Const generic parameters are treated as hygienic by `macro_rule` because it uses "`let` variable hygiene" rather than "item hygiene". See https://github.com/rust-lang/rust/issues/57523#issuecomment-453788106 and https://github.com/rust-lang/rust/pull/58191#discussion_r254251259. cc @petrochenkov
Const generic parameters are treated as hygienic by
macro_rulebecause it uses "letvariable hygiene" rather than "item hygiene".See #57523 (comment) and #58191 (comment).
cc @petrochenkov