Allow manual implementations of built-in traits

[RFC #3]

cc #13231

2 files changed, 1 insertions, 27 deletions

diff --git a/src/librustc/middle/typeck/collect.rs b/src/librustc/middle/typeck/collect.rs
index 9c49512d4dc..c87776ba893 100644
--- a/src/librustc/middle/typeck/collect.rs
+++ b/src/librustc/middle/typeck/collect.rs
@@ -631,14 +631,7 @@ pub fn convert(ccx: &CrateCtxt, it: &ast::Item) {
                             parent_visibility);
 
             for trait_ref in opt_trait_ref.iter() {
-                let trait_ref = instantiate_trait_ref(ccx, trait_ref, selfty);
-
-                // Prevent the builtin kind traits from being manually implemented.
-                if tcx.lang_items.to_builtin_kind(trait_ref.def_id).is_some() {
-                    tcx.sess.span_err(it.span,
-                        "cannot provide an explicit implementation \
-                         for a builtin kind");
-                }
+                instantiate_trait_ref(ccx, trait_ref, selfty);
             }
         },
         ast::ItemTrait(ref generics, _, _, ref trait_methods) => {
diff --git a/src/test/compile-fail/cant-implement-builtin-kinds.rs b/src/test/compile-fail/cant-implement-builtin-kinds.rs
deleted file mode 100644
index 6bedac6d12d..00000000000
--- a/src/test/compile-fail/cant-implement-builtin-kinds.rs
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-// See issue #8517 for why this should be illegal.
-
-struct X<T>(T);
-
-impl <T> Send for X<T> { } //~ ERROR cannot provide an explicit implementation for a builtin kind
-impl <T> Sized for X<T> { } //~ ERROR cannot provide an explicit implementation for a builtin kind
-impl <T> Share for X<T> { } //~ ERROR cannot provide an explicit implementation for a builtin kind
-
-fn main() { }