Prevent alias pass from inserting implicit copies for noncopyable types

Issue #1177

Author: marijnh

src/comp/middle/kind.rs

@@ -28,8 +28,6 @@ fn check_crate(tcx: ty::ctxt, crate: @crate) -> rval_map {
         with *visit::default_visitor()
     });
     visit::visit_crate(*crate, ctx, visit);
-    // FIXME go through alias's copy_map, check implicit copies (either here,
-    // or in alias.rs)
     tcx.sess.abort_if_errors();
     ret ctx.rval_map;
 }

src/comp/middle/ty.rs

@@ -1122,9 +1122,9 @@ pure fn type_has_dynamic_size(cx: ctxt, ty: t) -> bool {
     }
 }
 
-// Returns true for types where a copy of a value can be distinguished from
-// the value itself. I.e. types with mutable content that's not shared through
-// a pointer.
+// Returns true for noncopyable types and types where a copy of a value can be
+// distinguished from the value itself. I.e. types with mutable content that's
+// not shared through a pointer.
 fn type_allows_implicit_copy(cx: ctxt, ty: t) -> bool {
     ret !type_structurally_contains(cx, ty, fn (sty: sty) -> bool {
         ret alt sty {
@@ -1143,7 +1143,7 @@ fn type_allows_implicit_copy(cx: ctxt, ty: t) -> bool {
           }
           _ { false }
         };
-    });
+    }) && type_kind(cx, t) != ast::kind_noncopyable;
 }
 
 fn type_structurally_contains_uniques(cx: ctxt, ty: t) -> bool {