Replace check_shim with check_shim_abi in unix/foreign_items shims

[geetanshjuneja]

Links to #3842.

[geetanshjuneja]

Would you prefer I update all the remaining shims in this file as part of this PR, or should I submit a separate PR for that? Updating all check_shim calls here would result in a large change, which might make the review process more difficult.

[RalfJung]

No please don't make this PR any bigger. :)

[RalfJung]

Thanks! You uncovered a few cases where we are not properly consistent with our types.

We generally assume that long is isize and unsigned long is usize, so please also keep doing that here. Same for size_t and ssize_t, those are usize and isize, respectively.

For types like off_t, off64_t, clockid_t, we should be using their proper types, but some functions do not. So please do one of the following:

• change the logic inside these functions to use the proper type. Typically this means using e.g. to_int(this.libc_ty_layout("off_t").size) instead of to_i32().
• or keep the logic the same, put i32 into the check_shim_abi invocation, and add a comment saying "FIXME: should be off_t".

@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[geetanshjuneja]

@rustbot ready

[RalfJung]

This looks great, thanks! Please squash the commits, then we can land this. Please use the --keep-base flag when squashing so that the force-push diff is easier to review; do not rebase on the latest master branch. Then write @rustbot ready after you pushed the squashed PR.

@rustbot author

[geetanshjuneja]

@rustbot ready