Please provide a subcommand to refresh the crates.io index

[joshtriplett]

When writing other tools that use the cargo API, and that don't want to unconditionally update the crates.io index from the network, it would help to have a cargo subcommand that refreshes the crates.io index. That avoids having to add such a subcommand to every other such tool built on the cargo API.

[Eh2406]

Or more generally an subcommand for querying the index, so we are not each reinventing it. Maybe move the index stuff into a crate, like the crates.io library. There is rust-crates-index but it is not kept up to date with how cargo maintains the index.

[Eh2406]

Note that crater will in 178 use cargo search lazy_static as a way to get cargo to update the index. Then it will use the -Z no-index-update to skip checking if the index is still up to date.

[Arnavion]

You can use cargo search --limit 0 instead of using a crate like lazy_static.

[nabijaczleweli]

Since 5e680f2, cargo search will no longer update the registry. This has hit those users of cargo install-update who default to nightly so far, but will outright break every installation as that commits gets released down.

This also is a bug in cargo search: it doesn't provide accurate results. We either need a flag for cargo search to always update it, or another command to do so.

[Eh2406]

cc #5621 where the logic for search was changed.
Note that one of the users of the search hack was crater, so when we have somthing that works, they need a PR. In the meantime @pietroalbini how big a deal is it that this is broken?

[pietroalbini]

Uh, this means Crater won't update the registry when generating the lockfiles :/
While cargo update-registry rides the trains I guess we could use cargo install lazy_static, which should do nothing but update the registry (@Eh2406 want to send a PR to Crater?)