src/librustc_typeck/coherence/inherent_impls_overlap.rs

   1 // Copyright 2017 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.
   4 //
   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.
  10
  11 use rustc::hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
  12 use rustc::hir;
  13 use rustc::hir::itemlikevisit::ItemLikeVisitor;
  14 use rustc::traits::{self, Reveal};
  15 use rustc::ty::{self, TyCtxt};
  16
  17 pub fn crate_inherent_impls_overlap_check<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
  18                                                     crate_num: CrateNum) {
  19     assert_eq!(crate_num, LOCAL_CRATE);
  20     let krate = tcx.hir.krate();
  21     krate.visit_all_item_likes(&mut InherentOverlapChecker { tcx });
  22 }
  23
  24 struct InherentOverlapChecker<'a, 'tcx: 'a> {
  25     tcx: TyCtxt<'a, 'tcx, 'tcx>
  26 }
  27
  28 impl<'a, 'tcx> InherentOverlapChecker<'a, 'tcx> {
  29     fn check_for_common_items_in_impls(&self, impl1: DefId, impl2: DefId) {
  30         #[derive(Copy, Clone, PartialEq)]
  31         enum Namespace {
  32             Type,
  33             Value,
  34         }
  35
  36         let name_and_namespace = |def_id| {
  37             let item = self.tcx.associated_item(def_id);
  38             (item.name, match item.kind {
  39                 ty::AssociatedKind::Type => Namespace::Type,
  40                 ty::AssociatedKind::Const |
  41                 ty::AssociatedKind::Method => Namespace::Value,
  42             })
  43         };
  44
  45         let impl_items1 = self.tcx.associated_item_def_ids(impl1);
  46         let impl_items2 = self.tcx.associated_item_def_ids(impl2);
  47
  48         for &item1 in &impl_items1[..] {
  49             let (name, namespace) = name_and_namespace(item1);
  50
  51             for &item2 in &impl_items2[..] {
  52                 if (name, namespace) == name_and_namespace(item2) {
  53                     struct_span_err!(self.tcx.sess,
  54                                      self.tcx.span_of_impl(item1).unwrap(),
  55                                      E0592,
  56                                      "duplicate definitions with name `{}`",
  57                                      name)
  58                         .span_label(self.tcx.span_of_impl(item1).unwrap(),
  59                                     &format!("duplicate definitions for `{}`", name))
  60                         .span_label(self.tcx.span_of_impl(item2).unwrap(),
  61                                     &format!("other definition for `{}`", name))
  62                         .emit();
  63                 }
  64             }
  65         }
  66     }
  67
  68     fn check_for_overlapping_inherent_impls(&self, ty_def_id: DefId) {
  69         let impls = self.tcx.inherent_impls(ty_def_id);
  70
  71         for (i, &impl1_def_id) in impls.iter().enumerate() {
  72             for &impl2_def_id in &impls[(i + 1)..] {
  73                 self.tcx.infer_ctxt((), Reveal::UserFacing).enter(|infcx| {
  74                     if traits::overlapping_impls(&infcx, impl1_def_id, impl2_def_id).is_some() {
  75                         self.check_for_common_items_in_impls(impl1_def_id, impl2_def_id)
  76                     }
  77                 });
  78             }
  79         }
  80     }
  81 }
  82
  83 impl<'a, 'tcx, 'v> ItemLikeVisitor<'v> for InherentOverlapChecker<'a, 'tcx> {
  84     fn visit_item(&mut self, item: &'v hir::Item) {
  85         match item.node {
  86             hir::ItemEnum(..) |
  87             hir::ItemStruct(..) |
  88             hir::ItemTrait(..) |
  89             hir::ItemUnion(..) => {
  90                 let type_def_id = self.tcx.hir.local_def_id(item.id);
  91                 self.check_for_overlapping_inherent_impls(type_def_id);
  92             }
  93             _ => {}
  94         }
  95     }
  96
  97     fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
  98     }
  99
 100     fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
 101     }
 102 }
 103