doesn't support relative path dependencies about cargo-mutants

[sourcefrog]

Hi, thanks for the report and reproduction.

I think the problem here is that cargo-mutants makes a copy of the tree before mutating it, so any paths relative to the original location won't work, as in your reproduction tree.

https://github.com/sourcefrog/cargo-mutants#:~:text=dependencies%20by%20a%20relative%20path

Using an absolute path should work, but that's not always convenient, and I'd like for it to just work without the user needing to make any prior adjustments.

There seem to be a few options:

1. Rewrite Cargo.toml after copying to use absolute paths for any relative paths pointing out of the tree. Perhaps this is best. As a step towards this we could at least look for them and error cleanly.
2. Give an option to mutate the tree in place (and put it back afterwards.) This would avoid any patch related issues, but there's some risk that the mutation is actually not cleaned up properly if the program stops abruptly -- and anyhow the user would have to work out to use this option, which is not ideal.
3. An option to copy a larger, enclosing, directory, perhaps containing all the dependencies. But again the user needs to understand that they need it.

Probably rewriting paths in Cargo.toml is the best way to make it just work automatically. This also needs to handle the patch and .cargo/config.toml for overriding dependencies (https://doc.rust-lang.org/cargo/reference/overriding-dependencies.html).

[sourcefrog]

• Find all Cargo.toml files in the tree to be copied: there might be some in subdirectories. (Possibly we should not copy nested crates and instead turn them into relative references?)
• Parse Cargo.toml probably using https://docs.rs/toml/
• Write out the possibly-modified file into the scratch directory.
• Walk the toml looking for path attributes on dependencies.
• Also look for patch or replace sections.
• For every relative path, replace it with an absolute path, resolved from the directory where it occurs.
• Also look for and modify .cargo/config.toml.

[sourcefrog]

#43 fixes the particular case of path dependencies, although not yet all the other case. It does work on your reproduction repo. @dmoka , maybe you can try it on your bigger project?

[dmoka]

Wow, many thanks for your detailed investigation and your quick fix, much appreciated, Martin @sourcefrog !

Absolutely, happy to give it a try. I see that the latest crate version is still the v0.2.7 which does not contain this latest fix, if I am not mistaken.

What is the easiest way to get the fixed version of the crate and trying out locally?

Thanks again, and have a great day!

[sourcefrog]

Yep, it's not released yet. I'm pretty sure this works but let's check it:

1. Clone this repo
2. Switch to the 'relpath' branch
3. cargo install --path .
4. Run cargo mutants on your tree

[dmoka]

Just checked it, and the relative-path issue has been indeed resolved.

Great job, thanks for the support!

[sourcefrog]

ok this is released in 0.2.8