Compiler divergence when converting to ambiguous/inaccessible base rvalue

[johe...@gmail.com]

Greetings.

There is a compiler divergence (I tested with GCC and Clang) when converting to a base rvalue that's ambiguous/inaccessible. The wording in https://wg21.link/expr.static.cast#3 doesn't outright says that "the program is ill-formed," but it instead reads "a program that necessitates such a cast is ill-formed" in such cases. If the latter can be interpreted differently, could that be the reason for the divergence? See the LLVM bug 37691 and GCC bug 86105.

Thanks for reading.

[johe...@gmail.com]

The rvalue to rvalue base case is covered by the next paragraph, http://eel.is/c++draft/expr.static.cast#4.