[Bug preprocessor/41590] New: No __STDC__ definition in -g3 -E output on STDC_0_IN_SYSTEM_HEADERS systems

["ro at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

When investigating PR lto/40702, I noticed that no definition of __STDC__ is
emitted at all in the output of gcc -g3 -save-temps, making it very hard to
understand why conditional pieces of code are used.

$ cat head.h
#define HEAD 1
$ cat stdc0.c
#include <head.h>
#define STDC0
$ gcc -I. -g3 -save-temps -c stdc0.c
$ grep __STDC__ stdc0.i
$


-- 
           Summary: No __STDC__ definition in -g3 -E output on
                    STDC_0_IN_SYSTEM_HEADERS systems
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ro at gcc dot gnu dot org
GCC target triplet: *-*-solaris2*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41590