re PR c++/42466 (Multiple instantiations of template constructor fail)

	PR c++/42466
	* pt.c (reduce_template_parm_level): Check the type before
	returning cached TEMPLATE_PARM_INDEX.

From-SVN: r155411

gcc/cp/ChangeLog

 2009-12-22  Jason Merrill  <jason@redhat.com>
 
+	PR c++/42466
+	* pt.c (reduce_template_parm_level): Check the type before
+	returning cached TEMPLATE_PARM_INDEX.
+
 	PR c++/42331
 	* typeck.c (cp_build_modify_expr): Fix thinko.
 

gcc/cp/pt.c

@@ -3356,7 +3356,8 @@ reduce_template_parm_level (tree index, tree type, int levels, tree args,
 {
   if (TEMPLATE_PARM_DESCENDANTS (index) == NULL_TREE
       || (TEMPLATE_PARM_LEVEL (TEMPLATE_PARM_DESCENDANTS (index))
-	  != TEMPLATE_PARM_LEVEL (index) - levels))
+	  != TEMPLATE_PARM_LEVEL (index) - levels)
+      || !same_type_p (type, TREE_TYPE (TEMPLATE_PARM_DESCENDANTS (index))))
     {
       tree orig_decl = TEMPLATE_PARM_DECL (index);
       tree decl, t;

gcc/testsuite/ChangeLog

 2009-12-22  Jason Merrill  <jason@redhat.com>
 
+	PR c++/42466
+	* g++.dg/template/nontype19.C: New.
+
 	PR c++/42331
 	* g++.dg/cpp0x/initlist29.C: New.
 

gcc/testsuite/g++.dg/template/nontype19.C

+// PR c++/42466
+
+template<class IntT, IntT X>
+struct A
+{
+  A();
+
+  template<IntT X2>
+  A(const A<IntT, X2>& other);
+};
+
+int main(int argc, char** argv)
+{
+    A<int, 42> a;
+    A<int, 100> b = a;
+
+    A<unsigned, 42u> c;
+    A<unsigned, 100u> d = c;
+}