This patch fixes 66443, a defect introduced by a C++14 change concerning virtual
bases of abstract classes.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66443 points at DR1611 & 1658,
which describe the issue. Essentially, an abstract class type can only exist as
a base of some other (non-abstract) class. Any virtual bases of the abstract
class will be constructed by the containing class itself. In this specific
instance, a deleted default ctor of such a virtual base should not delete the
abstract class's default dtor.
built & tested on x6-64-linux, ok?
nathan
2015-06-29 Nathan Sidwell <nat...@acm.org>
PR c++/66443
* init.c (emit_mem_initializers): Do not emit initializers for
virtual bases of abstract classes.
* method.c (synthesized_method_walk): Skip virtual bases of
abstract classes in C++14 mode.
PR c++/66443
* cpp1y/pr66443.C: New test.
Index: cp/init.c
===================================================================
--- cp/init.c (revision 225103)
+++ cp/init.c (working copy)
@@ -1139,9 +1139,7 @@ emit_mem_initializers (tree mem_inits)
}
/* Initialize the base. */
- if (BINFO_VIRTUAL_P (subobject))
- construct_virtual_base (subobject, arguments);
- else
+ if (!BINFO_VIRTUAL_P (subobject))
{
tree base_addr;
@@ -1155,6 +1153,8 @@ emit_mem_initializers (tree mem_inits)
tf_warning_or_error);
expand_cleanup_for_base (subobject, NULL_TREE);
}
+ else if (!ABSTRACT_CLASS_TYPE_P (current_class_type))
+ construct_virtual_base (subobject, arguments);
}
in_base_initializer = 0;
Index: cp/method.c
===================================================================
--- cp/method.c (revision 225103)
+++ cp/method.c (working copy)
@@ -1505,7 +1505,10 @@ synthesized_method_walk (tree ctype, spe
vbases = CLASSTYPE_VBASECLASSES (ctype);
if (vec_safe_is_empty (vbases))
/* No virtual bases to worry about. */;
- else if (!assign_p)
+ else if (!assign_p
+ /* C++14 ignores virtual bases of abstract classes, as they
+ can never be directly called. */
+ && (cxx_dialect < cxx14 || !ABSTRACT_CLASS_TYPE_P (ctype)))
{
if (constexpr_p)
*constexpr_p = false;
Index: testsuite/g++.dg/cpp1y/pr66443.C
===================================================================
--- testsuite/g++.dg/cpp1y/pr66443.C (revision 0)
+++ testsuite/g++.dg/cpp1y/pr66443.C (working copy)
@@ -0,0 +1,22 @@
+// PR c++/66443
+// { dg-do compile { target c++14 } }
+
+class A {
+public:
+ A( int ) { }
+};
+
+// B's virtual base is ignored for default ctor determination as B is
+// abstract. DR1611 & DR1658
+
+class B: virtual public A {
+public:
+ virtual void do_something() = 0;
+};
+
+class C: public B {
+public:
+ C(): A( 1 ) { }
+ virtual void do_something() { }
+};
+
