Macro deprecate_feature

macro_rules! deprecate_feature {
    (     old:   $old_feature:literal
      $(, new:   $new_feature:literal )?
      $(, since:       $since:literal )?
    ) => { ... };
}

Configures a feature as deprecated, warning if it is enabled.

You can only call this macro once per deprecated feature.

Examples

deprecate_feature![old: "old-feature-1"];
deprecate_feature![old: "old-feature-2", since: "2.0.0"];
deprecate_feature![old: "old-feature-3", new: "new_feature_3"];
deprecate_feature![old: "old-feature-4", new: "new_feature_4", since: "4.0.0"];