[jayhemnani9910]

GNU grep -E takes a ) that closes no group as an ordinary character. Here the pattern is rejected:

$ printf 'a)\nb\n' | grep -E 'a)'
a)                                                         # GNU grep 3.12
grep: invalid pattern "a)": unmatched close parenthesis    # main, exit 2

Same for ), (a)), b|), ^), )* and so on. Oniguruma has a syntax flag for exactly this (ALLOW_UNMATCHED_CLOSE_SUBEXP, on in its own POSIX extended syntax), so the fix turns it on for -E only. In a basic regexp an unmatched \) is still an error, as in GNU; ) there was already a literal.

New test ere_unmatched_close_paren_is_literal (fails on main). cargo test: test_grep 104 pass (103 on main), clippy and fmt clean. Against GNU grep 3.12, 33 -E patterns with unmatched, nested, escaped, bracketed and repeated parentheses give the same output and exit status, and the BRE cases (a\), \(a\)\), ), \)) give the same exit status.

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[codspeed]

Merging this PR will not alter performance

1 warning

⚠️ 3 benchmarks are dominated by system calls

System calls cannot be simulated consistently and are left out of the measure. The reported value understates the real cost. Switch to the Walltime instrument to measure them.

Learn more about system calls

See affected benchmarks

✅ 10 untouched benchmarks
⏩ 17 skipped benchmarks¹

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_{Comparing jayhemnani9910:ere-unmatched-close-paren (d5f0828) with main (0be8c54)}

Footnotes

1. 17 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. ↩

[lhecker]

This seems a bit excessive. Are we unit testing the regex crate? :D

[jayhemnani9910]

Fair, cut it down to one case.

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