fix(ci): the invisible-character gate never matched anything - #142
fix(ci): the invisible-character gate never matched anything#142hyperpolymath 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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📝 WalkthroughSummary by CodeRabbit
WalkthroughThe workflow’s invisible-character scan now uses Unicode code-point escapes, includes additional C0 control characters, and treats binary files as text during ChangesInvisible-character gate
Estimated code review effort: 1 (Trivial) | ~5 minutes Merge Risk: ⚪ Minimal · up to This localized CI change corrects invisible-character matching and adds coverage for previously missed control characters without changing product runtime behavior. No actionable merge-blocking risk remains after normal checks and review. Poem
🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Linked Issues checkExplanation The PR implements the codepoint escapes, C0 control detection, and grep -a requirements from [ Resolution Add or provide evidence for the separate leading-BOM check, consistent C0-control detection in the compiled linter, and the required estate-wide updates to all affected gate copies. Verify the complete set of issue acceptance criteria after these changes are applied. Full details: Docstring CoverageExplanation No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)
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Pull Request Overview
This PR successfully migrates the invisible-character gate to use PCRE-compatible Unicode escapes and expands the detection range to include control characters and null bytes. While the core logic is an improvement and Codacy results are up to standards, there is a regression: the Narrow No-Break Space (U+202F) was omitted during the refactor. Additionally, the grep command in the workflow contains redundant flags and silences stderr, which could lead to false negatives if the PCRE engine encounters internal errors. These issues should be resolved before merging to ensure the linter is both comprehensive and reliable.
About this PR
- The PR does not include automated test cases or fixture files containing the 'invisible' characters. Without these, it is difficult to verify the fix or prevent future regressions in the patterns.
Test suggestions
- Verify detection of Non-Breaking Space (U+00A0)
- Verify detection of Soft Hyphen (U+00AD)
- Verify detection of Byte Order Mark (U+FEFF)
- Verify detection of C0 control character like Backspace (\x08)
- Verify grep processes files containing NUL bytes (\x00) instead of skipping them
- Verify detection of Bidi Override characters (e.g., U+202E)
Prompt proposal for missing tests
Consider implementing these tests if applicable:
1. Verify detection of Non-Breaking Space (U+00A0)
2. Verify detection of Soft Hyphen (U+00AD)
3. Verify detection of Byte Order Mark (U+FEFF)
4. Verify detection of C0 control character like Backspace (\x08)
5. Verify grep processes files containing NUL bytes (\x00) instead of skipping them
6. Verify detection of Bidi Override characters (e.g., U+202E)
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
Avoid silencing stderr with 2>/dev/null and remove the redundant -r flag. Silencing errors is risky when using grep -P because internal PCRE errors or malformed UTF-8 can cause the linter to silently fail, resulting in false negatives. Furthermore, using + instead of \; allows find to batch file paths, improving performance.
| -exec grep -aPrl "$PATTERNS" {} \; > /tmp/empty-lint-results.txt 2>/dev/null | |
| -exec grep -aPl "$PATTERNS" {} + > /tmp/empty-lint-results.txt |
| # 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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🟡 MEDIUM RISK
The pattern for U+202F (Narrow No-Break Space) is missing. This character was covered in the previous version and should be included to maintain full coverage of invisible characters.
| 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{200c}|\x{200d}|\x{200e}|\x{200f}|\x{202a}|\x{202b}|\x{202c}|\x{202d}|\x{202e}|\x{202f}|\x{2060}|\x{feff}' |
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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.