--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2006-10-11  Bruno Haible  <bruno@clisp.org>
+
+	* m4/longlong.m4: Add comments.
+	* m4/ulonglong.m4: Likewise.
+
 2006-10-10  Bruno Haible  <bruno@clisp.org>
 
 	Make it possible to #define stpcpy, strdup to aliases.

--- a/m4/longlong.m4
+++ b/m4/longlong.m4
@@ -1,4 +1,4 @@
-# longlong.m4 serial 7
+# longlong.m4 serial 8
 dnl Copyright (C) 1999-2006 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -10,6 +10,10 @@
 # This fixes a bug in Autoconf 2.60, but can be removed once we
 # assume 2.61 everywhere.
 
+# Note: If the type 'long long int' exists but is only 32 bits large
+# (as on some very old compilers), AC_TYPE_LONG_LONG_INT will not be
+# defined. In this case you can treat 'long long int' like 'long int'.
+
 AC_DEFUN([AC_TYPE_LONG_LONG_INT],
 [
   AC_CACHE_CHECK([for long long int], [ac_cv_type_long_long_int],

--- a/m4/ulonglong.m4
+++ b/m4/ulonglong.m4
@@ -1,4 +1,4 @@
-# ulonglong.m4 serial 5
+# ulonglong.m4 serial 6
 dnl Copyright (C) 1999-2006 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -10,6 +10,11 @@
 # This fixes a bug in Autoconf 2.60, but can be removed once we
 # assume 2.61 everywhere.
 
+# Note: If the type 'unsigned long long int' exists but is only 32 bits
+# large (as on some very old compilers), AC_TYPE_UNSIGNED_LONG_LONG_INT
+# will not be defined. In this case you can treat 'unsigned long long int'
+# like 'unsigned long int'.
+
 AC_DEFUN([AC_TYPE_UNSIGNED_LONG_LONG_INT],
 [
   AC_CACHE_CHECK([for unsigned long long int],