Load weak dll imports on Windows

[m-ou-se]

On Windows, some syscalls (e.g. WakeOnAddress) are loaded from an .CRT$XCU section, which doesn't get executed on Miri.

See rust-lang/rust#81478 (comment)

This means the standard library falls back to not using those, which is okay for now, but is a problem when implementing WakeOnAddress, as that mechanism falls back to another dynamic dll import which will also not have been loaded in miri.

[RalfJung]

So basically, #450 will be mandatory on Windows for things like WakeOnAddress?

[m-ou-se]

With the current implementation in std, yes. But there's big plans for changes that area: rust-lang/rust#81478 (comment)

[m-ou-se]

I suppose we could also add some #[cfg(miri)] in std to load these differently in miri?

[RalfJung]

Yeah, that would be one option.

Implementing these sections also shouldn't be terribly hard -- we just need some way to iterate over all static that are declared to live in that section, and then run those function pointers. It's just a bit annoying to get the code flow right here (I think this needs to be a new "stage" or so in our scheduler).

[RalfJung]

rust-lang/rust#95775 makes weak dll imports on Windows "work" in Miri via a hack (as already suggested above by @m-ou-se). Still, that's enough to close this issue I think. We have #450 for "properly" implementing this.