[Bug c++/81608] New: incompatible declarations of the same extern function at different scopes accepted

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81608

            Bug ID: 81608
           Summary: incompatible declarations of the same extern function
                    at different scopes accepted
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

G++ silently accepts the following ill-formed program that declares the same
function with three different return types.

Clang and GCC (in C mode) correctly detect the mismatch and reject the program
expected.

$ cat t.C && gcc -S -Wall -Wextra -Wpedantic t.C
int f (void)
{
  extern int g (void);

  return g ();
}

void* h (void)
{
  extern void* g (void);

  return g ();
}

void g (void) { }