[Bug c/90628] __builtin_mul_overflow writes to const qualified integer

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90628

--- Comment #4 from Marc Glisse <glisse at gcc dot gnu.org> ---
I wonder if in C it should be controlled by -Wdiscarded-qualifiers. I am happy
with the unconditional error, just asking.