re PR c++/47851 ([C++0x] Incorrect decltype result for conditional operator)

	PR c++/47851
	* call.c (standard_conversion): Provide requested cv-quals on
	class rvalue conversion.

From-SVN: r170601

gcc/cp/ChangeLog

 2011-03-01  Jason Merrill  <jason@redhat.com>
 
+	PR c++/47851
+	* call.c (standard_conversion): Provide requested cv-quals on
+	class rvalue conversion.
+
 	PR c++/46282
 	* decl2.c (grokbitfield): Handle type-dependent width.
 

gcc/cp/call.c

@@ -850,6 +850,7 @@ standard_conversion (tree to, tree from, tree expr, bool c_cast_p,
   enum tree_code fcode, tcode;
   conversion *conv;
   bool fromref = false;
+  tree qualified_to;
 
   to = non_reference (to);
   if (TREE_CODE (from) == REFERENCE_TYPE)
@@ -857,6 +858,7 @@ standard_conversion (tree to, tree from, tree expr, bool c_cast_p,
       fromref = true;
       from = TREE_TYPE (from);
     }
+  qualified_to = to;
   to = strip_top_quals (to);
   from = strip_top_quals (from);
 
@@ -918,7 +920,11 @@ standard_conversion (tree to, tree from, tree expr, bool c_cast_p,
     }
 
   if (same_type_p (from, to))
-    return conv;
+    {
+      if (CLASS_TYPE_P (to) && conv->kind == ck_rvalue)
+	conv->type = qualified_to;
+      return conv;
+    }
 
   /* [conv.ptr]
      A null pointer constant can be converted to a pointer type; ... A

gcc/testsuite/ChangeLog

 2011-03-01  Jason Merrill  <jason@redhat.com>
 
+	* g++.dg/cpp0x/decltype25.C: New.
+
 	* g++.dg/cpp0x/regress/bitfield-err1.C: New.
 
 2011-03-01  Richard Guenther  <rguenther@suse.de>

gcc/testsuite/g++.dg/cpp0x/decltype25.C

+// PR c++/47851
+// { dg-options -std=c++0x }
+
+struct Type {
+  void display_type();
+  void display_type() const { }
+};
+
+typedef Type const ConstType;
+
+struct ConvertibleToType {
+    operator Type&() { return *reinterpret_cast<Type*>(this); }
+};
+
+int main ()
+{
+  // Both lines should call the const variant.
+  (true ? ConvertibleToType() : ConstType()).display_type();
+  decltype((true ? ConvertibleToType() : ConstType()))().display_type();
+}