build(docs.rs): cover more Mac targets

[ErichDonGubler]

Expands the set of Mac targets to cover more Mac toolchains. 😀

Original OP text from draft

We've specified a default-target for docs.rs metadata in Cargo.toml, but the way to exclude other platforms is via the targets field, according to these docs on it:

# If `default-target` is unset, the first element of `targets` is treated as the default target.
# Otherwise, these `targets` are built in addition to the default target.
# If both `default-target` and `targets` are unset,
#   all tier-one targets will be built and `x86_64-unknown-linux-gnu` will be used as the default target.

---

Should fix #5. EDIT: Maybe not?

[MarijnS95]

Barring the cross-compilation issue, should iOS also be targeted for docs?

I'm unsure if there's anything cfg'd for that target, but might be useful to include it nonetheless.

EDIT: And if such a PR makes the documentation available elsewhere, the "docs are broken" module comment should be replaced with a link :)

[MarijnS95]

@ErichDonGubler can you pursue this again? #5 was fixed and closed via #303, and running cargo doc --open --no-deps --target x86_64-apple-darwin locally shows that the docs now build successfully! Don't forget about my and @xorza's query to extend the list of targets first.

[MarijnS95]

After all #303 was contained in the recent 0.28.0 release, and the default x86_64-apple-darwin target had a successful build already as seen at https://docs.rs/metal/0.28.0/metal/index.html!

[ErichDonGubler]

@xorza: I've adjusted PR title, summary, and the sole commit to note that this only covers more targets, since that seems like the only useful scope left in this contribution. 🙂

[ErichDonGubler]

@xorza: I've rebased, taken your review suggestion, adjusted PR title, summary, and the sole commit to note that this only covers more targets, since that seems like the only useful scope left in this contribution. 🙂

[ErichDonGubler]

Nightly CI appears to be complaining about an "unused" feature dispatch_queue, which got renamed waaay back in fb17c9e. Eek! That means the dispatch module has been disabled for…a long time, while a different route to dispatch module import in the sync module has been taken instead (maybe a private use from lib.rs?) and kept from breaking compilation.

[MarijnS95]

Looks good to have all Tier 1/2 Apple platforms listed, and instead of setting a "useless" default-target, no longer rely on the default targets = ["...windows..", "...linux...", ...] array on which docs.rs will fail anyway: https://docs.rs/crate/metal/0.28.0/builds/1204445/x86_64-unknown-linux-gnu.txt

[grovesNL]

Thank you!