fix(linter): add help text to no_control_regex, no_fallthrough, no_param_reassign

[anthonyamaro15]

Add .with_help() to diagnostics that only provide a warning message, giving developers actionable guidance on how to resolve each issue.

• no_control_regex: Avoid matching control characters or use Unicode escapes

• no_fallthrough (case/default): Use a break statement or add a fallthrough comment

• no_fallthrough (unused comment): Remove the unnecessary fallthrough comment

• no_param_reassign: Use a different variable to avoid side effects on the parameter

• no_param_reassign (property): Use a different variable to avoid side effects on properties

  Part of linter: Add help or notes to diagnostics only containing a message #19121

[Copilot]

Pull request overview

This PR enhances three ESLint linter rules (no_control_regex, no_fallthrough, and no_param_reassign) by adding actionable help text to their diagnostics. Previously, these rules only displayed warning messages without guidance on how to resolve the issues. This change is part of a broader effort (issue #19121) to improve the quality of linter diagnostics by ensuring all rules provide helpful context and resolution guidance.

Changes:

• Added help text to no_control_regex diagnostics advising to avoid control characters or use Unicode escapes
• Added help text to no_fallthrough diagnostics suggesting to use break statements or fallthrough comments
• Added help text to no_param_reassign diagnostics recommending the use of different variables to avoid side effects

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/oxc_linter/src/rules/eslint/no_param_reassign.rs	Added .with_help() to parameter and parameter property reassignment diagnostics
crates/oxc_linter/src/rules/eslint/no_fallthrough.rs	Added .with_help() to case, default, and unused fallthrough comment diagnostics
crates/oxc_linter/src/rules/eslint/no_control_regex.rs	Added .with_help() to control character detection diagnostic
crates/oxc_linter/src/snapshots/eslint_no_param_reassign.snap	Updated test snapshots to include new help text for all 49 test cases
crates/oxc_linter/src/snapshots/eslint_no_fallthrough.snap	Updated test snapshots to include new help text for all 32 test cases
crates/oxc_linter/src/snapshots/eslint_no_control_regex.snap	Updated test snapshots to include new help text for all 37 test cases
crates/oxc_linter/src/snapshots/eslint_no_control_regex@capture-group-indexing.snap	Updated test snapshots for capture group edge cases
apps/oxlint/src/lsp/snapshots/fixtures_lsp_regexp_feature@index.ts.snap	Updated LSP snapshot to reflect help text in diagnostic messages

[codspeed-hq]

Merging this PR will not alter performance

✅ 4 untouched benchmarks
⏩ 51 skipped benchmarks¹

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_{Comparing anthonyamaro15:fix/eslint-diagnostics-help-text-7 (eaa499e) with main (ce7e253)}

Footnotes

1. 51 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. ↩

[camc314]

Thank you!