failed to create span for type parameters, src/tools/clippy/clippy_lints/src/implicit_hasher.rs:175:34

[alexander-jackson]

This originally failed in CI here, however it also fails locally with the same error.

Meta

alexander@cinnamon ~/D/U/P/r/blackboards> rustc -Vv
rustc 1.57.0-nightly (308dffd25 2021-09-22)
binary: rustc
commit-hash: 308dffd25cb55bbb4a1fbee9822cf82c6a5d012d
commit-date: 2021-09-22
host: x86_64-apple-darwin
release: 1.57.0-nightly
LLVM version: 13.0.0

Error Output

alexander@cinnamon ~/D/U/P/r/blackboards> cargo clippy -- -D warnings
    Checking blackboards v0.1.0 (/Users/alexander/Documents/University/Programming/rust/blackboards)
thread 'rustc' panicked at 'failed to create span for type parameters', src/tools/clippy/clippy_lints/src/implicit_hasher.rs:175:34
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

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 0.1.57 (308dffd2 2021-09-22)

query stack during panic:
#0 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `blackboards`

[giraffate]

Thanks for the report!

async seems to cause this like here: https://github.com/alexander-jackson/blackboards/blob/81f35cdb8af9b61830d5fdc0f9b15b4b6919b34a/src/api.rs#L264.

The minimal reproduction is here: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=90e5cebbeb4561b17cb17b9dc42403a8

[Milo123459]

I'd be happy to contribute to fix this, how can I go about fixing it?

[xFrednet]

Hey @Milo123459, the thing with ICEs (Internal Compiler Errors) is, that it can be hard to determine where to start. If you want to dive into this, you can first look at the back trace to determine, where this originates inside Clippy. To then check if this is a mistake in our code, and illegal use of the rustc API (documented here) or an error inside the compiler. A sense of what triggers panics in Clippy and rustc is usually good for this. Those are the best pointers I can give you right now 😅