GNU bug report logs - #6170
24.0.50; Compiling on solaris2.10 with gcc doesn't define alloca

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Lawrence Mitchell <wence <at> gmx.li>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.0.50; Compiling on solaris2.10 with gcc doesn't define alloca
Date: Tue, 11 May 2010 11:57:17 +0100

On this system, <stdlib.h> is provided by Sun and therefore
doesn't define alloca, unlike on a typical GNU/linux system where
<stdlib.h> contains the following:

| #if defined __USE_GNU || defined __USE_BSD || defined __USE_MISC
| # include <alloca.h>
| #endif /* Use GNU, BSD, or misc.  */

When compiling emacs with gcc, alloca is therefore undefined.
The culprit is this snippet in configure.in:

| #ifndef __GNUC__
| # ifdef HAVE_ALLOCA_H
| #  include <alloca.h>
| # else /* AIX files deal with #pragma.  */
| #  ifndef alloca /* predefined by HP cc +Olibcalls */
| char *alloca ();
| #  endif
| # endif /* HAVE_ALLOCA_H */
| #endif /* __GNUC__ */

On this system, configure correctly defines both HAVE_ALLOCA_H
and HAVE_ALLOCA, but since the inclusion is guarded by __GNUC__
not being defined, we never include <alloca.h>.

I think the correct fix is to unconditionally define alloca if
__GNUC__ is detected, see patch below.  Note that this is closer
to how autoconf checks for the presence of the alloca function.

Possible changelog entry:

2010-05-11  Lawrence Mitchell  <wence <at> gmx.li>

	* configure.in: Unconditionally define alloca if __GNUC__ is
	detected.

diff --git a/configure.in b/configure.in
index 8a7d9be..98b6abb 100644
--- a/configure.in
+++ b/configure.in
@@ -3360,6 +3360,9 @@ extern char *getenv ();
 char *alloca ();
 #  endif
 # endif /* HAVE_ALLOCA_H */
+#else
+# undef alloca
+# define alloca __builtin_alloca
 #endif /* __GNUC__ */
 #ifndef HAVE_SIZE_T
 typedef unsigned size_t;

Message #8 received at 6170 <at> debbugs.gnu.org (full text, mbox):

From: Dan Nicolaescu <dann <at> gnu.org>
To: Lawrence Mitchell <wence <at> gmx.li>
Cc: 6170 <at> debbugs.gnu.org
Subject: Re: bug#6170: 24.0.50;
	Compiling on solaris2.10 with gcc doesn't define alloca
Date: Wed, 12 May 2010 14:29:40 -0400

Lawrence Mitchell <wence <at> gmx.li> writes:

> On this system, <stdlib.h> is provided by Sun and therefore
> doesn't define alloca, unlike on a typical GNU/linux system where
> <stdlib.h> contains the following:
>
> | #if defined __USE_GNU || defined __USE_BSD || defined __USE_MISC
> | # include <alloca.h>
> | #endif /* Use GNU, BSD, or misc.  */
>
> When compiling emacs with gcc, alloca is therefore undefined.
> The culprit is this snippet in configure.in:
>
> | #ifndef __GNUC__
> | # ifdef HAVE_ALLOCA_H
> | #  include <alloca.h>
> | # else /* AIX files deal with #pragma.  */
> | #  ifndef alloca /* predefined by HP cc +Olibcalls */
> | char *alloca ();
> | #  endif
> | # endif /* HAVE_ALLOCA_H */
> | #endif /* __GNUC__ */
>

"info autoconf" says that this is the proper way to do it:

          #ifdef HAVE_ALLOCA_H
          # include <alloca.h>
          #elif defined __GNUC__
          # define alloca __builtin_alloca
          #elif defined _AIX
          # define alloca __alloca
          #elif defined _MSC_VER
          # include <malloc.h>
          # define alloca _alloca
          #else
          # include <stddef.h>
          # ifdef  __cplusplus
          extern "C"
          # endif
          void *alloca (size_t);
          #endif

Not sure we need the last #else part, or the _MSC_VER part...

