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_errors::struct_span_err;
  11 use rustc_hir as hir;
  12 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
  13 use rustc_hir::itemlikevisit::ItemLikeVisitor;
  14 use rustc_middle::ty::{self, CrateInherentImpls, TyCtxt};
  15
  16 use rustc_ast::ast;
  17 use rustc_span::Span;
  18
  19 /// On-demand query: yields a map containing all types mapped to their inherent impls.
  20 pub fn crate_inherent_impls(tcx: TyCtxt<'_>, crate_num: CrateNum) -> CrateInherentImpls {
  21     assert_eq!(crate_num, LOCAL_CRATE);
  22
  23     let krate = tcx.hir().krate();
  24     let mut collect = InherentCollect { tcx, impls_map: Default::default() };
  25     krate.visit_all_item_likes(&mut collect);
  26     collect.impls_map
  27 }
  28
  29 /// On-demand query: yields a vector of the inherent impls for a specific type.
  30 pub fn inherent_impls(tcx: TyCtxt<'_>, ty_def_id: DefId) -> &[DefId] {
  31     assert!(ty_def_id.is_local());
  32
  33     let crate_map = tcx.crate_inherent_impls(ty_def_id.krate);
  34     match crate_map.inherent_impls.get(&ty_def_id) {
  35         Some(v) => &v[..],
  36         None => &[],
  37     }
  38 }
  39
  40 struct InherentCollect<'tcx> {
  41     tcx: TyCtxt<'tcx>,
  42     impls_map: CrateInherentImpls,
  43 }
  44
  45 impl ItemLikeVisitor<'v> for InherentCollect<'tcx> {
  46     fn visit_item(&mut self, item: &hir::Item<'_>) {
  47         let ty = match item.kind {
  48             hir::ItemKind::Impl { of_trait: None, ref self_ty, .. } => self_ty,
  49             _ => return,
  50         };
  51
  52         let def_id = self.tcx.hir().local_def_id(item.hir_id);
  53         let self_ty = self.tcx.type_of(def_id);
  54         let lang_items = self.tcx.lang_items();
  55         match self_ty.kind {
  56             ty::Adt(def, _) => {
  57                 self.check_def_id(item, def.did);
  58             }
  59             ty::Foreign(did) => {
  60                 self.check_def_id(item, did);
  61             }
  62             ty::Dynamic(ref data, ..) if data.principal_def_id().is_some() => {
  63                 self.check_def_id(item, data.principal_def_id().unwrap());
  64             }
  65             ty::Bool => {
  66                 self.check_primitive_impl(
  67                     def_id,
  68                     lang_items.bool_impl(),
  69                     None,
  70                     "bool",
  71                     "bool",
  72                     item.span,
  73                 );
  74             }
  75             ty::Char => {
  76                 self.check_primitive_impl(
  77                     def_id,
  78                     lang_items.char_impl(),
  79                     None,
  80                     "char",
  81                     "char",
  82                     item.span,
  83                 );
  84             }
  85             ty::Str => {
  86                 self.check_primitive_impl(
  87                     def_id,
  88                     lang_items.str_impl(),
  89                     lang_items.str_alloc_impl(),
  90                     "str",
  91                     "str",
  92                     item.span,
  93                 );
  94             }
  95             ty::Slice(slice_item) if slice_item == self.tcx.types.u8 => {
  96                 self.check_primitive_impl(
  97                     def_id,
  98                     lang_items.slice_u8_impl(),
  99                     lang_items.slice_u8_alloc_impl(),
 100                     "slice_u8",
 101                     "[u8]",
 102                     item.span,
 103                 );
 104             }
 105             ty::Slice(_) => {
 106                 self.check_primitive_impl(
 107                     def_id,
 108                     lang_items.slice_impl(),
 109                     lang_items.slice_alloc_impl(),
 110                     "slice",
 111                     "[T]",
 112                     item.span,
 113                 );
 114             }
 115             ty::RawPtr(ty::TypeAndMut { ty: inner, mutbl: hir::Mutability::Not })
 116                 if matches!(inner.kind, ty::Slice(_)) =>
 117             {
 118                 self.check_primitive_impl(
 119                     def_id,
 120                     lang_items.const_slice_ptr_impl(),
 121                     None,
 122                     "const_slice_ptr",
 123                     "*const [T]",
 124                     item.span,
 125                 );
 126             }
 127             ty::RawPtr(ty::TypeAndMut { ty: inner, mutbl: hir::Mutability::Mut })
