diff --git a/ChangeLog b/ChangeLog
index e8e84cdb68..ca4d518c9f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Mar 27 12:56:44 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/mkmf.rb (what_type?): checks more restrictively, and
+	  supports universal binary.
+
 Fri Mar 27 01:33:37 2009  Tanaka Akira  <akr@fsij.org>
 
 	* time.c (time_cmp): negate the result of reverse comparison.
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index f27f286d07..9153a3510d 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -372,6 +372,7 @@ end
 def link_command(ldflags, opt="", libpath=$DEFLIBPATH|$LIBPATH)
   conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote,
                                 'src' => CONFTEST_C,
+                                'extout' => $extout,
                                 'arch_hdrdir' => "#$arch_hdrdir",
                                 'top_srcdir' => $top_srcdir.quote,
                                 'INCFLAGS' => "#$INCFLAGS",
@@ -387,6 +388,7 @@ end
 
 def cc_command(opt="")
   conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote, 'srcdir' => $srcdir.quote,
+                                'extout' => $extout,
                                 'arch_hdrdir' => "#$arch_hdrdir",
                                 'top_srcdir' => $top_srcdir.quote)
   RbConfig::expand("$(CC) #$INCFLAGS #$CPPFLAGS #$CFLAGS #$ARCH_FLAG #{opt} -c #{CONFTEST_C}",
@@ -395,6 +397,7 @@ end
 
 def cpp_command(outfile, opt="")
   conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote, 'srcdir' => $srcdir.quote,
+                                'extout' => $extout,
                                 'arch_hdrdir' => "#$arch_hdrdir",
                                 'top_srcdir' => $top_srcdir.quote)
   RbConfig::expand("$(CPP) #$INCFLAGS #$CPPFLAGS #$CFLAGS #{opt} #{CONFTEST_C} #{outfile}",
@@ -983,7 +986,7 @@ def check_sizeof(type, headers = nil, &b)
   prelude << "typedef #{typename} rbcv_typedef_;\n"
   prelude << "static rbcv_typedef_ *rbcv_ptr_;\n"
   prelude = [prelude]
-  expr = "sizeof((*rbcv_ptr_)#{"."<<member if member})"
+  expr = "sizeof((*rbcv_ptr_)#{"." << member if member})"
   fmt = "%s"
   def fmt.%(x)
     x ? super : "failed"
@@ -1028,10 +1031,20 @@ end
 
 def what_type?(type, member = nil, headers = nil, &b)
   m = "#{type}"
-  name = type
+  var = "*rbcv_var_"
+  func = "rbcv_func_(void)"
   if member
     m << "." << member
-    name = "(((#{type} *)0)->#{member})"
+  else
+    type, member = type.split('.', 2)
+  end
+  prelude = cpp_include(headers).split(/$/)
+  prelude << "typedef #{type} rbcv_typedef_;\n"
+  prelude << "static rbcv_typedef_ #{var_};\n"
+  prelude << "extern rbcv_typedef_ #{func};\n"
+  headers = [prelude]
+  if member
+    var = "(#{var}).#{member}"
   end
   fmt = "seems %s"
   def fmt.%(x)
@@ -1040,21 +1053,24 @@ def what_type?(type, member = nil, headers = nil, &b)
   checking_for checking_message(m, headers), fmt do
     if scalar_ptr_type?(type, member, headers, &b)
       if try_static_assert("sizeof(*#{name}) == 1", headers)
-        "string"
+        return "string"
       end
+      ptr = "*"
     elsif scalar_type?(type, member, headers, &b)
-      if try_static_assert("sizeof(#{name}) > sizeof(long)", headers)
-        "long long"
-      elsif try_static_assert("sizeof(#{name}) > sizeof(int)", headers)
-        "long"
-      elsif try_static_assert("sizeof(#{name}) > sizeof(short)", headers)
-        "int"
-      elsif try_static_assert("sizeof(#{name}) > 1", headers)
-        "short"
-      else
-        "char"
-      end
+      ptr = ""
+    else
+      return
     end
+    unsigned = try_static_assert("(rbcv_typedef_)-1 < 0", headers) ? "unsigned" : ""
+    [
+     unsigned,
+     (UNIVERSAL_INTS+["short"]).find do |t|
+       prelude = headers + [["static #{unsigned} #{t} #{ptr}#{name};\n",
+                             "extern #{unsigned} #{t} #{ptr}#{func};\n"]]
+       try_static_assert("sizeof(#{ptr}#{name}) == sizeof(#{unsigned}#{t})", prelude)
+     end,
+     ptr
+    ].compact.join(" ")
   end
 end