Use typeck_results.node_type to resolve the type in suspicious trait object lint

[thomcc]

Thanks to @compiler-errors for helping me out here, this is much cleaner too.

Fixes #348 (we still may want to turn lints entirely off when compiling dependencies, but fixing it for real is better, and trying to parse a bunch of things out of the rustc args felt hairy without a bit more testing).

[thomcc]

Note that without the change, the example I added would hit a similar ICE to the rand one. I can't add a dep on rand to the compiletests, and I don't think the plrust test suite supports deps in trusted mode, so this is probably the best option.

[eeeebbbbrrrr]

I don't think the plrust test suite supports deps in trusted mode

It does. The test suite actually sets up an allow-list so it can test that. Would be no problem to add rand to it and use rand in a unit test.

see https://github.com/tcdi/plrust/blob/07bec8de9a6c0150eee1950b94301653ea0e9cdc/plrust/src/tests.rs#L1401-L1411

[thomcc]

It does. The test suite actually sets up an allow-list so it can test that. Would be no problem to add rand to it and use rand in a unit test.

Ah, I confused the sandbox feature (no network) with trusted. (I thought somehow it had been renamed and I hadn't noticed).

I've added the test.

[eeeebbbbrrrr]

This looks good to me. Thanks for the unit test!