[VorpalWay]

How many of those are between a crate and it's proc macro crate? E.g. serde and serde_derive. I believe that is a common use case for exact dependencies, as they are really the same crate but have to be split due to how proc-macros work. But that is getting down in the weeds of peculiarites of how rustc works.

[ryangibb]

As far as I can tell, checking for proc macro crates by suffix, only one: ergol -> ergol_proc_macro with >=0.0.1, <0.0.2.

I didn't include singular dependencies in this grep (=) just upper bounds (< and <=).

Some rough scripting is telling me there's over 600,000 singular dependencies of which just under 10,000 are proc-macro pairs.