Message #11 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Lawrence Mitchell <wence <at> gmx.li>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#6170: 24.0.50;
	Compiling on solaris2.10 with gcc doesn't define alloca
Date: Mon, 31 May 2010 17:42:34 +0100

Dan Nicolaescu wrote:
> Lawrence Mitchell <wence <at> gmx.li> writes:

>> On this system, <stdlib.h> is provided by Sun and therefore
>> doesn't define alloca, unlike on a typical GNU/linux system where
>> <stdlib.h> contains the following:

>> | #if defined __USE_GNU || defined __USE_BSD || defined __USE_MISC
>> | # include <alloca.h>
>> | #endif /* Use GNU, BSD, or misc.  */

>> When compiling emacs with gcc, alloca is therefore undefined.
>> The culprit is this snippet in configure.in:

>> | #ifndef __GNUC__
>> | # ifdef HAVE_ALLOCA_H
>> | #  include <alloca.h>
>> | # else /* AIX files deal with #pragma.  */
>> | #  ifndef alloca /* predefined by HP cc +Olibcalls */
>> | char *alloca ();
>> | #  endif
>> | # endif /* HAVE_ALLOCA_H */
>> | #endif /* __GNUC__ */


> "info autoconf" says that this is the proper way to do it:

>           #ifdef HAVE_ALLOCA_H
>           # include <alloca.h>
>           #elif defined __GNUC__
>           # define alloca __builtin_alloca
>           #elif defined _AIX
>           # define alloca __alloca
>           #elif defined _MSC_VER
>           # include <malloc.h>
>           # define alloca _alloca
>           #else
>           # include <stddef.h>
>           # ifdef  __cplusplus
>           extern "C"
>           # endif
>           void *alloca (size_t);
>           #endif

> Not sure we need the last #else part, or the _MSC_VER part...

Is there any movement on getting this fix, or something like it,
installed?  It doesn't seem like a controversial change.

Cheers,
Lawrence

-- 
Lawrence Mitchell <wence <at> gmx.li>

Message #16 received at 6170-done <at> debbugs.gnu.org (full text, mbox):

From: Dan Nicolaescu <dann <at> gnu.org>
To: Lawrence Mitchell <wence <at> gmx.li>
Cc: 6170-done <at> debbugs.gnu.org
Subject: Re: bug#6170: 24.0.50;
	Compiling on solaris2.10 with gcc doesn't define alloca
Date: Wed, 02 Jun 2010 05:24:36 -0400

Lawrence Mitchell <wence <at> gmx.li> writes:

> Dan Nicolaescu wrote:
>> Lawrence Mitchell <wence <at> gmx.li> writes:
>
>>> On this system, <stdlib.h> is provided by Sun and therefore
>>> doesn't define alloca, unlike on a typical GNU/linux system where
>>> <stdlib.h> contains the following:
>
>>> | #if defined __USE_GNU || defined __USE_BSD || defined __USE_MISC
>>> | # include <alloca.h>
>>> | #endif /* Use GNU, BSD, or misc.  */
>
>>> When compiling emacs with gcc, alloca is therefore undefined.
>>> The culprit is this snippet in configure.in:
>
>>> | #ifndef __GNUC__
>>> | # ifdef HAVE_ALLOCA_H
>>> | #  include <alloca.h>
>>> | # else /* AIX files deal with #pragma.  */
>>> | #  ifndef alloca /* predefined by HP cc +Olibcalls */
>>> | char *alloca ();
>>> | #  endif
>>> | # endif /* HAVE_ALLOCA_H */
>>> | #endif /* __GNUC__ */
>
>
>> "info autoconf" says that this is the proper way to do it:
>
>>           #ifdef HAVE_ALLOCA_H
>>           # include <alloca.h>
>>           #elif defined __GNUC__
>>           # define alloca __builtin_alloca
>>           #elif defined _AIX
>>           # define alloca __alloca
>>           #elif defined _MSC_VER
>>           # include <malloc.h>
>>           # define alloca _alloca
>>           #else
>>           # include <stddef.h>
>>           # ifdef  __cplusplus
>>           extern "C"
>>           # endif
>>           void *alloca (size_t);
>>           #endif
>
>> Not sure we need the last #else part, or the _MSC_VER part...
>
> Is there any movement on getting this fix, or something like it,
> installed?  It doesn't seem like a controversial change.

Should be fixed now.

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