+// Repro from #14910
+// Excess property error expected here
+Object.defineProperty(window, "prop", { value: "v1.0.0", readonly: false });
+// Excess property error expected here
+var a = { y: 10 };
+// Excess property error expected here
+var x = { y: "hello" };

tests/cases/compiler/excessPropertyCheckWithEmptyObject.ts

@@ -0,0 +1,14 @@
+// Repro from #14910
+
+// Excess property error expected here
+Object.defineProperty(window, "prop", { value: "v1.0.0", readonly: false });
+
+interface A { x?: string }
+
+// Excess property error expected here
+let a: A & ThisType<any> = { y: 10 };
+
+interface Empty {}
+
+// Excess property error expected here
+let x: Empty & { x: number } = { y: "hello" };