Address some review comments

tests/compile-fail/never_transmute_humans.rs

@@ -0,0 +1,18 @@
+// This should fail even without validation
+// compile-fail causes rustc ICE: rust-lang/rust#50570
+// compile-flags: -Zmir-emit-validate=0
+
+#![feature(never_type)]
+#![allow(unreachable_code)]
+#![allow(unused_variables)]
+
+struct Human;
+
+fn main() {
+    let x: ! = unsafe {
+        std::mem::transmute::<Human, !>(Human) //~ ERROR entered unreachable code
+    };
+    f(x)
+}
+
+fn f(x: !) -> ! { x }

tests/compile-fail/oom2.rs

@@ -1,14 +0,0 @@
-// Validation forces more allocation; disable it.
-// compile-flags: -Zmir-emit-validate=0
-#![feature(box_syntax, custom_attribute, attr_literals)]
-#![miri(memory_size=1024)]
-
-// On 64bit platforms, the allocator needs 32 bytes allocated to pass a return value, so that's the error we see.
-// On 32bit platforms, it's just 16 bytes.
-// error-pattern: tried to allocate
-
-fn main() {
-    loop {
-        ::std::mem::forget(box 42);
-    }
-}

tests/compile-fail/repeat2.rs

@@ -1,7 +0,0 @@
-// ignore-test
-
-fn main() {
-    let data: [u8; 1024*1024*1024] = [42; 1024*1024*1024];
-    //~^ ERROR: tried to allocate
-    assert_eq!(data.len(), 1024*1024*1024);
-}

tests/compile-fail/timeout.rs

@@ -1,9 +0,0 @@
-//error-pattern: reached the configured maximum execution time
-#![feature(custom_attribute, attr_literals)]
-#![miri(step_limit=1000)]
-
-fn main() {
-    for i in 0..1000000 {
-        assert!(i < 1000);
-    }
-}

tests/compiletest.rs

@@ -203,7 +203,7 @@ fn run_pass_rustc() {
 }
 
 #[test]
-#[ignore] // TODO: update test errors
+#[should_panic] // TODO: update test errors
 fn compile_fail_miri() {
     let sysroot = get_sysroot();
     let host = get_host();