[Bug libstdc++/91488] [9/10/11/12 Regression] char_traits::length causes "inlining failed in call to always_inline" error with -fgnu-tm -O2 -std=c++17

[gustavo at ugr dot es via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91488

--- Comment #7 from gustavo <gustavo at ugr dot es> ---
can be reproduced also trunk gcc in: 
https://gcc.godbolt.org/z/v6T9j3r4M