#[cfg(feature = "v1_9")] works for selecting v1.9, but selecting a range like >= v1.9 requires enumerating every such version manually.
Possible define macros like ge_1_9!() and lt_1_9!() (or const fns) that are always available and expand to true or false depending on what features are enabled.
#[cfg(feature = "v1_9")]
works for selecting v1.9, but selecting a range like>= v1.9
requires enumerating every such version manually.Possible define macros like
ge_1_9!()
andlt_1_9!()
(or const fns) that are always available and expand to true or false depending on what features are enabled.