C++ BUG: Missed ambiguity

[Nathan Sidwell <nathan at acm dot org>]

Hi,
the attached program contains 4 ambiguous accesses of a base class. The
current CVS tree fails to spot one of them

nathan50.C: In function `int fn(D0 *, D1 *, D2 *, D3 *)':
nathan50.C:15: type `A' is ambiguous base class for type `D1'
nathan50.C:16: type `A' is ambiguous base class for type `D2'
nathan50.C:17: type `A' is ambiguous base class for type `D3'

the missing ambiguity is in D0, where both B and C are virtual and each
contain a non-virtual A. so there are two distinct A bases.

shall I install the test case?

nathan

-- 
Dr Nathan Sidwell :: Computer Science Department :: Bristol University
        I have seen the death of PhotoShop -- it is called GIMP
nathan@acm.org  http://www.cs.bris.ac.uk/~nathan/  nathan@cs.bris.ac.uk
// Copyright (C) 1999 Free Software Foundation, Inc.
// Contributed by Nathan Sidwell 29 Aug 1999 <nathan@acm.org>

struct A {int m;};
struct B : A { int m; };
struct C : A { int m; };
struct D0 : virtual B, virtual C { int m; };
struct D1 : virtual B, C { int m; };
struct D2 : B, virtual C { int m; };
struct D3 : B, C { int m; };

int fn(D0 *d0, D1 *d1, D2 *d2, D3 *d3)
{
  A *a0 = d0;   // ERROR - A is an ambiguous base
  A *a1 = d1;   // ERROR - A is an ambiguous base
  A *a2 = d2;   // ERROR - A is an ambiguous base
  A *a3 = d3;   // ERROR - A is an ambiguous base
}