Warn about unrecognized sections

[jdm]

I regularly misspell patch overrides as [path."https://github.com/foo/bar"], and it's always quite frustrating and easy to overlook while I'm trying to figure out why my override isn't taking effect.

[iancormac84]

I'm interested in working on this, please. I believe I'll have to look for the code to parse the Cargo.toml manifests?

[alexcrichton]

@iancormac84 awesome! All the code for that is in cargo::util::toml currently, and while we do have code for processing unused manifest keys for some reason it's not catching the above!

[iancormac84]

So my proposed plan of action is to use lev_distance to detect strings that may be referring to a 'patch' section and then warn about a possible mistake. How does that sound? Any other suggested manifest keys that may need a little warning attention while I'm at it?

[kellerkindt]

Well, I just fell for this. A hint would have saved me quite few minutes. Try to spot the error:

serde = { version = "1.0.126", optional = true, feautres = ["derive"] }

$ cargo build
...
error[E0433]: failed to resolve: could not find `Deserialize` in `serde`
...

Solution

feautres (wrong)
features(correct)

[epage]

See also #3576

[weihanglo]

We already have serde_ignore to catch all unused keys, I believe this should already be resolved. Some sections accepting arbitrary keys are required special cares. I lean towards tackling them one by one if there is an issue.

• For this issue for [patch], we have Warn on unused patches. #6470 resolving it.
• For dependencies.<crate>.sometypo, the fix fix(toml): Provide a way to show unused manifest keys for dependencies #11630 is available in 1.69.0.

What else do we need to handle?

• [replace]? Though it is deprecated I am reluctant to put efforts on it.
• [target.<platform>.dependencies]? It's nearly impossible to check whether a platform is valid or not.
• [lints]? We should keep an eye on this as it is deserialized to toml::Value. For now it is handled very well.

[weihanglo]

Going to close this. If you have encountered any similar issue with a newer Cargo. Please leave a comment or file a new issue report.

For the three remaining items mentioned in #5264 (comment), I personally don't think they are worth fixing. If anyone wants to do it, please file a new issue and we can start the discussion.

Thank you!