Re: [uClinux-dev] [PATCH] debug: add a gcc-2 compat tweak

2010-01-23 Thread Mike Frysinger 
On Friday 22 January 2010 16:10:08 Jamie Lokier wrote:
 Mike Frysinger wrote:
  On Thursday 21 January 2010 20:21:31 Jamie Lokier wrote:
   Mike Frysinger wrote:
GCC-2.x has a bug with empty arg expansion in macros.
   
-   fprintf(stderr, %s:%i:  fmt, __func__, __LINE__, ## args); \
+   fprintf(stderr, %s:%i:  fmt, __func__, __LINE__ , ## args); \
  
   Assuming it's what it looks like, it's not a GCC-2.x bug, it's the old
   GCC varargs behavior, which was documented and behaved like that since
   very old versions of GCC.
 
  i'm not really familiar with gcc-2 ... i didnt get into messing with
  toolchain stuff until like gcc-3.4 era.
 
 Wow.  I haven't messed much with toolchain stuff since the 2.7.2 era ;-)
 
  it looks like a bug to me as gcc-3+ works fine.
  if you wanted to elaborate ...
 
 GCC 2.95 documentation:
 
 This is a special feature of the GNU C preprocessor: @samp{##}
 before a rest argument that is empty discards the preceding
 sequence of non-whitespace characters from the macro definition.
 (If another macro argument precedes, none of it is discarded.)
 
 It might be better to discard the last preprocessor token instead
 of the last preceding sequence of non-whitespace characters; in
 fact, we may someday change this feature to do so.  We advise you
 to write the macro definition so that the preceding sequence of
 non-whitespace characters is just a single token, so that the
 meaning will not change if we change the definition of this
 feature.
 
 It's behaved like that since the macro varargs feature was introduced
 in GCC 2.2 (released June 1992), and was consciously changed to
 in GCC 3.0 (released June 2001).
 
  this one fails:
  #define debug(fmt, args...) x(fmt, moo, ## args)
  main(){debug(a);}
 
  these work:
  #define debug(fmt, args...) x(fmt, moo , ## args)
  main(){debug(a);}
 
  #define debug(fmt, args...) x(fmt, ## args)
  main(){debug(a);}
 
 The last one compiles for a surprising reason: fmt is preexpanded to
 ' a ' (complete with spaces), so the word-removal rule goes back as
 far as the comma and stops at the last space of the preexpanded fmt.

thanks for the info

 Anyway, your patch is fine! :-)
 
 Only the commit message is misleading; this would be appropriate imho:
 
GCC-2.x's variadic macro behaviour requires an isolated comma
 
The behaviour of GCC before 3.0 was to remove the whole
non-whitespace word prior to ## (after argument expansion),
not just the comma.

i'd agree, but it's already been committed
-mike


signature.asc
Description: This is a digitally signed message part.
___
uClinux-dev mailing list
uClinux-dev@uclinux.org
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by uclinux-dev@uclinux.org
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev

Re: [uClinux-dev] [PATCH] debug: add a gcc-2 compat tweak

2010-01-22 Thread Jamie Lokier 
Mike Frysinger wrote:
 On Thursday 21 January 2010 20:21:31 Jamie Lokier wrote:
  Mike Frysinger wrote:
   GCC-2.x has a bug with empty arg expansion in macros.
  
   - fprintf(stderr, %s:%i:  fmt, __func__, __LINE__, ## args); \
   + fprintf(stderr, %s:%i:  fmt, __func__, __LINE__ , ## args); \
  
  Assuming it's what it looks like, it's not a GCC-2.x bug, it's the old
  GCC varargs behavior, which was documented and behaved like that since
  very old versions of GCC.
 
 i'm not really familiar with gcc-2 ... i didnt get into messing with 
 toolchain 
 stuff until like gcc-3.4 era.

Wow.  I haven't messed much with toolchain stuff since the 2.7.2 era ;-)

 it looks like a bug to me as gcc-3+ works fine.
 if you wanted to elaborate ...

GCC 2.95 documentation:

This is a special feature of the GNU C preprocessor: @samp{##}
before a rest argument that is empty discards the preceding
sequence of non-whitespace characters from the macro definition.
(If another macro argument precedes, none of it is discarded.)

It might be better to discard the last preprocessor token instead
of the last preceding sequence of non-whitespace characters; in
fact, we may someday change this feature to do so.  We advise you
to write the macro definition so that the preceding sequence of
non-whitespace characters is just a single token, so that the
meaning will not change if we change the definition of this
feature.

It's behaved like that since the macro varargs feature was introduced
in GCC 2.2 (released June 1992), and was consciously changed to 
in GCC 3.0 (released June 2001).

 this one fails:
 #define debug(fmt, args...) x(fmt, moo, ## args)
 main(){debug(a);}
 
 these work:
 #define debug(fmt, args...) x(fmt, moo , ## args)
 main(){debug(a);}
 
 #define debug(fmt, args...) x(fmt, ## args)
 main(){debug(a);}

The last one compiles for a surprising reason: fmt is preexpanded to
' a ' (complete with spaces), so the word-removal rule goes back as
far as the comma and stops at the last space of the preexpanded fmt.


