failed to resolve: could not find `XYZ` in `{{root}}`

[istvans]

Sublime Text Version

Sublime Text 3.1.1 (Build 3176)

Rust Enhanced Version

2.18.0

Operating system

OS Name: Microsoft Windows 10 Enterprise
Version: 1803
OS Build: 17134.472
System type: x64

Expected behavior

No error.

Actual behavior

error: failed to resolve: could not find client in {{root}}

Steps to reproduce

1. cargo new --lib namespace_error
2. cd namespace_error/src
3. Put the content of lib.rs (see below) into lib.rs
4. Save and the unexpected error message appears in Sublime Text, but on the command line cargo build or cargo check passes fine!

Rust Enhanced Debug Log

+0.000 Running: cargo metadata --no-deps
+0.057 Running: cargo metadata --no-deps
+0.059 Running: rustc --version
+0.058 Running: cargo check --lib --message-format=json --profile=test
+0.051     Checking ch7-02_error v0.1.0 (D:\odrive\Steve-OneDrive\Dev\Rust\ch7-02_error)
+0.064 error: Could not compile `ch7-02_error`.
+0.000 
+0.000 To learn more, run the command again with --verbose.
+0.007 On-save check finished.

The content of lib.rs

pub mod client {
    pub fn connect() {}
}

#[cfg(test)]
mod tests {
    #[test]
    fn it_works() {
        ::client::connect();
    }
}

Additional details

This is a simplified version of an example from the book, chapter 7.3.
super::client::connect() works with Rust Enhanced too, but the shorter :: version should work too.
cargo check --lib --message-format=json --profile=test in my Cmder mintty.exe (git for windows) command line works fine, but I get the same error if I run the same command in windows cmd.

$ which cargo
/c/Users/Aurora/.cargo/bin/cargo
...
>where cargo
C:\Users\Aurora\.cargo\bin\cargo.exe

It seems the same cargo binary produces different outputs in different environments.

However, running the test returns the same error in both mintty and cmd:

$ cargo test
   Compiling namespace_error v0.1.0 (D:\odrive\Steve-OneDrive\Dev\Rust\namespace_error)
error[E0433]: failed to resolve: could not find `client` in `{{root}}`
 --> src\lib.rs:9:11
  |
9 |         ::client::connect();
  |           ^^^^^^ could not find `client` in `{{root}}`

error: aborting due to previous error

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

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

Is this valid code or chapter 7.3 is wrong in the book?

[ehuss]

This is due to the difference between the 2018 and 2015 editions. cargo new defaults to creating new projects in the 2018 edition which handles paths differently. In this particular case, you want to use crate::client::connect();.

There are a few things you can do:

• Switch the edition in Cargo.toml to 2015 and continue following the book that you have.
• Switch to the 2018 edition of the book (https://doc.rust-lang.org/book/) which has been updated for the changes.

If you want to learn more about the 2018 edition, there is the edition guide. The only section that really matters for most people is the path clarity.

[ehuss]

I'm going to close this for now. If you have any more questions about Rust in general, I suggest one of the Rust forums (users, reddit, etc.) or chat platforms.