initial duplicate bevy version lint

[DaAlbrecht]

A first draft of a quick lint to check if multiple versions of bevy are defined. #15

todos:

• create ui test
• better error message, perhaps use cargo metadata to get information about the crate versions.
• fix the span ( this should point to the crate causing the issue in the Cargo.toml)

error: Multiple versions of `bevy` found
  --> /Users/didi/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bevy-0.13.2/src/lib.rs:1:1
   |
1  | / #![allow(clippy::single_component_path_imports)]
2  | |
3  | | //! [![](https://bevyengine.org/assets/bevy_logo_d...
4  | | //!
...  |
51 | | #[allow(unused_imports)]
52 | | use bevy_dylib;
   | |_______________^
   |
   = note: `#[deny(bevy::duplicate_bevy_dependencies)]` on by default

[BD103]

So far this looks good! I am interested in getting a span to Cargo.toml / Cargo.lock, though I'm unsure if the compiler will know that file exists. Ping me when this is ready for a final review!

[DaAlbrecht]

example of the lint message

error: Mismatching versions of `bevy` found
  --> Cargo.toml:10:26
   |
10 | leafwing-input-manager = "0.13"
   |                          ^^^^^^
   |
help: Expected all crates to use `bevy` 0.14.2
  --> Cargo.toml:8:8
   |
8  | bevy = { version = "0.14.2", features = ["android_shared_stdcxx"] }
   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[BD103]

One function you may find useful is was_invoked_from_cargo(), which detects whether we're being run from Cargo or not. We can use this to skip Cargo lints when bevy_lint_driver is called directly!

[DaAlbrecht]

One function you may find useful is was_invoked_from_cargo(), which detects whether we're being run from Cargo or not. We can use this to skip Cargo lints when bevy_lint_driver is called directly!

nice catch! Thanks will add this.