https://issues.dlang.org/show_bug.cgi?id=23745

          Issue ID: 23745
           Summary: Segfault with forward reference mismatched override
                    with undeclared type
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: dlang-bugzilla@thecybershadow.net

////////// test.d //////////
class B : A
{
    override void fun()
    {
    }
}

class A
{
    void fun(UndefinedType);
}
////////////////////////////

Seems to have regressed in 2.080.0. Previously it correctly complained:

test.d(3): Error: function `test.B.fun` does not override any function, did you mean to override `test.A.fun`?

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