1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Orphan checker: every impl either implements a trait defined in this
12 //! crate or pertains to a type defined in this crate.
16 use syntax::ast::{Item, ItemImpl};
19 use syntax::codemap::Span;
21 use util::ppaux::{Repr, UserString};
23 pub fn check(tcx: &ty::ctxt) {
24 let mut orphan = OrphanChecker { tcx: tcx };
25 visit::walk_crate(&mut orphan, tcx.map.krate());
28 struct OrphanChecker<'cx, 'tcx:'cx> {
29 tcx: &'cx ty::ctxt<'tcx>
32 impl<'cx, 'tcx> OrphanChecker<'cx, 'tcx> {
33 fn check_def_id(&self, span: Span, def_id: ast::DefId) {
34 if def_id.krate != ast::LOCAL_CRATE {
35 span_err!(self.tcx.sess, span, E0116,
36 "cannot associate methods with a type outside the \
37 crate the type is defined in; define and implement \
38 a trait or new type instead");
43 impl<'cx, 'tcx,'v> visit::Visitor<'v> for OrphanChecker<'cx, 'tcx> {
44 fn visit_item(&mut self, item: &'v ast::Item) {
45 let def_id = ast_util::local_def(item.id);
47 ast::ItemImpl(_, _, _, None, _, _) => {
48 // For inherent impls, self type must be a nominal type
49 // defined in this crate.
50 debug!("coherence2::orphan check: inherent impl {}", item.repr(self.tcx));
51 let self_ty = ty::lookup_item_type(self.tcx, def_id).ty;
53 ty::ty_enum(def_id, _) |
54 ty::ty_struct(def_id, _) => {
55 self.check_def_id(item.span, def_id);
57 ty::ty_trait(ref data) => {
58 self.check_def_id(item.span, data.principal_def_id());
61 self.check_def_id(item.span,
62 self.tcx.lang_items.owned_box()
66 span_err!(self.tcx.sess, item.span, E0118,
67 "no base type found for inherent implementation; \
68 implement a trait or new type instead");
72 ast::ItemImpl(_, _, _, Some(_), _, _) => {
74 debug!("coherence2::orphan check: trait impl {}", item.repr(self.tcx));
75 let trait_def_id = ty::impl_trait_ref(self.tcx, def_id).unwrap().def_id;
76 match traits::orphan_check(self.tcx, def_id) {
78 Err(traits::OrphanCheckErr::NoLocalInputType) => {
79 if !ty::has_attr(self.tcx, trait_def_id, "old_orphan_check") {
80 let self_ty = ty::lookup_item_type(self.tcx, def_id).ty;
82 self.tcx.sess, item.span, E0117,
83 "the type `{}` does not reference any \
84 types defined in this crate; \
85 only traits defined in the current crate can be \
86 implemented for arbitrary types",
87 self_ty.user_string(self.tcx));
90 Err(traits::OrphanCheckErr::UncoveredTy(param_ty)) => {
91 if !ty::has_attr(self.tcx, trait_def_id, "old_orphan_check") {
92 span_err!(self.tcx.sess, item.span, E0210,
93 "type parameter `{}` is not constrained by any local type; \
94 only traits defined in the current crate can be implemented \
95 for a type parameter",
96 param_ty.user_string(self.tcx));
97 self.tcx.sess.span_note(
99 format!("for a limited time, you can add \
100 `#![feature(old_orphan_check)]` to your crate \
101 to disable this rule").as_slice());
111 visit::walk_item(self, item);