Add a better error message for bypassing the curve25519 feature

src/lib.rs

@@ -4,6 +4,12 @@
 //! For complete examples, look at
 //! [the tests directory](https://github.com/PlasmaPower/brute-force/tree/master/src/tests).
 
+#[cfg(feature = "curve25519-dalek")]
+#[cfg(not(feature = "curve25519"))]
+compile_error!(
+    "Enable brute-force curve25519 support via the `curve25519` feature, not `curve25519-dalek`",
+);
+
 use log::warn;
 use std::{
     sync::atomic::{self, AtomicBool},

src/traits.rs

@@ -50,14 +50,14 @@ impl_for_primitive!(u32, i32);
 impl_for_primitive!(u64, i64);
 impl_for_primitive!(u128, i128);
 
-#[cfg(feature = "curve25519-dalek")]
+#[cfg(feature = "curve25519")]
 impl Start for curve25519_dalek::scalar::Scalar {
     fn start_for_thread(_thread: usize, _thread_count: usize) -> Self {
         Self::random(&mut rand::rngs::OsRng)
     }
 }
 
-#[cfg(feature = "curve25519-dalek")]
+#[cfg(feature = "curve25519")]
 impl Advance for curve25519_dalek::scalar::Scalar {
     fn advance(&mut self) {
         *self += curve25519_dalek::scalar::Scalar::one();