Anyway, your patch is fine! :-)

Only the commit message is misleading; this would be appropriate imho:

   GCC-2.x's variadic macro behaviour requires an isolated comma

   The behaviour of GCC before 3.0 was to remove the whole
   non-whitespace word prior to ## (after argument expansion),
   not just the comma.
___
uClinux-dev mailing list
uClinux-dev@uclinux.org
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by uclinux-dev@uclinux.org
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev

[uClinux-dev] [PATCH] debug: add a gcc-2 compat tweak

2010-01-21 Thread Mike Frysinger 
GCC-2.x has a bug with empty arg expansion in macros.

Signed-off-by: Mike Frysinger vap...@gentoo.org
---
 stubs.h |2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/stubs.h b/stubs.h
index 7e5308d..615cab5 100644
--- a/stubs.h
+++ b/stubs.h
@@ -41,7 +41,7 @@
 #define _debug(lvl, fmt, args...) \
do { \
if (lvl = DEBUG) { \
-   fprintf(stderr, %s:%i:  fmt, __func__, __LINE__, ## 
args); \
+   fprintf(stderr, %s:%i:  fmt, __func__, __LINE__ , ## 
args); \
fflush(stderr); \
} \
} while (0)
-- 
1.6.6

___
uClinux-dev mailing list
uClinux-dev@uclinux.org
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by uclinux-dev@uclinux.org
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev

Re: [uClinux-dev] [PATCH] debug: add a gcc-2 compat tweak

2010-01-21 Thread Jamie Lokier 
Mike Frysinger wrote:
 GCC-2.x has a bug with empty arg expansion in macros.

   if (lvl = DEBUG) { \
 - fprintf(stderr, %s:%i:  fmt, __func__, __LINE__, ## 
 args); \
 + fprintf(stderr, %s:%i:  fmt, __func__, __LINE__ , ## 
 args); \
   fflush(stderr); \

Assuming it's what it looks like, it's not a GCC-2.x bug, it's the old
GCC varargs behavior, which was documented and behaved like that since
very old versions of GCC.

You may wish to change the description if you submit it again.

If GCC 2.x support is still desired, this ought to be an easy thing to
grep for (comma followed by ##) and add to checkpatch.pl.

-- Jamie
___
uClinux-dev mailing list
uClinux-dev@uclinux.org
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by uclinux-dev@uclinux.org
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev

Re: [uClinux-dev] [PATCH] debug: add a gcc-2 compat tweak

2010-01-21 Thread David McCullough 

Jivin Mike Frysinger lays it down ...
 GCC-2.x has a bug with empty arg expansion in macros.

Applied with updated comment.

At first I wondered which uClinux stubs.h you were patching ;-)

Cheers,
Davidm

 Signed-off-by: Mike Frysinger vap...@gentoo.org
 ---
  stubs.h |2 +-
  1 files changed, 1 insertions(+), 1 deletions(-)
 
 diff --git a/stubs.h b/stubs.h
 index 7e5308d..615cab5 100644
 --- a/stubs.h
 +++ b/stubs.h
 @@ -41,7 +41,7 @@
  #define _debug(lvl, fmt, args...) \
   do { \
   if (lvl = DEBUG) { \
 - fprintf(stderr, %s:%i:  fmt, __func__, __LINE__, ## 
 args); \
 + fprintf(stderr, %s:%i:  fmt, __func__, __LINE__ , ## 
 args); \
   fflush(stderr); \
   } \
   } while (0)
 -- 
 1.6.6
 
 ___
 uClinux-dev mailing list
 uClinux-dev@uclinux.org
 http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
 This message was resent by uclinux-dev@uclinux.org
 To unsubscribe see:
 http://mailman.uclinux.org/mailman/options/uclinux-dev
 
 

-- 
David McCullough,  david_mccullo...@securecomputing.com,  Ph:+61 734352815
McAfee - SnapGear  http://www.snapgear.comhttp://www.uCdot.org
___
uClinux-dev mailing list
uClinux-dev@uclinux.org
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by uclinux-dev@uclinux.org
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev

Re: [uClinux-dev] [PATCH] debug: add a gcc-2 compat tweak

2010-01-21 Thread Mike Frysinger 
On Thursday 21 January 2010 20:21:31 Jamie Lokier wrote:
 Mike Frysinger wrote:
  GCC-2.x has a bug with empty arg expansion in macros.
 
  -   fprintf(stderr, %s:%i:  fmt, __func__, __LINE__, ## args); \
  +   fprintf(stderr, %s:%i:  fmt, __func__, __LINE__ , ## args); \
 
 Assuming it's what it looks like, it's not a GCC-2.x bug, it's the old
 GCC varargs behavior, which was documented and behaved like that since
 very old versions of GCC.

i'm not really familiar with gcc-2 ... i didnt get into messing with toolchain 
stuff until like gcc-3.4 era.  it looks like a bug to me as gcc-3+ works fine.  
if you wanted to elaborate ...

this one fails:
#define debug(fmt, args...) x(fmt, moo, ## args)
main(){debug(a);}

these work:
#define debug(fmt, args...) x(fmt, moo , ## args)
main(){debug(a);}

#define debug(fmt, args...) x(fmt, ## args)
main(){debug(a);}
-mike


signature.asc
Description: This is a digitally signed message part.
___
uClinux-dev mailing list
uClinux-dev@uclinux.org
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by uclinux-dev@uclinux.org
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev