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

[alban_sf@baker-research.com]

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

--- Comment #2 from alban_sf@baker-research.com ---
Created attachment 39544
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39544&action=edit
config.log from building gcc 6.2.0