[Bug c++/64077] dynamic_cast incorrectly rejected for private base

[gcc at dixie dot net.nz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64077

--- Comment #2 from Andrew Dixie <gcc at dixie dot net.nz> ---
(In reply to Daniel Krügler from comment #1)

Thanks for investigating and providing the reference.

I did not understand that upcasts were intended to override potential cross
casts, issue 665 makes this clear.

I agree the testcase is invalid.

In p5, is "inaccessible" meant to include friendship relationships granted by
the current scope or instead use the explicit public base rules spelt out in
p8?

The second part of the patch was implementing the latter, but I now also think
this is invalid.