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;
32 use hir::itemlikevisit::ItemLikeVisitor;
35 // The actual lang items defined come at the end of this file in one handy table.
36 // So you probably just want to nip down to the end.
37 macro_rules! language_item_table {
39 $( $variant:ident, $name:expr, $method:ident; )*
43 #[derive(Debug, 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, span)) = 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 mut err = struct_span_err!(self.tcx.sess, span, E0522,
115 "definition of an unknown language item: `{}`",
117 err.span_label(span, format!("definition of unknown language item `{}`", value));
123 fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
124 // at present, lang items are always items, not trait items
127 fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
128 // at present, lang items are always items, not impl items
132 impl<'a, 'tcx> LanguageItemCollector<'a, 'tcx> {
133 fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItemCollector<'a, 'tcx> {
134 let mut item_refs = FxHashMap();
136 $( item_refs.insert($name, $variant as usize); )*
138 LanguageItemCollector {
140 items: LanguageItems::new(),
145 fn collect_item(&mut self, item_index: usize, item_def_id: DefId) {
146 // Check for duplicates.
147 if let Some(original_def_id) = self.items.items[item_index] {
148 if original_def_id != item_def_id {
149 let name = LangItem::from_u32(item_index as u32).unwrap().name();
150 let mut err = match self.tcx.hir.span_if_local(item_def_id) {
151 Some(span) => struct_span_err!(
155 "duplicate lang item found: `{}`.",
157 None => self.tcx.sess.struct_err(&format!(
158 "duplicate lang item in crate `{}`: `{}`.",
159 self.tcx.crate_name(item_def_id.krate),
162 if let Some(span) = self.tcx.hir.span_if_local(original_def_id) {
163 span_note!(&mut err, span, "first defined here.");
165 err.note(&format!("first defined in crate `{}`.",
166 self.tcx.crate_name(original_def_id.krate)));
173 self.items.items[item_index] = Some(item_def_id);
177 pub fn extract(attrs: &[ast::Attribute]) -> Option<(Symbol, Span)> {
178 for attribute in attrs {
179 if attribute.check_name("lang") {
180 if let Some(value) = attribute.value_str() {
181 return Some((value, attribute.span));
183 } else if attribute.check_name("panic_implementation") ||
184 attribute.check_name("panic_handler")
186 return Some((Symbol::intern("panic_impl"), attribute.span))
187 } else if attribute.check_name("alloc_error_handler") {
188 return Some((Symbol::intern("oom"), attribute.span))
195 pub fn collect<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LanguageItems {
196 let mut collector = LanguageItemCollector::new(tcx);
197 for &cnum in tcx.crates().iter() {
198 for &(def_id, item_index) in tcx.defined_lang_items(cnum).iter() {
199 collector.collect_item(item_index, def_id);
202 tcx.hir.krate().visit_all_item_likes(&mut collector);
203 let LanguageItemCollector { mut items, .. } = collector;
204 weak_lang_items::check_crate(tcx, &mut items);
212 language_item_table! {
213 // Variant name, Name, Method name;
214 CharImplItem, "char", char_impl;
215 StrImplItem, "str", str_impl;
216 SliceImplItem, "slice", slice_impl;
217 SliceU8ImplItem, "slice_u8", slice_u8_impl;
218 StrAllocImplItem, "str_alloc", str_alloc_impl;
219 SliceAllocImplItem, "slice_alloc", slice_alloc_impl;
220 SliceU8AllocImplItem, "slice_u8_alloc", slice_u8_alloc_impl;
221 ConstPtrImplItem, "const_ptr", const_ptr_impl;
222 MutPtrImplItem, "mut_ptr", mut_ptr_impl;
223 I8ImplItem, "i8", i8_impl;
224 I16ImplItem, "i16", i16_impl;
225 I32ImplItem, "i32", i32_impl;
226 I64ImplItem, "i64", i64_impl;
227 I128ImplItem, "i128", i128_impl;
228 IsizeImplItem, "isize", isize_impl;
229 U8ImplItem, "u8", u8_impl;
230 U16ImplItem, "u16", u16_impl;
231 U32ImplItem, "u32", u32_impl;
232 U64ImplItem, "u64", u64_impl;
233 U128ImplItem, "u128", u128_impl;
234 UsizeImplItem, "usize", usize_impl;
235 F32ImplItem, "f32", f32_impl;
236 F64ImplItem, "f64", f64_impl;
237 F32RuntimeImplItem, "f32_runtime", f32_runtime_impl;
238 F64RuntimeImplItem, "f64_runtime", f64_runtime_impl;
