[PATCH] Fix uninitialized src_range within c_expr (Re: libcpp/C FE source range patch committed (r230331))

[David Malcolm]

On Tue, 2015-11-17 at 16:24 +0100, Bernd Schmidt wrote:
> On 11/17/2015 04:13 PM, David Malcolm wrote:
> > On Mon, 2015-11-16 at 22:34 +0100, Bernd Schmidt wrote:
> >>
> >> Should c_expr perhaps acquire a constructor so that this problem is
> >> avoided in the future? The whole thing seems somewhat error-prone.
> >
> > I agree that it's error prone, and the ctor approach is what I've been
> > trying for the C++ FE [1] but I suspect that touching that in the C FE
> > would be a much more invasive patch (unless we simply give it a default
> > ctor that makes the src_range be a pair of UNKNOWN_LOCATIONS?).
> 
> The UNKNOWN_LOCATIONS pair would have been my approach, yes.
> 
> > This case gains a pair of locals: start_loc and end_loc (so that we can
> > track the spelling range whilst retaining the "loc" used for the caret),
> > and I preferred to confine their scope to within the case, hence the
> > extra braced block.  Omitting the braced block leads to:
> > ../../src/gcc/c/c-parser.c:7494:7: error: jump to case label [-fpermissive]
> >    case RID_OFFSETOF:
> >         ^
> > ../../src/gcc/c/c-parser.c:7472:17: error:   crosses initialization of ‘location_t end_loc’
> >        location_t end_loc = c_parser_peek_token (parser)->get_finish ();
> >                   ^
> > etc.
> 
> Hmm, odd, I tried placing just the location_t start_loc line into the 
> switch and that appeared to compile fine. But I guess this is not a huge 
> problem.
> >
> > Is the combination of the 3 patches OK for trunk? (assuming
> > bootstrap®rest; it's only the braced-init tweak that hasn't been).
> 
> Yes.

Thanks.  I've committed the 3 patches to trunk as r230497, which should
fix the worst of the regressions caused by r230331 seen on AIX.  I'll
continue to investigate as per the discussion above.