1 files changed, 40 insertions, 0 deletions
diff --git a/src/safer_unchecked.rs b/src/safer_unchecked.rs
new file mode 100644
index 0000000..b556a6f
--- /dev/null
+++ b/src/safer_unchecked.rs
@@ -0,0 +1,40 @@
+//! tools to help validate correct use of `unchecked` functions.
+//!
+//! these `kinda_unchecked` functions will use equivalent implementations that panic when
+//! invariants are violated when the `debug_assertions` config is present, but use the
+//! corresponding `*_unchecked` otherwise.
+//!
+//! for example, `GetSaferUnchecked` uses a normal index when debug assertions are enabled, but
+//! `.get_unchecked()` otherwise. this means that tests and even fuzzing can be made to exercise
+//! panic-on-error cases as desired.
+
+use core::slice::SliceIndex;
+
+pub trait GetSaferUnchecked<T> {
+    unsafe fn get_kinda_unchecked<I>(&self, index: I) -> &<I as SliceIndex<[T]>>::Output
+    where
+        I: SliceIndex<[T]>;
+}
+
+impl<T> GetSaferUnchecked<T> for [T] {
+    #[inline(always)]
+    unsafe fn get_kinda_unchecked<I>(&self, index: I) -> &<I as SliceIndex<[T]>>::Output
+    where
+        I: SliceIndex<[T]>,
+    {
+        if cfg!(debug_assertions) {
+            &self[index]
+        } else {
+            self.get_unchecked(index)
+        }
+    }
+}
+
+#[inline(always)]
+pub unsafe fn unreachable_kinda_unchecked() -> ! {
+    if cfg!(debug_assertions) {
+        panic!("UB: Unreachable unchecked was executed")
+    } else {
+        core::hint::unreachable_unchecked()
+    }
+}