The grep 3.11 application when used in perl-regexp mode appears to now be broken

[Michael Goldshteyn]

I just updated my Cygwin64 installation, which includes the grep
utility and its behavior has changed. It no longer works like it used to
for Perl reg-ex matching, as demonstrated below:

Simple test cases:
======================
$ ls -l a
-rwxr-xr-x 1 Michael None 6 Mar 16 12:15 a

$ hexdump -C a
00000000  31 30 30 30 0d 0a                                 |1000..|
00000006

# Notice the CR/LF encoding after the "1000" text, as is the case for DOS
text files

# Now let's test grep regular match
$ grep --version
grep (GNU grep) 3.11
Packaged by Cygwin (3.11-1)
Copyright (C) 2023 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <
https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Mike Haertel and others; see
<https://git.savannah.gnu.org/cgit/grep.git/tree/AUTHORS>.

grep -P uses PCRE2 10.43 2024-02-16

$ grep '000' a
1000

# Match using pcre2
$ grep -P '000' a
1000

# OK, so far so good
$ grep -P '000$' a
# No match

# Put another way
$ grep -c -P '000$' a
0

# Now you may be thinking, OK, it's because of the CR/LF line ending
# But, I present the following
$ pcre2grep --version
pcre2grep version 10.43 2024-02-16

$ pcre2grep '000$' a
1000

# As a further cross-check, the same version of the cygpcre2-8-0.Dll is
used for both grep.exe and pcre2grep.exe, as shown below with an "=>"
annotation added by me to direct you to the Dll in question:

$ ldd grep.exe
        ntdll.dll => /cygdrive/c/Windows/SYSTEM32/ntdll.dll (0x7ffa87d50000)
        KERNEL32.DLL => /cygdrive/c/Windows/System32/KERNEL32.DLL
(0x7ffa87700000)
        KERNELBASE.dll => /cygdrive/c/Windows/System32/KERNELBASE.dll
(0x7ffa85570000)
        cygwin1.dll => /usr/bin/cygwin1.dll (0x7ff9c84d0000)
        cygintl-8.dll => /usr/bin/cygintl-8.dll (0x5ee2d0000)
=>        cygpcre2-8-0.dll => /usr/bin/cygpcre2-8-0.dll (0x5ec2b0000)
        cygiconv-2.dll => /usr/bin/cygiconv-2.dll (0x3dff10000)

$ ldd pcre2grep.exe
        ntdll.dll => /cygdrive/c/Windows/SYSTEM32/ntdll.dll (0x7ffa87d50000)
        KERNEL32.DLL => /cygdrive/c/Windows/System32/KERNEL32.DLL
(0x7ffa87700000)
        KERNELBASE.dll => /cygdrive/c/Windows/System32/KERNELBASE.dll
(0x7ffa85570000)
=>        cygpcre2-8-0.dll => /usr/bin/cygpcre2-8-0.dll (0x5ec2b0000)
        cygbz2-1.dll => /usr/bin/cygbz2-1.dll (0x3ed560000)
        cygwin1.dll => /usr/bin/cygwin1.dll (0x7ff9c84d0000)
        cygz.dll => /usr/bin/cygz.dll (0x5ebb10000)

# For what it's worth, I also checked into what versions of libintl8 and
libiconv-2 I have, and these are as follows:
# libintl8 0.22.4-1
# libiconv2 1.17-1

# And as an addition cross-check, I will include the following "complete
hack":
$ strings cygintl-8.dll | pcre2grep '^\d\.\d\d'
0.22.4
0.22.4

$ strings cygiconv-2.dll | pcre2grep '^\d\.\d\d'
1.17
1.17

# For completeness, here is my CYGWIN environment variable setting and some
other info:
$ echo "$CYGWIN"
glob:ignorecase winsymlinks:native pipe_byte
$ echo "$CYGWIN64_DIR"
c:\cygwin64
$ which grep
/usr/bin/grep
$ which pcre2grep
/usr/bin/pcre2grep
# No aliases are set up for these, either
$ alias grep pcre2grep
bash: alias: grep: not found
bash: alias: pcre2grep: not found
======================
Further comments:
I do not know with which version of grep.exe this misbehavior (or at least
misaligned behavior with respect to grep2pcre) of the '-P' switch began. I
discovered it after updating my Cygwin64 install to use the latest grep
version, which likely also picked up the latest version of PCRE2 and
other dependencies along the way.

Thank you for looking into this and/or providing constructive comments on
the source of the issue,

Michael Goldshteyn