Cargo info does not support underscore (_) for packages named with hyphen (-)

[iampi31415]

Problem

I expected the commands to be equivalent:

cargo info esp_println # with _ 
cargo info esp-println # with -

The latter is the actual name and runs fine. The former (with underscore) instead, says:

error: could not find esp_println in registry https://github.com/rust-lang/crates.io-index

Steps

cargo info esp_println # with _ 
cargo info esp-println # with -

Possible Solution(s)

Both should return the same output.

But if this is intentional a help message here suggesting replacing _ with - would be helpful.

I would say the same about -F flag, they should both be consistent with add imho and check for both _ and -.

---

Thanks for this great software, it's one of my favourites ever.

[ranger-ross]

I think cargo info matching the behavior of cargo add makes sense

Checking the behavior of cargo add we see Cargo emits a warning to the user and automatically replaces the underscore with a hyphen

$ cargo add esp_println
    Updating crates.io index
warning: translating `esp_println` to `esp-println`
      Adding esp-println v0.16.1 to dependencies
     ....

[weihanglo]

Yeah agree with @ranger-ross . Cargo has stopped enumerating all combinations of dash-underscore for a while in order to reduce HTTP requests. For all-dashes/all-underscores we can still do that

@rustbot label +Command-info +S-needs-mentor -S-triage

cc @0xPoe

[dhruv-38]

Hi! I’d like to work on this issue.

Based on the discussion, I plan to make cargo info match the behavior of
cargo add by translating all underscores to hyphens (with a warning),
without enumerating mixed combinations.

Please let me know if that sounds good before I start coding.

[ranger-ross]

The issue is marked as S-needs-mentor which mean that the issue is accepted but no one from the Cargo team has agreed to mentor or review the PR. (see status labels meanings)

I took a quick look at the code and it seems that there is not a lot of code reuse between cargo add and cargo info.
Though I think the core change here is going to change the registry query used in cargo info to use QueryKind::Normalized instead of QueryKind::Exact to match cargo add (ref) (ref)

Then updating the surrounding code to handle that change and emitting a warning like cargo add. (example)

I am not on the Cargo team but I wouldn't mind helping mentor this change and help review your PR. :)
I'd recommend reading through the Cargo contributor guide (there is a lot of good information in there).

As for this change, I'd recommend:

1. First create a test for the current behavior (the command errors) using Cargo's testsuite in its own commit
2. Then make the required changes and update the test you added with newly expected behavior.

[dhruv-38]

Ok i will start working on it.

[dhruv-38]

should the test show that the error exist or what do we have to show in the test? also should it be categorised in functional test or UI test? @ranger-ross

[epage]

In this case, that seems the most relevant. Sometimes we go the other way and contrast it with other behavior (e.g. when adding a new flag, show what happens without the flag, rather than an unknown flag error)

[ranger-ross]

replied in your Zulip thread #general > writing test for cargo @ 💬