C++ PATCH for c++/40944 (SFINAE and reference binding)

[Jason Merrill <jason at redhat dot com>]

Just another case where we need to pass tsubst flags down.

Tested x86_64-pc-linux-gnu, applied to trunk.
commit 7ef7e918581c6717c3efb167560c3252b2c97061
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Nov 3 11:20:26 2009 -0500

    	PR c++/40944
    	* call.c (initialize_reference): Add complain parm.
    	* typeck.c (convert_for_initialization): Pass it.
    	* decl.c (grok_reference_init): Likewise.
    	* cp-tree.h: Declare it.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 463257c..674e59d 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -7617,7 +7617,8 @@ set_up_extended_ref_temp (tree decl, tree expr, tree *cleanup, tree *initp)
    Return the converted expression.  */
 
 tree
-initialize_reference (tree type, tree expr, tree decl, tree *cleanup)
+initialize_reference (tree type, tree expr, tree decl, tree *cleanup,
+		      tsubst_flags_t complain)
 {
   conversion *conv;
   void *p;
@@ -7632,16 +7633,19 @@ initialize_reference (tree type, tree expr, tree decl, tree *cleanup)
 			    LOOKUP_NORMAL);
   if (!conv || conv->bad_p)
     {
-      if (!(TYPE_QUALS (TREE_TYPE (type)) & TYPE_QUAL_CONST)
-	  && !TYPE_REF_IS_RVALUE (type)
-	  && !real_lvalue_p (expr))
-	error ("invalid initialization of non-const reference of "
-	       "type %qT from an rvalue of type %qT",
-	       type, TREE_TYPE (expr));
-      else
-	error ("invalid initialization of reference of type "
-	       "%qT from expression of type %qT", type,
-	       TREE_TYPE (expr));
+      if (complain & tf_error)
+	{
+	  if (!(TYPE_QUALS (TREE_TYPE (type)) & TYPE_QUAL_CONST)
+	      && !TYPE_REF_IS_RVALUE (type)
+	      && !real_lvalue_p (expr))
+	    error ("invalid initialization of non-const reference of "
+		   "type %qT from an rvalue of type %qT",
+		   type, TREE_TYPE (expr));
+	  else
+	    error ("invalid initialization of reference of type "
+		   "%qT from expression of type %qT", type,
+		   TREE_TYPE (expr));
+	}
       return error_mark_node;
     }
 
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 7965514..c4b088b 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4429,7 +4429,7 @@ extern tree type_passed_as			(tree);
 extern tree convert_for_arg_passing		(tree, tree);
 extern bool is_properly_derived_from		(tree, tree);
 extern tree set_up_extended_ref_temp		(tree, tree, tree *, tree *);
-extern tree initialize_reference		(tree, tree, tree, tree *);
+extern tree initialize_reference		(tree, tree, tree, tree *, tsubst_flags_t);
 extern tree make_temporary_var_for_ref_to_temp	(tree, tree);
 extern tree strip_top_quals			(tree);
 extern bool reference_related_p			(tree, tree);
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index de29d0b..97f1ac1 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -4390,7 +4390,7 @@ grok_reference_init (tree decl, tree type, tree init, tree *cleanup)
      DECL_INITIAL for local references (instead assigning to them
      explicitly); we need to allow the temporary to be initialized
      first.  */
-  tmp = initialize_reference (type, init, decl, cleanup);
+  tmp = initialize_reference (type, init, decl, cleanup, tf_warning_or_error);
 
   if (tmp == error_mark_node)
     return NULL_TREE;
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 25c257f..5b8523d 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -6879,7 +6879,7 @@ convert_for_initialization (tree exp, tree type, tree rhs, int flags,
       if (fndecl)
 	savew = warningcount, savee = errorcount;
       rhs = initialize_reference (type, rhs, /*decl=*/NULL_TREE,
-				  /*cleanup=*/NULL);
+				  /*cleanup=*/NULL, complain);
       if (fndecl)
 	{
 	  if (warningcount > savew)
diff --git a/gcc/testsuite/g++.dg/template/sfinae15.C b/gcc/testsuite/g++.dg/template/sfinae15.C
new file mode 100644
index 0000000..27bce25
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/sfinae15.C
@@ -0,0 +1,23 @@
+// PR c++/40944
+// { dg-options -std=c++0x }
+// { dg-do run }
+
+template<typename T>
+struct make { static T&& it(); };
+
+void (*pf)(int&) = 0;
+
+template< typename T >
+int bar(T const& x,
+        decltype( pf(make<T const&>::it()) )* = 0 // SFINAE!
+        ) {
+    return 1;
+}
+
+int bar(...) {
+    return 0;
+}
+
+int main() {
+    return bar(42);
+}