src/librustc/middle/lang_items.rs

   1 // Copyright 2012 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 // Detecting language items.
  12 //
  13 // Language items are items that represent concepts intrinsic to the language
  14 // itself. Examples are:
  15 //
  16 // * Traits that specify "kinds"; e.g. "Sync", "Send".
  17 //
  18 // * Traits that represent operators; e.g. "Add", "Sub", "Index".
  19 //
  20 // * Functions called by the compiler itself.
  21
  22 pub use self::LangItem::*;
  23
  24 use hir::def_id::DefId;
  25 use ty::{self, TyCtxt};
  26 use middle::weak_lang_items;
  27 use util::nodemap::FxHashMap;
  28
  29 use syntax::ast;
  30 use syntax::symbol::Symbol;
  31 use hir::itemlikevisit::ItemLikeVisitor;
  32 use hir;
  33
  34 // The actual lang items defined come at the end of this file in one handy table.
  35 // So you probably just want to nip down to the end.
  36 macro_rules! language_item_table {
  37     (
  38         $( $variant:ident, $name:expr, $method:ident; )*
  39     ) => {
  40
  41
  42 enum_from_u32! {
  43     #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
  44     pub enum LangItem {
  45         $($variant,)*
  46     }
  47 }
  48
  49 impl LangItem {
  50     fn name(self) -> &'static str {
  51         match self {
  52             $( $variant => $name, )*
  53         }
  54     }
  55 }
  56
  57 pub struct LanguageItems {
  58     pub items: Vec<Option<DefId>>,
  59     pub missing: Vec<LangItem>,
  60 }
  61
  62 impl LanguageItems {
  63     pub fn new() -> LanguageItems {
  64         fn foo(_: LangItem) -> Option<DefId> { None }
  65
  66         LanguageItems {
  67             items: vec![$(foo($variant)),*],
  68             missing: Vec::new(),
  69         }
  70     }
  71
  72     pub fn items(&self) -> &[Option<DefId>] {
  73         &*self.items
  74     }
  75
  76     pub fn require(&self, it: LangItem) -> Result<DefId, String> {
  77         self.items[it as usize].ok_or(format!("requires `{}` lang_item", it.name()))
  78     }
  79
  80     pub fn fn_trait_kind(&self, id: DefId) -> Option<ty::ClosureKind> {
  81         match Some(id) {
  82             x if x == self.fn_trait() => Some(ty::ClosureKind::Fn),
  83             x if x == self.fn_mut_trait() => Some(ty::ClosureKind::FnMut),
  84             x if x == self.fn_once_trait() =>  Some(ty::ClosureKind::FnOnce),
  85             _ => None
  86         }
  87     }
  88
  89     $(
  90         #[allow(dead_code)]
  91         pub fn $method(&self) -> Option<DefId> {
  92             self.items[$variant as usize]
  93         }
  94     )*
  95 }
  96
  97 struct LanguageItemCollector<'a, 'tcx: 'a> {
  98     items: LanguageItems,
  99
 100     tcx: TyCtxt<'a, 'tcx, 'tcx>,
 101
 102     item_refs: FxHashMap<&'static str, usize>,
 103 }
 104
 105 impl<'a, 'v, 'tcx> ItemLikeVisitor<'v> for LanguageItemCollector<'a, 'tcx> {
 106     fn visit_item(&mut self, item: &hir::Item) {
 107         if let Some(value) = extract(&item.attrs) {
 108             let item_index = self.item_refs.get(&*value.as_str()).cloned();
 109
 110             if let Some(item_index) = item_index {
 111                 let def_id = self.tcx.hir.local_def_id(item.id);
 112                 self.collect_item(item_index, def_id);
 113             } else {
 114                 let span = self.tcx.hir.span(item.id);
 115                 span_err!(self.tcx.sess, span, E0522,
 116                           "definition of an unknown language item: `{}`.",
 117                           value);
 118             }
 119         }
 120     }
 121
 122     fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
 123         // at present, lang items are always items, not trait items
 124     }
 125
 126     fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
 127         // at present, lang items are always items, not impl items
 128     }
 129 }
 130
 131 impl<'a, 'tcx> LanguageItemCollector<'a, 'tcx> {
 132     fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItemCollector<'a, 'tcx> {
 133         let mut item_refs = FxHashMap();
 134
 135         $( item_refs.insert($name, $variant as usize); )*
 136
 137         LanguageItemCollector {
 138             tcx,
 139             items: LanguageItems::new(),
 140             item_refs,
 141         }
 142     }
 143
 144     fn collect_item(&mut self, item_index: usize, item_def_id: DefId) {
 145         // Check for duplicates.
