From patchwork Mon Oct  4 00:25:49 2010
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Subject: C++ PATCH for another sfinae case
Date: Sun, 03 Oct 2010 14:25:49 -0000
From: Jason Merrill <jason@redhat.com>
X-Patchwork-Id: 66608
Message-Id: <4CA91F0D.6020106@redhat.com>
To: gcc-patches List <gcc-patches@gcc.gnu.org>

Yet another case where we want to swallow an error during template 
deduction.

Tested x86_64-pc-linux-gnu, applied to trunk.


commit e8ae70530688aa2b0bcc0560773d55ff10d46017
Author: Jason Merrill <jason@redhat.com>
Date:   Sun Oct 3 14:27:03 2010 -0400

    	* typeck.c (require_complete_type_sfinae): Add complain parm to...
    	(require_complete_type): ...this function.
    	(cp_build_array_ref, convert_arguments): Use it.
    	(convert_for_initialization, cp_build_modify_expr): Likewise.
    	* cp-tree.h: Declare it.
    	* call.c (build_over_call): Use it.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 2e7083d..e0911ac 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -5655,7 +5655,7 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
       if (TREE_THIS_VOLATILE (fn) && cfun)
 	current_function_returns_abnormally = 1;
       if (!VOID_TYPE_P (return_type))
-	require_complete_type (return_type);
+	require_complete_type_sfinae (return_type, complain);
       return convert_from_reference (expr);
     }
 
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index aa1fe4d..6ce10e6 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -5432,6 +5432,7 @@ extern int string_conv_p			(const_tree, const_tree, int);
 extern tree cp_truthvalue_conversion		(tree);
 extern tree condition_conversion		(tree);
 extern tree require_complete_type		(tree);
+extern tree require_complete_type_sfinae	(tree, tsubst_flags_t);
 extern tree complete_type			(tree);
 extern tree complete_type_or_else		(tree, tree);
 extern tree complete_type_or_maybe_complain	(tree, tree, tsubst_flags_t);
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index eff6704..b2b8e5f 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -64,11 +64,11 @@ static int convert_arguments (tree, VEC(tree,gc) **, tree, int,
 
 /* Do `exp = require_complete_type (exp);' to make sure exp
    does not have an incomplete type.  (That includes void types.)
-   Returns the error_mark_node if the VALUE does not have
+   Returns error_mark_node if the VALUE does not have
    complete type when this function returns.  */
 
 tree
-require_complete_type (tree value)
+require_complete_type_sfinae (tree value, tsubst_flags_t complain)
 {
   tree type;
 
@@ -87,12 +87,18 @@ require_complete_type (tree value)
   if (COMPLETE_TYPE_P (type))
     return value;
 
-  if (complete_type_or_else (type, value))
+  if (complete_type_or_maybe_complain (type, value, complain))
     return value;
   else
     return error_mark_node;
 }
 
+tree
+require_complete_type (tree value)
+{
+  return require_complete_type_sfinae (value, tf_warning_or_error);
+}
+
 /* Try to complete TYPE, if it is incomplete.  For example, if TYPE is
    a template instantiation, do the instantiation.  Returns TYPE,
    whether or not it could be completed, unless something goes
@@ -3039,7 +3045,8 @@ cp_build_array_ref (location_t loc, tree array, tree idx,
 	|= (CP_TYPE_VOLATILE_P (type) | TREE_SIDE_EFFECTS (array));
       TREE_THIS_VOLATILE (rval)
 	|= (CP_TYPE_VOLATILE_P (type) | TREE_THIS_VOLATILE (array));
-      ret = require_complete_type (fold_if_not_in_template (rval));
+      ret = require_complete_type_sfinae (fold_if_not_in_template (rval),
+					  complain);
       protected_set_expr_location (ret, loc);
       return ret;
     }
@@ -3542,7 +3549,7 @@ convert_arguments (tree typelist, VEC(tree,gc) **values, tree fndecl,
 	    /* Don't do ellipsis conversion for __built_in_constant_p
 	       as this will result in spurious errors for non-trivial
 	       types.  */
-	    val = require_complete_type (val);
+	    val = require_complete_type_sfinae (val, complain);
 	  else
 	    val = convert_arg_to_ellipsis (val);
 
@@ -6744,7 +6751,7 @@ cp_build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs,
     }
   else
     {
-      lhs = require_complete_type (lhs);
+      lhs = require_complete_type_sfinae (lhs, complain);
       if (lhs == error_mark_node)
 	return error_mark_node;
 
@@ -7592,7 +7599,7 @@ convert_for_initialization (tree exp, tree type, tree rhs, int flags,
     }
 
   if (exp != 0)
-    exp = require_complete_type (exp);
+    exp = require_complete_type_sfinae (exp, complain);
   if (exp == error_mark_node)
     return error_mark_node;
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/sfinae5.C b/gcc/testsuite/g++.dg/cpp0x/sfinae5.C
new file mode 100644
index 0000000..8474fb3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/sfinae5.C
@@ -0,0 +1,16 @@
+// { dg-options -std=c++0x }
+
+template<class T>
+T&& create();
+
+template <class T, class U,
+	  class = decltype(create<T>() = create<U>())
+	  >
+char test(int);
+
+template <class, class>
+double test(...);
+
+int main() {
+  test<int[], int[]>(0); // #1
+}