 128                 if matches!(inner.kind, ty::Slice(_)) =>
 129             {
 130                 self.check_primitive_impl(
 131                     def_id,
 132                     lang_items.mut_slice_ptr_impl(),
 133                     None,
 134                     "mut_slice_ptr",
 135                     "*mut [T]",
 136                     item.span,
 137                 );
 138             }
 139             ty::RawPtr(ty::TypeAndMut { ty: _, mutbl: hir::Mutability::Not }) => {
 140                 self.check_primitive_impl(
 141                     def_id,
 142                     lang_items.const_ptr_impl(),
 143                     None,
 144                     "const_ptr",
 145                     "*const T",
 146                     item.span,
 147                 );
 148             }
 149             ty::RawPtr(ty::TypeAndMut { ty: _, mutbl: hir::Mutability::Mut }) => {
 150                 self.check_primitive_impl(
 151                     def_id,
 152                     lang_items.mut_ptr_impl(),
 153                     None,
 154                     "mut_ptr",
 155                     "*mut T",
 156                     item.span,
 157                 );
 158             }
 159             ty::Int(ast::IntTy::I8) => {
 160                 self.check_primitive_impl(
 161                     def_id,
 162                     lang_items.i8_impl(),
 163                     None,
 164                     "i8",
 165                     "i8",
 166                     item.span,
 167                 );
 168             }
 169             ty::Int(ast::IntTy::I16) => {
 170                 self.check_primitive_impl(
 171                     def_id,
 172                     lang_items.i16_impl(),
 173                     None,
 174                     "i16",
 175                     "i16",
 176                     item.span,
 177                 );
 178             }
 179             ty::Int(ast::IntTy::I32) => {
 180                 self.check_primitive_impl(
 181                     def_id,
 182                     lang_items.i32_impl(),
 183                     None,
 184                     "i32",
 185                     "i32",
 186                     item.span,
 187                 );
 188             }
 189             ty::Int(ast::IntTy::I64) => {
 190                 self.check_primitive_impl(
 191                     def_id,
 192                     lang_items.i64_impl(),
 193                     None,
 194                     "i64",
 195                     "i64",
 196                     item.span,
 197                 );
 198             }
 199             ty::Int(ast::IntTy::I128) => {
 200                 self.check_primitive_impl(
 201                     def_id,
 202                     lang_items.i128_impl(),
 203                     None,
 204                     "i128",
 205                     "i128",
 206                     item.span,
 207                 );
 208             }
 209             ty::Int(ast::IntTy::Isize) => {
 210                 self.check_primitive_impl(
 211                     def_id,
 212                     lang_items.isize_impl(),
 213                     None,
 214                     "isize",
 215                     "isize",
 216                     item.span,
 217                 );
 218             }
 219             ty::Uint(ast::UintTy::U8) => {
 220                 self.check_primitive_impl(
 221                     def_id,
 222                     lang_items.u8_impl(),
 223                     None,
 224                     "u8",
 225                     "u8",
 226                     item.span,
 227                 );
 228             }
 229             ty::Uint(ast::UintTy::U16) => {
 230                 self.check_primitive_impl(
 231                     def_id,
 232                     lang_items.u16_impl(),
 233                     None,
 234                     "u16",
 235                     "u16",
 236                     item.span,
 237                 );
 238             }
 239             ty::Uint(ast::UintTy::U32) => {
 240                 self.check_primitive_impl(
 241                     def_id,
 242                     lang_items.u32_impl(),
 243                     None,
 244                     "u32",
 245                     "u32",
 246                     item.span,
 247                 );
 248             }
 249             ty::Uint(ast::UintTy::U64) => {
 250                 self.check_primitive_impl(
 251                     def_id,
 252                     lang_items.u64_impl(),
 253                     None,
 254                     "u64",
 255                     "u64",
