https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86978
Bug ID: 86978
Summary: constraints for friend functions ignored
Product: gcc
Version: c++-concepts
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: h2+bugs at fsfe dot org
Target Milestone: ---
Take the following code:
template <typename t>
struct S
{
template <typename t2>
requires false
friend void foobar(S, t2) {}
};
int main()
{
foobar(S<double>{}, int{});
}
Obviously the friend function should never be available, but the code compiles
just fine, because apparently the constraints on friend functions are ignored
entirely? This took quite long to find, because there is no diagnostic of any
kind, just wrong behaviour.
Tested with GCC 7.3 and 8.1 on godbolt.org
I think this explains https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68093 as
well, because of the constraints are stripped from friend functions than two
functions which differ only in constraints appear as redefinitions.
