Why does ripgrep fail to parse \[[^[]*\*[^[]*\] but tools like grep and ag don't?

[limusch]

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• I have a different issue.

What version of ripgrep are you using?

ripgrep version: 14.1.1 on ArchLinux

rg --version
ripgrep 14.1.1

features:+pcre2
simd(compile):+SSE2,-SSSE3,-AVX2
simd(runtime):+SSE2,+SSSE3,+AVX2

PCRE2 10.43 is available (JIT is available)

How did you install ripgrep?

pacman -S ripgrep

What operating system are you using ripgrep on?

ArchLinux updated today

Describe your bug.

try to search for array definitions in C code where a '*' is used inside the brackets.
For example:
char stringbuf[12*128];
should match but not matching text like this: "element[3]", val * len[3]

What are the steps to reproduce the behavior?

command:

rg "\[[^[]*\*[^[]*\]"
rg: regex parse error:
    (?:\[[^[]*\*[^[]*\])
                  ^^
error: unclosed character class

This regex works with standard Linux grep or ag commands.

What is the actual behavior?

see above

What is the expected behavior?

actually search and find the proper matches

[BurntSushi]

This is working as expected. Here's how to do what you want with ripgrep:

$ echo 'char stringbuf[12*128];' | rg '\[[^\[]*\*[^\[]*\]'
char stringbuf[12*128];
$ echo '"element[3]", val * len[3]' | rg '\[[^\[]*\*[^\[]*\]'
$

It is a non-goal for ripgrep to be compatible with grep.

ripgrep's regex engine tends to require escapes more than older regex dialects in an effort to improve error messages and reduce ambiguity. Moreover, ripgrep's regex engine supports nested character classes. For example:

$ echo 'δaΔ' | rg -o '[\pL--[a-z]]'
δ
Δ

Neither grep nor ag supports this. This is one of the many reasons ripgrep doesn't try to be a POSIX compatible grep.

[limusch]

Thanks!