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 use syntax_pos::DUMMY_SP;
  18
  19 pub fn crate_inherent_impls_overlap_check<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
  20                                                     crate_num: CrateNum) {
  21     assert_eq!(crate_num, LOCAL_CRATE);
  22     let krate = tcx.hir.krate();
  23     krate.visit_all_item_likes(&mut InherentOverlapChecker { tcx });
  24 }
  25
  26 struct InherentOverlapChecker<'a, 'tcx: 'a> {
  27     tcx: TyCtxt<'a, 'tcx, 'tcx>
  28 }
  29
  30 impl<'a, 'tcx> InherentOverlapChecker<'a, 'tcx> {
  31     fn check_for_common_items_in_impls(&self, impl1: DefId, impl2: DefId) {
  32         #[derive(Copy, Clone, PartialEq)]
  33         enum Namespace {
  34             Type,
  35             Value,
  36         }
  37
  38         let name_and_namespace = |def_id| {
  39             let item = self.tcx.associated_item(def_id);
  40             (item.name, match item.kind {
  41                 ty::AssociatedKind::Type => Namespace::Type,
  42                 ty::AssociatedKind::Const |
  43                 ty::AssociatedKind::Method => Namespace::Value,
  44             })
  45         };
  46
  47         let impl_items1 = self.tcx.associated_item_def_ids(impl1);
  48         let impl_items2 = self.tcx.associated_item_def_ids(impl2);
  49
  50         for &item1 in &impl_items1[..] {
  51             let (name, namespace) = name_and_namespace(item1);
  52
  53             for &item2 in &impl_items2[..] {
  54                 if (name, namespace) == name_and_namespace(item2) {
  55                     struct_span_err!(self.tcx.sess,
  56                                      self.tcx.span_of_impl(item1).unwrap(),
  57                                      E0592,
  58                                      "duplicate definitions with name `{}`",
  59                                      name)
  60                         .span_label(self.tcx.span_of_impl(item1).unwrap(),
  61                                     &format!("duplicate definitions for `{}`", name))
  62                         .span_label(self.tcx.span_of_impl(item2).unwrap(),
  63                                     &format!("other definition for `{}`", name))
  64                         .emit();
  65                 }
  66             }
  67         }
  68     }
  69
  70     fn check_for_overlapping_inherent_impls(&self, ty_def_id: DefId) {
  71         let impls = ty::queries::inherent_impls::get(self.tcx, DUMMY_SP, ty_def_id);
  72
  73         for (i, &impl1_def_id) in impls.iter().enumerate() {
  74             for &impl2_def_id in &impls[(i + 1)..] {
  75                 self.tcx.infer_ctxt((), Reveal::UserFacing).enter(|infcx| {
  76                     if traits::overlapping_impls(&infcx, impl1_def_id, impl2_def_id).is_some() {
  77                         self.check_for_common_items_in_impls(impl1_def_id, impl2_def_id)
  78                     }
  79                 });
  80             }
  81         }
  82     }
  83 }
  84
  85 impl<'a, 'tcx, 'v> ItemLikeVisitor<'v> for InherentOverlapChecker<'a, 'tcx> {
  86     fn visit_item(&mut self, item: &'v hir::Item) {
  87         match item.node {
  88             hir::ItemEnum(..) |
  89             hir::ItemStruct(..) |
  90             hir::ItemTrait(..) |
  91             hir::ItemUnion(..) => {
  92                 let type_def_id = self.tcx.hir.local_def_id(item.id);
  93                 self.check_for_overlapping_inherent_impls(type_def_id);
  94             }
  95             _ => {}
  96         }
  97     }
  98
  99     fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
 100     }
 101
 102     fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
 103     }
 104 }
 105