1 files changed, 37 insertions, 0 deletions
diff --git a/tests/ui/transmutability/enums/should_respect_endianness.rs b/tests/ui/transmutability/enums/should_respect_endianness.rs
new file mode 100644
index 000000000..f3567b405
--- /dev/null
+++ b/tests/ui/transmutability/enums/should_respect_endianness.rs
@@ -0,0 +1,37 @@
+//! The target endianness should be a consideration in computing the layout of
+//! an enum with a multi-byte tag.
+
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code)]
+
+mod assert {
+    use std::mem::{Assume, BikeshedIntrinsicFrom};
+    pub struct Context;
+
+    pub fn is_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, {
+            Assume::ALIGNMENT
+                .and(Assume::LIFETIMES)
+                .and(Assume::SAFETY)
+                .and(Assume::VALIDITY)
+        }>
+    {}
+}
+
+#[repr(u16)] enum Src { V = 0xCAFE }
+
+#[repr(u8)] enum OxCA { V = 0xCA }
+#[repr(u8)] enum OxFE { V = 0xFE }
+
+#[cfg(target_endian = "big")] #[repr(C)] struct Expected(OxCA, OxFE);
+#[cfg(target_endian = "big")] #[repr(C)] struct Unexpected(OxFE, OxCA);
+
+#[cfg(target_endian = "little")] #[repr(C)] struct Expected(OxFE, OxCA);
+#[cfg(target_endian = "little")] #[repr(C)] struct Unexpected(OxCA, OxFE);
+
+fn should_respect_endianness() {
+    assert::is_transmutable::<Src, Expected>();
+    assert::is_transmutable::<Src, Unexpected>(); //~ ERROR cannot be safely transmuted
+}