perf(derive): Improve build times #4777
Merged
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The more widely available improvement is the dropping of
proc-macro-error
. This dependency was less than ideal because it itself was a proc macro, further serializing our builds (requiring all proc macro machiner to be built beforeproc-macro-error
beforeclap_derive
). Now, we don't just have fewer dependencies but hopefully more parallelism.This unblock the second almost as widely scoped improvement: upgrading to syn v2. proc-macro-error was on syn v1 and it hadn't been touched in a while, so I wasn't confident in a timely upgrade (plus I've been wanting to drop it anyways, see above). Now, it'll be easier to only have one version of
syn
in the dependency tree (as of 5 days ago, 39.3% of all crates depended on syn v2 already)