fixup! f7c438 Add a test for unique_masks, update docs

Author: tgross35

libm/src/math/support/feature_detect.rs

@@ -1,4 +1,4 @@
-//! Helpers for runtime target feature detection.
+//! Helpers for runtime target feature detection that are shared across architectures.
 
 use core::sync::atomic::{AtomicU32, Ordering};
 
@@ -147,6 +147,21 @@ pub fn get_or_init_flags_cache(cache: &AtomicU32, init: impl FnOnce() -> Flags)
 mod tests {
     use super::*;
 
+    #[test]
+    fn unique_masks() {
+        unique_masks! {
+            u32,
+            V0,
+            V1,
+            V2,
+        }
+        assert_eq!(V0, 1u32 << 0);
+        assert_eq!(V1, 1u32 << 1);
+        assert_eq!(V2, 1u32 << 2);
+        assert_eq!(ALL, [V0, V1, V2]);
+        assert_eq!(NAMES, ["V0", "V1", "V2"]);
+    }
+
     #[test]
     fn flag_cache_is_used() {
         // Sanity check that flags are only ever set once