Fix isLeftHandSideExpression to handle AwaitExpression correctly

Co-authored-by: RyanCavanaugh <[email protected]>

Author: Copilot

src/compiler/utilitiesPublic.ts

@@ -1990,11 +1990,11 @@ export function isTemplateLiteral(node: Node): node is TemplateLiteral {
         || kind === SyntaxKind.NoSubstitutionTemplateLiteral;
 }
 
-export function isLeftHandSideExpression(node: Node): node is LeftHandSideExpression {
-    return isLeftHandSideExpressionKind(skipPartiallyEmittedExpressions(node).kind);
+export function isLeftHandSideExpression(node: Node): node is LeftHandSideExpression {
+    return isLeftHandSideExpressionKind(skipPartiallyEmittedExpressions(node).kind);
 }
 
-function isLeftHandSideExpressionKind(kind: SyntaxKind): boolean {
+function isLeftHandSideExpressionKind(kind: SyntaxKind): boolean {
     switch (kind) {
         case SyntaxKind.PropertyAccessExpression:
         case SyntaxKind.ElementAccessExpression:
@@ -2022,11 +2022,13 @@ function isLeftHandSideExpressionKind(kind: SyntaxKind): boolean {
         case SyntaxKind.ThisKeyword:
         case SyntaxKind.TrueKeyword:
         case SyntaxKind.SuperKeyword:
-        case SyntaxKind.NonNullExpression:
-        case SyntaxKind.ExpressionWithTypeArguments:
-        case SyntaxKind.MetaProperty:
-        case SyntaxKind.ImportKeyword: // technically this is only an Expression if it's in a CallExpression
-        case SyntaxKind.MissingDeclaration:
+        case SyntaxKind.NonNullExpression:
+        case SyntaxKind.ExpressionWithTypeArguments:
+        case SyntaxKind.MetaProperty:
+        case SyntaxKind.ImportKeyword: // technically this is only an Expression if it's in a CallExpression
+        case SyntaxKind.MissingDeclaration:
+        case SyntaxKind.PartiallyEmittedExpression:
+        case SyntaxKind.AwaitExpression:
             return true;
         default:
             return false;

tests/baselines/reference/partiallyEmittedExpressionLeftHandSide.js

@@ -0,0 +1,24 @@
+//// [tests/cases/compiler/partiallyEmittedExpressionLeftHandSide.ts] ////
+
+//// [partiallyEmittedExpressionLeftHandSide.ts]
+async function testNonNullWithAwait() {
+    const result = (await null as any)!;
+    return result;
+}
+
+async function testNonNullWithComplexExpression() {
+    const obj = { prop: Promise.resolve("test") };
+    const result = (await obj.prop as string)!;
+    return result;
+}
+
+//// [partiallyEmittedExpressionLeftHandSide.js]
+async function testNonNullWithAwait() {
+    const result = await null;
+    return result;
+}
+async function testNonNullWithComplexExpression() {
+    const obj = { prop: Promise.resolve("test") };
+    const result = await obj.prop;
+    return result;
+}

