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* [Bug preprocessor/36279]  New: division by zero in #if
@ 2008-05-20 14:00 aldot at gcc dot gnu dot org
  2008-05-20 14:32 ` [Bug preprocessor/36279] " schwab at suse dot de
  0 siblings, 1 reply; 2+ messages in thread
From: aldot at gcc dot gnu dot org @ 2008-05-20 14:00 UTC (permalink / raw)
  To: gcc-bugs

$ cat argh.h 
#define __x(y) __NR_##y
#define x(y) __x(y)
/* define HAVE_FOO if __NR_XXX is defined: */
#define __NR_read 0
#undef __NR_write
#ifdef BUG2
#define __NR_ac%scess 1
#endif

#if defined XXX
# if x(XXX) >= 0
#  define HAVE_FOO 1
#  warning HAVE_FOO
# else
#  undef HAVE_FOO
#  warning no FOO
# endif
#endif

$ echo | gcc-4.4-trunk -DXXX=acce%ss -include argh.h -c - -E -P
In file included from <command-line>:0:
./argh.h:11:13: error: division by zero in #if
./argh.h:13:4: warning: #warning HAVE_FOO



Another (alleged) one, BUG2:
$ echo | gcc-4.4-trunk -DBUG2 -DXXX=read -include argh.h -c - -E -P
In file included from <command-line>:0:
./argh.h:7:16: warning: missing whitespace after the macro name
./argh.h:13:4: warning: #warning HAVE_FOO


And something that would be handy to have but that doesn't seem to work for me:
This is Ok, __NR_read is defined:
$ echo | gcc-4.4-trunk -DXXX=read -include argh.h -c - -E -P
In file included from <command-line>:0:
./argh.h:13:4: warning: #warning HAVE_FOO

This is not OK, i'd expect this to be "no FOO" since __NR_write is *not*
defined:
$ echo | gcc-4.4-trunk -DXXX=write -include argh.h -c - -E -P
In file included from <command-line>:0:
./argh.h:13:4: warning: #warning HAVE_FOO


-- 
           Summary: division by zero in #if
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: aldot at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36279


^ permalink raw reply	[flat|nested] 2+ messages in thread
* [Bug preprocessor/36279] division by zero in #if
  2008-05-20 14:00 [Bug preprocessor/36279] New: division by zero in #if aldot at gcc dot gnu dot org
@ 2008-05-20 14:32 ` schwab at suse dot de
  0 siblings, 0 replies; 2+ messages in thread
From: schwab at suse dot de @ 2008-05-20 14:32 UTC (permalink / raw)
  To: gcc-bugs



------- Comment #1 from schwab at suse dot de  2008-05-20 14:31 -------
Undefined identifiers are replaced by 0 in #if.


-- 

schwab at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36279


^ permalink raw reply	[flat|nested] 2+ messages in thread
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2008-05-20 14:00 [Bug preprocessor/36279] New: division by zero in #if aldot at gcc dot gnu dot org
2008-05-20 14:32 ` [Bug preprocessor/36279] " schwab at suse dot de

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