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

[redi at gcc dot gnu.org]

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

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Andreas Schwab from comment #4)
> \ is not special inside bracket expressions, [b\-a] means b and the range
> between \ and a.  If you want to include a - in a bracket expression, put it
> first or last.

That's true for POSIX BREs and EREs, but for ECMAScript escaping the dash
should work (and does on trunk).