... and this version passes testing. For real.
Paolo.
////////////////////////////
Index: cp/decl.c
===================================================================
--- cp/decl.c (revision 237285)
+++ cp/decl.c (working copy)
@@ -6002,6 +6002,13 @@ check_initializer (tree decl, tree init, int flags
tree init_code = NULL;
tree core_type;
+ if (init && init != error_mark_node
+ && TREE_TYPE (init) == error_mark_node)
+ {
+ TREE_TYPE (decl) = error_mark_node;
+ return NULL_TREE;
+ }
+
/* Things that are going to be initialized need to have complete
type. */
TREE_TYPE (decl) = type = complete_type (TREE_TYPE (decl));
Index: testsuite/g++.dg/inherit/crash6.C
===================================================================
--- testsuite/g++.dg/inherit/crash6.C (revision 0)
+++ testsuite/g++.dg/inherit/crash6.C (working copy)
@@ -0,0 +1,10 @@
+// PR c++/70202
+
+class A
+{
+ virtual void foo () { }
+};
+class B : public A, A { }; // { dg-error "duplicate base type" }
+
+B b1, &b2 = b1; // { dg-error "incomplete type" }
+A a = b2;
