feat(linter): add suggestion for `no-misleading-character-class` by Sysix · Pull Request #22631 · oxc-project/oxc

Sysix · 2026-05-20T21:06:15Z

Pull request overview

Adds an auto-fix suggestion capability to the eslint/no-misleading-character-class rule (focused on surrogate pairs without a Unicode-mode flag) and refactors regex-utility helpers to expose pattern/flags spans for reuse.

Changes:
* Exposes regex constructor argument span helpers (`RegexFlagsParseResult`, `get_regex_flags_span`, `get_regex_pattern_span`) for rule-level fixers.

* Updates `no-misleading-character-class` to emit a suggestion to add a Unicode flag (`u`) for `RegExp(...)` / `new RegExp(...)` cases (while intentionally skipping regex literals).

* Expands/adjusts fixer test cases to cover constructor calls.

Sysix · 2026-05-20T21:06:32Z

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codspeed-hq · 2026-05-20T21:13:39Z

Merging this PR will not alter performance

✅ 5 untouched benchmarks
⏩ 55 skipped benchmarks¹

_{Comparing 05-20-feat_linter_add_suggestion_for_no-misleading-character-class_ (43342ed) with 05-21-fix_linter_no-misleading-character-class_fix_is_unicode_code_point_escape_check (24a35a8)}

55 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

Adds an auto-fix suggestion capability to the eslint/no-misleading-character-class rule (focused on surrogate pairs without a Unicode-mode flag) and refactors regex-utility helpers to expose pattern/flags spans for reuse.

Changes:

Exposes regex constructor argument span helpers (RegexFlagsParseResult, get_regex_flags_span, get_regex_pattern_span) for rule-level fixers.
Updates no-misleading-character-class to emit a suggestion to add a Unicode flag (u) for RegExp(...) / new RegExp(...) cases (while intentionally skipping regex literals).
Expands/adjusts fixer test cases to cover constructor calls.

Reviewed changes

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

File	Description
crates/oxc_linter/src/utils/regex.rs	Makes regex-argument span parsing utilities public and factors out pattern-span extraction.
crates/oxc_linter/src/rules/eslint/no_misleading_character_class.rs	Adds a suggestion fixer to append/extend flags with `u` for `RegExp` constructor usage; updates rule category and tests.

Comments suppressed due to low confidence (3)

crates/oxc_linter/src/rules/eslint/no_misleading_character_class.rs:491

When there is no flags argument, the fixer inserts , "u" after pattern_span (the inner string/template literal span). If the first RegExp argument is parenthesized (e.g. new RegExp(("[🇯🇵]"))), inserting at the inner literal produces a SequenceExpression inside the parentheses (e.g. ("[🇯🇵]", "u")), which changes the argument value to "u" and breaks the fix’s intent.

To avoid changing semantics, the insertion point needs to be the full first-argument expression span (including parentheses), while still using the inner literal span for ConstructorParser validation.

    } else {
        fixer.insert_text_after(&pattern_span, r#", "u""#)
    }

crates/oxc_linter/src/rules/eslint/no_misleading_character_class.rs:856

These expected fix outputs place , "u" inside the parenthesized first argument (e.g. RegExp(("…", "u"))), which changes the first argument into a SequenceExpression and makes the pattern argument evaluate to "u". The expected fixes should add the flags as a second argument to RegExp, outside any parentheses that belong to the first argument expression.

        (r#"var r = new RegExp(("[🇯🇵]"))"#, r#"var r = new RegExp(("[🇯🇵]", "u"))"#, None),
        (r#"var r = new RegExp((("[🇯🇵]")))"#, r#"var r = new RegExp((("[🇯🇵]", "u")))"#, None),
        (r#"var r = new RegExp(("[🇯🇵]"),)"#, r#"var r = new RegExp(("[🇯🇵]", "u"),)"#, None),

crates/oxc_linter/src/rules/eslint/no_misleading_character_class.rs:891

In a template literal, \👍 is an identity escape, so the resulting string value does not contain a literal backslash (it evaluates to 👍). If the intention is to test a pattern that actually contains a backslash before the emoji (and to align with the preceding string-literal case that expects no fix because the regex would be invalid), the source should use \\👍 inside the template.

As written, this case is effectively just [👍] and doesn’t test the “Backslash + …” scenario described in the comment.

