[Bug c++/64266] Can GCC produce local mergeable symbols for *.__FUNCTION__ and *.__PRETTY_FUNCTION__ functions?

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64266

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
C++11 says that the address of __func__ can be the same as address of other
string literals, so I think that allows putting it into mergeable section.
But what isn't clear to me is if __func__ is used in some inline function,
if the standard allows __func__ to have different addresses between different
compilation units.  Say a.h:
extern void bar (const char *);
inline void foo () { bar (__func__); }
a.C:
#include "a.h"
void bar (const char *x)
{
  static const char *p;
  if (p && p != x) __builtin_abort ();
  p = x;
}
extern void baz ();
int
main ()
{
  foo ();
  baz ();
  foo ();
}
b.C:
#include "a.h"
void baz ()
{
  foo ();
}

Now, if you compile b.C into a shared library and a.C into executable linked
with the shared library, this will fail.  If instead of bar (__func__) you use
static const char func[] = "func"; bar (func) it will presumably work fine.
So, the question is if C++ should just say that address comparisons on the
__func__ variables are undefined, or if we really need to make sure we use a
public symbol rather than private in that case.

And, for __func__ occurrences in non-inline functions, supposedly we can keep
them local and could consider using local symbols instead of the mangled names
to decrease .symtab/.strtab size.  Though, perhaps that will make it harder for
users to inspect those in gdb.