Re: [patch, fortran] Fix PR29458 - spurious warning for implied do-loop counter

[Jerry DeLisle <jvdelisle at verizon dot net>]

Steve Kargl wrote:
> On Sun, Apr 05, 2009 at 03:16:58PM +0200, Daniel Franke wrote:
> > This code gives a warning about 'i' being used uninitialized:
> >
> >   integer :: n, i
> >   n = 5
> >   n = SUM((/(i,i=1,n)/))
> > end
> >
> > Attached patch fixes this by shadowing 'i' with a temporary variable. Further, 
> > it wraps the implied-do in its own block instead of placing it in the parent 
> > block directly. The relevant part now looks like this, 'i' is never touched:
> >
> >     {                         
> >       shadow_loopvar.4 = 1;
> >       D.1515 = n;
> >       [...]
> >       while (1)
> >         {
> >           if (shadow_loopvar.4 > D.1515) goto L.1;
> >           (*(integer(kind=4)[0] *) atmp.2.data)[offset.3] = shadow_loopvar.4;
> >           offset.3 = offset.3 + 1;
> >           shadow_loopvar.4 = shadow_loopvar.4 + 1;
> >         }
> >       L.1:;
> >     }
>
> What happens if someone used shadow_loopvar as a variable
> in their code?  Do we need to use _shadow_loopvar (note 
> the leading underscore)?
I have previously used a % or similar appended to the name that makes it invalid 
fortran lbel, but valid from the rest of gcc.  It was in a patch for run-time 
error I think, its been a while back.

Jerry