https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107470
Bug ID: 107470
Summary: GCC falsely accepts friend declaration with
mismatching requirements
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: h2+bugs at fsfe dot org
Target Milestone: ---
#include <concepts>
template <std::integral T>
requires std::unsigned_integral<T>
struct S
{
template <std::integral T2> // template <typename T2>
friend class S;
};
int main()
{
S<unsigned> s;
}
The code is accepted by GCC and rejected by clang. However, if the friend
declaration is fully unconstrained, it is also rejected by GCC.
Code like this exists in libstdc++ which clang stumbles over (I will create a
separate library issue for that).
