Auto merge of #2125 - RalfJung:ref-validity, r=RalfJung

test for validity of references pointing to uninhabited types

The new tests for rust-lang/rust#97116

rust-version

@@ -1 +1 @@
-e1ec3260d79497080ca86540562d410ba67d2a95
+77972d2d0134fb597249b3b64dcf9510a790c34e

tests/compile-fail/validity/ref_to_uninhabited1.rs

@@ -0,0 +1,7 @@
+#![feature(never_type)]
+use std::mem::{transmute, forget};
+
+fn main() { unsafe {
+    let x: Box<!> = transmute(&mut 42); //~ERROR encountered a box pointing to uninhabited type !
+    forget(x);
+} }

tests/compile-fail/validity/ref_to_uninhabited2.rs

@@ -0,0 +1,7 @@
+use std::mem::transmute;
+
+enum Void {}
+
+fn main() { unsafe {
+    let _x: &(i32, Void) = transmute(&42); //~ERROR encountered a reference pointing to uninhabited type (i32, Void)
+} }