fix(parser): consume semicolon after let.x and let?.x

[Copilot]

let.x; and let?.x; were parsed as two statements (ExpressionStatement + EmptyStatement) instead of one. This caused codegen idempotency failures.

Root cause: In parse_let(), the branch handling member access and optional chaining on let directly constructed the statement without consuming the semicolon:

} else if matches!(peeked, Kind::Dot | Kind::QuestionDot | Kind::LParen) {
    let expr = self.parse_expr();
    self.ast.statement_expression(self.end_span(span), expr)  // semicolon left unparsed

Fix: Call parse_expression_statement() to apply ASI:

} else if matches!(peeked, Kind::Dot | Kind::QuestionDot | Kind::LParen) {
    let expr = self.parse_expr();
    self.parse_expression_statement(span, expr)  // consumes semicolon

This matches the pattern used in other branches of the same function.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Parser: let.x; or let?.x; is parsed as 2 statements</issue_title>
<issue_description>Fixing #16839 surfaced another obscure bug.

let.x;
let?.x;

These are each parsed as 2 statements - 1 x ExpressionStatement + 1 x EmptyStatement.

Playground

Once fixed, this idempotency test failure for oxc_codegen should be resolved:

oxc/tasks/coverage/snapshots/codegen_misc.snap

Line 4 in c7c05ba

Normal: tasks/coverage/misc/pass/let-optional-chaining.cjs

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Parser: let.x; or let?.x; is parsed as 2 statements #16856

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[charliecreates]

No issues found in the modified lines. The change correctly routes the let member/optional-chain/call branch through parse_expression_statement(...), aligning it with other branches and fixing the semicolon/ASI consumption bug described in the PR context.

Summary of changes

What changed

• Parser fix in crates/oxc_parser/src/js/declaration.rs:

  • In the parse_let() branch for member access / optional chaining / calls (e.g. let.x, let?.x, let()), replaced direct construction of an ExpressionStatement via self.ast.statement_expression(self.end_span(span), expr) with self.parse_expression_statement(span, expr).
  • This ensures the statement is finalized using the shared expression-statement path (including semicolon consumption / ASI behavior), preventing let.x; / let?.x; from being split into an ExpressionStatement + EmptyStatement.

• Snapshot update in tasks/coverage/snapshots/codegen_misc.snap:

  • codegen_misc positive pass count moved from 52/53 to 53/53 and removed the previously failing let-optional-chaining.cjs entry.

[Copilot]

Pull request overview

This PR fixes a parser bug where let.x; and let?.x; were incorrectly parsed as two separate statements (ExpressionStatement + EmptyStatement) instead of a single ExpressionStatement. The fix ensures proper Automatic Semicolon Insertion (ASI) by using parse_expression_statement() instead of directly constructing the statement.

Key changes:

• Modified parse_let() to call parse_expression_statement() for member access and optional chaining on let, ensuring semicolons are properly consumed
• Resolved codegen idempotency test failure for let-optional-chaining.cjs

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
crates/oxc_parser/src/js/declaration.rs	Changed line 30 to use parse_expression_statement() instead of ast.statement_expression() to properly consume semicolons via ASI
tasks/coverage/snapshots/codegen_misc.snap	Updated test results showing the idempotency test now passes (53/53 instead of 52/53)

The implementation is correct and consistent with the other branches in the same function. All expression statement branches in parse_let() now properly handle semicolon consumption through parse_expression_statement(), which internally calls self.asi().

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[codspeed-hq]

CodSpeed Performance Report

Merging #16857 will not alter performance

_{Comparing copilot/fix-parser-empty-statements (c8426ed) with main (d402242)}

Summary

✅ 42 untouched
⏩ 3 skipped¹

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