Make cargo recognize commands from uninstalled plugins

[estebank]

Problem

When executing cargo foo, without having executed cargo install cargo-foo beforehand, the error message will be something along the lines of

error: no such subcommand: `foo`

        Did you mean `doc`?

Given that we can have the full list crates available to us, we can detect that a user is trying to use a not-yet-installed subcommand.

Proposed Solution

No response

Notes

No response

[weihanglo]

Given that we can have the full list crates available to us, we can detect that a user is trying to use a not-yet-installed subcommand.

Mind that the precondition might not be fulfilled when the sparse-registry becomes the default in the future, unless we address it with a solution like #10928.

[epage]

btw some recent improvements around "no such command" was done in #10924

[epage]

Until we have a full list of crates, we could potentially check the registry specifically for cargo-foo but

• We would want to do this offline as it would be surprising to reach out over the network
• Sparse registry only caches locally what you use which would make offline checking for cargo-foo very limited

[epage]

Would it be worthwhile to always add a suggestion To install the command, run 'cargo install cargo-foo' until we can show it only when needed?

I lean towards "no" but thought it worth bringing up.

[weihanglo]

If Cargo found a crate with the exact name, but it were a malicious/low-quality/abandoned crate, should Cargo recommend it?

[epage]

Was going to respond but I finally found the issue is this is a duplicate of (I knew I had seen this before).

Closing in favor of #4682, let's continue the discussion there.