Support __proto__ in object literal (type-check only)

src/compiler/checker.ts

@@ -27633,6 +27633,26 @@ namespace ts {
             return links.immediateTarget;
         }
 
+        /**
+         * If the node is a `__proto__` literal declaration.
+         * According to ECMA262 B.3.1 only this syntax counted in
+         *      PropertyName ":" AssignmentExpression
+         *
+         * It works in thoes forms:
+         *      { __proto__: value }; { "__proto__": value }; { __proto_\u005f: value };
+         *  It does not work in thoes forms:
+         *      { ["__proto__"]: value }; { __proto__ }
+         */
+        function getProtoLiteralDeclarationInitializer(node: ObjectLiteralElementLike): false | Expression {
+            if (node.kind !== SyntaxKind.PropertyAssignment) return false;
+            const name = node.name;
+            if (!name) return false;
+            // Identifier.escapedText says if the identifier starts with __, it will starts with 3 "_".
+            if (name.kind === SyntaxKind.Identifier && name.escapedText === "___proto__") return node.initializer;
+            if (name.kind === SyntaxKind.StringLiteral && name.text === "__proto__") return node.initializer;
+            return false;
+        }
+
         function checkObjectLiteral(node: ObjectLiteralExpression, checkMode?: CheckMode): Type {
             const inDestructuringPattern = isAssignmentTarget(node);
             // Grammar checking
@@ -27666,8 +27686,26 @@ namespace ts {
                 }
             }
 
+            const skippedProperties = new Set<ObjectLiteralElementLike>();
+            // It should be the left-most spread element so we loop this first
+            for (const memberDecl of node.properties) {
+                const item = getProtoLiteralDeclarationInitializer(memberDecl);
+                if (!item) continue;
+                // Don't add __proto__ literal to the properties table
+                skippedProperties.add(memberDecl);
+                // it's prototype is null so it works like normal object (despite Object.prototype things).
+                if (item.kind === SyntaxKind.NullKeyword) continue;
+                const type = getReducedType(checkExpression(item));
+                if (!(type.flags & TypeFlags.Object)) {
+                    error(memberDecl, Diagnostics.Type_0_is_not_assignable_to_type_1, typeToString(type), "object | null");
+                }
+                else {
+                    spread = getSpreadType(spread, type, node.symbol, objectFlags, inConstContext);
+                }
+            }
             let offset = 0;
             for (const memberDecl of node.properties) {
+                if (skippedProperties.has(memberDecl)) continue;
                 let member = getSymbolOfNode(memberDecl);
                 const computedNameType = memberDecl.name && memberDecl.name.kind === SyntaxKind.ComputedPropertyName ?
                     checkComputedPropertyName(memberDecl.name) : undefined;

tests/baselines/reference/__proto__literal.errors.txt

@@ -0,0 +1,38 @@
+tests/cases/compiler/__proto__literal.ts(10,28): error TS1117: An object literal cannot have multiple properties with the same name.
+tests/cases/compiler/__proto__literal.ts(20,13): error TS2322: Type '1' is not assignable to type 'object | null'.
+
+
+==== tests/cases/compiler/__proto__literal.ts (2 errors) ====
+    const o = { a: 1 }
+    const __proto__ = o
+    // Should
+    const x1 = { __proto__: o }
+    const x2 = { __proto_\u005f: o }
+    const x3 = { "__proto__": o }
+    const x4 = { "__proto_\u005f": o }
+
+    // Duplicate
+    const y1 = { __proto__: o, __proto_\u005f: o }
+                               ~~~~~~~~~~~~~~
+!!! error TS1117: An object literal cannot have multiple properties with the same name.
+
+    // Spread order
+    const z1 = { ...({a: ''}), __proto__: o }
+    const z2 = { __proto__: o, ...({a: ''}) }
+
+    // Null
+    const w = { __proto__: null }
+
+    // Non-object
+    const q = { __proto__: 1, x: 1 }
+                ~~~~~~~~~~~~
+!!! error TS2322: Type '1' is not assignable to type 'object | null'.
+
+    // Should not
+    const x5 = { ["__proto__"]: o }
+    const x6 = { __proto__ }
+    const x7 = { __proto__() {} }
+    enum e { __proto__ = 1 }
+    {
+        const { __proto__ } = { ['__proto__']: 1 }
+    }

