refactor(parser): shorten code handling illegal modifiers

[overlookmotel]

illegal_modifier_error contained a large amount of repetitious code, and was hard to read. Convert it to a shorter version which makes the logic clearer, reusing the lookup table introduced in #20748.

This change also reduces the size of generated code considerably and makes it faster, but #20748 moved this code onto a cold path, so that doesn't really matter. The main benefit is greater readability.

One test case produces a slightly different error after this change.

class D extends B {
  constructor(override readonly public foo: string) {}
}

- TS(1029): 'public' modifier must precede 'override' modifier.
+ TS(1029): 'public' modifier must precede 'readonly' modifier.

Both errors are correct, and which gets flagged was arbitrary before - it wasn't dependent on the order of modifiers in the source code, only the order of if branches in illegal_modifier_error. So IMO this change isn't important - it's just a different arbitrary order now.

[overlookmotel]

• perf(parser): defer calculation of Modifier spans #20823 : 2 dependent PRs (#20824 , #20826 )
• perf(parser): remove branch from parse_modifiers #20821
• perf(parser): reduce Kind to ModifierKind conversions in eat_modifiers_before_declaration #20820
• refactor(parser): shorten code handling illegal modifiers #20781 👈 (View in Graphite)
• perf(parser): fast path for no syntax errors when checking modifiers #20748
• perf(parser): remove a lookahead from eat_modifiers_before_declaration #20755
• refactor(parser): nest modifiers types in modules #20754
• refactor(parser): re-order modifiers code #20753
• perf(parser): store Modifiers on stack #20742
• perf(parser): add Modifiers::get method #20741
• refactor(parser): rename ModifierKinds::empty to none #20740
• refactor(parser): rename ModifierFlags to ModifierKinds #20739
• refactor(parser): simplify ModifierFlags #20738
• refactor(parser): import from std at top level #20737
• refactor(parser): remove Modifier::is_static() #20736
• refactor(parser): remove dead code from modifier parsing #20735
• main

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[codspeed-hq]

Merging this PR will not alter performance

✅ 48 untouched benchmarks
⏩ 8 skipped benchmarks¹

---

_{Comparing om/03-26-refactor_parser_shorten_code_handling_illegal_modifiers (bdb5960) with om/03-23-perf_parser_fast_path_for_no_syntax_errors_when_checking_modifiers (1e19687)}

Footnotes

1. 8 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. ↩

[Copilot]

Pull request overview

Refactors the parser’s illegal_modifier_error logic to reduce repetition and improve readability, with a corresponding snapshot update for the one changed diagnostic message.

Changes:

• Added ModifierKinds::intersection helper for bitset operations.
• Rewrote illegal_modifier_error to compute illegal-preceding sets and emit diagnostics more compactly.
• Updated the Babel parser snapshot to reflect the updated TS1029 message in one fixture.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 1 comment.

File	Description
tasks/coverage/snapshots/parser_babel.snap	Updates expected TS1029 diagnostic text for one invalid-modifier-order fixture.
crates/oxc_parser/src/modifiers.rs	Refactors illegal modifier error generation and adds a ModifierKinds intersection helper.

[Copilot]

Pull request overview

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

[camc314]

Merge activity

• Mar 29, 3:30 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Mar 29, 3:31 PM UTC: camc314 added this pull request to the Graphite merge queue.
• Mar 29, 3:35 PM UTC: The Graphite merge queue couldn't merge this PR because it had merge conflicts.
• Mar 29, 3:36 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Mar 29, 3:37 PM UTC: Graphite rebased this pull request, because this pull request is set to merge when ready.
• Mar 29, 3:39 PM UTC: camc314 added this pull request to the Graphite merge queue.
• Mar 29, 3:47 PM UTC: Merged by the Graphite merge queue.