Function error

enumset_derive/src/lib.rs:14–16

Helper function for emitting compile errors.

(span: proc_macro2::Span, message: impl Display)

/// Helper function for emitting compile errors.
fn error<T>(span: proc_macro2::Span, message: impl Display) -> syn::Result<T> {
    Err(syn::Error::new(span, message))
}

#[proc_macro_derive(EnumSetType, attributes(enumset))]
pub fn derive_enum_set_type(input: TokenStream) -> TokenStream {