fix(ci): the invisible-character gate never matched anything - #207
fix(ci): the invisible-character gate never matched anything#207hyperpolymath wants to merge 1 commit into
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MEASURED 2026-08-27: this gate's pattern caught 0 OF 6 invisible-character test
cases. It has never detected an NBSP, zero-width space, BOM, soft hyphen, bidi
override or word joiner.
ROOT CAUSE: the pattern used UTF-8 BYTE sequences (\xc2\xa0) while grep -P
matches CHARACTERS. Bytes c2 a0 are ONE character U+00A0; \xc2\xa0 asks for TWO
characters, U+00C2 then U+00A0, which is never present.
grep -P '\xc2\xa0' -> miss
grep -P '\x{a0}' -> MATCH
Only \x00 worked, being single-byte in both readings.
FIXED: codepoint escapes; C0 control characters \x01-\x08,\x0B,\x0C,\x0E-\x1F
added (TAB/LF/CR excluded); and grep -a, without which grep skips any NUL-bearing
file as binary.
The C0 range matters: a stray BACKSPACE byte made a workflow unparseable in
developer-ecosystem, so it never ran, and this linter called it clean.
Canonical fix: hyperpolymath/empty-linter#70. 1 file(s) here.
VERIFIED: YAML re-parsed, and the corrected pattern was confirmed to catch a real
NBSP before the change was kept.
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Up to standards ✅🟢 Issues
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Pull Request Overview
This PR successfully restores the functionality of the invisible-character CI gate by adopting PCRE-compatible Unicode codepoint escapes and utilizing the grep -a flag to ensure files containing null bytes are processed as text rather than skipped. Codacy analysis confirms the implementation meets quality standards.
While the logic correction is verified, the PR lacks automated regression tests. The repository currently contains no 'canary' files with prohibited characters to ensure the gate remains effective in the future. Additionally, minor optimizations for the regex pattern and the file traversal command are recommended to improve maintainability and performance in large-scale scans.
About this PR
- The PR lacks automated regression tests. To prevent future regressions and ensure the gate remains functional across environment updates, consider adding a sample file containing known 'illegal' invisible characters to the test suite or a dedicated 'failure-case' directory.
Test suggestions
- Verify detection of Non-Breaking Space (U+00A0)
- Verify detection of Zero-Width Space (U+200B)
- Verify detection of C0 Control Character (e.g., Backspace \x08)
- Verify scanning of files containing Null Bytes (\x00) using the -a flag
- Verify detection of Byte Order Mark (U+FEFF)
Prompt proposal for missing tests
Consider implementing these tests if applicable:
1. Verify detection of Non-Breaking Space (U+00A0)
2. Verify detection of Zero-Width Space (U+200B)
3. Verify detection of C0 Control Character (e.g., Backspace \x08)
4. Verify scanning of files containing Null Bytes (\x00) using the -a flag
5. Verify detection of Byte Order Mark (U+FEFF)
TIP Improve review quality by adding custom instructions
TIP How was this review? Give us feedback
| -o -name '*.idr' -o -name '*.zig' -o -name '*.v' -o -name '*.jl' \ | ||
| -o -name '*.gleam' -o -name '*.hs' -o -name '*.ml' -o -name '*.sh' \) \ | ||
| -exec grep -Prl "$PATTERNS" {} \; > /tmp/empty-lint-results.txt 2>/dev/null | ||
| -exec grep -aPrl "$PATTERNS" {} \; > /tmp/empty-lint-results.txt 2>/dev/null |
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🟡 MEDIUM RISK
Suggestion: Executing grep once per file with \; is inefficient. Using + allows find to batch multiple files into a single grep invocation, significantly reducing overhead. Additionally, the -r flag is redundant here because find provides the specific file paths to grep. The -a flag remains essential for handling null bytes.
| -exec grep -aPrl "$PATTERNS" {} \; > /tmp/empty-lint-results.txt 2>/dev/null | |
| -exec grep -aPl "$PATTERNS" {} + > /tmp/empty-lint-results.txt 2>/dev/null |
| # non-breaking spaces, null bytes, and other invisible Unicode in source files. | ||
| set +e | ||
| PATTERNS='\xc2\xa0|\xe2\x80\x8b|\xe2\x80\x8c|\xe2\x80\x8d|\xef\xbb\xbf|\xc2\xad|\xe2\x80\x8e|\xe2\x80\x8f|\xe2\x80\xaa|\xe2\x80\xab|\xe2\x80\xac|\xe2\x80\xad|\xe2\x80\xae|\x00' | ||
| PATTERNS='\x00|[\x01-\x08\x0B\x0C\x0E-\x1F]|\x{a0}|\x{ad}|\x{200b}|\x{200c}|\x{200d}|\x{200e}|\x{200f}|\x{202a}|\x{202b}|\x{202c}|\x{202d}|\x{202e}|\x{2060}|\x{feff}' |
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⚪ LOW RISK
Nitpick: Several of the Unicode code points are contiguous and can be grouped into character classes to improve the maintainability and readability of the pattern.
| PATTERNS='\x00|[\x01-\x08\x0B\x0C\x0E-\x1F]|\x{a0}|\x{ad}|\x{200b}|\x{200c}|\x{200d}|\x{200e}|\x{200f}|\x{202a}|\x{202b}|\x{202c}|\x{202d}|\x{202e}|\x{2060}|\x{feff}' | |
| PATTERNS='\x00|[\x01-\x08\x0B\x0C\x0E-\x1F]|\x{a0}|\x{ad}|[\x{200b}-\x{200f}]|[\x{202a}-\x{202e}]|\x{2060}|\x{feff}' |
1 participant
Measured 2026-08-27: this gate caught 0 of 6 invisible-character test cases. It has never detected an NBSP, zero-width space, BOM, soft hyphen, bidi override or word joiner.
Root cause
The pattern used UTF-8 byte sequences (
\xc2\xa0) whilegrep -Pmatches characters. Bytesc2 a0are one character U+00A0;\xc2\xa0asks for two, U+00C2 then U+00A0 — never present.Only
\x00worked, being single-byte in both readings. The gate ran, passed, and could not see what it exists to see.Fixed
\x01-\x08,\x0B,\x0C,\x0E-\x1Fadded (TAB/LF/CR excluded)grep -a— without it grep skips any NUL-bearing file as binaryThe C0 range matters: a stray backspace byte made a workflow unparseable in
developer-ecosystem, so it never ran — and this linter called it clean.Canonical fix: hyperpolymath/empty-linter#70. 1 file(s) here.
Verified: YAML re-parsed, and the corrected pattern was confirmed to catch a real NBSP before the change was kept.