Problems with gcc + exceptions + -pedantic + libiberty.h

Problems with gcc + exceptions + -pedantic + libiberty.h

[John Levon]

This is on my system : binutils-2.10.0.18-1

libiberty.h has code as follows :

     39 /* HAVE_DECL_* is a three-state macro: undefined, 0 or 1.  If it is
     40    undefined, we haven't run the autoconf check so provide the
     41    declaration without arguments.  If it is 0, we checked and failed
     42    to find the declaration so provide a fully prototyped one.  If it
     43    is 1, we found it so don't provide any declaration at all.  */
     44 #if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__) || (defined (HAVE_DECL_BASENAME) && !HAVE_DECL_BASENAME)
     45 extern char *basename PARAMS ((const char *));
     46 #else
     47 # if !defined (HAVE_DECL_BASENAME)
     48 extern char *basename ();
     49 # endif
     50 #endif

unfortunately, when compiled with g++ 3.x with exceptions enabled, and with -pedantic,
you get a (correct I think) error message stating that this prototype clashes with my
system's string.h :

    328 /* Return the file name within directory of FILENAME.  We don't
    329    declare the function if the `basename' macro is available (defined
    330    in <libgen.h>) which makes the XPG version of this function
    331    available.  */
    332 extern char *basename (__const char *__filename) __THROW;
    333 # endif

(from glibc-devel-2.2-12, RH 7.0). These clash as __THROW becomes throw(), unlike
libiberty's prototype which obviously has no exception specification.

Currently I have just worked around this problem by disabling -pedantic; however I would
prefer a real fix.

Does someone have any comments on whose bug this is, and, more importantly, what needs to
be done to fix the problem ?

thanks
john

-- 
"I went to set up a Yahoo ID for my dog. (Don't ask, but the DOG'S email was cluttering my inbox)." 
	- Ruthless Advisorette

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[DJ Delorie]

Since Linux is specifically mentioned in libiberty.h, and linux is the
one having the problem, I suppose it would be acceptable for the
linux-specific case to do something different in libiberty.h.

However, a better solution is to add the gcc-specific prototype
detection logic to some common area, and teach projects to use it.
Then, libiberty.h can default to "no prototype" unless the detection
tells it what to do.

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[Alan Modra]

On Mon, Jan 07, 2002 at 07:07:04PM -0500, DJ Delorie wrote:
> 
> Since Linux is specifically mentioned in libiberty.h, and linux is the
> one having the problem, I suppose it would be acceptable for the
> linux-specific case to do something different in libiberty.h.
> 
> However, a better solution is to add the gcc-specific prototype
> detection logic to some common area, and teach projects to use it.
> Then, libiberty.h can default to "no prototype" unless the detection
> tells it what to do.

Why is it that __linux__ etc. means we disregard HAVE_DECL_BASENAME ?
How about the following change?

#if HAVE_DECL_BASENAME
/* Cool.  */
#else
#if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__)
extern char *basename PARAMS ((const char *));
#else
extern char *basename ();
# endif
#endif

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[DJ Delorie]

> Why is it that __linux__ etc. means we disregard HAVE_DECL_BASENAME ?

The original problem is subdirectories that don't even test for the
decl.  In those cases, HAVE_DECL_BASENAME is not set at all.  Hence,
given an OS, we must try to guess what the right thing to do is.  I
didn't add that code myself; I would have defaulted to *no* decl, and
force projects to adopt some sort of detection.

This code also breaks when included by a C++ source :-(

However, now that you've pointed it out, the existing logic is flawed
in that a defined HAVE_DECL_* doesn't override the os-based guess.
Patches welcome ;)

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[Andrew Cagney]

>  332 extern char *basename (__const char *__filename) __THROW;


BTW, is it actually used.  GDB certainly doesn't.  I think I removed all 
uses from GCC.

enjoy,
Andrew

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[Alan Modra]

On Mon, Jan 07, 2002 at 07:28:25PM -0500, DJ Delorie wrote:
> 
> However, now that you've pointed it out, the existing logic is flawed
> in that a defined HAVE_DECL_* doesn't override the os-based guess.
> Patches welcome ;)

Here ya go.

	* libiberty.h (basename): Don't declare if HAVE_DECL_BASENAME.