 146         match self.items.items[item_index] {
 147             Some(original_def_id) if original_def_id != item_def_id => {
 148                 let name = LangItem::from_u32(item_index as u32).unwrap().name();
 149                 let mut err = match self.tcx.hir.span_if_local(item_def_id) {
 150                     Some(span) => struct_span_err!(
 151                         self.tcx.sess,
 152                         span,
 153                         E0152,
 154                         "duplicate lang item found: `{}`.",
 155                         name),
 156                     None => self.tcx.sess.struct_err(&format!(
 157                             "duplicate lang item in crate `{}`: `{}`.",
 158                             self.tcx.crate_name(item_def_id.krate),
 159                             name)),
 160                 };
 161                 if let Some(span) = self.tcx.hir.span_if_local(original_def_id) {
 162                     span_note!(&mut err, span,
 163                                "first defined here.");
 164                 } else {
 165                     err.note(&format!("first defined in crate `{}`.",
 166                                       self.tcx.crate_name(original_def_id.krate)));
 167                 }
 168                 err.emit();
 169             }
 170             _ => {
 171                 // OK.
 172             }
 173         }
 174
 175         // Matched.
 176         self.items.items[item_index] = Some(item_def_id);
 177     }
 178 }
 179
 180 pub fn extract(attrs: &[ast::Attribute]) -> Option<Symbol> {
 181     for attribute in attrs {
 182         if attribute.check_name("lang") {
 183             if let Some(value) = attribute.value_str() {
 184                 return Some(value)
 185             }
 186         }
 187     }
 188
 189     return None;
 190 }
 191
 192 pub fn collect<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItems {
 193     let mut collector = LanguageItemCollector::new(tcx);
 194     for &cnum in tcx.crates().iter() {
 195         for &(index, item_index) in tcx.defined_lang_items(cnum).iter() {
 196             let def_id = DefId { krate: cnum, index: index };
 197             collector.collect_item(item_index, def_id);
 198         }
 199     }
 200     tcx.hir.krate().visit_all_item_likes(&mut collector);
 201     let LanguageItemCollector { mut items, .. } = collector;
 202     weak_lang_items::check_crate(tcx, &mut items);
 203     items
 204 }
 205
 206 // End of the macro
 207     }
 208 }
 209
 210 language_item_table! {
 211 //  Variant name,                    Name,                      Method name;
 212     CharImplItem,                    "char",                    char_impl;
 213     StrImplItem,                     "str",                     str_impl;
 214     SliceImplItem,                   "slice",                   slice_impl;
 215     ConstPtrImplItem,                "const_ptr",               const_ptr_impl;
 216     MutPtrImplItem,                  "mut_ptr",                 mut_ptr_impl;
 217     I8ImplItem,                      "i8",                      i8_impl;
 218     I16ImplItem,                     "i16",                     i16_impl;
 219     I32ImplItem,                     "i32",                     i32_impl;
 220     I64ImplItem,                     "i64",                     i64_impl;
 221     I128ImplItem,                     "i128",                   i128_impl;
 222     IsizeImplItem,                   "isize",                   isize_impl;
 223     U8ImplItem,                      "u8",                      u8_impl;
 224     U16ImplItem,                     "u16",                     u16_impl;
 225     U32ImplItem,                     "u32",                     u32_impl;
 226     U64ImplItem,                     "u64",                     u64_impl;
 227     U128ImplItem,                    "u128",                    u128_impl;
 228     UsizeImplItem,                   "usize",                   usize_impl;
 229     F32ImplItem,                     "f32",                     f32_impl;
 230     F64ImplItem,                     "f64",                     f64_impl;
 231
 232     SendTraitLangItem,               "send",                    send_trait;
 233     SizedTraitLangItem,              "sized",                   sized_trait;
 234     UnsizeTraitLangItem,             "unsize",                  unsize_trait;
 235     CopyTraitLangItem,               "copy",                    copy_trait;
 236     CloneTraitLangItem,              "clone",                   clone_trait;
 237     SyncTraitLangItem,               "sync",                    sync_trait;
 238     FreezeTraitLangItem,             "freeze",                  freeze_trait;
 239
 240     DropTraitLangItem,               "drop",                    drop_trait;
 241
 242     CoerceUnsizedTraitLangItem,      "coerce_unsized",          coerce_unsized_trait;
 243
 244     AddTraitLangItem,                "add",                     add_trait;
