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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++/107461] GCC rejects program with ambiguity error
Date: Sun, 30 Oct 2022 19:13:18 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107461

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-10-30
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. reduced testcase:
template <class T> constexpr const T min(const T t0, const T t1) { return 0=
; }
template<int MAX>
struct Matrix{
    template<int MAXOP, int other_MAXOP>
friend Matrix<min(MAXOP, other_MAXOP)>
operator+(Matrix<MAXOP> const& lhs, Matrix<other_MAXOP> const& rhs);
};

template<int MAXOP, int other_MAXOP>
Matrix<min(MAXOP, other_MAXOP)>
operator+(Matrix<MAXOP> const& lhs, Matrix<other_MAXOP> const& rhs);

void f()
{
    Matrix<1> a;
    a+a;
}

---- CUT ----
Note the min function inside the return type is important and is looking li=
ke
is what is causing issues to not match the two decls to be the same.
Having min as a non-template function allows it to be matched.=