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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/109150] std::fill should use __gnu_cxx::__is_scalar
 overloads for all scalars
Date: Wed, 15 Mar 2023 20:54:53 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109150

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-03-15

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This terminates with an exception, but I think it's valid.

#include <algorithm>

const int global =3D 0;

struct X {
  void operator=3D(const int& i) { if (&i !=3D &global) throw 1; }
};

int main()
{
  X x;
  std::fill(&x, &x+1, global);
}

So I think the std::fill (and std::fill_n) optimizations need to consider t=
he
iterator's value type as well as the _Tp type.=