Originally, clap carried a lifetime parameter. When moving away from
that, we took the approach that dynamically generated strings are always
supported and `&'static str` was just an optimization.
The problem is the code size increase from this is dramatic. So we're
taking the opposite approach and making dynamic formatting opt-in under
the `string` feature flag. When deciding on an implementation, I
favored the faster one rather than the one with smaller code size since
small code size can be gotten through other means.
Before: 567.2 KiB, 15.975 µs
After: 541.1 KiB, 9.7855 µs
With `string`: 576.6 KiB, 13.016 µs
The binary size and performance difference is enough to make it
configurable.
Code size:
- default: 565.7 KiB
- perf: 578.5 KiB
Build time:
- default: 9.1706 us
- perf: 7.0479 us
Parse time:
- default: 12.673 us
- perf: 8.1708 us
Parse with subcommand time:
- default: 12.112 us
- perf: 7.9874 us
This adds a new `Cargo.toml` feature named `deprecated` that opts
controls whether deprecation warnings show up. This is starting off as
non-default though that may change (see below).
Benefits
- Allows a staged rollout so a smaller subset of users see new
deprecations and can report their experience with them before everyone
sees them. For example, this reduces the number of people who have to
deal with #3822.
- This allows people to defer responding to each new batch of
deprecations and instead do it at once. This means we should
reconsider #3616.
The one risk is people who don't follow blog posts and guides having a
harder time upgrading to the next breaking release without the warnings
on by default. For these users, we reserve the right to make the
`deprecated` feature `default`. This is most likely to happen in a
minor release that is released in conjunction with the next major
release (e.g. when releasing 4.0.0, we release a 3.3.0 that enables
deprecations by default). By using a feature, users can still disable
this if they want.
Thanks @joshtriplett for the idea
`multicall` allows you to have one binary expose itself as multiple
programs, like busybox does. This also works well for user clap for
parsing REPLs.
Fixes#2861
`-h` (short help) still shows the same.
This gates it behind an `unstable-v4` feature flag to avoid disrupting users who set the help without knowing where all it shows up (particularly derive users where `ArgEnum` is automatically extracting the help).
Fixes#3312
These were broken in #17 and #38 when renaming `hidden` to `hide`. These
weren't caught because we test with `--all-targets` which is mutually
exclusive with `--doc`.
In #27, we removed some default features. When doing so, some places
weren't updated but `doc` feature covered it ... except it was only
partially updated. This makes sure we test all the features.
