Generally, cargo avoids positional arguments. Mostly for the commands
that might forward arguments to another command, like `cargo test`.
It also allows some flexibility in turning flags into options.
For `cargo add` and `cargo remove`, we decided to accept positionals
because the motivations didn't seem to apply as much (similar to `cargo
install`).
This applies the pattern to `cargo update` as well which is in the same
category of commands as `cargo add` and `cargo remove`.
As for `--help` formatting, I'm mixed on whether `[SPEC]...` should be at the top like
other positionals or should be relegated to "Package selection". I went
with the latter mostly to make it easier to visualize the less common
choice.
Switching to a positional for `cargo update` (while keeping `-p` for
backwards compatibility) was referenced in #12425.
This is an improvement over the previous version which would use unshallowing that effectively
makes a shallow repo *not* shallow.
Furthermore, we will now only fetch a single commit, each time we fetch, which should be faster
for the server as well as for the client.
We also make it possible to fetch individual commits that would be specified via Cargo.lock.
This changes sparse registries to instead return not found when a non-cached crate is requested in offline mode.
The resolver can then suggest removing the --offline flag if resolution
fails.
This commit is targeted at further improving the error messages
generated from git errors. For authentication errors the actual URL
fetched is now printed out as well if it's different from the original
URL. This should help handle `insteadOf` logic where SSH urls are used
instead of HTTPS urls and users can know to track that down.
Otherwise the logic about recommending `net.git-fetch-with-cli` was
tweaked a bit and moved to the same location as the rest of our error
reporting.
Note that a change piggy-backed here as well is that `Caused by:` errors
are now automatically all tabbed over a bit instead of only having the
first line tabbed over. This required a good number of tests to be
updated, but it's just an updated in renderings.
This makes two changes:
- If an index has never been downloaded, and `-Z offline` is used, provide a
suggestion to run without `-Z offline`.
- If an index needs to be updated, and the network appears to be down, suggest
running with `-Z offline`.
