autoupdate

[gnulib.git] / m4 / alloca.m4

diff --git a/m4/alloca.m4 b/m4/alloca.m4
index fa026fc..f3ee343 100644 (file)
--- a/m4/alloca.m4
+++ b/m4/alloca.m4
@@ -1,21 +1,47 @@
-# alloca.m4 serial 1
-dnl Copyright (C) 2002 Free Software Foundation, Inc.
-dnl This file is free software, distributed under the terms of the GNU
-dnl General Public License.  As a special exception to the GNU General
-dnl Public License, this file may be distributed as part of a program
-dnl that contains a configuration script generated by Autoconf, under
-dnl the same distribution terms as the rest of that program.
+# alloca.m4 serial 9
+dnl Copyright (C) 2002-2004, 2006-2007, 2009-2010 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_ALLOCA],
 [
+  dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57.
+  AC_REQUIRE([AC_PROG_CPP])
+  AC_REQUIRE([AC_PROG_EGREP])
+
   AC_REQUIRE([AC_FUNC_ALLOCA])
   if test $ac_cv_func_alloca_works = no; then
     gl_PREREQ_ALLOCA
   fi
+
+  # Define an additional variable used in the Makefile substitution.
+  if test $ac_cv_working_alloca_h = yes; then
+    AC_CACHE_CHECK([for alloca as a compiler built-in], [gl_cv_rpl_alloca], [
+      AC_EGREP_CPP([Need own alloca], [
+#if defined __GNUC__ || defined _AIX || defined _MSC_VER
+        Need own alloca
+#endif
+        ], [gl_cv_rpl_alloca=yes], [gl_cv_rpl_alloca=no])
+    ])
+    if test $gl_cv_rpl_alloca = yes; then
+      dnl OK, alloca can be implemented through a compiler built-in.
+      AC_DEFINE([HAVE_ALLOCA], [1],
+        [Define to 1 if you have 'alloca' after including <alloca.h>,
+         a header that may be supplied by this distribution.])
+      ALLOCA_H=alloca.h
+    else
+      dnl alloca exists as a library function, i.e. it is slow and probably
+      dnl a memory leak. Don't define HAVE_ALLOCA in this case.
+      ALLOCA_H=
+    fi
+  else
+    ALLOCA_H=alloca.h
+  fi
+  AC_SUBST([ALLOCA_H])
 ])
 
 # Prerequisites of lib/alloca.c.
 # STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
-AC_DEFUN([gl_PREREQ_ALLOCA], [
-  AC_CHECK_HEADERS_ONCE(stdlib.h string.h)
-])
+AC_DEFUN([gl_PREREQ_ALLOCA], [:])