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.
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.
11 // Detecting language items.
13 // Language items are items that represent concepts intrinsic to the language
14 // itself. Examples are:
16 // * Traits that specify "kinds"; e.g. "Sync", "Send".
18 // * Traits that represent operators; e.g. "Add", "Sub", "Index".
20 // * Functions called by the compiler itself.
22 pub use self::LangItem::*;
24 use hir::def_id::DefId;
25 use ty::{self, TyCtxt};
26 use middle::weak_lang_items;
27 use util::nodemap::FxHashMap;
30 use syntax::symbol::Symbol;
31 use hir::itemlikevisit::ItemLikeVisitor;
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 {
38 $( $variant:ident, $name:expr, $method:ident; )*
43 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
50 fn name(self) -> &'static str {
52 $( $variant => $name, )*
57 pub struct LanguageItems {
58 pub items: Vec<Option<DefId>>,
59 pub missing: Vec<LangItem>,
63 pub fn new() -> LanguageItems {
64 fn foo(_: LangItem) -> Option<DefId> { None }
67 items: vec![$(foo($variant)),*],
72 pub fn items(&self) -> &[Option<DefId>] {
76 pub fn require(&self, it: LangItem) -> Result<DefId, String> {
77 self.items[it as usize].ok_or_else(|| format!("requires `{}` lang_item", it.name()))
80 pub fn fn_trait_kind(&self, id: DefId) -> Option<ty::ClosureKind> {
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),
91 pub fn $method(&self) -> Option<DefId> {
92 self.items[$variant as usize]
97 struct LanguageItemCollector<'a, 'tcx: 'a> {
100 tcx: TyCtxt<'a, 'tcx, 'tcx>,
102 item_refs: FxHashMap<&'static str, usize>,
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();
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);
114 let span = self.tcx.hir.span(item.id);
115 span_err!(self.tcx.sess, span, E0522,
116 "definition of an unknown language item: `{}`.",
122 fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
123 // at present, lang items are always items, not trait items
126 fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
127 // at present, lang items are always items, not impl items
131 impl<'a, 'tcx> LanguageItemCollector<'a, 'tcx> {
132 fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItemCollector<'a, 'tcx> {
133 let mut item_refs = FxHashMap();
135 $( item_refs.insert($name, $variant as usize); )*
137 LanguageItemCollector {
139 items: LanguageItems::new(),
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!(
154 "duplicate lang item found: `{}`.",
156 None => self.tcx.sess.struct_err(&format!(
157 "duplicate lang item in crate `{}`: `{}`.",
158 self.tcx.crate_name(item_def_id.krate),
161 if let Some(span) = self.tcx.hir.span_if_local(original_def_id) {
162 span_note!(&mut err, span,
163 "first defined here.");
165 err.note(&format!("first defined in crate `{}`.",
166 self.tcx.crate_name(original_def_id.krate)));
176 self.items.items[item_index] = Some(item_def_id);
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() {
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);
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);
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;
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;
240 DropTraitLangItem, "drop", drop_trait;
242 CoerceUnsizedTraitLangItem, "coerce_unsized", coerce_unsized_trait;
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;
269 UnsafeCellTypeLangItem, "unsafe_cell", unsafe_cell_type;
271 DerefTraitLangItem, "deref", deref_trait;
272 DerefMutTraitLangItem, "deref_mut", deref_mut_trait;
274 FnTraitLangItem, "fn", fn_trait;
275 FnMutTraitLangItem, "fn_mut", fn_mut_trait;
276 FnOnceTraitLangItem, "fn_once", fn_once_trait;
278 GeneratorStateLangItem, "generator_state", gen_state;
279 GeneratorTraitLangItem, "generator", gen_trait;
281 EqTraitLangItem, "eq", eq_trait;
282 OrdTraitLangItem, "ord", ord_trait;
284 StrEqFnLangItem, "str_eq", str_eq_fn;
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.
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;
299 ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn;
300 BoxFreeFnLangItem, "box_free", box_free_fn;
301 DropInPlaceFnLangItem, "drop_in_place", drop_in_place_fn;
303 StartFnLangItem, "start", start_fn;
305 EhPersonalityLangItem, "eh_personality", eh_personality;
306 EhUnwindResumeLangItem, "eh_unwind_resume", eh_unwind_resume;
307 MSVCTryFilterLangItem, "msvc_try_filter", msvc_try_filter;
309 OwnedBoxLangItem, "owned_box", owned_box;
311 PhantomDataItem, "phantom_data", phantom_data;
313 NonZeroItem, "non_zero", non_zero;
315 DebugTraitLangItem, "debug_trait", debug_trait;
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)