Permit IntKind::Custom to represent Paths instead of just Idents

[eggyal]

If one implements ParseCallbacks::int_macro to specify a custom IntKind, one is currently restricted to mere Idents which must therefore be brought into the generated bindings' scope; this PR permits paths to be specified instead.

r? @emilio

[highfive]

Thanks for the pull request, and welcome! The Servo team is excited to review your changes, and you should hear from @emilio (or someone else) soon.

[emilio]

Looks fair, but could you add a test for this to the bindgen-integration directory?

[eggyal]

The actual use-case here is likely to be no_std crates which have to provide their own equivalent of std::os::raw—but the bindgen-integration crate is not currently no_std; should I change that just for this test, or do something rather contrived (e.g. wrap c_void in a newtype struct, and export it together with the std types from a new module)? Else I'm not sure how this can be tested?

[emilio]

That use case should already be solved by --use_core and --ctypes-prefix, shouldn't it?

The actual use-case here is likely to be no_std crates which have to provide their own equivalent of std::os::raw—but the bindgen-integration crate is not currently no_std; should I change that just for this test, or do something rather contrived (e.g. wrap c_void in a newtype struct, and export it together with the std types from a new module)? Else I'm not sure how this can be tested?

It should be pretty easy to test without making the crate no_std, just make a module in the crate and use it for a particular macro?

[eggyal]

I'm not entirely sure know what I was thinking—must have been a bad day. Will this suffice?

[emilio]

We somehow need to check this is doing the right thing. What about making this conditional only on _name (so use it for a single macro), and then use it in a #[test] function below like let _: isize = MY_MACRO?

[eggyal]

I've opted to verify the type via Any::is instead, so that failures will still compile (albeit fail the assertion).

[emilio]

LGTM, thanks!