I have a proc-macro based error-handling crate similar to thiserror and anyhow called ResExt, I used to use syn for enum parsing, but now, I removed syn from deps and refactored to manually parse TokenStream.

I benchmarked compilation speed which was the main motivation of the refactor, and it's indeed faster, but cargo clippy is ~1.1x slower.

This wouldn't matter for my crate at all and it wouldn't matter for proc-macro users in general, but for CI systems and especially for larger proc-macros, this would matter, any idea why this happened? I benchmarked using hyperfine the before and after using this command:

hyperfine --prepare "cargo clean" \
    "cargo clippy" \
    --cleanup "sed -i 's/resext-macro = \"1.3.3\"/resext-macro = { path = \"..\/resext-macro\" }/' resext/Cargo.toml" \
    "cargo clippy"

repo structure:

ResExt/
  |
  |_ resext/ -> Main crate
  |
  \_ resext-macro/ -> proc-macro crate

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