X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Falloca.m4;h=689da75a2aca0a309cd9cf6d7186743f91fe95b1;hb=b9bb8b95df6833738f8e5b22cc57246f71fe4b2e;hp=3e70d12a7cc5b8873253f1ba4c007ecf0ade25d1;hpb=2f4895969d1eb99a897b757c5c55c2b526a8ab06;p=gnulib.git

diff --git a/m4/alloca.m4 b/m4/alloca.m4
index 3e70d12a7..689da75a2 100644
--- a/m4/alloca.m4
+++ b/m4/alloca.m4
@@ -1,15 +1,12 @@
-# alloca.m4 serial 6
-dnl Copyright (C) 2002-2004, 2006 Free Software Foundation, Inc.
+# alloca.m4 serial 11
+dnl Copyright (C) 2002-2004, 2006-2007, 2009-2011 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
@@ -17,29 +14,29 @@ AC_DEFUN([gl_FUNC_ALLOCA],
 
   # Define an additional variable used in the Makefile substitution.
   if test $ac_cv_working_alloca_h = yes; then
-    AC_CACHE_VAL([gl_cv_rpl_alloca], [
+    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
+        Need own alloca
 #endif
         ], [gl_cv_rpl_alloca=yes], [gl_cv_rpl_alloca=no])
     ])
     if test $gl_cv_rpl_alloca = yes; then
-      AC_DEFINE([HAVE_ALLOCA], 1,
-        [Define to 1 if you have `alloca' after including <alloca.h>,
+      dnl OK, alloca can be implemented through a compiler built-in.
+      AC_DEFINE([HAVE_ALLOCA], [1],
+        [Define to 1 if you have 'alloca' after including <alloca.h>,
          a header that may be supplied by this distribution.])
       ALLOCA_H=alloca.h
     else
+      dnl alloca exists as a library function, i.e. it is slow and probably
+      dnl a memory leak. Don't define HAVE_ALLOCA in this case.
       ALLOCA_H=
     fi
   else
     ALLOCA_H=alloca.h
   fi
   AC_SUBST([ALLOCA_H])
-
-  AC_DEFINE(HAVE_ALLOCA_H, 1,
-    [Define HAVE_ALLOCA_H for backward compatibility with older code
-     that includes <alloca.h> only if HAVE_ALLOCA_H is defined.])
+  AM_CONDITIONAL([GL_GENERATE_ALLOCA_H], [test -n "$ALLOCA_H"])
 ])
 
 # Prerequisites of lib/alloca.c.