Fix assert failure in await expression with non-null assertion

Co-authored-by: RyanCavanaugh <6685088+RyanCavanaugh@users.noreply.github.com>

Author: Copilot

src/compiler/transformers/ts.ts

@@ -1721,10 +1721,10 @@ export function transformTypeScript(context: TransformationContext): Transformer
         return factory.createPartiallyEmittedExpression(expression, node);
     }
 
-    function visitNonNullExpression(node: NonNullExpression): Expression {
-        const expression = visitNode(node.expression, visitor, isLeftHandSideExpression);
-        Debug.assert(expression);
-        return factory.createPartiallyEmittedExpression(expression, node);
+    function visitNonNullExpression(node: NonNullExpression): Expression {
+        const expression = visitNode(node.expression, visitor, isExpression);
+        Debug.assert(expression);
+        return factory.createPartiallyEmittedExpression(expression, node);
     }
 
     function visitSatisfiesExpression(node: SatisfiesExpression): Expression {

tests/baselines/reference/awaitNonNullAssertion.js

@@ -0,0 +1,67 @@
+//// [tests/cases/compiler/awaitNonNullAssertion.ts] ////
+
+//// [awaitNonNullAssertion.ts]
+// Test for await expression followed by non-null assertion
+async function test() {
+    const result1 = (await null as any)!;
+    const result2 = (await Promise.resolve(42))!;
+    const result3 = (await null)!;
+}
+
+//// [awaitNonNullAssertion.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 = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
+    return g.next = verb(0), g["throw"] = verb(1), g["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 (g && (g = 0, op[0] && (_ = 0)), _) 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 };
+    }
+};
+// Test for await expression followed by non-null assertion
+function test() {
+    return __awaiter(this, void 0, void 0, function () {
+        var result1, result2, result3;
+        return __generator(this, function (_a) {
+            switch (_a.label) {
+                case 0: return [4 /*yield*/, null];
+                case 1:
+                    result1 = _a.sent();
+                    return [4 /*yield*/, Promise.resolve(42)];
+                case 2:
+                    result2 = (_a.sent());
+                    return [4 /*yield*/, null];
+                case 3:
+                    result3 = (_a.sent());
+                    return [2 /*return*/];
+            }
+        });
+    });
+}

tests/baselines/reference/awaitNonNullAssertion.symbols

@@ -0,0 +1,19 @@
+//// [tests/cases/compiler/awaitNonNullAssertion.ts] ////
+
+=== awaitNonNullAssertion.ts ===
+// Test for await expression followed by non-null assertion
+async function test() {
+>test : Symbol(test, Decl(awaitNonNullAssertion.ts, 0, 0))
+
+    const result1 = (await null as any)!;
+>result1 : Symbol(result1, Decl(awaitNonNullAssertion.ts, 2, 9))
+
+    const result2 = (await Promise.resolve(42))!;
+>result2 : Symbol(result2, Decl(awaitNonNullAssertion.ts, 3, 9))
+>Promise.resolve : Symbol(PromiseConstructor.resolve, Decl(lib.es2015.promise.d.ts, --, --), 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, --, --), Decl(lib.es2015.promise.d.ts, --, --))
+
+    const result3 = (await null)!;
+>result3 : Symbol(result3, Decl(awaitNonNullAssertion.ts, 4, 9))
+}

tests/baselines/reference/awaitNonNullAssertion.types

@@ -0,0 +1,45 @@
+//// [tests/cases/compiler/awaitNonNullAssertion.ts] ////
+
+=== awaitNonNullAssertion.ts ===
+// Test for await expression followed by non-null assertion
+async function test() {
+>test : () => Promise<void>
+>     : ^^^^^^^^^^^^^^^^^^^
+
+    const result1 = (await null as any)!;
+>result1 : any
+>(await null as any)! : any
+>(await null as any) : any
+>await null as any : any
+>await null : null
+>           : ^^^^
+
+    const result2 = (await Promise.resolve(42))!;
+>result2 : number
+>        : ^^^^^^
+>(await Promise.resolve(42))! : number
+>                             : ^^^^^^
+>(await Promise.resolve(42)) : number
+>                            : ^^^^^^
+>await Promise.resolve(42) : number
+>                          : ^^^^^^
+>Promise.resolve(42) : Promise<number>
+>                    : ^^^^^^^^^^^^^^^
+>Promise.resolve : { (): Promise<void>; <T>(value: T): Promise<Awaited<T>>; <T>(value: T | PromiseLike<T>): Promise<Awaited<T>>; }
+>                : ^^^^^^             ^^^ ^^     ^^ ^^^                   ^^^ ^^     ^^                  ^^^                   ^^^
+>Promise : PromiseConstructor
+>        : ^^^^^^^^^^^^^^^^^^
+>resolve : { (): Promise<void>; <T>(value: T): Promise<Awaited<T>>; <T>(value: T | PromiseLike<T>): Promise<Awaited<T>>; }
+>        : ^^^^^^             ^^^ ^^     ^^ ^^^                   ^^^ ^^     ^^                  ^^^                   ^^^
+>42 : 42
+>   : ^^
+
+    const result3 = (await null)!;
+>result3 : any
+>(await null)! : null
+>              : ^^^^
+>(await null) : null
+>             : ^^^^
+>await null : null
+>           : ^^^^
+}

tests/cases/compiler/awaitNonNullAssertion.ts

@@ -0,0 +1,7 @@
+// @lib: es2015
+// Test for await expression followed by non-null assertion
+async function test() {
+    const result1 = (await null as any)!;
+    const result2 = (await Promise.resolve(42))!;
+    const result3 = (await null)!;
+}