Function is_feature_flaggable

pub fn is_feature_flaggable() -> Option<bool>

Checks whether the running or installed rustc supports feature flags.

Returns true if the channel is either “nightly” or “dev”.

Please see the note on feature detection.

Note that support for specific rustc features can be enabled or disabled via the allow-features compiler flag, which this function does not check. That is, this function does not check whether a specific feature is supported, but instead whether features are supported at all. To check for support for a specific feature, use supports_feature().

If the version could not be determined, returns None. Otherwise returns true if the running version supports feature flags and false otherwise.