src/librustc_typeck/coherence/inherent_impls.rs

   1 //! The code in this module gathers up all of the inherent impls in
   2 //! the current crate and organizes them in a map. It winds up
   3 //! touching the whole crate and thus must be recomputed completely
   4 //! for any change, but it is very cheap to compute. In practice, most
   5 //! code in the compiler never *directly* requests this map. Instead,
   6 //! it requests the inherent impls specific to some type (via
   7 //! `tcx.inherent_impls(def_id)`). That value, however,
   8 //! is computed by selecting an idea from this table.
   9
  10 use rustc::hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
  11 use rustc::hir;
  12 use rustc::hir::itemlikevisit::ItemLikeVisitor;
  13 use rustc::ty::{self, CrateInherentImpls, TyCtxt};
  14
  15 use syntax::ast;
  16 use syntax_pos::Span;
  17
  18 /// On-demand query: yields a map containing all types mapped to their inherent impls.
  19 pub fn crate_inherent_impls(
  20     tcx: TyCtxt<'_>,
  21     crate_num: CrateNum,
  22 ) -> &CrateInherentImpls {
  23     assert_eq!(crate_num, LOCAL_CRATE);
  24
  25     let krate = tcx.hir().krate();
  26     let mut collect = InherentCollect {
  27         tcx,
  28         impls_map: Default::default(),
  29     };
  30     krate.visit_all_item_likes(&mut collect);
  31     tcx.arena.alloc(collect.impls_map)
  32 }
  33
  34 /// On-demand query: yields a vector of the inherent impls for a specific type.
  35 pub fn inherent_impls(tcx: TyCtxt<'_>, ty_def_id: DefId) -> &[DefId] {
  36     assert!(ty_def_id.is_local());
  37
  38     let crate_map = tcx.crate_inherent_impls(ty_def_id.krate);
  39     match crate_map.inherent_impls.get(&ty_def_id) {
  40         Some(v) => &v[..],
  41         None => &[],
  42     }
  43 }
  44
  45 struct InherentCollect<'tcx> {
  46     tcx: TyCtxt<'tcx>,
  47     impls_map: CrateInherentImpls,
  48 }
  49
  50 impl ItemLikeVisitor<'v> for InherentCollect<'tcx> {
  51     fn visit_item(&mut self, item: &hir::Item) {
  52         let ty = match item.node {
  53             hir::ItemKind::Impl(.., None, ref ty, _) => ty,
  54             _ => return
  55         };
  56
  57         let def_id = self.tcx.hir().local_def_id(item.hir_id);
  58         let self_ty = self.tcx.type_of(def_id);
  59         let lang_items = self.tcx.lang_items();
  60         match self_ty.sty {
  61             ty::Adt(def, _) => {
  62                 self.check_def_id(item, def.did);
  63             }
  64             ty::Foreign(did) => {
  65                 self.check_def_id(item, did);
  66             }
  67             ty::Dynamic(ref data, ..) if data.principal_def_id().is_some() => {
  68                 self.check_def_id(item, data.principal_def_id().unwrap());
  69             }
  70             ty::Bool => {
  71                 self.check_primitive_impl(def_id,
  72                                           lang_items.bool_impl(),
  73                                           None,
  74                                           "bool",
  75                                           "bool",
  76                                           item.span);
  77             }
  78             ty::Char => {
  79                 self.check_primitive_impl(def_id,
  80                                           lang_items.char_impl(),
  81                                           None,
  82                                           "char",
  83                                           "char",
  84                                           item.span);
  85             }
  86             ty::Str => {
  87                 self.check_primitive_impl(def_id,
  88                                           lang_items.str_impl(),
  89                                           lang_items.str_alloc_impl(),
  90                                           "str",
  91                                           "str",
  92                                           item.span);
  93             }
  94             ty::Slice(slice_item) if slice_item == self.tcx.types.u8 => {
  95                 self.check_primitive_impl(def_id,
  96                                           lang_items.slice_u8_impl(),
  97                                           lang_items.slice_u8_alloc_impl(),
  98                                           "slice_u8",
  99                                           "[u8]",
 100                                           item.span);
 101             }
 102             ty::Slice(_) => {
 103                 self.check_primitive_impl(def_id,
 104                                           lang_items.slice_impl(),
 105                                           lang_items.slice_alloc_impl(),
 106                                           "slice",
 107                                           "[T]",
 108                                           item.span);
 109             }
 110             ty::RawPtr(ty::TypeAndMut { ty: _, mutbl: hir::MutImmutable }) => {
 111                 self.check_primitive_impl(def_id,
 112                                           lang_items.const_ptr_impl(),
 113                                           None,
 114                                           "const_ptr",
 115                                           "*const T",
 116                                           item.span);
 117             }
 118             ty::RawPtr(ty::TypeAndMut { ty: _, mutbl: hir::MutMutable }) => {
 119                 self.check_primitive_impl(def_id,
 120                                           lang_items.mut_ptr_impl(),
 121                                           None,
 122                                           "mut_ptr",
 123                                           "*mut T",
 124                                           item.span);
 125             }
 126             ty::Int(ast::IntTy::I8) => {
 127                 self.check_primitive_impl(def_id,
 128                                           lang_items.i8_impl(),
 129                                           None,
 130                                           "i8",
 131                                           "i8",
 132                                           item.span);
 133             }
 134             ty::Int(ast::IntTy::I16) => {
 135                 self.check_primitive_impl(def_id,
 136                                           lang_items.i16_impl(),
 137                                           None,
 138                                           "i16",
 139                                           "i16",
 140                                           item.span);
 141             }
 142             ty::Int(ast::IntTy::I32) => {
 143                 self.check_primitive_impl(def_id,
 144                                           lang_items.i32_impl(),
 145                                           None,
 146                                           "i32",
 147                                           "i32",
 148                                           item.span);
 149             }
 150             ty::Int(ast::IntTy::I64) => {
 151                 self.check_primitive_impl(def_id,
 152                                           lang_items.i64_impl(),
 153                                           None,
 154                                           "i64",
 155                                           "i64",
 156                                           item.span);
