Misleading error message when ambiguity between a function and module is introduced

[davidbarsky]

Given this code (playground):

use tokio::sync::mpsc;

fn main() {
    let (tx, rx) = mpsc::channel::new(1);
}

I expected that rustc would indicate that new() is not function but channel(1) is. Instead, I got:

   Compiling playground v0.0.1 (/playground)
error[E0433]: failed to resolve: could not find `channel` in `mpsc`
 --> src/main.rs:4:26
  |
4 |     let (tx, rx) = mpsc::channel::new(1);
  |                          ^^^^^^^ could not find `channel` in `mpsc`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0433`.
error: could not compile `playground`.

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

A diagnostic along the lines of new(..) isn't a function, but channel(..) is would be helpful.

Meta

rustc --version --verbose:

❯ rustc --version --verbose
rustc 1.42.0 (b8cedc004 2020-03-09)
binary: rustc
commit-hash: b8cedc00407a4c56a3bda1ed605c6fc166655447
commit-date: 2020-03-09
host: x86_64-apple-darwin
release: 1.42.0
LLVM version: 9.0

[contrun]

I tried to resolve this issue with #71419

The error message now is

`channel` in `mpsc` is a concrete value (function, constant), not a module or Struct you specified

Any informative error message suggestions?

[davidbarsky]

@contrun Thanks for trying to address this. I'll comment on the PR you opened.