[Bug c++/86652] New: pointer to function type cannot have 'const' qualifier

[zhonghao at pku dot org.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86652

            Bug ID: 86652
           Summary: pointer to function type cannot have 'const' qualifier
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhonghao at pku dot org.cn
  Target Milestone: ---

The code is as follow:

class C { 
public: 
 template <typename i> 
 int (*f())() const; 
};

g++ accepts the code, but clang++ rejects it:

code4.cpp:4:7: error: pointer to function type cannot have 'const' qualifier
     int (*f())() const; 
          ^
    1 error generated.

If it's a pointer to a const function, the line shall be:

int (*f() const)();

If the return type is const (which is of course meaningless), the line shall
be:

const int (*f())();

However, I do not quite understant int (*f())() const;. Maybe it is illegal as
clang++ says?