src/librustc_typeck/coherence/inherent_impls_overlap.rs

   1 use rustc_errors::struct_span_err;
   2 use rustc_hir as hir;
   3 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
   4 use rustc_hir::itemlikevisit::ItemLikeVisitor;
   5 use rustc_middle::ty::TyCtxt;
   6 use rustc_trait_selection::traits::{self, SkipLeakCheck};
   7
   8 pub fn crate_inherent_impls_overlap_check(tcx: TyCtxt<'_>, crate_num: CrateNum) {
   9     assert_eq!(crate_num, LOCAL_CRATE);
  10     let krate = tcx.hir().krate();
  11     krate.visit_all_item_likes(&mut InherentOverlapChecker { tcx });
  12 }
  13
  14 struct InherentOverlapChecker<'tcx> {
  15     tcx: TyCtxt<'tcx>,
  16 }
  17
  18 impl InherentOverlapChecker<'tcx> {
  19     /// Checks whether any associated items in impls 1 and 2 share the same identifier and
  20     /// namespace.
  21     fn impls_have_common_items(&self, impl1: DefId, impl2: DefId) -> bool {
  22         let impl_items1 = self.tcx.associated_items(impl1);
  23         let impl_items2 = self.tcx.associated_items(impl2);
  24
  25         for item1 in impl_items1.in_definition_order() {
  26             let collision = impl_items2.filter_by_name_unhygienic(item1.ident.name).any(|item2| {
  27                 // Symbols and namespace match, compare hygienically.
  28                 item1.kind.namespace() == item2.kind.namespace()
  29                     && item1.ident.normalize_to_macros_2_0()
  30                         == item2.ident.normalize_to_macros_2_0()
  31             });
  32
  33             if collision {
  34                 return true;
  35             }
  36         }
  37
  38         false
  39     }
  40
  41     fn check_for_common_items_in_impls(
  42         &self,
  43         impl1: DefId,
  44         impl2: DefId,
  45         overlap: traits::OverlapResult<'_>,
  46     ) {
  47         let impl_items1 = self.tcx.associated_items(impl1);
  48         let impl_items2 = self.tcx.associated_items(impl2);
  49
  50         for item1 in impl_items1.in_definition_order() {
  51             let collision = impl_items2.filter_by_name_unhygienic(item1.ident.name).find(|item2| {
  52                 // Symbols and namespace match, compare hygienically.
  53                 item1.kind.namespace() == item2.kind.namespace()
  54                     && item1.ident.normalize_to_macros_2_0()
  55                         == item2.ident.normalize_to_macros_2_0()
  56             });
  57
  58             if let Some(item2) = collision {
  59                 let name = item1.ident.normalize_to_macros_2_0();
  60                 let mut err = struct_span_err!(
  61                     self.tcx.sess,
  62                     self.tcx.span_of_impl(item1.def_id).unwrap(),
  63                     E0592,
  64                     "duplicate definitions with name `{}`",
  65                     name
  66                 );
  67                 err.span_label(
  68                     self.tcx.span_of_impl(item1.def_id).unwrap(),
  69                     format!("duplicate definitions for `{}`", name),
  70                 );
  71                 err.span_label(
  72                     self.tcx.span_of_impl(item2.def_id).unwrap(),
  73                     format!("other definition for `{}`", name),
  74                 );
  75
  76                 for cause in &overlap.intercrate_ambiguity_causes {
  77                     cause.add_intercrate_ambiguity_hint(&mut err);
  78                 }
  79
  80                 if overlap.involves_placeholder {
  81                     traits::add_placeholder_note(&mut err);
  82                 }
  83
  84                 err.emit();
  85             }
  86         }
  87     }
  88
  89     fn check_for_overlapping_inherent_impls(&self, impl1_def_id: DefId, impl2_def_id: DefId) {
  90         traits::overlapping_impls(
  91             self.tcx,
  92             impl1_def_id,
  93             impl2_def_id,
  94             // We go ahead and just skip the leak check for
  95             // inherent impls without warning.
  96             SkipLeakCheck::Yes,
  97             |overlap| {
  98                 self.check_for_common_items_in_impls(impl1_def_id, impl2_def_id, overlap);
  99                 false
 100             },
 101             || true,
 102         );
 103     }
 104 }
 105
 106 impl ItemLikeVisitor<'v> for InherentOverlapChecker<'tcx> {
 107     fn visit_item(&mut self, item: &'v hir::Item<'v>) {
 108         match item.kind {
 109             hir::ItemKind::Enum(..)
 110             | hir::ItemKind::Struct(..)
 111             | hir::ItemKind::Trait(..)
 112             | hir::ItemKind::Union(..) => {
 113                 let ty_def_id = self.tcx.hir().local_def_id(item.hir_id);
 114                 let impls = self.tcx.inherent_impls(ty_def_id);
 115
 116                 for (i, &impl1_def_id) in impls.iter().enumerate() {
 117                     for &impl2_def_id in &impls[(i + 1)..] {
 118                         if self.impls_have_common_items(impl1_def_id, impl2_def_id) {
 119                             self.check_for_overlapping_inherent_impls(impl1_def_id, impl2_def_id);
 120                         }
 121                     }
 122                 }
 123             }
 124             _ => {}
 125         }
 126     }
 127
 128     fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem<'v>) {}
 129
 130     fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem<'v>) {}
 131 }