Building SQLx with -Z features fails

[jplatte]

Here's what I've found fails:

• cargo build -Z features=all
• cargo build -Z features=all --no-default-features --features runtime-async-std,migrate
• cargo build -Z features=all --no-default-features --features runtime-async-std,any

I haven't (yet) been able to surface this just compiling sqlx-core.

[jplatte]

Okay, I think I've found the pattern: This happens whenever the async-std runtime is enabled (none of the other runtimes have this issue) and at least some additional features are used (migrate and any work, others may too).

I think what must be happening here is that sqlx is using some feature(s) without activating its feature flag, but with the old feature resolver they are enabled through a build or dev dependency. The actix and tokio runtimes apparently also enable this feaure, but the async-std runtime does not.

[jplatte]

Error:

   Compiling sqlx-core v0.4.0-pre (/home/jplatte/Projekte/_work/sqlx/sqlx-core)
error[E0599]: no method named `send` found for struct `futures_channel::mpsc::Sender<std::result::Result<T, error::Error>>` in the current scope
   --> sqlx-core/src/ext/async_stream.rs:29:32
    |
29  |                 let _ = sender.send(Err(error)).await;
    |                                ^^^^ method not found in `futures_channel::mpsc::Sender<std::result::Result<T, error::Error>>`
    | 
   ::: /home/jplatte/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-channel-0.3.5/src/mpsc/mod.rs:125:1
    |
125 | pub struct Sender<T>(Option<BoundedSenderInner<T>>);
    | ----------------------------------------------------
    | |
    | doesn't satisfy `_: futures_util::SinkExt<_>`
    | doesn't satisfy `_: futures_util::sink::Sink<_>`
    |
    = note: the method `send` exists but the following trait bounds were not satisfied:
            `futures_channel::mpsc::Sender<std::result::Result<T, error::Error>>: futures_util::sink::Sink<_>`
            which is required by `futures_channel::mpsc::Sender<std::result::Result<T, error::Error>>: futures_util::SinkExt<_>`
    = help: items from traits can only be used if the trait is in scope
    = note: the following trait is implemented but not in scope; perhaps add a `use` for it:
            `use futures_util::sink::SinkExt;`