tests/baselines/reference/__proto__literal.js

@@ -0,0 +1,71 @@
+//// [__proto__literal.ts]
+const o = { a: 1 }
+const __proto__ = o
+// Should
+const x1 = { __proto__: o }
+const x2 = { __proto_\u005f: o }
+const x3 = { "__proto__": o }
+const x4 = { "__proto_\u005f": o }
+
+// Duplicate
+const y1 = { __proto__: o, __proto_\u005f: o }
+
+// Spread order
+const z1 = { ...({a: ''}), __proto__: o }
+const z2 = { __proto__: o, ...({a: ''}) }
+
+// Null
+const w = { __proto__: null }
+
+// Non-object
+const q = { __proto__: 1, x: 1 }
+
+// Should not
+const x5 = { ["__proto__"]: o }
+const x6 = { __proto__ }
+const x7 = { __proto__() {} }
+enum e { __proto__ = 1 }
+{
+    const { __proto__ } = { ['__proto__']: 1 }
+}
+
+//// [__proto__literal.js]
+var __assign = (this && this.__assign) || function () {
+    __assign = Object.assign || function(t) {
+        for (var s, i = 1, n = arguments.length; i < n; i++) {
+            s = arguments[i];
+            for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+                t[p] = s[p];
+        }
+        return t;
+    };
+    return __assign.apply(this, arguments);
+};
+var _a, _b;
+var o = { a: 1 };
+var __proto__ = o;
+// Should
+var x1 = { __proto__: o };
+var x2 = { __proto_\u005f: o };
+var x3 = { "__proto__": o };
+var x4 = { "__proto_\u005f": o };
+// Duplicate
+var y1 = { __proto__: o, __proto_\u005f: o };
+// Spread order
+var z1 = __assign(__assign({}, ({ a: '' })), { __proto__: o });
+var z2 = __assign({ __proto__: o }, ({ a: '' }));
+// Null
+var w = { __proto__: null };
+// Non-object
+var q = { __proto__: 1, x: 1 };
+// Should not
+var x5 = (_a = {}, _a["__proto__"] = o, _a);
+var x6 = { __proto__: __proto__ };
+var x7 = { __proto__: function () { } };
+var e;
+(function (e) {
+    e[e["__proto__"] = 1] = "__proto__";
+})(e || (e = {}));
+{
+    var __proto__1 = (_b = {}, _b['__proto__'] = 1, _b).__proto__;
+}

tests/baselines/reference/__proto__literal.symbols

@@ -0,0 +1,86 @@
+=== tests/cases/compiler/__proto__literal.ts ===
+const o = { a: 1 }
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+>a : Symbol(a, Decl(__proto__literal.ts, 0, 11))
+
+const __proto__ = o
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 1, 5))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+
+// Should
+const x1 = { __proto__: o }
+>x1 : Symbol(x1, Decl(__proto__literal.ts, 3, 5))
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 3, 12))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+
+const x2 = { __proto_\u005f: o }
+>x2 : Symbol(x2, Decl(__proto__literal.ts, 4, 5))
+>__proto_\u005f : Symbol(__proto_\u005f, Decl(__proto__literal.ts, 4, 12))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+
+const x3 = { "__proto__": o }
+>x3 : Symbol(x3, Decl(__proto__literal.ts, 5, 5))
+>"__proto__" : Symbol("__proto__", Decl(__proto__literal.ts, 5, 12))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+
+const x4 = { "__proto_\u005f": o }
+>x4 : Symbol(x4, Decl(__proto__literal.ts, 6, 5))
+>"__proto_\u005f" : Symbol("__proto_\u005f", Decl(__proto__literal.ts, 6, 12))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+
+// Duplicate
+const y1 = { __proto__: o, __proto_\u005f: o }
+>y1 : Symbol(y1, Decl(__proto__literal.ts, 9, 5))
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 9, 12), Decl(__proto__literal.ts, 9, 26))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+>__proto_\u005f : Symbol(__proto__, Decl(__proto__literal.ts, 9, 12), Decl(__proto__literal.ts, 9, 26))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+
+// Spread order
+const z1 = { ...({a: ''}), __proto__: o }
+>z1 : Symbol(z1, Decl(__proto__literal.ts, 12, 5))
+>a : Symbol(a, Decl(__proto__literal.ts, 12, 18))
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 12, 26))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+
+const z2 = { __proto__: o, ...({a: ''}) }
+>z2 : Symbol(z2, Decl(__proto__literal.ts, 13, 5))
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 13, 12))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+>a : Symbol(a, Decl(__proto__literal.ts, 13, 32))
+
+// Null
+const w = { __proto__: null }
+>w : Symbol(w, Decl(__proto__literal.ts, 16, 5))
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 16, 11))
+
+// Non-object
+const q = { __proto__: 1, x: 1 }
+>q : Symbol(q, Decl(__proto__literal.ts, 19, 5))
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 19, 11))
+>x : Symbol(x, Decl(__proto__literal.ts, 19, 25))
+
+// Should not
+const x5 = { ["__proto__"]: o }
+>x5 : Symbol(x5, Decl(__proto__literal.ts, 22, 5))
+>["__proto__"] : Symbol(["__proto__"], Decl(__proto__literal.ts, 22, 12))
+>"__proto__" : Symbol(["__proto__"], Decl(__proto__literal.ts, 22, 12))
+>o : Symbol(o, Decl(__proto__literal.ts, 0, 5))
+
+const x6 = { __proto__ }
+>x6 : Symbol(x6, Decl(__proto__literal.ts, 23, 5))
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 23, 12))
+
+const x7 = { __proto__() {} }
+>x7 : Symbol(x7, Decl(__proto__literal.ts, 24, 5))
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 24, 12))
+
+enum e { __proto__ = 1 }
+>e : Symbol(e, Decl(__proto__literal.ts, 24, 29))
+>__proto__ : Symbol(e.__proto__, Decl(__proto__literal.ts, 25, 8))
+{
+    const { __proto__ } = { ['__proto__']: 1 }
+>__proto__ : Symbol(__proto__, Decl(__proto__literal.ts, 27, 11))
+>['__proto__'] : Symbol(['__proto__'], Decl(__proto__literal.ts, 27, 27))
+>'__proto__' : Symbol(['__proto__'], Decl(__proto__literal.ts, 27, 27))
+}