Index: include/libiberty.h
===================================================================
RCS file: /cvs/src/src/include/libiberty.h,v
retrieving revision 1.15
diff -u -p -r1.15 libiberty.h
--- libiberty.h	2001/10/23 15:31:55	1.15
+++ libiberty.h	2002/01/08 04:12:30
@@ -73,12 +73,12 @@ extern char **dupargv PARAMS ((char **))
    declaration without arguments.  If it is 0, we checked and failed
    to find the declaration so provide a fully prototyped one.  If it
    is 1, we found it so don't provide any declaration at all.  */
-#if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__) || (defined (HAVE_DECL_BASENAME) && !HAVE_DECL_BASENAME)
+#if !HAVE_DECL_BASENAME
+#if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__) || (defined (HAVE_DECL_BASENAME)
 extern char *basename PARAMS ((const char *));
 #else
-# if !defined (HAVE_DECL_BASENAME)
 extern char *basename ();
-# endif
+#endif
 #endif
 
 /* A well-defined basename () that is always compiled in.  */

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[DJ Delorie]

Ok, minus the obvious typo.  A similar patch for getopt.h is
preapproved.  I think this leaves two problems remaining:

1. subdirs that don't yet test for a decl - should they get the ()
   decl, or no decl?

2. C++ source shouldn't ever see the () decl, me thinks.  It's inside
   an extern "C" but I have this nagging feeling I've seen C++ sources
   complain if they don't also see the real prototype.

And all those platform-specific things really bother me :-(

> Here ya go.
> 
> 	* libiberty.h (basename): Don't declare if HAVE_DECL_BASENAME.
> 
> Index: include/libiberty.h
> ===================================================================
> RCS file: /cvs/src/src/include/libiberty.h,v
> retrieving revision 1.15
> diff -u -p -r1.15 libiberty.h
> --- libiberty.h	2001/10/23 15:31:55	1.15
> +++ libiberty.h	2002/01/08 04:12:30
> @@ -73,12 +73,12 @@ extern char **dupargv PARAMS ((char **))
>     declaration without arguments.  If it is 0, we checked and failed
>     to find the declaration so provide a fully prototyped one.  If it
>     is 1, we found it so don't provide any declaration at all.  */
> -#if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__) || (defined (HAVE_DECL_BASENAME) && !HAVE_DECL_BASENAME)
> +#if !HAVE_DECL_BASENAME
> +#if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__) || (defined (HAVE_DECL_BASENAME)
>  extern char *basename PARAMS ((const char *));
>  #else
> -# if !defined (HAVE_DECL_BASENAME)
>  extern char *basename ();
> -# endif
> +#endif
>  #endif
>  
>  /* A well-defined basename () that is always compiled in.  */
> 
> -- 
> Alan Modra
> IBM OzLabs - Linux Technology Centre
> 

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[Alan Modra]

On Mon, Jan 07, 2002 at 07:07:04PM -0500, DJ Delorie wrote:
> 
> Since Linux is specifically mentioned in libiberty.h, and linux is the
> one having the problem, I suppose it would be acceptable for the
> linux-specific case to do something different in libiberty.h.
> 
> However, a better solution is to add the gcc-specific prototype
> detection logic to some common area, and teach projects to use it.
> Then, libiberty.h can default to "no prototype" unless the detection
> tells it what to do.

Why is it that __linux__ etc. means we disregard HAVE_DECL_BASENAME ?
How about the following change?

#if HAVE_DECL_BASENAME
/* Cool.  */
#else
#if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__)
extern char *basename PARAMS ((const char *));
#else
extern char *basename ();
# endif
#endif

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[John Levon]

On Tue, Jan 08, 2002 at 02:47:38PM +1030, Alan Modra wrote:

> On Mon, Jan 07, 2002 at 07:28:25PM -0500, DJ Delorie wrote:
> > 
> > However, now that you've pointed it out, the existing logic is flawed
> > in that a defined HAVE_DECL_* doesn't override the os-based guess.
> > Patches welcome ;)
> 
> Here ya go.

the patch is incomplete. Perhaps I should have mentioned it, but I also
have problems with asprintf() and vasprintf() from stdio.h when __USE_GNU is
enabled.

regards
john

-- 
"I went to set up a Yahoo ID for my dog. (Don't ask, but the DOG'S email was cluttering my inbox)." 
	- Ruthless Advisorette

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[John Levon]

On Mon, Jan 07, 2002 at 11:28:47PM -0500, DJ Delorie wrote:

> 2. C++ source shouldn't ever see the () decl, me thinks.  It's inside
>    an extern "C" but I have this nagging feeling I've seen C++ sources
>    complain if they don't also see the real prototype.

How about :

1) teaching GNU libc string.h to set HAVE_DECL_BASENAME

and

2) including string.h (+ stdio.h) in libiberty.h

That way the headers will "just work" in C++ without my application having to
worry about setting HAVE_DECL_BASENAME myself.

