Check for _isnan besides for isnan.

git-svn-id: https://svn.dealii.org/trunk@3341 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/aclocal.m4 b/deal.II/aclocal.m4
index f6003906c5dda22c80bca2a27a82ee383a953205..0b9b7f43a17e4b7fe6fbde115d7df241a0161d38 100644 (file)
--- a/deal.II/aclocal.m4
+++ b/deal.II/aclocal.m4
@@ -181,6 +181,7 @@ AC_DEFUN(DEAL_II_CHECK_ISNAN_FLAG, dnl
   AC_MSG_CHECKING(whether isnan is declared with $1 flags)
   AC_REQUIRE([AC_LANG_CPLUSPLUS])
   CXXFLAGS=$2
+  deal_II_isnan_flag=""
   AC_TRY_COMPILE(
     [
 #include <cmath>
@@ -193,42 +194,78 @@ AC_DEFUN(DEAL_II_CHECK_ISNAN_FLAG, dnl
        AC_MSG_RESULT("yes")
        deal_II_isnan_flag="-DHAVE_ISNAN"
        $3
-    ],
-    [
-       dnl We need to define something. Unfortunately, this is system 
-       dnl dependent (argh!)
-       deal_II_isnan_flag=""
-       for testflag in -D_ISOC99_SOURCE -D__EXTENSIONS__ ; do 
-         CXXFLAGS="$2 $testflag"
-          AC_TRY_COMPILE(
-           [
+    ])
+
+
+  if test $deal_II_isnan_flag = "" ; then
+    dnl Simply using isnan doesn't work. On Microsoft Windows systems, the function
+    dnl is called _isnan, so check that
+    AC_TRY_COMPILE(
+      [
 #include <cmath>
-           ],
-           [
-               double d=0;
-               isnan (d);
-           ],
-           [
-               dnl We found a flag by which isnan is defined; store
-               dnl this flag and exit the loop
-               deal_II_isnan_flag="-DHAVE_ISNAN $testflag"
-               break;
-           ],
-           [
-                dnl The flag didn't work, don't do nothing.
-           ])
-       done
-
-       dnl if no such flag was found, then abort ./configure since
-       dnl the library will not be compilable on this platform
-       dnl without knowledge of the right flag
-       if test "$deal_II_isnan_flag" = "" ; then
-         AC_MSG_RESULT(no.)
-       else
-
-         dnl we found something, lets us it
-         AC_MSG_RESULT(using $testflag)
+      ],
+      [
+         double d=0;
+         _isnan (d);
+      ],
+      [
+         AC_MSG_RESULT("yes")
+         deal_II_isnan_flag="-DHAVE_UNDERSCORE_ISNAN"
          $3
-       fi
-    ])
+      ])
+  fi
+
+
+  dnl Let's see whether we _now_ have found something
+  if test $deal_II_isnan_flag = "" ; then
+    dnl We need to define something. Unfortunately, this is system 
+    dnl dependent (argh!)
+    deal_II_isnan_flag=""
+    for testflag in -D_ISOC99_SOURCE -D__EXTENSIONS__ ; do 
+      CXXFLAGS="$2 $testflag"
+      AC_TRY_COMPILE(
+        [
+#include <cmath>
+       ],
+       [
+         double d=0;
+         isnan (d);
+       ],
+       [
+         dnl We found a flag by which isnan is defined; store
+         dnl this flag and exit the loop
+         deal_II_isnan_flag="-DHAVE_ISNAN $testflag"
+         break;
+       ])
+
+      dnl If that didn't work (and it didn't as we are still inside the
+      dnl loop), then try the _isnan function (maybe we are on a
+      dnl Microsoft Windows system)
+      AC_TRY_COMPILE(
+        [
+#include <cmath>
+       ],
+       [
+         double d=0;
+         _isnan (d);
+       ],
+       [
+         dnl We found a flag by which isnan is defined; store
+         dnl this flag and exit the loop
+         deal_II_isnan_flag="-DHAVE_UNDERSCORE_ISNAN $testflag"
+         break;
+       ])
+    done
+
+    dnl if no such flag was found, then abort ./configure since
+    dnl the library will not be compilable on this platform
+    dnl without knowledge of the right flag
+    if test "$deal_II_isnan_flag" = "" ; then
+      AC_MSG_RESULT(no.)
+    else
+      dnl we found something, lets us it
+      AC_MSG_RESULT(using $testflag)
+      $3
+    fi
+  fi
 )