 256                     item.span,
 257                 );
 258             }
 259             ty::Uint(ast::UintTy::U128) => {
 260                 self.check_primitive_impl(
 261                     def_id,
 262                     lang_items.u128_impl(),
 263                     None,
 264                     "u128",
 265                     "u128",
 266                     item.span,
 267                 );
 268             }
 269             ty::Uint(ast::UintTy::Usize) => {
 270                 self.check_primitive_impl(
 271                     def_id,
 272                     lang_items.usize_impl(),
 273                     None,
 274                     "usize",
 275                     "usize",
 276                     item.span,
 277                 );
 278             }
 279             ty::Float(ast::FloatTy::F32) => {
 280                 self.check_primitive_impl(
 281                     def_id,
 282                     lang_items.f32_impl(),
 283                     lang_items.f32_runtime_impl(),
 284                     "f32",
 285                     "f32",
 286                     item.span,
 287                 );
 288             }
 289             ty::Float(ast::FloatTy::F64) => {
 290                 self.check_primitive_impl(
 291                     def_id,
 292                     lang_items.f64_impl(),
 293                     lang_items.f64_runtime_impl(),
 294                     "f64",
 295                     "f64",
 296                     item.span,
 297                 );
 298             }
 299             ty::Error(_) => {}
 300             _ => {
 301                 struct_span_err!(
 302                     self.tcx.sess,
 303                     ty.span,
 304                     E0118,
 305                     "no base type found for inherent implementation"
 306                 )
 307                 .span_label(ty.span, "impl requires a base type")
 308                 .note(
 309                     "either implement a trait on it or create a newtype \
 310                        to wrap it instead",
 311                 )
 312                 .emit();
 313             }
 314         }
 315     }
 316
 317     fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem<'_>) {}
 318
 319     fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem<'_>) {}
 320 }
 321
 322 impl InherentCollect<'tcx> {
 323     fn check_def_id(&mut self, item: &hir::Item<'_>, def_id: DefId) {
 324         if def_id.is_local() {
 325             // Add the implementation to the mapping from implementation to base
 326             // type def ID, if there is a base type for this implementation and
 327             // the implementation does not have any associated traits.
 328             let impl_def_id = self.tcx.hir().local_def_id(item.hir_id);
 329             let vec = self.impls_map.inherent_impls.entry(def_id).or_default();
 330             vec.push(impl_def_id.to_def_id());
 331         } else {
 332             struct_span_err!(
 333                 self.tcx.sess,
 334                 item.span,
 335                 E0116,
 336                 "cannot define inherent `impl` for a type outside of the crate \
 337                               where the type is defined"
 338             )
 339             .span_label(item.span, "impl for type defined outside of crate.")
 340             .note("define and implement a trait or new type instead")
 341             .emit();
 342         }
 343     }
 344
 345     fn check_primitive_impl(
 346         &self,
 347         impl_def_id: LocalDefId,
 348         lang_def_id: Option<DefId>,
 349         lang_def_id2: Option<DefId>,
 350         lang: &str,
 351         ty: &str,
 352         span: Span,
 353     ) {
 354         match (lang_def_id, lang_def_id2) {
 355             (Some(lang_def_id), _) if lang_def_id == impl_def_id.to_def_id() => {
 356                 // OK
 357             }
 358             (_, Some(lang_def_id)) if lang_def_id == impl_def_id.to_def_id() => {
 359                 // OK
 360             }
 361             _ => {
 362                 struct_span_err!(
 363                     self.tcx.sess,
 364                     span,
 365                     E0390,
 366                     "only a single inherent implementation marked with `#[lang = \
 367                                   \"{}\"]` is allowed for the `{}` primitive",
 368                     lang,
 369                     ty
 370                 )
 371                 .span_help(span, "consider using a trait to implement these methods")
 372                 .emit();
 373             }
 374         }
 375     }
 376 }