move object safety test to library/core

library/core/tests/hash/mod.rs

@@ -1,7 +1,7 @@
 mod sip;
 
 use std::default::Default;
-use std::hash::{Hash, Hasher};
+use std::hash::{BuildHasher, Hash, Hasher};
 use std::rc::Rc;
 
 struct MyHasher {
@@ -139,3 +139,10 @@ fn test_indirect_hasher() {
     }
     assert_eq!(hasher.hash, 5);
 }
+
+#[test]
+fn test_build_hasher_object_safe() {
+    use std::collections::hash_map::{DefaultHasher, RandomState};
+
+    let _: &dyn BuildHasher<Hasher = DefaultHasher> = &RandomState::new();
+}

src/test/ui/build-hasher-object-safe.rs

@@ -1,10 +0,0 @@
-// run-pass
-
-use std::hash::BuildHasher;
-use std::collections::hash_map::{DefaultHasher, RandomState};
-
-fn ensure_object_safe(_: &dyn BuildHasher<Hasher = DefaultHasher>) {}
-
-fn main() {
-    ensure_object_safe(&RandomState::new());
-}