Best way to report nightly breakage?

Hello, everyone,
What's the best way to report a break that I believe to be caused by nightly update?

The following crate compiles fine under recent nightly and nightly-2018-06-27:

But if you try to run cargo run --example thor, recent nightly breaks with really difficult to understand error messages, where previous nightly (nightly-2018-06-27) works just fine