Re: libcpp: registering both a pragma and a pragma namespace with the same name

[Aldy Hernandez <aldyh at redhat dot com>]

On 04/11/13 00:32, Jakub Jelinek wrote:
> On Wed, Apr 10, 2013 at 05:16:17PM -0700, Andrew Pinski wrote:
> > On Wed, Apr 10, 2013 at 3:24 PM, Aldy Hernandez <aldyh@redhat.com> wrote:
> > > Hi Tom.  Hi folks.
> > >
> > > We've asked Balaji to rewrite the <#pragma simd> handling for cilkplus as we
> > > currently do for OMP, etc, in init_pragma().
> > >
> > > The cilkplus branch currently has something like:
> > >
> > >        cpp_register_deferred_pragma (parse_in, "simd", "",
> > >                                    PRAGMA_SIMD_EMPTY, true, false);
> > >        cpp_register_deferred_pragma (parse_in, "simd", "assert",
> > >                                      PRAGMA_SIMD_ASSERT, true, false);
> > >        cpp_register_deferred_pragma (parse_in, "simd", "noassert",
> > >                                      PRAGMA_SIMD_NOASSERT, true, false);
> > >        cpp_register_deferred_pragma (parse_in, "simd", "vectorlength",
> > >                                      PRAGMA_SIMD_VECTORLENGTH, true, false);
> >
> > What about just registering simd as the pragma and then look for the
> > right keyword after that?  Like diagnostic is handled?
>
> Yeah, the above is definitely wrong.  Just
>    if (flag_cilkplus)
>      cpp_register_deferred_pragma (parse_in, NULL, "simd", PRAGMA_SIMD, true, false);

Well, the thing is that you can't just use NULL for "#pragma simd" as a 
pragma and then define "#pragma simd assert" to use "simd" as a pragma 
namespace.  I had already tried that:

  if (flag_enable_cilk)
    {
      cpp_register_deferred_pragma (parse_in, NULL, "simd",
                                  PRAGMA_SIMD_EMPTY, true, false);
      cpp_register_deferred_pragma (parse_in, "simd", "assert",
	                            PRAGMA_SIMD_ASSERT, true, false);
      // etc
    }

In which case, we ICE because we're registering simd as both a pragma 
and a pragma namespace:

    cpp_error (pfile, CPP_DL_ICE,
	       "registering \"%s\" as both a pragma and a pragma namespace",
	       NODE_NAME (node));

> and parse the clauses in c/c-parser.c and cp/parser.c, look at how OpenMP
> pragmas are parsed (those have the "omp" space, you just use NULL, 
otherwise
> it is not any different).

I see Balaji is already parsing the simd pragmas in c_parser_pragma.