Auto merge of #2036 - RalfJung:vec, r=RalfJung

regression test for reverse() unsoundness

Cc rust-lang/rust#90821

tests/run-pass/vec.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Zmiri-tag-raw-pointers
+// compile-flags: -Zmiri-tag-raw-pointers -Zmiri-check-number-validity
 // Gather all references from a mutable iterator and make sure Miri notices if
 // using them is dangerous.
 fn test_all_refs<'a, T: 'a>(dummy: &mut T, iter: impl Iterator<Item = &'a mut T>) {
@@ -148,6 +148,16 @@ fn swap_remove() {
     vec.swap_remove(1);
 }
 
+fn reverse() {
+    #[repr(align(2))]
+    #[derive(Debug)]
+    struct Foo(u8);
+
+    let mut v: Vec<_> = (0..50).map(Foo).collect();
+    v.reverse();
+    assert!(v[0].0 == 49);
+}
+
 fn main() {
     assert_eq!(vec_reallocate().len(), 5);
 
@@ -176,4 +186,5 @@ fn main() {
     sort();
     swap();
     swap_remove();
+    reverse();
 }