x.py clippy fails with E0277 and E0658

[Nicholas-Baron]

Trying to run ./x.py clippy using the beta toolchain's clippy results in ~32 errors.

Raw output

There are a bunch of attribute should be applied to a macro errors, then a E0658 (impl Trait not allowed on const fns), and finally 3 E0277 (the size of Self is not known at compile time). All seem to come out of library/core.

[Nicholas-Baron]

@rustbot modify labels to +A-clippy and +A-rustbuild.

[jyn514]

@Nicholas-Baron you need to update your version of beta. This is the error I get, which is an internal error in clippy:

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src/tools/clippy/clippy_lints/src/methods/mod.rs:3904:68
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 0.0.212 (603ab5b 2020-11-15)

[Nicholas-Baron]

My version of clippy (from cargo clippy -V) is clippy 0.0.212 (7eac88a 2020-11-16), which is technically later than yours, @jyn514.

[jyn514]

Whoops, I was using the wrong clippy, sorry.

[Nicholas-Baron]

@jyn514 I ran ./x.py clippy on a whim today and I got the same error you got.

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src/tools/clippy/clippy_lints/src/methods/mod.rs:3904:68
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 0.0.212 (21dea46 2020-11-18)

query stack during panic:
#0 [analysis] running analysis passes on this crate
end of query stack
warning: 280 warnings emitted

In the end, whether running either version documented here, ./x.py clippy cannot go through the entire project.

Update: checked the version number (cargo clippy -V) and it is clippy 0.0.212 (21dea46 2020-11-18).

[jyn514]

@Nicholas-Baron I am unlikely to have time to look into this in the near future. I vaguely remember there being an issue open for the clippy ICE, but feel free to open one (in the clippy repo, not here) if there isn't.

[Nicholas-Baron]

@jyn514 Set up an issue on the clippy end. Closing as it will probably be handled by clippy.

[Nicholas-Baron]

@jyn514 So the issue is resolved on their end. (See pull request 6304)
However, it looks like the commit that fixes the issue is not synced with what ./x.py is using.

[jyn514]

@Nicholas-Baron x.py clippy uses your host version of clippy, it's not related to the commit you have checked out. You need to rustup update nightly.

[jyn514]

Hmm, and that fails with its own error:

thread 'rustc' panicked at 'forcing query with already existing `DepNode`
- query-key: (DefId(0:3866 ~ rustc_middle[1bf6]::ty::codec::TyDecoder), Some(Error#7290))
- dep-node: super_predicates_that_define_assoc_type(5a78152153c9663-dcf2c310262fcf17)', /rustc/349b3b324dade7ca638091db93ba08bbc443c63d/compiler/rustc_query_system/src/query/plumbing.rs:586:5
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 0.0.212 (349b3b3 2020-11-29)

query stack during panic:
#0 [fn_sig] computing function signature of `<rustc_index::vec::IndexVec<mir::Promoted, mir::Body<'tcx>> as ty::codec::RefDecodable<'tcx, D>>::decode`
#1 [collect_mod_item_types] collecting item types in module `ty::codec`
end of query stack

which looks like #79560.

[Nicholas-Baron]

So, when developing rustc, is it best to use nightly and not beta?
I do not remember reading which one was correct.

[jyn514]

x.py clippy is not really supported either way - it's "best-effort" for both. I used nightly because beta panics, that's the bug you pointed out in #79244 (comment).

[Nicholas-Baron]

So clippy is not even officially supported for this repo. No wonder it dumps hundreds of warnings and broke because of some edits somewhere.

In the meantime, I will switch to nightly and report the error to clippy.

[jyn514]

@Nicholas-Baron no need to report an error, there's already an issue open: #79560

[jyn514]

and yeah, I don't think anyone even tried to use clippy before you opened an issue 😆 you saw I had to add a whole new part of bootstrap just for it.

[Nicholas-Baron]

@jyn514 I just want Rust tools to work in the Rust compiler, that is all. Also, the option was there. If you give people a button, they will push it.
Ok, so "sit and wait" is what I am hearing.

[matthiaskrgr]

@Nicholas-Baron in order to use clippy on rustc, I found this recipe to work in most of the cases (trying to deal with beta-clippy or outdated nightly clippy is just too much pain imo)
rust-lang/rust-clippy#6383 (comment)
hope it helps somehow.

[Nicholas-Baron]

@matthiaskrgr Even if it works, the recipe seems a bit long to get a simple ./x.py clippy working. To me, the fact that ./x.py help even shows a clippy option means to me that it should work like ./x.py check or ./x.py build:

• Without hassle
• No special recipes
• "It just works"

To me, if a tool provides an option, that option must be maintained and "just work". All of x.py's other options work, so why not this one?

[jyn514]

@Nicholas-Baron the alternative is I can remove the option 🤷 all the work in this repo is on a volunteer basis and we just don't have the manpower to make everything work out of the box. If you want help fixing the issues I'm happy to give you suggestions, but complaining about it doesn't help anything.