[Bug libstdc++/77469] New: std::regex x("[b\\-a]") throws with message "Invalid range in bracket expression."

["alban_sf at baker-research dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77469

            Bug ID: 77469
           Summary: std::regex x("[b\\-a]") throws with message "Invalid
                    range in bracket expression."
           Product: gcc
           Version: 6.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: alban_sf@baker-research.com
  Target Milestone: ---

Hello,

The std::regex constructor throws when passed "[b\\-a]".  The message is
"Invalid range in bracket expression.".

I understand that this is a valid regular expression that specifies a character
class consisting of a literal "b", a literal "-", and a literal "a".

g++ version:  6.2.0.

System:  Ubuntu 12.04.2 LTS.

Output of 'uname -a':  Linux zeus 3.2.0-68-generic #102-Ubuntu SMP Tue Aug 12
22:02:15 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

gcc configuration options:  ./configure --disable-multilib

Build command line:  g++ testRegex.cc -o testRegex -std=c++11 -Wall -Wextra
-fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations
-fsanitize=undefined

There are no compiler messages.

This behaviour does not occur with gcc Ubuntu 4.9.2-0ubuntu1~14.04.

This behaviour also occurs with MinGW-W64 5.3.0 and 6.1.0.

Thank you,
Alban