Book: Listing 12-14: `use minigrep;` instead of `extern crate minigrep;` results in error

Created on 10 Dec 2018 · 4Comments · Source: rust-lang/book

I'm following the current live version of the Rust book (master on Github) and encountered the following issue:

Listing 12-14 states to use use minigrep; "... to bring the library crate into the binary crate". Yet when I do that I get the following compile errors when calling cargo run:

error[E0432]: unresolved import `minigrep`                                                                                                                                
 --> src/main.rs:2:5                                                                                                                                                      
  |                                                                                                                                                                       
2 | use minigrep;                                                                                                                                                         
  |     ^^^^^^^^ no `minigrep` in the root                                                                                                                                

error[E0433]: failed to resolve. Use of undeclared type or module `Config`                                                                                                
  --> src/main.rs:11:18                                                                                                                                                   
   |                                                                                                                                                                      
11 |     let config = Config::new(&args).unwrap_or_else(|err| {                                                                                                           
   |                  ^^^^^^ Use of undeclared type or module `Config`

If I change use minigrep; to extern crate minigrep; the problem goes away.

I'd be happy to open a pull request if this is a legitimate bug.

Source

jvivian

Most helpful comment

@jvivian and @anuj1102 Do you have edition="2018" in your Cargo.toml and are you using Rust 1.31.0? The current version of the book assumes 2018 Edition Rust.

carols10cents on 10 Dec 2018

👍6

All 4 comments

I'm running into the same issue as well, and the fix above worked for me.

anuj1102 on 10 Dec 2018

@jvivian and @anuj1102 Do you have edition="2018" in your Cargo.toml and are you using Rust 1.31.0? The current version of the book assumes 2018 Edition Rust.

carols10cents on 10 Dec 2018

👍6

Hi @carols10cents,

Thank you for the reply — I see now that the book is in lockstep with the latest release of Rust and the version I installed last week (1.30.1) doesn't include the edition="2018" in Cargo.toml. I updated via rustup update and added edition = "2018" which resolved my issue. Thank you very much! I'll go ahead and close this.

jvivian on 10 Dec 2018

❤3

Yep, the edition switchover is a bit confusing right now. Glad this solved
your problem!

On Mon, Dec 10, 2018, 12:54 PM John Vivian <[email protected] wrote:

Hi @carols10cents https://github.com/carols10cents,

Thank you for the reply — I see now that the book is in lockstep with the
latest release of Rust and the version I installed last week (1.30.1)
doesn't include the edition="2018" in Cargo.toml. I updated via rustup
update and added edition = "2018" which resolved my issue. Thank you very
much! I'll go ahead and close this.

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