Remove dependency on proc-macro-hack by taiki-e · Pull Request #2520 · rust-lang...

Just FYI, this PR was backported and released in 0.3.18, and it removed the features proc-macro-hack and proc-macro-nested that were part of the default feature set of futures-util.

The Cargo docs recommend not removing features in semver-compatible releases:

The resolver will skip over versions of packages that are missing required features. For example, if a package depends on version ^1 of regex with the perf feature, then the oldest version it can select is 1.3.0, because versions prior to that did not contain the perf feature. Similarly, if a feature is removed from a new release, then packages that require that feature will be stuck on the older releases that contain that feature. It is discouraged to remove features in a SemVer-compatible release. Beware that optional dependencies also define an implicit feature, so removing an optional dependency or making it non-optional can cause problems, see removing an optional dependency.

More documentation here.

I've fixed the problem in the project I'm working on, but it took a while to figure out this was the root cause preventing cargo update from updating the project from futures-util 0.3.17 to 0.3.18.

Thanks!