Obvious match missing from results when using group: a(.*c) does not match abc

[phiresky]

What version of ripgrep are you using?

ripgrep 0.10.0
-SIMD -AVX (compiled)
+SIMD +AVX (runtime)

Bug

Example:

echo abc | rg --debug 'a(.*c)'

DEBUG|grep_regex::literal|grep-regex/src/literal.rs:110: required literal found: "ac"
DEBUG|globset|globset/src/lib.rs:429: built glob set; 0 literals, 0 basenames, 8 extensions, 0 prefixes, 0 suffixes, 0 required extensions, 0 regexes

doesn't find any results. The following all work:

echo ac | rg 'a(.*c)'

echo abc | rg 'a.*c'

echo abc | ag 'a(.*c)'

echo abc | grep 'a\(.*c\)'

[lespea]

Interestingly enough this also fails: echo abc | rg --debug 'a(?:.*c)' but this works: echo abc | rg --debug 'a(.*)c'

[BurntSushi]

Ug. This looks like a bug in ripgrep's inner literal extractor. It thinks ac is a literal that must appear in every match, but this is obviously wrong. The regex engine prefix/suffix detection is correct:

[andrew@Cheetah ~]$ regex-debug prefixes 'a(.*c)'
Cut(a)
[andrew@Cheetah ~]$ regex-debug suffixes 'a(.*c)'
Cut(c)

I diagnosed this from the --debug output. Cutting out the irrelevant stuff, you can see the problem here:

[andrew@Cheetah ~]$ echo abc | rg 'a(.*c)' --debug
DEBUG|grep_regex::literal|grep-regex/src/literal.rs:110: required literal found: "ac"
[andrew@Cheetah ~]$ echo abc | rg 'a.*c' --debug
DEBUG|grep_regex::literal|grep-regex/src/literal.rs:110: required literal found: "a"

I would have thought this was a regression since I touched this code as part of libripgrep work, but 0.9.0 exhibits the same bug.

[phiresky]

checking out ripgrep 0.0.1 (with regex = "0.1.75") has the same bug