1 files changed, 32 insertions, 0 deletions

diff --git a/src/test/ui/issues/issue-46845.rs b/src/test/ui/issues/issue-46845.rs
new file mode 100644
index 000000000..fc85b2551
--- /dev/null
+++ b/src/test/ui/issues/issue-46845.rs
@@ -0,0 +1,32 @@
+// run-pass
+// To work around #46855
+// compile-flags: -Z mir-opt-level=0
+// Regression test for the inhabitedness of unions with uninhabited variants, issue #46845
+
+use std::mem;
+
+#[derive(Copy, Clone)]
+enum Never { }
+
+// A single uninhabited variant shouldn't make the whole union uninhabited.
+union Foo {
+    a: u64,
+    _b: Never
+}
+
+// If all the variants are uninhabited, however, the union should be uninhabited.
+// NOTE(#49298) the union being uninhabited shouldn't change its size.
+union Bar {
+    _a: (Never, u64),
+    _b: (u64, Never)
+}
+
+fn main() {
+    assert_eq!(mem::size_of::<Foo>(), 8);
+    // See the note on `Bar`'s definition for why this isn't `0`.
+    assert_eq!(mem::size_of::<Bar>(), 8);
+
+    let f = [Foo { a: 42 }, Foo { a: 10 }];
+    println!("{}", unsafe { f[0].a });
+    assert_eq!(unsafe { f[1].a }, 10);
+}