https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105615
Bug ID: 105615
Summary: Partial ordering of constraints with empty parameter
mapping
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: pilarlatiesa at gmail dot com
Target Milestone: ---
The following testcase is accepted by GCC 10 and newer versions:
```
template<typename>
constexpr bool b = true;
template<typename T>
concept C = b<T>;
template<typename T, typename U>
class foo
{
public:
void bar() const requires C<T> {}
void bar() const requires (C<T> && C<U>) {}
};
int main()
{
foo<int, int> x;
x.bar();
return 0;
}
```
However, if we make the concept independent of the template parameter, it fails
to compile:
```
template<typename T>
concept C = true;
template<typename T, typename U>
class foo
{
public:
void bar() const requires C<T> {}
void bar() const requires (C<T> && C<U>) {}
};
int main()
{
foo<int, int> x;
x.bar();
return 0;
}
```
