How to tell Cargo to use a git repository as source for an indirect dependency instead of crates.io?

Question

A few days ago, cross-compiling to JavaScript via Emscripten has finally hit nightly. I wanted to compile a project using glium in that manner. However, there are still many Emscripten-related bugs in many crates. While maintainers usually fix those bugs quickly, they don't necessarily release those bug fixes to crates.io immediately.

In my case, glium depends on glutin. glutin had a bug which is fixed now, but only in the git repository, not on crates.io. Note: glutin is not a direct dependency of my project; only an indirect one through glium!

How do I tell Cargo to use the glutin repository as source for glutin instead of crates.io?

Answer 1

You can use the [replace] section in your project's Cargo.toml. You can find the documentation about that feature here in the Cargo documentation.

In your case, glium depends on glutin 0.6.1. The version 0.6.1 on crates.io still contains the bug. So just add this to your Cargo.toml:

[replace]
"glutin:0.6.1" = { git = 'https://github.com/tomaka/glutin' }

---

Note however,

[...] that the replaced crate must not only have the same name but also the same version.

But even in the case of a version-mismatch (the repository already contains a newer version), you could still be in luck if the crate's maintainer creates git tags for every version (many in the Rust community do). In that case you can just specify the tag:

[replace]
"glutin:0.6.1" = { 
    git = 'https://github.com/tomaka/glutin' 
    tag = 'v0.6.1'
}

Sadly, this won't work with glutin, because the maintainer did not create tags for every version. In that case you can simply find the last commit before the version was bumped and specify it with rev = 'b4a3d0...' or specify a specific branch with the branch = '...' key.