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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/113713] static_assert result depends on optimization
 settings
Date: Fri, 02 Feb 2024 08:28:15 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113713

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-02-02
             Status|UNCONFIRMED                 |NEW

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed, this is a constexpr issue in both clang and GCC (unless there is
some unspecified behavior I don't know of).

Take:
```
#if defined(CE)
#define CONSTEXPR constexpr
#else
#define CONSTEXPR
#endif
struct A{};
template<class T>
CONSTEXPR
bool p(T) { return false; }
template<class T>
CONSTEXPR
bool f(T v) { return p(v); }
CONSTEXPR
bool g() { return f(A()); }
CONSTEXPR
bool p(A) { return true; }

int main()
{
        A a;
        if (!f(a))
          __builtin_abort();
}
```

Without CE being defined, this works at all optimizations level. With CE be=
ing
defined this works at -O0 only (like there is some [incorrect?] caching goi=
ng
on at -O1 and above and clang is doing the caching at all levels).=