3 files changed, 32 insertions, 18 deletions

diff --git a/ChangeLog b/ChangeLog
index 75813c9e7aa..a6b47ed9415 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-11-13  Dan Nicolaescu  <dann@ics.uci.edu>
+
+        Fix alloca definition when using gcc on non-gnu systems.
+        * configure.in: Use the code sequence indicated by "info autoconf"
+        for alloca (bug#6170).
+
 2010-11-08  Stefan Monnier  <monnier@iro.umontreal.ca>
 
         * .dir-locals.el (log-edit-mode): Set log-edit-rewrite-fixes.
diff --git a/configure.in b/configure.in
index ca68db1b83d..b9e183cad3e 100644
--- a/configure.in
+++ b/configure.in
@@ -2927,15 +2927,19 @@ extern char *getenv ();
 #ifdef HAVE_STDLIB_H
 #include <stdlib.h>
 #endif
-#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__ */
+#ifdef HAVE_ALLOCA_H
+# include <alloca.h>
+#elif defined __GNUC__
+# define alloca __builtin_alloca
+#elif defined _AIX
+# define alloca __alloca
+#else
+# include <stddef.h>
+# ifdef  __cplusplus
+extern "C"
+# endif
+void *alloca (size_t);
+#endif
 #ifndef HAVE_SIZE_T
 typedef unsigned size_t;
 #endif
diff --git a/src/config.in b/src/config.in
index 4667c0feb28..90098719511 100644
--- a/src/config.in
+++ b/src/config.in
@@ -1178,15 +1178,19 @@ extern char *getenv ();
 #ifdef HAVE_STDLIB_H
 #include <stdlib.h>
 #endif
-#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__ */
+#ifdef HAVE_ALLOCA_H
+# include <alloca.h>
+#elif defined __GNUC__
+# define alloca __builtin_alloca
+#elif defined _AIX
+# define alloca __alloca
+#else
+# include <stddef.h>
+# ifdef  __cplusplus
+extern "C"
+# endif
+void *alloca (size_t);
+#endif
 #ifndef HAVE_SIZE_T
 typedef unsigned size_t;
 #endif