[PATCH] docs: update alloca recommendations

[Eric Blake]

* doc/autoconf.texi (Particular Functions): Don't redeclare alloca
on FreeBSD.
* THANKS: Update.
Reported by Giorgos Keramidas.

Signed-off-by: Eric Blake <address@hidden>
---

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

> Then again, since AC_FUNC_ALLOCA does indeed set HAVE_ALLOCA via
> AC_DEFINE, your patch proposal probably makes sense.

Actually, your patch is not quite right - to get alloca on FreeBSD,
you still have to include the right system headers.  The
AC_FUNC_ALLOCA macro is already including <stdlib.h> at configure
time, by virtue of AC_INCLUDES_DEFAULT, but your C code must do the
same.  I don't see a problem with the configure test having a
redundant redeclaration, without evidence of it causing a false
negative test result, but agree that we might as well avoid the
redundant declaration in user code.  Here's what I will be pushing.

 ChangeLog         |    5 +++++
 doc/autoconf.texi |   14 ++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c874eab..8fa6874 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2010-09-08  Eric Blake  <address@hidden>

+       docs: update alloca recommendations
+       * doc/autoconf.texi (Particular Functions): Don't redeclare alloca
+       on FreeBSD.
+       Reported by Giorgos Keramidas.
+
        docs: link to GNU Coding Standards in intro
        * doc/autoconf.texi (Introduction): Actually link to the
        standards.  Make other references consistent.
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 99054c5..780e93a 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -4816,6 +4816,14 @@ Particular Functions

 @example
 @group
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
 #ifdef HAVE_ALLOCA_H
 # include <alloca.h>
 #elif defined __GNUC__
@@ -4827,10 +4835,12 @@ Particular Functions
 # define alloca _alloca
 #else
 # include <stddef.h>
-# ifdef  __cplusplus
+# ifndef HAVE_ALLOCA
+#  ifdef  __cplusplus
 extern "C"
-# endif
+#  endif
 void *alloca (size_t);
+# endif
 #endif
 @end group
 @end example
-- 
1.7.2.2