On Windows, these types were causing warnings to be emitted during the
build. These types are allowed to not have idiomatic names, so the
warning should be supressed.

Use trait_object_dummy_self instead of err

r? @eddyb

cc rust-lang#70866.

Add some regression tests

Closes rust-lang#29988
Closes rust-lang#34979
Pick up two snippets that have been fixed from rust-lang#67945 (shouldn't be closed yet!)

…acrum

tests: Fix warnings in `rust_test_helpers.c`

MSVC is silly and doesn't recognize `assert` as diverging.

Grammar

I've split this into individual changes so that people can veto individually. I'm not attached to most of them.

`zeroes` vs. `zeros` is why I took the effort to run this through app.grammarly (which disappointingly didn't even notice).

…, r=oli-obk

use hex for pointers in Miri error messages

Also refine vtable error message: distinguish between "drop fn does not point to a function" and "drop fn points to a function with the wrong signature".

…-Simulacrum

Allow a few warnings.

On Windows, these types were causing warnings to be emitted during the
build. These types are allowed to not have idiomatic names, so the
warning should be supressed.