`cargo doc` fails

[tomharmon]

Trying to build the docs from the root of this repository fails on macOS 10.15.2 with rustc 1.42.0-nightly (698fcd38f 2020-01-26)

I receive the following error:

error[E0277]: the trait bound `(): std::future::Future` is not satisfied
  --> noria/src/controller.rs:65:5
   |
65 |     type Future = impl Future<Output = Result<Self::Response, Self::Error>> + Send;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::future::Future` is not implemented for `()`
   |
   = note: the return type of a function must have a statically known size

error[E0277]: the trait bound `(): std::future::Future` is not satisfied
  --> noria/src/view.rs:38:5
   |
38 | /     type Future = impl Future<
39 | |         Output = Result<multiplex::MultiplexTransport<Transport, Tagger>, tokio::io::Error>,
40 | |     >;
   | |______^ the trait `std::future::Future` is not implemented for `()`
   |
   = note: the return type of a function must have a statically known size

error[E0277]: the trait bound `(): std::future::Future` is not satisfied
  --> noria/src/table.rs:42:5
   |
42 | /     type Future = impl Future<
43 | |         Output = Result<multiplex::MultiplexTransport<Transport, Tagger>, tokio::io::Error>,
44 | |     >;
   | |______^ the trait `std::future::Future` is not implemented for `()`
   |
   = note: the return type of a function must have a statically known size

error[E0277]: the trait bound `(): std::future::Future` is not satisfied
   --> noria/src/controller.rs:179:1
    |
179 | type RpcFuture<A, R> = impl Future<Output = Result<R, failure::Error>>;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::future::Future` is not implemented for `()`
    |
    = note: the return type of a function must have a statically known size

error[E0277]: the trait bound `(): std::future::Future` is not satisfied
   --> noria/src/table.rs:235:5
    |
235 |     type Future = impl Future<Output = Result<Tagged<()>, TableError>> + Send;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::future::Future` is not implemented for `()`
    |
    = note: the return type of a function must have a statically known size

error[E0277]: the trait bound `(): std::future::Future` is not satisfied
   --> noria/src/view.rs:201:5
    |
201 |     type Future = impl Future<Output = Result<Vec<Datas>, ViewError>> + Send;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::future::Future` is not implemented for `()`
    |
    = note: the return type of a function must have a statically known size

error: aborting due to 6 previous errors

For more information about this error, try `rustc --explain E0277`.
error: Could not document `noria`.

[jonhoo]

That's fascinating... cargo check and cargo test both work fine. I have absolutely no idea why it'd fail under cargo doc... Sort of sounds like a cargo bug. Any suggestions?

[tomharmon]

No idea. My friend tried it on Manjaro and it fails with the same error. cargo check and cargo test work for me so yes, definitely weird.

[intendednull]

Failing for me too on arch 5.5.3 w/ rustc 1.43.0-nightly (58b834344 2020-02-05). Can confirm everything else works.

[jonhoo]

Ah, this is https://github.com/rust-lang/rust/issues/65863, which also prevents the noria crates from working on docs.rs :cry:

[anandijain]

this may be a different bug, but on cargo doc --open, I get:

The binary 'vote' is specified by packages 'noria-applications v0.3.0' and 'noria-orchestration v0.3.0' but can be documented only once. Consider renaming or marking one of the targets as 'doc = false'.

it's not exactly clear where I should mark the target doc=false. thanks!

[jonhoo]

Ah, interesting... That's super weird. We can really mark both of those as doc = false. In the meantime, I think you'll want cargo doc --lib -p noria.

[jonhoo]

I pushed a commit to master now that should take care of it!

[anandijain]

Thanks!

[anandijain]

after git pulling, running cargo doc --lib -p noria and cargo doc --open now gives:

the trait `core::future::future::Future` is not implemented for `()`... 
error: Could not document `tokio-tower`.

So unlike the original issue, the error is on tokio-tower not noria.

[jonhoo]

Yup, although it's still the same underlying issue :)

[jonhoo]

This should now work (there are also now docs on docs.rs!), though you'll have to comment out the line indicate in the root-level Cargo.toml (or you'll hit https://github.com/rust-lang/rust/issues/73061).