https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97704
Bug ID: 97704
Summary: [11 Regression][concepts] Not working with explicit
types in function signatures?
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gcc-bugs at marehr dot dialup.fu-berlin.de
Target Milestone: ---
Hi gcc-team,
consider the following program:
```c++
struct non_exisiting {};
template <typename t>
auto hard_error(t in)
{
static_assert(in, "Failure");
return;
}
template <typename t>
requires requires { hard_error(t{}); }
constexpr auto foo(t, non_exisiting);
template <typename t>
constexpr auto foo(t, bool) { return false; };
int main()
{
foo(0, false);
};
```
This worked since at least g++-7 up until g++-10.2, works with clang (11 and
trunk), as well as msvc.
I would expect that `foo(t, non_exisiting)` will not be considered, because it
would not be meaningful in this case (`bool` is not of type `non_exisiting` and
there is no conversion sequence from `bool` to `non_exisiting`).
See https://godbolt.org/z/3W5eG8
I hope this is a bug and not intended behaviour, because I encountered this
problem by using a range adaptor from the stdlib inside a templated class which
all of a sudden found `operator|` (a hidden friend of that range adaptor) by
ADL even though that operator did not match signature-wise.
If this is intended behaviour, what in world is the type of the second
parameter of `foo(t, non_exisiting)`?
Thank you!
