fix(stdlib): avoid panic in nom convert_error on lines >= 65535 bytes - #1847
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pront
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July 7, 2026 18:36
Rust 1.87 capped the fmt width at 0xffff; nom's convert_error panics when a parse error column >= 65536. This affects parse_key_value, parse_cef, decode_mime_q, and parse_ruby_hash. Add safe_convert_error() in the parsing module: delegates to nom_language::error::convert_error for normal inputs; for inputs with a line >= 65535 bytes it returns a plain message with the line and column number instead. Deny direct calls to convert_error via clippy to prevent regressions. Workaround for rust-bakery/nom#1867. Fixes vectordotdev/vector#23606.
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thomasqueirozb
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pront
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Summary
The fix adds
parsing::safe_convert_error(): if any line of the input is ≥ 65,535 bytes it returns a plain "line too long" message; otherwise it delegates tonom_language::error::convert_erroras before. All four call sites are updated.The helper is intentionally a workaround pending rust-bakery/nom#1868 (open since Oct 2025, maintainer has limited availability). A comment marks it for removal once that PR lands.
Change Type
Is this a breaking change?
How did you test this PR?
Added a unit test in
parse_key_valuethat constructs a 65,535-byte line with no=delimiter andstandalone_key=false, which forces a nomErr::Errorat EOF. Without the fix this panics; with it the function returnsErr.Ran
cargo fmt,./scripts/clippy.sh, and the fullparse_key_valueunit test suite.Does this PR include user facing changes?
our guidelines.
Changelog fragment:
changelog.d/1848.fix.mdReferences
convert_errorrust-bakery/nom#1868