Macro is_enabled

macro_rules! is_enabled {
    (context: $context:expr, $feature:literal $(, $default:expr)? $(,)?) => { ... };
    ($feature:literal $(, $default:expr)? $(,)?) => { ... };
}

Check if a feature is enabled.

is_enabled!("feature", default) is equivalent to feature!("feature", default).is_enabled().

A context can be passed to use instead of the current context, by passing is_enabled!(context: some_context, "feature", default).