internal compiler error: Switch on discriminant of non-ADT

[russcam]

Hi! I'm using the github clippy action, and have started to see the following internal compiler error when clippy runs

    Checking rustc-ap-rustc_parse v642.0.0
error: internal compiler error: src\librustc_mir\dataflow\generic\engine.rs:315: Switch on discriminant of non-ADT

thread 'rustc' panicked at 'Box<Any>', src\librustc_errors\lib.rs:881:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust-clippy/issues/new

note: Clippy version: clippy 0.0.212 (fc5d0cc5 2020-02-24)

error: aborting due to previous error

This can be seen in https://github.com/elastic/elasticsearch-rs/commit/d0efcc8e174682da9d2cf215f1dacdedaf802b0b/checks?check_suite_id=487235109.

I can reproduce it locally with latest nightly.

[JohnTitor]

Thanks for the report! We also saw that in our CI: https://github.com/rust-lang/rust-clippy/runs/473320782
I've investigated and prepared a fix.

[matthiaskrgr]

reduced crash sample:

#![feature(generators, generator_trait)]

fn main() {
    let _ = || { yield; };
}

[repi]

We also ran into this with the same clippy version and latest nightly