fix(parser): switch to module goal eagerly on export (#22684)

## Summary

In unambiguous (`.js` auto-detect) sources, `export var x = await + 1;` reported a spurious `Duplicated export 'x'` error. The parser first parsed the statement with `await` as an identifier, then re-parsed it under `Context::Await` to patch the AST — but the second pass re-invoked `visit_export_named_declaration`, recording the binding `x` a second time in the module record.

`export` is unambiguously module syntax per ECMA-262 §16.2.3 (`ExportDeclaration` is only a `ModuleItem`, never a Script production). So commit to the Module goal — enable `Context::Await` — as soon as the next top-level token is `Kind::Export`. The statement then parses correctly on the first attempt; no reparse and no duplicate record.

`Kind::Import` is intentionally **not** eager-switched. TypeScript's `import name = ns.path` is a script-compatible namespace alias (see `topLevelAwait.2.ts`), so treating `import` as a module starter would break that case.

The only TS snapshot churn is +16 lines of additional error messages for already-failing tests (`topLevelAwaitErrors.5.ts`, `topLevelAwaitErrors.6.ts` — `export ... await`). Summary counts unchanged.

Closes #22520
Fixes #22158

crates/oxc_parser/src/js/statement.rs

@@ -50,9 +50,14 @@ impl<'a, C: Config> ParserImpl<'a, C> {
                 break;
             }
 
-            // Once ESM syntax is detected, enable await context for remaining statements
-            // and stop tracking (we'll reparse earlier statements at the end)
-            if track_await_reparse && self.module_record_builder.has_module_syntax() {
+            // Eagerly commit to Module goal on `export` so the statement is parsed
+            // under `Await` on the first pass; otherwise the reparse below runs it
+            // again and the export binding gets recorded twice.
+            // `import` is not eager: TypeScript's `import name = ns.foo` is a
+            // script-compatible namespace alias, not module syntax.
+            if track_await_reparse
+                && (self.module_record_builder.has_module_syntax() || self.at(Kind::Export))
+            {
                 track_await_reparse = false;
                 self.ctx = self.ctx.and_await(true);
             }

tasks/coverage/misc/pass/oxc-22158.js

@@ -0,0 +1,6 @@
+// https://github.com/oxc-project/oxc/issues/22158
+// `await` in initializer of an `export var` declaration must not be
+// reported as a duplicated export when parsed with unambiguous `.js`.
+export var a = await + 1;
+export var b = await(1);
+export var c = await + 0;

tasks/coverage/snapshots/codegen_misc.snap

@@ -1,3 +1,3 @@
 codegen_misc Summary:
-AST Parsed     : 66/66 (100.00%)
-Positive Passed: 66/66 (100.00%)
+AST Parsed     : 67/67 (100.00%)
+Positive Passed: 67/67 (100.00%)

tasks/coverage/snapshots/formatter_misc.snap

@@ -1,3 +1,3 @@
 formatter_misc Summary:
-AST Parsed     : 66/66 (100.00%)
-Positive Passed: 66/66 (100.00%)
+AST Parsed     : 67/67 (100.00%)
+Positive Passed: 67/67 (100.00%)

tasks/coverage/snapshots/parser_misc.snap

@@ -1,6 +1,6 @@
 parser_misc Summary:
-AST Parsed     : 66/66 (100.00%)
-Positive Passed: 66/66 (100.00%)
+AST Parsed     : 67/67 (100.00%)
+Positive Passed: 67/67 (100.00%)
 Negative Passed: 137/137 (100.00%)
 
   × Cannot assign to 'arguments' in strict mode

tasks/coverage/snapshots/parser_typescript.snap

@@ -21019,6 +21019,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/parser/ecmasc
    ·      ─────
    ╰────
 
+  × Cannot use `await` as an identifier in an async context
+   ╭─[typescript/tests/cases/conformance/externalModules/topLevelAwaitErrors.5.ts:2:14]
+ 1 │ // await in exported class name should fail
+ 2 │ export class await {
+   ·              ─────
+ 3 │ }
+   ╰────
+
   × The keyword 'await' is reserved
    ╭─[typescript/tests/cases/conformance/externalModules/topLevelAwaitErrors.5.ts:2:14]
  1 │ // await in exported class name should fail
@@ -21027,6 +21035,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/parser/ecmasc
  3 │ }
    ╰────
 
+  × Cannot use `await` as an identifier in an async context
+   ╭─[typescript/tests/cases/conformance/externalModules/topLevelAwaitErrors.6.ts:2:17]
+ 1 │ // await in exported function name should fail
+ 2 │ export function await() {
+   ·                 ─────
+ 3 │ }
+   ╰────
+
   × The keyword 'await' is reserved
    ╭─[typescript/tests/cases/conformance/externalModules/topLevelAwaitErrors.6.ts:2:17]
  1 │ // await in exported function name should fail

tasks/coverage/snapshots/semantic_misc.snap

@@ -1,6 +1,6 @@
 semantic_misc Summary:
-AST Parsed     : 66/66 (100.00%)
-Positive Passed: 52/66 (78.79%)
+AST Parsed     : 67/67 (100.00%)
+Positive Passed: 53/67 (79.10%)
 semantic Error: tasks/coverage/misc/pass/conditional-arrow-alternate-return-type.ts
 Unresolved references mismatch:
 after transform: ["Pick", "Record"]

tasks/coverage/snapshots/transformer_misc.snap

@@ -1,3 +1,3 @@
 transformer_misc Summary:
-AST Parsed     : 66/66 (100.00%)
-Positive Passed: 66/66 (100.00%)
+AST Parsed     : 67/67 (100.00%)
+Positive Passed: 67/67 (100.00%)