[Bug c++/91464] New: C++ extern "C" namespace A {int value;}; is definition not declaration

[dje at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91464

            Bug ID: 91464
           Summary: C++ extern "C" namespace A {int value;}; is definition
                    not declaration
           Product: gcc
           Version: 9.2.1
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dje at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org, jason at gcc dot gnu.org
  Target Milestone: ---

From Twitter

extern "C" namespace A
{
    int value;
}

int getValue ()
{
    return A::value;
}

Clang compiles correctly this first scenario:
https://godbolt.org/z/FjUGov

while GCC doesn't compile:
https://godbolt.org/z/Ohfsgi

Clang compiles correctly this 2nd scenario:
https://godbolt.org/z/LhzeOo

while GCC compiles it wrongly:
https://godbolt.org/z/Nsiy5_