Comment by dathinab

yesn't they require you to compile a binary (or multiple ones when nested) before being able to compile your binary and depending on a lot of factors that can add quite a bunch of overhead especially for non-incremental non-release builds (and probably can be fixed by adding sand-boxing for reproducibility making most of them pure cache-able functions allowing distributed caching of both their binaries and output, like theoretically, not sure if rust will ever end up there).

And the majority of procedural macros don't produce that much code and like you said their execution isn't the biggest problem.

E.g. the recent article about a db system ending up with 30?min compiler times and then cutting them down to 4min was a case of auto generating a whole (very enormously huge) crate (no idea if proc-macros where involved, didn't really matter there anyway).

So yeah, kinda what you said, proc macros can and should be improved, but rarely are they the root cause.