fix(cmd): handle UTF-8 characters correctly in diagnostic printing

[magic-akari]

Summary

Related Links

• fix: [Bug]: UTF-8 multi-byte characters rendered incorrectly in error output #478

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

[gemini-code-assist]

Summary of Changes

Hello @magic-akari, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves an issue where the rslint command-line tool's diagnostic printing failed to correctly display multi-byte UTF-8 characters, leading to formatting inaccuracies. The changes introduce byte-aware processing for text within diagnostic codeboxes, ensuring that character positions and line formatting are accurately calculated regardless of the character encoding, thereby improving the readability and correctness of diagnostic output for internationalized content.

Highlights

• UTF-8 Character Handling: Implemented correct handling of multi-byte UTF-8 characters in diagnostic printing by switching from character-based indexing to byte-based indexing.
• Dependency Update: Imported the unicode/utf8 package to facilitate accurate byte length calculations for runes.
• Code Refactoring: Refactored the printDiagnosticDefault function to iterate over runes and explicitly track byte positions, ensuring precise calculation of line starts and ends for diagnostic highlights.

Changelog

• cmd/rslint/cmd.go
  • Updated diagnostic printing logic to correctly handle multi-byte UTF-8 characters.
  • Switched from rune-based indexing to byte-based indexing for position calculations within codebox text.
  • Imported the unicode/utf8 package to assist with rune byte length determination.

Activity

• No specific activity (comments, reviews, or progress updates) has been recorded for this pull request yet.

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[gemini-code-assist]

Code Review

The pull request correctly addresses the handling of UTF-8 characters in diagnostic printing. The changes involve importing the unicode/utf8 package, renaming lastNonSpaceIndex to lastNonSpaceByteIndex for clarity, and adjusting the loop logic to explicitly track byte positions using bytePos and utf8.RuneLen. This ensures that line start and end calculations are accurate for multi-byte characters, improving the correctness of diagnostic output.

[Copilot]

Pull request overview

This pull request attempts to fix UTF-8 multi-byte character rendering issues in diagnostic output (issue #478). The changes modify the printDiagnosticDefault function in cmd/rslint/cmd.go to iterate over runes instead of bytes when calculating line start and end positions for code frame display.

Changes:

• Added unicode/utf8 import for UTF-8 rune handling
• Modified code frame calculation loop to iterate by runes while tracking byte positions
• Renamed lastNonSpaceIndex to lastNonSpaceByteIndex for clarity

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[magic-akari]

Test cases generated by kimi-k2.5

[fansenze]

@magic-akari Thanks for the PR! It looks like the CI is failing due to some style/linting issues. You'll need to run npm run check-spell, npm run format:check and npm run lint:go to catch the issues.