[Bug c++/91705] [9/10 Regression] operator++ broken in constexpr floating point code

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91705

--- Comment #7 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Stuff like (int *) 4 is invalid in constexpr, but that's what OFFSET can be. 
Comes from
 6442         inc = cp_convert (argtype, inc, complain);
in cp_build_unary_op.

E.g.,

int array[4];

constexpr int *foo (int *p)
{
  return ++p;
}
constexpr int *p = foo(array);