tests/baselines/reference/partiallyEmittedExpressionLeftHandSide.symbols

@@ -0,0 +1,32 @@
+//// [tests/cases/compiler/partiallyEmittedExpressionLeftHandSide.ts] ////
+
+=== partiallyEmittedExpressionLeftHandSide.ts ===
+async function testNonNullWithAwait() {
+>testNonNullWithAwait : Symbol(testNonNullWithAwait, Decl(partiallyEmittedExpressionLeftHandSide.ts, 0, 0))
+
+    const result = (await null as any)!;
+>result : Symbol(result, Decl(partiallyEmittedExpressionLeftHandSide.ts, 1, 9))
+
+    return result;
+>result : Symbol(result, Decl(partiallyEmittedExpressionLeftHandSide.ts, 1, 9))
+}
+
+async function testNonNullWithComplexExpression() {
+>testNonNullWithComplexExpression : Symbol(testNonNullWithComplexExpression, Decl(partiallyEmittedExpressionLeftHandSide.ts, 3, 1))
+
+    const obj = { prop: Promise.resolve("test") };
+>obj : Symbol(obj, Decl(partiallyEmittedExpressionLeftHandSide.ts, 6, 9))
+>prop : Symbol(prop, Decl(partiallyEmittedExpressionLeftHandSide.ts, 6, 17))
+>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, --, --), Decl(lib.es2018.promise.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 result = (await obj.prop as string)!;
+>result : Symbol(result, Decl(partiallyEmittedExpressionLeftHandSide.ts, 7, 9))
+>obj.prop : Symbol(prop, Decl(partiallyEmittedExpressionLeftHandSide.ts, 6, 17))
+>obj : Symbol(obj, Decl(partiallyEmittedExpressionLeftHandSide.ts, 6, 9))
+>prop : Symbol(prop, Decl(partiallyEmittedExpressionLeftHandSide.ts, 6, 17))
+
+    return result;
+>result : Symbol(result, Decl(partiallyEmittedExpressionLeftHandSide.ts, 7, 9))
+}

tests/baselines/reference/partiallyEmittedExpressionLeftHandSide.types

@@ -0,0 +1,63 @@
+//// [tests/cases/compiler/partiallyEmittedExpressionLeftHandSide.ts] ////
+
+=== partiallyEmittedExpressionLeftHandSide.ts ===
+async function testNonNullWithAwait() {
+>testNonNullWithAwait : () => Promise<any>
+>                     : ^^^^^^^^^^^^^^^^^^
+
+    const result = (await null as any)!;
+>result : any
+>(await null as any)! : any
+>(await null as any) : any
+>await null as any : any
+>await null : null
+>           : ^^^^
+
+    return result;
+>result : any
+}
+
+async function testNonNullWithComplexExpression() {
+>testNonNullWithComplexExpression : () => Promise<string>
+>                                 : ^^^^^^^^^^^^^^^^^^^^^
+
+    const obj = { prop: Promise.resolve("test") };
+>obj : { prop: Promise<string>; }
+>    : ^^^^^^^^^^^^^^^^^^^^^^^^^^
+>{ prop: Promise.resolve("test") } : { prop: Promise<string>; }
+>                                  : ^^^^^^^^^^^^^^^^^^^^^^^^^^
+>prop : Promise<string>
+>     : ^^^^^^^^^^^^^^^
+>Promise.resolve("test") : Promise<string>
+>                        : ^^^^^^^^^^^^^^^
+>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>>; }
+>        : ^^^^^^             ^^^ ^^     ^^ ^^^                   ^^^ ^^     ^^                  ^^^                   ^^^
+>"test" : "test"
+>       : ^^^^^^
+
+    const result = (await obj.prop as string)!;
+>result : string
+>       : ^^^^^^
+>(await obj.prop as string)! : string
+>                            : ^^^^^^
+>(await obj.prop as string) : string
+>                           : ^^^^^^
+>await obj.prop as string : string
+>                         : ^^^^^^
+>await obj.prop : string
+>               : ^^^^^^
+>obj.prop : Promise<string>
+>         : ^^^^^^^^^^^^^^^
+>obj : { prop: Promise<string>; }
+>    : ^^^^^^^^^^^^^^^^^^^^^^^^^^
+>prop : Promise<string>
+>     : ^^^^^^^^^^^^^^^
+
+    return result;
+>result : string
+>       : ^^^^^^
+}

tests/cases/compiler/partiallyEmittedExpressionLeftHandSide.ts

@@ -0,0 +1,12 @@
+// @target: es2018
+
+async function testNonNullWithAwait() {
+    const result = (await null as any)!;
+    return result;
+}
+
+async function testNonNullWithComplexExpression() {
+    const obj = { prop: Promise.resolve("test") };
+    const result = (await obj.prop as string)!;
+    return result;
+}