        (
            r"RegExp(`[\👍]`)",
            r#"RegExp(`[\👍]`, "u")"#,
            Some(serde_json::json!([{ "allowEscape": true }])),
        ),

camc314 · 2026-05-21T21:13:07Z

Merge activity

May 21, 9:13 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
May 21, 9:13 PM UTC: camc314 added this pull request to the Graphite merge queue.
May 21, 9:19 PM UTC: Merged by the Graphite merge queue.

) > ## Pull request overview > > Adds an auto-fix _suggestion_ capability to the `eslint/no-misleading-character-class` rule (focused on surrogate pairs without a Unicode-mode flag) and refactors regex-utility helpers to expose pattern/flags spans for reuse. > > **Changes:** > > * Exposes regex constructor argument span helpers (`RegexFlagsParseResult`, `get_regex_flags_span`, `get_regex_pattern_span`) for rule-level fixers. > > * Updates `no-misleading-character-class` to emit a suggestion to add a Unicode flag (`u`) for `RegExp(...)` / `new RegExp(...)` cases (while intentionally skipping regex literals). > > * Expands/adjusts fixer test cases to cover constructor calls. >

# Oxlint ### 🚀 Features - 10da26b linter: `no-misleading-character-class` add suggestions for regex literal (#22681) (Sysix) - b84941e linter/vue: Implement no-expose-after-await rule (#22675) (bab) - 98b98c1 linter/vue: Implement no-computed-properties-in-data rule (#22674) (bab) - 868e2e8 linter: Add suggestion for `no-misleading-character-class` (#22631) (Sysix) - 2d4c919 oxlint: Support `vite-plus/resolveConfig` for vite.config.ts (#22456) (leaysgur) - 2a60012 linter/vue: Implement require-render-return rule (#22613) (bab) - 9f227fd linter/vue: Implement no-deprecated-props-default-this rule (#21892) (bab) - 9cd28b3 linter: Add debug option to print files to be linted (#22546) (camchenry) - 87f065e linter/vue: Implement return-in-emits-validator rule (#21935) (bab) - ea0380c linter/unicorn: Implement `import-style` rule (#22173) (Hao Chen) - dde40fe linter/vue: Implement no-watch-after-await rule (#22006) (bab) - a735eb0 linter/vue: Implement valid-next-tick rule (#22531) (bab) - 6dc615d linter/vue: Implement no-shared-component-data rule (#21842) (bab) - a656418 linter/vue: Implement valid-define-options rule (#22107) (bab) - bb6f1b2 linter/vue: Implement require-slots-as-functions rule (#22244) (bab) - 5fa4774 linter/n: Implement `callback-return` rule (#22470) (Mikhail Baev) ### 🐛 Bug Fixes - 52bd016 linter: Respect allow unused disable directives in LSP (#22715) (camc314) - fa7c463 semantic: Correct TS enum member symbol spans (#22689) (camc314) - ed445ba linter: Respect flags overrides for `RegExp(/regex/i, "u")` (#22678) (Sysix) - 26b9396 semantic: Resolve parameter decorators outside parameter scope (#22623) (camc314) - 203952d linter: `no-misleading-character-class` fix `is_unicode_code_point_escape` check (#22655) (Sysix) - 2f64d3d linter: `no-misleading-character-class` own diagnostic for surrogate pairs without u flag (#22654) (Sysix) - 0c6ebc2 linter/eslint/no-lone-blocks: Do not flag empty loops (#22649) (Mikhail Baev) - 2a7562e linter/no-focused-tests: Mark fixer as a suggestion (#22645) (camc314) - dbe644f linter: Respect args none for unused rest parameters (#22627) (camc314) - d0211b0 linter: Allow undefined in DummyRuleMap index (#22626) (camc314) - 36fc0ec oxlint/lsp: "ignore this" actions merge with existing directive (#22604) (Sysix) - f7f370e linter/vitest/prefer-expect-type-of: Recommend `toBeTypeOf` instead of `expectTypeOf` (#22612) (Mikhail Baev) - 77063e5 linter/consistent-indexed-object-style: Preserve interface modifiers in fixes (#22579) (camc314) - 4f33aa7 linter: Treat `TSGlobalDeclaration` as ambient in `has_ambient_typescript_ancestor` (#22577) (camc314) ### ⚡ Performance - c22938d linter/no-async-endpoint-handlers: Populate node types (#22601) (camc314) - 607486e linter/no-negated-condition: Populate node types (#22602) (camc314) - 4dcaa59 linter/consistent-type-imports: Populate node types (#22600) (camc314) - 5bd3b25 linter/no-unused-vars: Avoid cloned ancestor iterator (#22598) (camc314) - 97fe9ba linter/no-extra-non-null-assertion: Reduce node matches (#22588) (camc314) - ae98296 linter/consistent-indexed-object-style: Populate node types (#22578) (camc314) # Oxfmt ### 🚀 Features - 16b8058 oxfmt: Support `vite-plus/resolveConfig` for vite.config.ts (#22454) (leaysgur) ### 🐛 Bug Fixes - 5a26479 formatter: Preserve import phases (#22692) (Cameron) ### ⚡ Performance - 78cf83f formatter: Pre-size output buffer using source text length (#22594) (Dunqing) Co-authored-by: Dunqing <[email protected]>

