Fix: TopLevelAwait should respect await identifiers defined in sub scope.

packages/babel-parser/src/parser/expression.js

@@ -39,6 +39,7 @@ import {
   SCOPE_DIRECT_SUPER,
   SCOPE_SUPER,
   SCOPE_PROGRAM,
+  SCOPE_ASYNC,
 } from "../util/scopeflags";
 
 export default class ExpressionParser extends LValParser {
@@ -96,7 +97,11 @@ export default class ExpressionParser extends LValParser {
 
   // Convenience method to parse an Expression only
   getExpression(): N.Expression {
-    this.scope.enter(SCOPE_PROGRAM);
+    let scopeFlags = SCOPE_PROGRAM;
+    if (this.hasPlugin("topLevelAwait") && this.inModule) {
+      scopeFlags |= SCOPE_ASYNC;
+    }
+    this.scope.enter(scopeFlags);
     this.nextToken();
     const expr = this.parseExpression();
     if (!this.match(tt.eof)) {
@@ -2186,7 +2191,9 @@ export default class ExpressionParser extends LValParser {
   isAwaitAllowed(): boolean {
     if (this.scope.inFunction) return this.scope.inAsync;
     if (this.options.allowAwaitOutsideFunction) return true;
-    if (this.hasPlugin("topLevelAwait")) return this.inModule;
+    if (this.hasPlugin("topLevelAwait")) {
+      return this.inModule && this.scope.inAsync;
+    }
     return false;
   }
 

packages/babel-parser/src/parser/index.js

@@ -5,7 +5,7 @@ import type { File, JSXOpeningElement } from "../types";
 import type { PluginList } from "../plugin-utils";
 import { getOptions } from "../options";
 import StatementParser from "./statement";
-import { SCOPE_PROGRAM } from "../util/scopeflags";
+import { SCOPE_ASYNC, SCOPE_PROGRAM } from "../util/scopeflags";
 import ScopeHandler from "../util/scope";
 
 export type PluginsMap = Map<string, { [string]: any }>;
@@ -35,7 +35,11 @@ export default class Parser extends StatementParser {
   }
 
   parse(): File {
-    this.scope.enter(SCOPE_PROGRAM);
+    let scopeFlags = SCOPE_PROGRAM;
+    if (this.hasPlugin("topLevelAwait") && this.inModule) {
+      scopeFlags |= SCOPE_ASYNC;
+    }
+    this.scope.enter(scopeFlags);
     const file = this.startNode();
     const program = this.startNode();
     this.nextToken();

packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/input.js

@@ -0,0 +1,3 @@
+export class C {
+  p = await 0;
+}

packages/babel-parser/test/fixtures/experimental/top-level-await/inside-class-property/options.json

@@ -0,0 +1,8 @@
+{
+  "plugins": [
+    "topLevelAwait",
+    "classProperties"
+  ],
+  "sourceType": "module",
+  "throws": "Unexpected token, expected \";\" (2:12)"
+}

packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/input.ts

@@ -0,0 +1,3 @@
+namespace N {
+    const x = await 42;
+}

packages/babel-parser/test/fixtures/typescript/module-namespace/top-level-await/options.json

@@ -0,0 +1,8 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "typescript",
+    "topLevelAwait"
+  ],
+  "throws": "Unexpected token, expected \";\" (2:20)"
+}