Re: FW: 2.5.34: IR __FUNCTION__ breakage

Re: FW: 2.5.34: IR __FUNCTION__ breakage

[Jean Tourrilhes]

On Fri, Sep 13, 2002 at 08:25:50AM +0200, Dag Brattli wrote:
> -----Original Message-----
> From: Thunder from the hill [mailto:thunder@lightweight.ods.org]
> Sent: 12. september 2002 22:17
> To: Bob_Tracy
> Cc: dag@brattli.net; linux-kernel@vger.kernel.org
> Subject: Re: 2.5.34: IR __FUNCTION__ breakage
> 
> 
> Hi,
> 
> On Thu, 12 Sep 2002, Bob_Tracy wrote:
> > define DERROR(dbg, args...) \
> > 	{if(DEBUG_##dbg){\
> > 		printk(KERN_INFO "irnet: %s(): ", __FUNCTION__);\
> > 		printk(KERN_INFO args);}}
> > 
> > which strikes me as not quite what the author intended, although it
> > should work.
> 
> Why not
> 
> #define DERROR(dbg, fmt, args...) \
> 	do { if (DEBUG_##dbg) \
> 		printk(KERN_INFO "irnet: %s(): " fmt, __FUNCTION, args); \
> 	} while(0)
> 
> ?
> 
> 			Thunder

	Try it, it won't work when there is zero args.

	Jean

Re: FW: 2.5.34: IR __FUNCTION__ breakage

[Jeff Garzik]

Jean Tourrilhes wrote:
> On Fri, Sep 13, 2002 at 08:25:50AM +0200, Dag Brattli wrote:
> 
>>-----Original Message-----
>>From: Thunder from the hill [mailto:thunder@lightweight.ods.org]
>>Sent: 12. september 2002 22:17
>>To: Bob_Tracy
>>Cc: dag@brattli.net; linux-kernel@vger.kernel.org
>>Subject: Re: 2.5.34: IR __FUNCTION__ breakage
>>
>>
>>Hi,
>>
>>On Thu, 12 Sep 2002, Bob_Tracy wrote:
>>
>>>define DERROR(dbg, args...) \
>>>	{if(DEBUG_##dbg){\
>>>		printk(KERN_INFO "irnet: %s(): ", __FUNCTION__);\
>>>		printk(KERN_INFO args);}}
>>>
>>>which strikes me as not quite what the author intended, although it
>>>should work.
>>
>>Why not
>>
>>#define DERROR(dbg, fmt, args...) \
>>	do { if (DEBUG_##dbg) \
>>		printk(KERN_INFO "irnet: %s(): " fmt, __FUNCTION, args); \
>>	} while(0)
>>
>>?
>>
>>			Thunder
> 
> 
> 	Try it, it won't work when there is zero args.


I fixed up a bunch of these __FUNCTION__ breakage, you can grab them 
from 2.5.37 (just released)

Also, specifically relating to varargs macros as described above, you 
can certainly have a varargs macro with zero args, just look at C99 
varargs macros...

	Jeff

Re: FW: 2.5.34: IR __FUNCTION__ breakage

[Jean Tourrilhes]

On Fri, Sep 20, 2002 at 01:17:01PM -0400, Jeff Garzik wrote:
> 
> I fixed up a bunch of these __FUNCTION__ breakage, you can grab them 
> from 2.5.37 (just released)

	I'll catch up with my e-mail and I'll look at that.

> Also, specifically relating to varargs macros as described above, you 
> can certainly have a varargs macro with zero args, just look at C99 
> varargs macros...

	I remember that it didn't work. Ok, I'll try again.

> 	Jeff

	Have fun...

	Jean

Re: FW: 2.5.34: IR __FUNCTION__ breakage

[Bjoern A. Zeeb]

On Fri, 20 Sep 2002, Jean Tourrilhes wrote:

Hi,

> > Also, specifically relating to varargs macros as described above, you
> > can certainly have a varargs macro with zero args, just look at C99
> > varargs macros...
>
> 	I remember that it didn't work. Ok, I'll try again.

if I remember corretly with C99 if you do s.th. like this (simple
sample):

#define LOG(level, format, ...)					\
                log(level, format, ##__VA_ARGS__);

you _need_ to give an argument:

	LOG(debug, "blah", 0);

w/o the ", 0" this is an error.

There have been gcc extentions that allow(ed) zero arguments.

*searching*

See: http://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html

-- 
Bjoern A. Zeeb				bzeeb at Zabbadoz dot NeT
56 69 73 69 74				http://www.zabbadoz.net/

Re: FW: 2.5.34: IR __FUNCTION__ breakage

[Neil Booth]

Bjoern A. Zeeb wrote:-

> > > Also, specifically relating to varargs macros as described above, you
> > > can certainly have a varargs macro with zero args, just look at C99
> > > varargs macros...
> >
> > 	I remember that it didn't work. Ok, I'll try again.
> 
> if I remember corretly with C99 if you do s.th. like this (simple
> sample):
> 
> #define LOG(level, format, ...)					\
>                 log(level, format, ##__VA_ARGS__);

No, this is only valid C99 if __VA_ARGS__ is the empty list.

I posted the correct way to write this macro about a week ago that
works with all versions of GCC (and follows their documented
behaviour; this stuff *is* all documented).

Neil.

Re: FW: 2.5.34: IR __FUNCTION__ breakage

[Jean Tourrilhes]

On Fri, Sep 20, 2002 at 10:41:38PM +0100, Neil Booth wrote:
> Bjoern A. Zeeb wrote:-
> 
> > > > Also, specifically relating to varargs macros as described above, you
> > > > can certainly have a varargs macro with zero args, just look at C99
> > > > varargs macros...
> > >
> > > 	I remember that it didn't work. Ok, I'll try again.
> > 
> > if I remember corretly with C99 if you do s.th. like this (simple
> > sample):
> > 
> > #define LOG(level, format, ...)					\
> >                 log(level, format, ##__VA_ARGS__);
> 
> No, this is only valid C99 if __VA_ARGS__ is the empty list.
> 
> I posted the correct way to write this macro about a week ago that
> works with all versions of GCC (and follows their documented
> behaviour; this stuff *is* all documented).
> 
> Neil.

	Err... Can you point me to your post ?

	Jean

Re: FW: 2.5.34: IR __FUNCTION__ breakage

[Thunder from the hill]

Hi,

On Fri, 20 Sep 2002, Jean Tourrilhes wrote:
> > Why not
> > 
> > #define DERROR(dbg, fmt, args...) \
> > 	do { if (DEBUG_##dbg) \
> > 		printk(KERN_INFO "irnet: %s(): " fmt, __FUNCTION, args); \
> > 	} while(0)
> > 
> > ?
> > 
> > 			Thunder
> 
> 	Try it, it won't work when there is zero args.

It got corrected shortly afterwards. The non-typo version is:

#define DERROR(dbg, fmt, args...) \
	do { if(DEBUG_##dbg) \
		printk(KERN_INFO "irnet: %s(): " fmt, __FUNCTION__, ##args); \
	} while(0)

Example:
#define DEBUG(fmt, args...) \
        printf("%s(): " fmt, __FUNCTION__, ## args)

int main(void)
{
        DEBUG("I am hungry.\n");

        exit(0);
}

# gcc -Wall -Os -o moehre -s moehre.c
# ./moehre
main(): I am hungry.
# 

			Thunder
-- 
assert(typeof((fool)->next) == typeof(fool));	/* wrong */