tests/baselines/reference/__proto__literal.types

@@ -0,0 +1,112 @@
+=== tests/cases/compiler/__proto__literal.ts ===
+const o = { a: 1 }
+>o : { a: number; }
+>{ a: 1 } : { a: number; }
+>a : number
+>1 : 1
+
+const __proto__ = o
+>__proto__ : { a: number; }
+>o : { a: number; }
+
+// Should
+const x1 = { __proto__: o }
+>x1 : { a: number; }
+>{ __proto__: o } : { a: number; }
+>__proto__ : { a: number; }
+>o : { a: number; }
+
+const x2 = { __proto_\u005f: o }
+>x2 : { a: number; }
+>{ __proto_\u005f: o } : { a: number; }
+>__proto_\u005f : { a: number; }
+>o : { a: number; }
+
+const x3 = { "__proto__": o }
+>x3 : { a: number; }
+>{ "__proto__": o } : { a: number; }
+>"__proto__" : { a: number; }
+>o : { a: number; }
+
+const x4 = { "__proto_\u005f": o }
+>x4 : { a: number; }
+>{ "__proto_\u005f": o } : { a: number; }
+>"__proto_\u005f" : { a: number; }
+>o : { a: number; }
+
+// Duplicate
+const y1 = { __proto__: o, __proto_\u005f: o }
+>y1 : { a: number; }
+>{ __proto__: o, __proto_\u005f: o } : { a: number; }
+>__proto__ : { a: number; }
+>o : { a: number; }
+>__proto_\u005f : { a: number; }
+>o : { a: number; }
+
+// Spread order
+const z1 = { ...({a: ''}), __proto__: o }
+>z1 : { a: string; }
+>{ ...({a: ''}), __proto__: o } : { a: string; }
+>({a: ''}) : { a: string; }
+>{a: ''} : { a: string; }
+>a : string
+>'' : ""
+>__proto__ : { a: number; }
+>o : { a: number; }
+
+const z2 = { __proto__: o, ...({a: ''}) }
+>z2 : { a: string; }
+>{ __proto__: o, ...({a: ''}) } : { a: string; }
+>__proto__ : { a: number; }
+>o : { a: number; }
+>({a: ''}) : { a: string; }
+>{a: ''} : { a: string; }
+>a : string
+>'' : ""
+
+// Null
+const w = { __proto__: null }
+>w : {}
+>{ __proto__: null } : {}
+>__proto__ : null
+>null : null
+
+// Non-object
+const q = { __proto__: 1, x: 1 }
+>q : { x: number; }
+>{ __proto__: 1, x: 1 } : { x: number; }
+>__proto__ : number
+>1 : 1
+>x : number
+>1 : 1
+
+// Should not
+const x5 = { ["__proto__"]: o }
+>x5 : { __proto__: { a: number; }; }
+>{ ["__proto__"]: o } : { __proto__: { a: number; }; }
+>["__proto__"] : { a: number; }
+>"__proto__" : "__proto__"
+>o : { a: number; }
+
+const x6 = { __proto__ }
+>x6 : { __proto__: { a: number; }; }
+>{ __proto__ } : { __proto__: { a: number; }; }
+>__proto__ : { a: number; }
+
+const x7 = { __proto__() {} }
+>x7 : { __proto__(): void; }
+>{ __proto__() {} } : { __proto__(): void; }
+>__proto__ : () => void
+
+enum e { __proto__ = 1 }
+>e : e
+>__proto__ : e.__proto__
+>1 : 1
+{
+    const { __proto__ } = { ['__proto__']: 1 }
+>__proto__ : number
+>{ ['__proto__']: 1 } : { __proto__: number; }
+>['__proto__'] : number
+>'__proto__' : "__proto__"
+>1 : 1
+}