Re: [PATCH] Warn about unclosed pragma omp declare target.

[Ilya Tocar <tocarip dot intel at gmail dot com>]

On 02 Feb 13:05, Jakub Jelinek wrote:
> On Tue, Jul 29, 2014 at 06:45:01PM +0400, Ilya Tocar wrote:
> > Hi,
> > 
> > As discussed here in https://gcc.gnu.org/ml/gcc/2014-01/msg00189.html
> > Gcc should complain about pragma omp declare target without
> > corresponding pragma omp end declare target. This patch adds a warning
> > for those cases.
> > Bootstraps/passes make-check.
> > Ok for trunk?
> > 
> > ChangeLog:
> > 
> > 2014-07-29  Ilya Tocar  <ilya.tocar@intel.com>
> > 
> > 	* c-decl.c (omp_declare_target_location_stack): New.
> > 	* c-lang.h (omp_declare_target_location_stack): Declare.
> > 	* c-parser.c (warn_unclosed_pragma_omp_target): New.
> > 	(c_parser_translation_unit): Call it.
> > 	(c_parser_omp_declare_target): Remeber location.
> > 	(c_parser_omp_end_declare_target): Forget location.
> 
> Sorry for the long delay on this.
> Can you check what will happen if you have unclosed #pragma omp declare target
> in some header you precompile?  If you get the warning during the header
> compilation and then not during compilation using that PCH header,
> supposedly it might be fine and the patch might be ok as is.
>
I've completely forgot about PCH.
With them this patch fails with segfault.
Moreover even if I fix segfault, we will produce strange results for
something like:
#include "a.h"
#pragma omp end declare target
// some code
> 
> If we wanted to warn even on a.c, supposedly the vector would need to be
> marked for GC.
>
I've tried:

static GTY(()) vec<int,va_gc_atomic>
*omp_declare_target_location_stack;

However it fails with:

vec.h:1118: undefined reference to `gt_pch_nx(int&)'

But in ggc.h (included in c-parser.c) i see

gt_pch_nx (unsigned int)
{
}

So I'm not sure how to properly mark vector for PCH.