This crate defines various macro_rules macros
used as part of Salsa's internal plumbing.
These macros are re-exported under salsa::plumbing``. The procedural macros emit calls to these macro_rules` macros after doing error checking.
Using macro_rules macro definitions is generally
more ergonomic and also permits true hygiene for local variables
(sadly not items).
Currently the only way to have a macro that is re-exported from a submodule is to use multiple crates, hence the existence of this crate.