Should be possible to use the select!() macro within deny(unsafe_code)

[Ms2ger]

[steveklabnik]

I believe that this is a duplicate, but I can't remember enough about the other bug :(

[mitaa]

Did you perhaps think of #8472?

The unsafe block in select! could be annotated allow(unsafe_code), but that would require all crates the macro is used in to have feature(stmt_expr_attrs).

Another solution would be to move the unsafe block into a safe helper function...

[Ms2ger]

Also, while deny(unsafe_code) is my primary concern, something that works with forbid too would be even better.

[Mark-Simulacrum]

select! macro is gone today and we have a way of doing this I believe (rustc_internal_unsafe or some similar attribute on macros)