Hello, While using GNU grep v3.4 in an Ubuntu 20.04 userspace running on top of Win10 WSL (yeah, i know... but also checked in other envs) i discovered what seems like an obvious bug (if i'm not mistaken). The bug: ----- me@host:~$ echo 'xxxxy' |grep -E '^x+x+x+x+y$' xxxxy me@host:~$ echo 'xxxy' |grep -E '^x+x+x+x+y$' xxxy me@host:~$ echo 'xxy' |grep -E '^x+x+x+x+y$' xxy me@host:~$ echo 'xy' |grep -E '^x+x+x+x+y$'
---- ...the terminal supports ansi color escapes, and what's really weird is that only the result from the first command is colored in red. First and fourth commands yield correct results; the second and third do not, as they should not match it's input. I've tested releases from v3.1 to latest v3.5 and found the anomalous behaviour in version v3.2 through v3.5. A (quick and clunky) git bisect led me to believe it was introduced about two years ago, possibly in commit 123620af88f55c3e0cc9f0aed7311c72f625bc82 ( https://git.savannah.gnu.org/cgit/grep.git/commit/?id=123620af88f55c3e0cc9f0aed7311c72f625bc82). If this is true, it would mean either the bug is in gnulib, or maybe grep needed to do some kind of extra handling on it's side. Kind regards. Gonzalo Padrino. P.S.: I had to patch some things in order to successfully compile the code after checking out some problematic commits (pragmas to avoid warnings about "pure" and "noreturn" function attributes, a missing configmake dependency in bootstrap.conf, etc ).
