Since we call `cargo_out_dir()` - which is the preferred way of using
`protobuf_codegen::Codegen` in `build.rs` - our call to `out_dir()`
has no effect.
I ran an upgraded Clippy on the codebase. All the changes seem to be
about using variables directly in format strings instead of passing
them as separate arguments.
Let's acknowledge everyone's contributions by replacing "Google LLC"
in the copyright header by "The Jujutsu Authors". If I understand
correctly, it won't have any legal effect, but maybe it still helps
reduce concerns from contributors (though I haven't heard any
concerns).
Google employees can read about Google's policy at
go/releasing/contributions#copyright.
The biggest difference in the API is that fields are now public. The
exception from that is `oneof` fields, which still require setters and
getters.
I couldn't measure any difference in performance. I didn't expect any
difference either, but it's good that it didn't seem to regress. I
timed `jj debug operation <some hash prefix>`, which will read the
whole operation log (to check that the prefix is unambiguous).
I had tried to generate the protobuf code at build time many months
ago, but decided against it because it slowed down the build too
much. I didn't realize there was the
"cargo:rerun-if-changed=<filename>" feature that time. Given that that
exists, it seems like an obvious win to generate the source code at
build time.
I put the generated sources in `$OUT_DIR` (where [1] says they should
be), then include them in the `protos` module by using the `include!`
macro. The biggest problem with that is that I couldn't get IntelliJ
to understand it, even after enabling the experimental features
described in [2].
[1] https://doc.rust-lang.org/cargo/reference/build-script-examples.html#code-generation
[2] https://github.com/intellij-rust/intellij-rust/issues/1908#issuecomment-592773865
