[Bug c++/95686] undefined reference to static local variable within inline function

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95686

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|11.0                        |9.3.0
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
      Known to fail|                            |9.3.0
   Last reconfirmed|                            |2020-06-16
           Keywords|                            |accepts-invalid

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
clang complains

t.C:9:16: error: non-type template argument refers to object 'i' that does not
      have linkage
            return S<&i>{};
                      ^
t.C:8:26: note: non-type template argument refers to object here
        static const int i = 0;
                         ^

so this means your code is ill-formed.  I can confirm your observation
with GCC 9.3 but GCC 10.1 rejects the code as well:

t.C: In function ?auto foo()?:
t.C:9:17: error: ?& i? is not a valid template argument of type ?const int*?
because ?i? has no linkage
    9 |      return S<&i>{};
      |                 ^