 157             }
 158             ty::Int(ast::IntTy::I128) => {
 159                 self.check_primitive_impl(def_id,
 160                                           lang_items.i128_impl(),
 161                                           None,
 162                                           "i128",
 163                                           "i128",
 164                                           item.span);
 165             }
 166             ty::Int(ast::IntTy::Isize) => {
 167                 self.check_primitive_impl(def_id,
 168                                           lang_items.isize_impl(),
 169                                           None,
 170                                           "isize",
 171                                           "isize",
 172                                           item.span);
 173             }
 174             ty::Uint(ast::UintTy::U8) => {
 175                 self.check_primitive_impl(def_id,
 176                                           lang_items.u8_impl(),
 177                                           None,
 178                                           "u8",
 179                                           "u8",
 180                                           item.span);
 181             }
 182             ty::Uint(ast::UintTy::U16) => {
 183                 self.check_primitive_impl(def_id,
 184                                           lang_items.u16_impl(),
 185                                           None,
 186                                           "u16",
 187                                           "u16",
 188                                           item.span);
 189             }
 190             ty::Uint(ast::UintTy::U32) => {
 191                 self.check_primitive_impl(def_id,
 192                                           lang_items.u32_impl(),
 193                                           None,
 194                                           "u32",
 195                                           "u32",
 196                                           item.span);
 197             }
 198             ty::Uint(ast::UintTy::U64) => {
 199                 self.check_primitive_impl(def_id,
 200                                           lang_items.u64_impl(),
 201                                           None,
 202                                           "u64",
 203                                           "u64",
 204                                           item.span);
 205             }
 206             ty::Uint(ast::UintTy::U128) => {
 207                 self.check_primitive_impl(def_id,
 208                                           lang_items.u128_impl(),
 209                                           None,
 210                                           "u128",
 211                                           "u128",
 212                                           item.span);
 213             }
 214             ty::Uint(ast::UintTy::Usize) => {
 215                 self.check_primitive_impl(def_id,
 216                                           lang_items.usize_impl(),
 217                                           None,
 218                                           "usize",
 219                                           "usize",
 220                                           item.span);
 221             }
 222             ty::Float(ast::FloatTy::F32) => {
 223                 self.check_primitive_impl(def_id,
 224                                           lang_items.f32_impl(),
 225                                           lang_items.f32_runtime_impl(),
 226                                           "f32",
 227                                           "f32",
 228                                           item.span);
 229             }
 230             ty::Float(ast::FloatTy::F64) => {
 231                 self.check_primitive_impl(def_id,
 232                                           lang_items.f64_impl(),
 233                                           lang_items.f64_runtime_impl(),
 234                                           "f64",
 235                                           "f64",
 236                                           item.span);
 237             }
 238             ty::Error => {
 239                 return;
 240             }
 241             _ => {
 242                 struct_span_err!(self.tcx.sess,
 243                                  ty.span,
 244                                  E0118,
 245                                  "no base type found for inherent implementation")
 246                     .span_label(ty.span, "impl requires a base type")
 247                     .note(&format!("either implement a trait on it or create a newtype \
 248                                     to wrap it instead"))
 249                     .emit();
 250                 return;
 251             }
 252         }
 253     }
 254
 255     fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
 256     }
 257
 258     fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
 259     }
 260 }
 261
 262 impl InherentCollect<'tcx> {
 263     fn check_def_id(&mut self, item: &hir::Item, def_id: DefId) {
 264         if def_id.is_local() {
 265             // Add the implementation to the mapping from implementation to base
 266             // type def ID, if there is a base type for this implementation and
 267             // the implementation does not have any associated traits.
 268             let impl_def_id = self.tcx.hir().local_def_id(item.hir_id);
 269             let vec = self.impls_map.inherent_impls.entry(def_id).or_default();
 270             vec.push(impl_def_id);
 271         } else {
 272             struct_span_err!(self.tcx.sess,
 273                              item.span,
 274                              E0116,
 275                              "cannot define inherent `impl` for a type outside of the crate \
 276                               where the type is defined")
 277                 .span_label(item.span, "impl for type defined outside of crate.")
 278                 .note("define and implement a trait or new type instead")
 279                 .emit();
 280         }
 281     }
 282
 283     fn check_primitive_impl(&self,
 284                             impl_def_id: DefId,
 285                             lang_def_id: Option<DefId>,
 286                             lang_def_id2: Option<DefId>,
 287                             lang: &str,
 288                             ty: &str,
 289                             span: Span) {
 290         match (lang_def_id, lang_def_id2) {
 291             (Some(lang_def_id), _) if lang_def_id == impl_def_id => {
 292                 // OK
 293             }
 294             (_, Some(lang_def_id)) if lang_def_id == impl_def_id => {
 295                 // OK
 296             }
 297             _ => {
 298                 struct_span_err!(self.tcx.sess,
 299                                  span,
 300                                  E0390,
 301                                  "only a single inherent implementation marked with `#[lang = \
 302                                   \"{}\"]` is allowed for the `{}` primitive",
 303                                  lang,
 304                                  ty)
 305                     .span_help(span, "consider using a trait to implement these methods")
 306                     .emit();
 307             }
 308         }
 309     }
 310 }