Suspicious state from syntax checker rust-cargo: Flycheck checker rust-cargo returned 101, but its output contained no errors: error: no library targets found in package ...

[arcimboldo]

Hi, I installed flycheck from elpa, I am running emacs from ubuntu 25.04.

I just created a crate and opened the main.rs with emacs and I get:

Suspicious state from syntax checker rust-cargo: Flycheck checker rust-cargo returned 101, but its output contained no errors: error: no library targets found in package `hw_cargo`

Try installing a more recent version of rust-cargo, and please open a bug report if the issue persists in the latest release.  Thanks!
Type q in help window to delete it

Output of flycheck-verify-setup:

Syntax checkers for buffer main.rs in rust-mode:

First checker to run:

  rust-cargo
    - may enable:  yes
    - may run:     t
    - executable:  Found at /usr/bin/cargo
    - Cargo.toml:  Found
    - Crate type:  lib
    - Binary name: Not required

Checkers that could run if selected:

  rust  select
    - may enable: yes
    - may run:    t
    - executable: Found at /usr/bin/rustc

  rust-clippy  select
    - may enable: yes
    - may run:    t
    - executable: Found at /usr/bin/cargo
    - Clippy:     Found
    - Cargo.toml: Found

Flycheck Mode is enabled.  Use C-u C-c ! x to enable disabled
checkers.

--------------------

Flycheck version: nil
Emacs version:    30.1
System:           x86_64-pc-linux-gnu
Window system:    x

Versions:

• flycheck 35.0, but I manually patched with the fix from Rust: couldn't create a temp dir: Operation not permitted flycheck#2043
• rustup 1.27.1-3 (debian package)
• rustc, cargo: 1.91.1 (from rustup update)
• emacs: 30.1 (debian package)

[LukasBauza]

I am having the same issue, it seems as though it thinks that my project is a library.

At the moment I am using the flycheck-rust package to fix the issue.