Import upstream version 1.27

[debian/tar] / m4 / alloca.m4

diff --git a/m4/alloca.m4 b/m4/alloca.m4
index e2e8a05a6eaa7a7bd06e698d74dd8b7fa76995ef..270abd0cd94af42ea8da413f116f687ac0213f38 100644 (file)
--- a/m4/alloca.m4
+++ b/m4/alloca.m4
@@ -1,5 +1,5 @@
-# alloca.m4 serial 10
-dnl Copyright (C) 2002-2004, 2006-2007, 2009-2011 Free Software Foundation,
+# alloca.m4 serial 14
+dnl Copyright (C) 2002-2004, 2006-2007, 2009-2013 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,
@@ -36,8 +36,86 @@ AC_DEFUN([gl_FUNC_ALLOCA],
     ALLOCA_H=alloca.h
   fi
   AC_SUBST([ALLOCA_H])
+  AM_CONDITIONAL([GL_GENERATE_ALLOCA_H], [test -n "$ALLOCA_H"])
 ])
 
 # Prerequisites of lib/alloca.c.
 # STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
 AC_DEFUN([gl_PREREQ_ALLOCA], [:])
+
+# This works around a bug in autoconf <= 2.68.
+# See <http://lists.gnu.org/archive/html/bug-gnulib/2011-06/msg00277.html>.
+
+m4_version_prereq([2.69], [] ,[
+
+# This is taken from the following Autoconf patch:
+# http://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=6cd9f12520b0d6f76d3230d7565feba1ecf29497
+
+# _AC_LIBOBJ_ALLOCA
+# -----------------
+# Set up the LIBOBJ replacement of 'alloca'.  Well, not exactly
+# AC_LIBOBJ since we actually set the output variable 'ALLOCA'.
+# Nevertheless, for Automake, AC_LIBSOURCES it.
+m4_define([_AC_LIBOBJ_ALLOCA],
+[# The SVR3 libPW and SVR4 libucb both contain incompatible functions
+# that cause trouble.  Some versions do not even contain alloca or
+# contain a buggy version.  If you still want to use their alloca,
+# use ar to extract alloca.o from them instead of compiling alloca.c.
+AC_LIBSOURCES(alloca.c)
+AC_SUBST([ALLOCA], [\${LIBOBJDIR}alloca.$ac_objext])dnl
+AC_DEFINE(C_ALLOCA, 1, [Define to 1 if using 'alloca.c'.])
+
+AC_CACHE_CHECK(whether 'alloca.c' needs Cray hooks, ac_cv_os_cray,
+[AC_EGREP_CPP(webecray,
+[#if defined CRAY && ! defined CRAY2
+webecray
+#else
+wenotbecray
+#endif
+], ac_cv_os_cray=yes, ac_cv_os_cray=no)])
+if test $ac_cv_os_cray = yes; then
+  for ac_func in _getb67 GETB67 getb67; do
+    AC_CHECK_FUNC($ac_func,
+                  [AC_DEFINE_UNQUOTED(CRAY_STACKSEG_END, $ac_func,
+                                      [Define to one of '_getb67', 'GETB67',
+                                       'getb67' for Cray-2 and Cray-YMP
+                                       systems. This function is required for
+                                       'alloca.c' support on those systems.])
+    break])
+  done
+fi
+
+AC_CACHE_CHECK([stack direction for C alloca],
+               [ac_cv_c_stack_direction],
+[AC_RUN_IFELSE([AC_LANG_SOURCE(
+[AC_INCLUDES_DEFAULT
+int
+find_stack_direction (int *addr, int depth)
+{
+  int dir, dummy = 0;
+  if (! addr)
+    addr = &dummy;
+  *addr = addr < &dummy ? 1 : addr == &dummy ? 0 : -1;
+  dir = depth ? find_stack_direction (addr, depth - 1) : 0;
+  return dir + dummy;
+}
+
+int
+main (int argc, char **argv)
+{
+  return find_stack_direction (0, argc + !argv + 20) < 0;
+}])],
+               [ac_cv_c_stack_direction=1],
+               [ac_cv_c_stack_direction=-1],
+               [ac_cv_c_stack_direction=0])])
+AH_VERBATIM([STACK_DIRECTION],
+[/* If using the C implementation of alloca, define if you know the
+   direction of stack growth for your system; otherwise it will be
+   automatically deduced at runtime.
+        STACK_DIRECTION > 0 => grows toward higher addresses
+        STACK_DIRECTION < 0 => grows toward lower addresses
+        STACK_DIRECTION = 0 => direction of growth unknown */
+@%:@undef STACK_DIRECTION])dnl
+AC_DEFINE_UNQUOTED(STACK_DIRECTION, $ac_cv_c_stack_direction)
+])# _AC_LIBOBJ_ALLOCA
+])