fix(36989): 'async' modifier cannot be used in an ambient context.ts (#37010)

* fix(36989): omit 'async' modifier for methods in declaration files.

* remove useless condition

src/compiler/checker.ts

@@ -6206,7 +6206,7 @@ namespace ts {
                             && isTypeIdenticalTo(getTypeOfSymbol(p), getTypeOfPropertyOfType(baseType, p.escapedName)!))) {
                             return [];
                         }
-                        const flag = modifierFlags | (isStatic ? ModifierFlags.Static : 0);
+                        const flag = (modifierFlags & ~ModifierFlags.Async) | (isStatic ? ModifierFlags.Static : 0);
                         const name = getPropertyNameNodeForSymbol(p, context);
                         const firstPropertyLikeDecl = find(p.declarations, or(isPropertyDeclaration, isAccessor, isVariableDeclaration, isPropertySignature, isBinaryExpression, isPropertyAccessExpression));
                         if (p.flags & SymbolFlags.Accessor && useAccessors) {

tests/baselines/reference/jsFileCompilationAwaitModifier.js

@@ -0,0 +1,84 @@
+//// [a.js]
+class Foo {
+    async a() {
+        await Promise.resolve(1);
+    }
+
+    b = async () => {
+        await Promise.resolve(1);
+    }
+}
+
+
+//// [a.js]
+var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
+    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
+    return new (P || (P = Promise))(function (resolve, reject) {
+        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
+        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
+        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
+        step((generator = generator.apply(thisArg, _arguments || [])).next());
+    });
+};
+var __generator = (this && this.__generator) || function (thisArg, body) {
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
+    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    function verb(n) { return function (v) { return step([n, v]); }; }
+    function step(op) {
+        if (f) throw new TypeError("Generator is already executing.");
+        while (_) try {
+            if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
+            if (y = 0, t) op = [op[0] & 2, t.value];
+            switch (op[0]) {
+                case 0: case 1: t = op; break;
+                case 4: _.label++; return { value: op[1], done: false };
+                case 5: _.label++; y = op[1]; op = [0]; continue;
+                case 7: op = _.ops.pop(); _.trys.pop(); continue;
+                default:
+                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
+                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
+                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
+                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
+                    if (t[2]) _.ops.pop();
+                    _.trys.pop(); continue;
+            }
+            op = body.call(thisArg, _);
+        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
+        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
+    }
+};
+var Foo = /** @class */ (function () {
+    function Foo() {
+        var _this = this;
+        this.b = function () { return __awaiter(_this, void 0, void 0, function () {
+            return __generator(this, function (_a) {
+                switch (_a.label) {
+                    case 0: return [4 /*yield*/, Promise.resolve(1)];
+                    case 1:
+                        _a.sent();
+                        return [2 /*return*/];
+                }
+            });
+        }); };
+    }
+    Foo.prototype.a = function () {
+        return __awaiter(this, void 0, void 0, function () {
+            return __generator(this, function (_a) {
+                switch (_a.label) {
+                    case 0: return [4 /*yield*/, Promise.resolve(1)];
+                    case 1:
+                        _a.sent();
+                        return [2 /*return*/];
+                }
+            });
+        });
+    };
+    return Foo;
+}());
+
+
+//// [a.d.ts]
+declare class Foo {
+    a(): Promise<void>;
+    b: () => Promise<void>;
+}

tests/baselines/reference/jsFileCompilationAwaitModifier.symbols

@@ -0,0 +1,23 @@
+=== tests/cases/compiler/a.js ===
+class Foo {
+>Foo : Symbol(Foo, Decl(a.js, 0, 0))
+
+    async a() {
+>a : Symbol(Foo.a, Decl(a.js, 0, 11))
+
+        await Promise.resolve(1);
+>Promise.resolve : Symbol(PromiseConstructor.resolve, Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+>resolve : Symbol(PromiseConstructor.resolve, Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --))
+    }
+
+    b = async () => {
+>b : Symbol(Foo.b, Decl(a.js, 3, 5))
+
+        await Promise.resolve(1);
+>Promise.resolve : Symbol(PromiseConstructor.resolve, Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+>resolve : Symbol(PromiseConstructor.resolve, Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --))
+    }
+}
+

tests/baselines/reference/jsFileCompilationAwaitModifier.types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/a.js ===
+class Foo {
+>Foo : Foo
+
+    async a() {
+>a : () => Promise<void>
+
+        await Promise.resolve(1);
+>await Promise.resolve(1) : number
+>Promise.resolve(1) : Promise<number>
+>Promise.resolve : { <T>(value: T | PromiseLike<T>): Promise<T>; (): Promise<void>; }
+>Promise : PromiseConstructor
+>resolve : { <T>(value: T | PromiseLike<T>): Promise<T>; (): Promise<void>; }
+>1 : 1
+    }
+
+    b = async () => {
+>b : () => Promise<void>
+>async () => {        await Promise.resolve(1);    } : () => Promise<void>
+
+        await Promise.resolve(1);
+>await Promise.resolve(1) : number
+>Promise.resolve(1) : Promise<number>
+>Promise.resolve : { <T>(value: T | PromiseLike<T>): Promise<T>; (): Promise<void>; }
+>Promise : PromiseConstructor
+>resolve : { <T>(value: T | PromiseLike<T>): Promise<T>; (): Promise<void>; }
+>1 : 1
+    }
+}
+

tests/cases/compiler/jsFileCompilationAwaitModifier.ts

@@ -0,0 +1,14 @@
+// @declaration: true
+// @allowJs: true
+// @outDir: ./out
+// @lib: es2015
+// @filename: a.js
+class Foo {
+    async a() {
+        await Promise.resolve(1);
+    }
+
+    b = async () => {
+        await Promise.resolve(1);
+    }
+}