github-actions Bot added the A-linter Area - Linter label May 20, 2026

Sysix mentioned this pull request May 20, 2026

test(linter): add suggestions tests for no-misleading-character-class #22629

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Sysix mentioned this pull request May 20, 2026

refactor(linter): add helper function get_regex_flags_span #22630

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camc314 self-assigned this May 21, 2026

graphite-app Bot changed the base branch from 05-19-refactor_linter_add_helper_function_get_regex_flag_span_ to graphite-base/22631 May 21, 2026 11:58

graphite-app Bot force-pushed the 05-20-feat_linter_add_suggestion_for_no-misleading-character-class_ branch from e2d8d7c to 721289e Compare May 21, 2026 12:01

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Sysix changed the base branch from main to graphite-base/22631 May 21, 2026 17:36

Sysix force-pushed the 05-20-feat_linter_add_suggestion_for_no-misleading-character-class_ branch from 7e80386 to 127a6bc Compare May 21, 2026 17:36

This was referenced May 21, 2026

fix(linter): no-misleading-character-class own diagnostic for surrogate pairs without u flag #22654

Merged

fix(linter): no-misleading-character-class fix is_unicode_code_point_escape check #22655

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Sysix force-pushed the 05-20-feat_linter_add_suggestion_for_no-misleading-character-class_ branch from 127a6bc to 86b405c Compare May 21, 2026 19:29

Sysix changed the base branch from graphite-base/22631 to 05-21-fix_linter_no-misleading-character-class_fix_is_unicode_code_point_escape_check May 21, 2026 19:29

Sysix force-pushed the 05-21-fix_linter_no-misleading-character-class_fix_is_unicode_code_point_escape_check branch from 09a70c5 to 75c660f Compare May 21, 2026 19:53

Sysix force-pushed the 05-20-feat_linter_add_suggestion_for_no-misleading-character-class_ branch 2 times, most recently from 74d63ff to 48e7221 Compare May 21, 2026 19:58

Sysix force-pushed the 05-21-fix_linter_no-misleading-character-class_fix_is_unicode_code_point_escape_check branch from 75c660f to a31a88a Compare May 21, 2026 19:58

Sysix force-pushed the 05-20-feat_linter_add_suggestion_for_no-misleading-character-class_ branch from 48e7221 to 55ea218 Compare May 21, 2026 20:06

Sysix force-pushed the 05-21-fix_linter_no-misleading-character-class_fix_is_unicode_code_point_escape_check branch from a31a88a to 24a35a8 Compare May 21, 2026 20:06

Sysix requested a review from Copilot May 21, 2026 20:09

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Comment thread crates/oxc_linter/src/rules/eslint/no_misleading_character_class.rs

Sysix marked this pull request as ready for review May 21, 2026 20:25

Sysix requested a review from camc314 as a code owner May 21, 2026 20:25

Sysix marked this pull request as draft May 21, 2026 20:25

Sysix force-pushed the 05-20-feat_linter_add_suggestion_for_no-misleading-character-class_ branch from 55ea218 to 43342ed Compare May 21, 2026 20:39

Sysix added the C-enhancement Category - New feature or request label May 21, 2026

Sysix marked this pull request as ready for review May 21, 2026 20:55

camc314 approved these changes May 21, 2026

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graphite-app Bot merged commit 868e2e8 into main May 21, 2026
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oxc-guard Bot mentioned this pull request May 26, 2026

release(apps): oxlint v1.67.0 && oxfmt v0.52.0 #22735

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feat(linter): add suggestion for `no-misleading-character-class`#22631

feat(linter): add suggestion for `no-misleading-character-class`#22631
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