I'm not exactly fond of platform-specific hacks myself, but it would perhaps
reduce the complexity of the necessary autoconfigurey in my project to see if
c++ -pedantic is going to work in this case or not

regards
john

-- 
"I went to set up a Yahoo ID for my dog. (Don't ask, but the DOG'S email was cluttering my inbox)." 
	- Ruthless Advisorette

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[DJ Delorie]

> 1) teaching GNU libc string.h to set HAVE_DECL_BASENAME

We have no control over libc.

> 2) including string.h (+ stdio.h) in libiberty.h

What about older platforms that don't have string.h?

> That way the headers will "just work" in C++ without my application having to
> worry about setting HAVE_DECL_BASENAME myself.

Perhaps libiberty could provide a config.h that libiberty.h uses?

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[DJ Delorie]

> the patch is incomplete. Perhaps I should have mentioned it, but I also
> have problems with asprintf() and vasprintf() from stdio.h when __USE_GNU is
> enabled.

That doesn't make the patch incomplete; he does solve the problem he
posted.  If there are additional cases that need similar solutions,
they're similar but independent problems.  They can be patched
independently.

Re: Problems with gcc + exceptions + -pedantic + libiberty.h

[Alan Modra]

On Mon, Jan 07, 2002 at 11:28:47PM -0500, DJ Delorie wrote:
> 
> Ok, minus the obvious typo.  A similar patch for getopt.h is
> preapproved.

Somehow, I never got around to committing the change, and there are
enough other changes in my local trees that these got lost.  Here's
what I finally committed to gcc mainline.  binutils can wait for
your automatic merge.

include/ChangeLog
	* libiberty.h (basename): Don't declare if HAVE_DECL_BASENAME.
	* getopt.h (getopt): Don't declare if HAVE_DECL_GETOPT.

Index: include/getopt.h
===================================================================
RCS file: /cvs/gcc/gcc/include/getopt.h,v
retrieving revision 1.6
diff -u -p -r1.6 getopt.h
--- include/getopt.h	14 Mar 2001 19:44:38 -0000	1.6
+++ include/getopt.h	24 Jun 2002 04:51:24 -0000
@@ -105,16 +105,17 @@ struct option
    declaration without arguments.  If it is 0, we checked and failed
    to find the declaration so provide a fully prototyped one.  If it
    is 1, we found it so don't provide any declaration at all.  */
-#if defined (__GNU_LIBRARY__) || (defined (HAVE_DECL_GETOPT) && !HAVE_DECL_GETOPT)
+#if !HAVE_DECL_GETOPT
+#if defined (__GNU_LIBRARY__) || defined (HAVE_DECL_GETOPT)
 /* Many other libraries have conflicting prototypes for getopt, with
    differences in the consts, in stdlib.h.  To avoid compilation
    errors, only prototype getopt for the GNU C library.  */
 extern int getopt (int argc, char *const *argv, const char *shortopts);
-#else /* not __GNU_LIBRARY__ */
-# if !defined (HAVE_DECL_GETOPT)
+#else
 extern int getopt ();
-# endif
-#endif /* __GNU_LIBRARY__ */
+#endif
+#endif /* !HAVE_DECL_GETOPT */
+
 extern int getopt_long (int argc, char *const *argv, const char *shortopts,
 		        const struct option *longopts, int *longind);
 extern int getopt_long_only (int argc, char *const *argv,
Index: include/libiberty.h
===================================================================
RCS file: /cvs/gcc/gcc/include/libiberty.h,v
retrieving revision 1.27
diff -u -p -r1.27 libiberty.h
--- include/libiberty.h	28 Jan 2002 21:08:34 -0000	1.27
+++ include/libiberty.h	24 Jun 2002 04:51:25 -0000
@@ -73,12 +73,12 @@ extern char **dupargv PARAMS ((char **))
    declaration without arguments.  If it is 0, we checked and failed
    to find the declaration so provide a fully prototyped one.  If it
    is 1, we found it so don't provide any declaration at all.  */
-#if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__) || (defined (HAVE_DECL_BASENAME) && !HAVE_DECL_BASENAME)
+#if !HAVE_DECL_BASENAME
+#if defined (__GNU_LIBRARY__ ) || defined (__linux__) || defined (__FreeBSD__) || defined (__OpenBSD__) || defined (__CYGWIN__) || defined (__CYGWIN32__) || defined (HAVE_DECL_BASENAME)
 extern char *basename PARAMS ((const char *));
 #else
-# if !defined (HAVE_DECL_BASENAME)
 extern char *basename ();
-# endif
+#endif
 #endif
 
 /* A well-defined basename () that is always compiled in.  */

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre