Fix delete operator (#1160)

GlassBricks · web-flow · commit 284a672844f4 · 2021-11-09T20:42:18.000+01:00
* Fix delete operator

* Fix delete test formatting

* strict mode on object delete test
diff --git a/src/LuaLib.ts b/src/LuaLib.ts
@@ -106,7 +106,7 @@ const luaLibDependencies: Partial<Record<LuaLibFeature, LuaLibFeature[]>> = {
     Await: [LuaLibFeature.InstanceOf, LuaLibFeature.New],
     Decorate: [LuaLibFeature.ObjectGetOwnPropertyDescriptor, LuaLibFeature.SetDescriptor, LuaLibFeature.ObjectAssign],
     DelegatedYield: [LuaLibFeature.StringAccess],
-    Delete: [LuaLibFeature.ObjectGetOwnPropertyDescriptors],
+    Delete: [LuaLibFeature.ObjectGetOwnPropertyDescriptors, LuaLibFeature.Error, LuaLibFeature.New],
     Error: [LuaLibFeature.Class, LuaLibFeature.ClassExtends, LuaLibFeature.New],
     FunctionBind: [LuaLibFeature.Unpack],
     Generator: [LuaLibFeature.Symbol],
diff --git a/src/lualib/Delete.ts b/src/lualib/Delete.ts
@@ -3,17 +3,13 @@ function __TS__Delete(this: void, target: any, key: any): boolean {
     const descriptor = descriptors[key];
     if (descriptor) {
         if (!descriptor.configurable) {
-            throw `Cannot delete property ${key} of ${target}.`;
+            throw new TypeError(`Cannot delete property ${key} of ${target}.`);
         }
 
         descriptors[key] = undefined;
         return true;
     }
 
-    if (target[key] !== undefined) {
-        target[key] = undefined;
-        return true;
-    }
-
-    return false;
+    target[key] = undefined;
+    return true;
 }
diff --git a/test/unit/builtins/object.spec.ts b/test/unit/builtins/object.spec.ts
@@ -222,22 +222,45 @@ describe("delete from object", () => {
     test("delete from object", () => {
         util.testFunction`
             const obj = { foo: "bar", bar: "baz" };
-            delete obj["foo"];
-            return obj;
-        `
-            .setTsHeader("declare function setmetatable<T extends object>(this: void, table: T, metatable: any): T;")
-            .expectToEqual({ bar: "baz" });
+            return [delete obj["foo"], obj];
+        `.expectToMatchJsResult();
+    });
+
+    test("delete nonexistent property", () => {
+        util.testFunction`
+            const obj = {} as any
+            return [delete obj["foo"], obj];
+        `.expectToMatchJsResult();
     });
 
     // https://github.com/TypeScriptToLua/TypeScriptToLua/issues/993
     test("delete from object with metatable", () => {
         util.testFunction`
         const obj = { foo: "bar", bar: "baz" };
         setmetatable(obj, {});
-        delete obj["foo"];
-        return obj;
+        return [delete obj["foo"], obj];
     `
             .setTsHeader("declare function setmetatable<T extends object>(this: void, table: T, metatable: any): T;")
-            .expectToEqual({ bar: "baz" });
+            .expectToEqual([true, { bar: "baz" }]);
+    });
+
+    test("delete nonconfigurable own property", () => {
+        util.testFunction`
+            const obj = {} as any
+            Object.defineProperty(obj, "foo", {
+                configurable: false,
+                value: true
+            })
+            try {
+                delete obj["foo"]
+                return "deleted"
+            } catch (e) {
+                return e instanceof TypeError
+            }
+        `
+            .setOptions({
+                strict: true,
+            })
+            .expectToMatchJsResult();
     });
 });

Original file line number	Diff line number	Diff line change
`@@ -3,17 +3,13 @@ function __TS__Delete(this: void, target: any, key: any): boolean {`
`3`	`3`	`const descriptor = descriptors[key];`
`4`	`4`	`if (descriptor) {`
`5`	`5`	`if (!descriptor.configurable) {`
`6`		- throw `Cannot delete property ${key} of ${target}.`;
	`6`	+ throw new TypeError(`Cannot delete property ${key} of ${target}.`);
`7`	`7`	`}`
`8`	`8`
`9`	`9`	`descriptors[key] = undefined;`
`10`	`10`	`return true;`
`11`	`11`	`}`
`12`	`12`
`13`		`- if (target[key] !== undefined) {`
`14`		`- target[key] = undefined;`
`15`		`- return true;`
`16`		`- }`
`17`		`-`
`18`		`- return false;`
	`13`	`+ target[key] = undefined;`
	`14`	`+ return true;`
`19`	`15`	`}`