cpp problem with asm

[Neil Booth]

Jonathan Larmour wrote:-

> Hi guys,

Hi Jonathan!

> [...].  Still, it is useful for preprocessing assembler, and even
> the driver recognises that by accepting .S files and passing
> -lang-asm to cpp0, which then knows to not complain about unknown
> directives (in cpplib.c:354). However there is still a problem:

Yup, you should be able to preprocess most assembler.

> The issue is revealed in the following snippet
> [...]
> If this is saved as foo.S, and compiled with (e.g.) "sh-elf-gcc -Wundef -E
> foo.S" with current gcc, we get:
> 
> foo.S:6:11: warning: "fum" is not defined
> foo.S:5:11: warning: "foe" is not defined
> foo.S:5:11: missing binary operator

Hmmm...

How does this look?

bash-2.04$ cat /tmp/test.c
#if 0           // must be false
        # foo
        # fee
        # fie
        # foe
        # fum

#elif 0         // dont care
        # bundy
#endif
bash-2.04$ ./cpp0 -Wundef /tmp/test.c
bash-2.04$ 

:-)

> Curiously, as described, this only matters when a #elif is present
> and the #if is false. The only tokens reported are the latter two.

False conditional skipping bug, maybe?

> I think the code at cpplib.c:354 isn't correct. It does not result in the #
> and token just being output verbatim - instead it is put in the lookahead
> list for possible processing in subsequent directives. I think.

Close, but no cigar.  You'd be a bit pissed if your "# fum" or
whatever disappeared from output wouldn't you?  (Assuming we're not in
a false conditional, of course).

In fact, it's just a typo.  Ages ago I updated this code to replace
pfile->skipping with buffer->was_skipping (because we now set
pfile->skipping to 0 in directives - skipping the directive name
wouldn't do, would it?), but missed 2 places.  This is the second one
(unbelievable, yes, I know)!

IMHO this patch isn't obvious, though I think it's OK.  I'll commit it
after I bootstrap and make check, so that means tomorrow morning UK
time.

Neil.

	* cpplib.c (_cpp_handle_directive): Check buffer->was_skipping
	not pfile->skipping (== 0).

Index: cpplib.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cpplib.c,v
retrieving revision 1.236
diff -u -p -r1.236 cpplib.c
--- cpplib.c	2001/01/13 18:39:26	1.236
+++ cpplib.c	2001/01/16 22:29:23
@@ -349,7 +349,7 @@ _cpp_handle_directive (pfile, indented)
 	    }
 	}
     }
-  else if (dname.type != CPP_EOF && ! pfile->skipping)
+  else if (dname.type != CPP_EOF && ! buffer->was_skipping)
     {
       /* An unknown directive.  Don't complain about it in assembly
 	 source: we don't know where the comments are, and # may