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super excited to see the proc-macro server RPC rewrite being worked on, once this here is finished it should allow us to implement all the remaining proc-macro features (except for `expand_expr`)! And afterwards we'll be tackling parallelization! github.com/rust-lang/ru...

For context as to why we still cannot implement `expand_expr`, that feature effectively turns all proc-macro into eager macro expansions which would basically prevent rust-analyzer from doing a lot of incremental caching, so we just cannot implement this as designed doc.rust-lang.org/stable/proc_...

And some additional notes for parallel proc-macro expansion, today r-a spawns a single proc-macro server that does expansion one at a time, meaning whenever r-a wants to expand a proc-macro, it takes a global lock on the proc-macro server!

The annoying part, you can't trivially parallelize this on the proc-macro server because proc-macros execute in (and are in control 😵‍💫 of) the process environment, so technically running multiple at once can cause issues. But even ignoring that they can change the environment,