Rollup merge of #23867 - nikomatsakis:issue-23086-take-3, r=pnkfelix

This PR implements rust-lang/rfcs#1023. In the process it fixes #23086 and #23516. A few impls in libcore had to be updated, but the impact is generally pretty minimal. Most of the fallout is in the tests that probed the limits of today's coherence.

I tested and we were able to build the most popular crates along with iron (modulo errors around errors being sendable).

Fixes #23918.

3 files changed, 7 insertions, 11 deletions

diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 550b25ac3a7..c4541e34cdb 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -86,6 +86,7 @@ pub static HEAP: () = ();
 /// See the [module-level documentation](../../std/boxed/index.html) for more.
 #[lang = "owned_box"]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[fundamental]
 pub struct Box<T>(Unique<T>);
 
 impl<T> Box<T> {
@@ -278,13 +279,6 @@ impl<T: fmt::Debug + ?Sized> fmt::Debug for Box<T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl fmt::Debug for Box<Any> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.pad("Box<Any>")
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Deref for Box<T> {
     type Target = T;
 
diff --git a/src/liballoc/boxed_test.rs b/src/liballoc/boxed_test.rs
index 682d5f407c4..fc44ac4eac6 100644
--- a/src/liballoc/boxed_test.rs
+++ b/src/liballoc/boxed_test.rs
@@ -55,17 +55,17 @@ fn test_show() {
     let b = Box::new(Test) as Box<Any>;
     let a_str = format!("{:?}", a);
     let b_str = format!("{:?}", b);
-    assert_eq!(a_str, "Box<Any>");
-    assert_eq!(b_str, "Box<Any>");
+    assert_eq!(a_str, "Any");
+    assert_eq!(b_str, "Any");
 
     static EIGHT: usize = 8;
     static TEST: Test = Test;
     let a = &EIGHT as &Any;
     let b = &TEST as &Any;
     let s = format!("{:?}", a);
-    assert_eq!(s, "&Any");
+    assert_eq!(s, "Any");
     let s = format!("{:?}", b);
-    assert_eq!(s, "&Any");
+    assert_eq!(s, "Any");
 }
 
 #[test]
diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index b92dfa9117e..a8be63d6373 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -71,6 +71,8 @@
 #![feature(no_std)]
 #![no_std]
 #![feature(allocator)]
+#![feature(custom_attribute)]
+#![feature(fundamental)]
 #![feature(lang_items, unsafe_destructor)]
 #![feature(box_syntax)]
 #![feature(optin_builtin_traits)]