Core 234 - allow const objects with no initializer or user-provided default...

	Core 234 - allow const objects with no initializer or
	user-provided default constructor if the defaulted constructor
	initializes all the subobjects.
	PR c++/20039
	PR c++/42844
	* class.c (default_init_uninitialized_part): New.
	* cp-tree.h: Declare it.
	* decl.c (check_for_uninitialized_const_var): Use it.
	* init.c (perform_member_init): Likewise.
	(build_new_1): Likewise.
	* method.c (walk_field_subobs): Likewise.

From-SVN: r179130

1 files changed, 7 insertions, 4 deletions

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 709deca..495d8a0 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -4899,15 +4899,16 @@ check_for_uninitialized_const_var (tree decl)
   if (TREE_CODE (decl) == VAR_DECL
       && TREE_CODE (type) != REFERENCE_TYPE
       && CP_TYPE_CONST_P (type)
-      && (!TYPE_NEEDS_CONSTRUCTING (type)
-	  || !type_has_user_provided_default_constructor (type))
       && !DECL_INITIAL (decl))
     {
+      tree field = default_init_uninitialized_part (type);
+      if (!field)
+	return;
+
       permerror (DECL_SOURCE_LOCATION (decl),
 		 "uninitialized const %qD", decl);
 
-      if (CLASS_TYPE_P (type)
-	  && !type_has_user_provided_default_constructor (type))
+      if (CLASS_TYPE_P (type))
 	{
 	  tree defaulted_ctor;
 
@@ -4918,6 +4919,8 @@ check_for_uninitialized_const_var (tree decl)
 	    inform (DECL_SOURCE_LOCATION (defaulted_ctor),
 		    "constructor is not user-provided because it is "
 		    "explicitly defaulted in the class body");
+	  inform (0, "and the implicitly-defined constructor does not "
+		  "initialize %q+#D", field);
 	}
     }
 }