error[E0277]: the trait bound `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>: futures_util::sink::Sink<_>` is not satisfied
   --> sqlx-core/src/ext/async_stream.rs:66:29
    |
66  |                     let _ = futures_util::sink::SinkExt::send(&mut sender, Ok($v)).await;
    |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `futures_util::sink::Sink<_>` is not implemented for `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>`
    | 
   ::: /home/jplatte/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/sink/mod.rs:208:21
    |
208 |         where Self: Unpin,
    |                     ----- required by this bound in `futures_util::SinkExt::send`
    | 
   ::: sqlx-core/src/pool/executor.rs:32:17
    |
32  |                 r#yield!(v);
    |                 ------------ in this macro invocation
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>: futures_util::sink::Sink<std::result::Result<either::Either<<DB as database::Database>::Done, <DB as database::Database>::Row>, _>>` is not satisfied
  --> sqlx-core/src/ext/async_stream.rs:66:29
   |
66 |                     let _ = futures_util::sink::SinkExt::send(&mut sender, Ok($v)).await;
   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `futures_util::sink::Sink<std::result::Result<either::Either<<DB as database::Database>::Done, <DB as database::Database>::Row>, _>>` is not implemented for `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>`
   | 
  ::: sqlx-core/src/pool/executor.rs:32:17
   |
32 |                 r#yield!(v);
   |                 ------------ in this macro invocation
   |
   = note: required because of the requirements on the impl of `futures_core::Future` for `futures_util::sink::Send<'_, futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>, std::result::Result<either::Either<<DB as database::Database>::Done, <DB as database::Database>::Row>, _>>`
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>: futures_util::sink::Sink<_>` is not satisfied
   --> sqlx-core/src/ext/async_stream.rs:66:29
    |
66  |                       let _ = futures_util::sink::SinkExt::send(&mut sender, Ok($v)).await;
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `futures_util::sink::Sink<_>` is not implemented for `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>`
    | 
   ::: /home/jplatte/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/sink/mod.rs:208:21
    |
208 |           where Self: Unpin,
    |                       ----- required by this bound in `futures_util::SinkExt::send`
    | 
   ::: sqlx-core/src/query.rs:249:17
    |
249 | /                 r#yield!(match v {
250 | |                     Either::Left(v) => Either::Left(v),
251 | |                     Either::Right(row) => {
252 | |                         Either::Right((self.mapper)(row)?)
253 | |                     }
254 | |                 });
    | |___________________- in this macro invocation
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>: futures_util::sink::Sink<std::result::Result<either::Either<<DB as database::Database>::Done, O>, _>>` is not satisfied
   --> sqlx-core/src/ext/async_stream.rs:66:29
    |
66  |                       let _ = futures_util::sink::SinkExt::send(&mut sender, Ok($v)).await;
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `futures_util::sink::Sink<std::result::Result<either::Either<<DB as database::Database>::Done, O>, _>>` is not implemented for `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>`
    | 
   ::: sqlx-core/src/query.rs:249:17
    |
249 | /                 r#yield!(match v {
250 | |                     Either::Left(v) => Either::Left(v),
251 | |                     Either::Right(row) => {
252 | |                         Either::Right((self.mapper)(row)?)
253 | |                     }
254 | |                 });
    | |___________________- in this macro invocation
    |
    = note: required because of the requirements on the impl of `futures_core::Future` for `futures_util::sink::Send<'_, futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>, std::result::Result<either::Either<<DB as database::Database>::Done, O>, _>>`
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>: futures_util::sink::Sink<_>` is not satisfied
   --> sqlx-core/src/ext/async_stream.rs:66:29
    |
66  |                       let _ = futures_util::sink::SinkExt::send(&mut sender, Ok($v)).await;
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `futures_util::sink::Sink<_>` is not implemented for `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>`
    | 
   ::: /home/jplatte/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/sink/mod.rs:208:21
    |
208 |           where Self: Unpin,
    |                       ----- required by this bound in `futures_util::SinkExt::send`
    | 
   ::: sqlx-core/src/query_as.rs:89:17
    |
89  | /                 r#yield!(match v {
90  | |                     Either::Left(v) => Either::Left(v),
91  | |                     Either::Right(row) => Either::Right(O::from_row(&row)?),
92  | |                 });
    | |___________________- in this macro invocation
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>: futures_util::sink::Sink<std::result::Result<either::Either<<DB as database::Database>::Done, O>, _>>` is not satisfied
  --> sqlx-core/src/ext/async_stream.rs:66:29
   |
66 |                       let _ = futures_util::sink::SinkExt::send(&mut sender, Ok($v)).await;
   |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `futures_util::sink::Sink<std::result::Result<either::Either<<DB as database::Database>::Done, O>, _>>` is not implemented for `futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>`
   | 
  ::: sqlx-core/src/query_as.rs:89:17
   |
89 | /                 r#yield!(match v {
90 | |                     Either::Left(v) => Either::Left(v),
91 | |                     Either::Right(row) => Either::Right(O::from_row(&row)?),
92 | |                 });
   | |___________________- in this macro invocation
   |
   = note: required because of the requirements on the impl of `futures_core::Future` for `futures_util::sink::Send<'_, futures_channel::mpsc::Sender<std::result::Result<_, error::Error>>, std::result::Result<either::Either<<DB as database::Database>::Done, O>, _>>`
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

warning: unused import: `SinkExt`
 --> sqlx-core/src/ext/async_stream.rs:8:40
  |
8 | use futures_util::{pin_mut, FutureExt, SinkExt};
  |                                        ^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

error: aborting due to 7 previous errors; 1 warning emitted

Some errors have detailed explanations: E0277, E0599.
For more information about an error, try `rustc --explain E0277`.
error: could not compile `sqlx-core`.

To learn more, run the command again with --verbose.

[mehcode]

this almost looks like a bug in Cargo

    | doesn't satisfy `_: futures_util::SinkExt<_>`
    | doesn't satisfy `_: futures_util::sink::Sink<_>`
    |
    = note: the method `send` exists but the following trait bounds were not satisfied:
            `futures_channel::mpsc::Sender<std::result::Result<T, error::Error>>: futures_util::sink::Sink<_>`
            which is required by `futures_channel::mpsc::Sender<std::result::Result<T, error::Error>>: futures_util::SinkExt<_>`
    = help: items from traits can only be used if the trait is in scope
    = note: the following trait is implemented but not in scope; perhaps add a `use` for it:
            `use futures_util::sink::SinkExt;`

and two versions of futures-util are definitely not in play

[mehcode]

I dug a little bit. The impl of Send for futures_channel::mpsc::Sender is only gated on a sink feature in futures-channel. That's globally enabled in sqlx-core.

[jplatte]

I guess one needs to build with --verbose to see what features flags are being passed.

this almost looks like a bug in Cargo

Seems plausible considering what you found and the fact the error is in sqlx-core but I haven't (so far) found a way of triggering it without telling cargo to build the main sqlx crate.

[jplatte]

This seems to still be happening, but with different errors. This time I'm not sure it's a Cargo issue. But if it is, should maybe mention it on the tracking issue for the new feature resolver (rust-lang/rfcs#2957) which is now in FCP.

[jplatte]

I can't reproduce this anymore, even by checking out an old version of SQLx.