[Bug c/101832] __builtin_object_size(P->M, 1) where M ends with a flex-array behaves like sizeof()

[kees at outflux dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832

--- Comment #1 from Kees Cook <kees at outflux dot net> ---
This is even more visible when the size IS known (via malloc hinting, for
example):

https://godbolt.org/z/4v5rKbhaf