(jm_AC_TYPE_UNSIGNED_LONG_LONG): Make sure

[gnulib.git] / m4 / ulonglong.m4

diff --git a/m4/ulonglong.m4 b/m4/ulonglong.m4
index afc765a..e2fbb55 100644 (file)
--- a/m4/ulonglong.m4
+++ b/m4/ulonglong.m4
@@ -1,12 +1,13 @@
-#serial 1
+#serial 2
 
 dnl From Paul Eggert.
 
 AC_DEFUN(jm_AC_TYPE_UNSIGNED_LONG_LONG,
 [
   AC_CACHE_CHECK([for unsigned long long], ac_cv_type_unsigned_long_long,
-  [AC_TRY_COMPILE([],
-    [unsigned long long i = (unsigned long long) -1;],
+  [AC_TRY_LINK([unsigned long long ull = 1; int i = 63;],
+    [unsigned long long ullmax = (unsigned long long) -1;
+     return ull << i | ull >> i | ullmax / ull | ullmax % ull;],
     ac_cv_type_unsigned_long_long=yes,
     ac_cv_type_unsigned_long_long=no)])
   if test $ac_cv_type_unsigned_long_long = yes; then