macro-error expected leaf: `;` when using a macro

I'm seeing an error message on a macro expansion in rust-analyzer expected leaf: ; rust-analyzer(macro-error). I can run and build the crate fine. Removing the generic parameters on the macro resolves the error.

The macro is building a enum definiton as well as implementing parsing traits based on the macro arguments.

I created https://github.com/semicoleon/macro-error-demo with a (mostly) minimal example of a macro that causes the error. The README has slightly more information about the error as well as the cargo expand output.

I encountered this in rust-analyzer d15f646ff 2021-08-30 stable on macOS. I also tried building from source rust-analyzer c16e6474f 2021-09-04 dev and also encountered the issue there.

Start with the mostly minimal reproducer in the linked macro-error-demo repository, read its README, and compare the reported diagnostic with the cargo expand output. Trace how rust-analyzer handles the macro's generic parameters and generated enum and parsing traits; done means the false expected leaf: ; diagnostic no longer appears while the crate still builds.