 245     SubTraitLangItem,                "sub",                     sub_trait;
 246     MulTraitLangItem,                "mul",                     mul_trait;
 247     DivTraitLangItem,                "div",                     div_trait;
 248     RemTraitLangItem,                "rem",                     rem_trait;
 249     NegTraitLangItem,                "neg",                     neg_trait;
 250     NotTraitLangItem,                "not",                     not_trait;
 251     BitXorTraitLangItem,             "bitxor",                  bitxor_trait;
 252     BitAndTraitLangItem,             "bitand",                  bitand_trait;
 253     BitOrTraitLangItem,              "bitor",                   bitor_trait;
 254     ShlTraitLangItem,                "shl",                     shl_trait;
 255     ShrTraitLangItem,                "shr",                     shr_trait;
 256     AddAssignTraitLangItem,          "add_assign",              add_assign_trait;
 257     SubAssignTraitLangItem,          "sub_assign",              sub_assign_trait;
 258     MulAssignTraitLangItem,          "mul_assign",              mul_assign_trait;
 259     DivAssignTraitLangItem,          "div_assign",              div_assign_trait;
 260     RemAssignTraitLangItem,          "rem_assign",              rem_assign_trait;
 261     BitXorAssignTraitLangItem,       "bitxor_assign",           bitxor_assign_trait;
 262     BitAndAssignTraitLangItem,       "bitand_assign",           bitand_assign_trait;
 263     BitOrAssignTraitLangItem,        "bitor_assign",            bitor_assign_trait;
 264     ShlAssignTraitLangItem,          "shl_assign",              shl_assign_trait;
 265     ShrAssignTraitLangItem,          "shr_assign",              shr_assign_trait;
 266     IndexTraitLangItem,              "index",                   index_trait;
 267     IndexMutTraitLangItem,           "index_mut",               index_mut_trait;
 268
 269     UnsafeCellTypeLangItem,          "unsafe_cell",             unsafe_cell_type;
 270
 271     DerefTraitLangItem,              "deref",                   deref_trait;
 272     DerefMutTraitLangItem,           "deref_mut",               deref_mut_trait;
 273
 274     FnTraitLangItem,                 "fn",                      fn_trait;
 275     FnMutTraitLangItem,              "fn_mut",                  fn_mut_trait;
 276     FnOnceTraitLangItem,             "fn_once",                 fn_once_trait;
 277
 278     GeneratorStateLangItem,          "generator_state",         gen_state;
 279     GeneratorTraitLangItem,          "generator",               gen_trait;
 280
 281     EqTraitLangItem,                 "eq",                      eq_trait;
 282     OrdTraitLangItem,                "ord",                     ord_trait;
 283
 284     StrEqFnLangItem,                 "str_eq",                  str_eq_fn;
 285
 286     // A number of panic-related lang items. The `panic` item corresponds to
 287     // divide-by-zero and various panic cases with `match`. The
 288     // `panic_bounds_check` item is for indexing arrays.
 289     //
 290     // The `begin_unwind` lang item has a predefined symbol name and is sort of
 291     // a "weak lang item" in the sense that a crate is not required to have it
 292     // defined to use it, but a final product is required to define it
 293     // somewhere. Additionally, there are restrictions on crates that use a weak
 294     // lang item, but do not have it defined.
 295     PanicFnLangItem,                 "panic",                   panic_fn;
 296     PanicBoundsCheckFnLangItem,      "panic_bounds_check",      panic_bounds_check_fn;
 297     PanicFmtLangItem,                "panic_fmt",               panic_fmt;
 298
 299     ExchangeMallocFnLangItem,        "exchange_malloc",         exchange_malloc_fn;
 300     BoxFreeFnLangItem,               "box_free",                box_free_fn;
 301     DropInPlaceFnLangItem,             "drop_in_place",           drop_in_place_fn;
 302
 303     StartFnLangItem,                 "start",                   start_fn;
 304
 305     EhPersonalityLangItem,           "eh_personality",          eh_personality;
 306     EhUnwindResumeLangItem,          "eh_unwind_resume",        eh_unwind_resume;
 307     MSVCTryFilterLangItem,           "msvc_try_filter",         msvc_try_filter;
 308
 309     OwnedBoxLangItem,                "owned_box",               owned_box;
 310
 311     PhantomDataItem,                 "phantom_data",            phantom_data;
 312
 313     NonZeroItem,                     "non_zero",                non_zero;
 314
 315     DebugTraitLangItem,              "debug_trait",             debug_trait;
 316 }
 317
 318 impl<'a, 'tcx, 'gcx> ty::TyCtxt<'a, 'tcx, 'gcx> {
 319     pub fn require_lang_item(&self, lang_item: LangItem) -> DefId {
 320         self.lang_items().require(lang_item).unwrap_or_else(|msg| {
 321             self.sess.fatal(&msg)
 322         })
 323     }
 324 }