RFA: Prevent an ICE when redeclaring a static function as weak

[Nick Clifton]

Hi Jeff,

>>    Redefining a previously defined static function as both public and
>>    weak triggers an ICE in ipa-visibility.c:
>>
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49899


> Does this fix a regression?

How far back am I allowed to go ? :-)

The bug as reported in the PR existed in 4.7.0.  I suspect, but have not 
actually tested, that the bug has always been present.  Hence I have to
admit that it is probably not a regression.


> Essentially I'm trying to figure out if we want this for gcc-6 or gcc-7.

Technically I guess the patch ought to be for gcc-7.  It just feels wrong
to have a patch to fix a known bug, but not to be able to apply it because
the bug has always existed...

Cheers
  Nick