Here are instructions for various chores we should do periodically, as well as background for why we do them.
These are manual tasks now, but would be ideal candidates for future automation.
These chores pertain to our Rust codebase.
The Rust team releases a new stable version of Rust every 6 weeks, with announcements posted to the Rust Blog. To ensure we are benefitting from all the improvements to the language, we should plan to update the version of Rust we are using periodically.
To do this, you must update the channel entry in our toolchain
file to the appropriate version identifier.
Note that there may be new compiler warnings to address after updating the version of Rust we use; please be sure to take care of these at this time.
We also currently make us of unstable Rust (more specifically, unstable
rustfmt) for formatting our code. Rather than using the toolchain file (which
applies to everything), we specify this particular constraint in the
formatting script via the RUSTUP_TOOLCHAIN
environment variable. To ensure stability across time and consistency
across team members, we specify a particular nightly release to use.
New versions of the unstable toolchain are released every night, but we don't want to make corresponding changes in our codebase that frequently. Instead, when we update our main Rust toolchain (as described above), we should also update which unstable nightly Rust we're using for our formatting; a good option would be to use the one released last night!
Note, however, that because unstable Rust is, well, unstable, there is no
guarantee that there is actually a usable build of rustfmt for any given
nightly Rust release (this is less common that it has been in the past, but it
can still happen). Therefore, when selecting a new nightly Rust, make sure the
rustfmt component is actually available in that release. To help, consult the
Rustup Components History page.
Since we currently only need an unstable Rust for specific unstable rustfmt
configuration options, you should take this opportunity to see which of the
options we use have been stabilized since we last
checked. Once they have all been stabilized, we will no longer need to use
unstable Rust for anything. The current status of any rustfmt configuration
option can be discovered here.
Also see below, as well!
After updating the version of nightly Rust that rustfmt
uses, or modifying any of the rustfmt
configuration options we use, we will need to update the code
pick up any changes.
To do this, run the following command and commit the results in the same PR as the nightly / configuration changes:
cd src/rust
bin/format --update(This can also be useful when rebasing any work-in-flight on top of a non-trivial formatting change.)