[Bug c++/94944] New: compile error accessing member function of dependent base class template in exception specification

[eracpp at eml dot cc]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94944

            Bug ID: 94944
           Summary: compile error accessing member function of dependent
                    base class template in exception specification
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eracpp at eml dot cc
  Target Milestone: ---

GCC fails to compile a qualified invocation of a member function of a dependent
base class template when used within an exception specification:

----
template <typename T>
struct B {
  void foo(T t) {}
};

template <typename T>
struct D : B<T> {
  void foo(T t) noexcept(noexcept(B<T>::foo(t))) {}
};

template struct D<int>;
----

The error message is as follows:

----
error: cannot call member function 'void B<T>::foo(T) [with T = int]' without
object
    8 |   void foo(T t) noexcept(noexcept(B<T>::foo(t))) {}
      |
----

Clang and MSVC accept the code as given without error:
https://gcc.godbolt.org/z/MW2iQz

Note, a workaround accepted by all three major compilers is to qualify the
invocation with `this->`:

----
void foo(T t) noexcept(noexcept(this->B<T>::foo(t))) {}
----