https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116640
--- Comment #2 from Joshua Maiche <joshua.maiche at gmail dot com> ---
I thought the inconsistency was just tied to whether the default template
parameter was a dependent name, but even within cases where a private dependent
type is used, there seems to be some inconsistency on whether the private type
is considered "off limit" or not:
```
template <typename T>
class Private
{
private:
class Internal;
template <typename>
friend class Accessor;
};
template <typename T>
class Accessor
{
public:
template <typename = typename Private<T>::Internal>
static constexpr int val = 0;
template <typename = typename Private<T>::Internal>
static int GetVal() { return 0; };
};
class Dummy {};
int main()
{
int val;
val = Accessor<Dummy>::val<>; // Fails to compile.
val = Accessor<Dummy>::GetVal<>(); // Succeeds.
return val;
}
```
For comparison, Clang and MSVC compile all parts of this code successfully.