240 SizedTraitLangItem, "sized", sized_trait;
241 UnsizeTraitLangItem, "unsize", unsize_trait;
242 CopyTraitLangItem, "copy", copy_trait;
243 CloneTraitLangItem, "clone", clone_trait;
244 SyncTraitLangItem, "sync", sync_trait;
245 FreezeTraitLangItem, "freeze", freeze_trait;
247 DropTraitLangItem, "drop", drop_trait;
249 CoerceUnsizedTraitLangItem, "coerce_unsized", coerce_unsized_trait;
251 AddTraitLangItem, "add", add_trait;
252 SubTraitLangItem, "sub", sub_trait;
253 MulTraitLangItem, "mul", mul_trait;
254 DivTraitLangItem, "div", div_trait;
255 RemTraitLangItem, "rem", rem_trait;
256 NegTraitLangItem, "neg", neg_trait;
257 NotTraitLangItem, "not", not_trait;
258 BitXorTraitLangItem, "bitxor", bitxor_trait;
259 BitAndTraitLangItem, "bitand", bitand_trait;
260 BitOrTraitLangItem, "bitor", bitor_trait;
261 ShlTraitLangItem, "shl", shl_trait;
262 ShrTraitLangItem, "shr", shr_trait;
263 AddAssignTraitLangItem, "add_assign", add_assign_trait;
264 SubAssignTraitLangItem, "sub_assign", sub_assign_trait;
265 MulAssignTraitLangItem, "mul_assign", mul_assign_trait;
266 DivAssignTraitLangItem, "div_assign", div_assign_trait;
267 RemAssignTraitLangItem, "rem_assign", rem_assign_trait;
268 BitXorAssignTraitLangItem, "bitxor_assign", bitxor_assign_trait;
269 BitAndAssignTraitLangItem, "bitand_assign", bitand_assign_trait;
270 BitOrAssignTraitLangItem, "bitor_assign", bitor_assign_trait;
271 ShlAssignTraitLangItem, "shl_assign", shl_assign_trait;
272 ShrAssignTraitLangItem, "shr_assign", shr_assign_trait;
273 IndexTraitLangItem, "index", index_trait;
274 IndexMutTraitLangItem, "index_mut", index_mut_trait;
276 UnsafeCellTypeLangItem, "unsafe_cell", unsafe_cell_type;
278 DerefTraitLangItem, "deref", deref_trait;
279 DerefMutTraitLangItem, "deref_mut", deref_mut_trait;
281 FnTraitLangItem, "fn", fn_trait;
282 FnMutTraitLangItem, "fn_mut", fn_mut_trait;
283 FnOnceTraitLangItem, "fn_once", fn_once_trait;
285 GeneratorStateLangItem, "generator_state", gen_state;
286 GeneratorTraitLangItem, "generator", gen_trait;
288 EqTraitLangItem, "eq", eq_trait;
289 PartialOrdTraitLangItem, "partial_ord", partial_ord_trait;
290 OrdTraitLangItem, "ord", ord_trait;
292 // A number of panic-related lang items. The `panic` item corresponds to
293 // divide-by-zero and various panic cases with `match`. The
294 // `panic_bounds_check` item is for indexing arrays.
296 // The `begin_unwind` lang item has a predefined symbol name and is sort of
297 // a "weak lang item" in the sense that a crate is not required to have it
298 // defined to use it, but a final product is required to define it
299 // somewhere. Additionally, there are restrictions on crates that use a weak
300 // lang item, but do not have it defined.
301 PanicFnLangItem, "panic", panic_fn;
302 PanicBoundsCheckFnLangItem, "panic_bounds_check", panic_bounds_check_fn;
303 PanicInfoLangItem, "panic_info", panic_info;
304 PanicImplLangItem, "panic_impl", panic_impl;
305 // Libstd panic entry point. Necessary for const eval to be able to catch it
306 BeginPanicFnLangItem, "begin_panic", begin_panic_fn;
308 ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn;
309 BoxFreeFnLangItem, "box_free", box_free_fn;
310 DropInPlaceFnLangItem, "drop_in_place", drop_in_place_fn;
311 OomLangItem, "oom", oom;
312 AllocLayoutLangItem, "alloc_layout", alloc_layout;
314 StartFnLangItem, "start", start_fn;
316 EhPersonalityLangItem, "eh_personality", eh_personality;
317 EhUnwindResumeLangItem, "eh_unwind_resume", eh_unwind_resume;
318 MSVCTryFilterLangItem, "msvc_try_filter", msvc_try_filter;
320 OwnedBoxLangItem, "owned_box", owned_box;
322 PhantomDataItem, "phantom_data", phantom_data;
324 ManuallyDropItem, "manually_drop", manually_drop;
326 DebugTraitLangItem, "debug_trait", debug_trait;
328 // A lang item for each of the 128-bit operators we can optionally lower.
329 I128AddFnLangItem, "i128_add", i128_add_fn;
330 U128AddFnLangItem, "u128_add", u128_add_fn;
331 I128SubFnLangItem, "i128_sub", i128_sub_fn;
332 U128SubFnLangItem, "u128_sub", u128_sub_fn;
333 I128MulFnLangItem, "i128_mul", i128_mul_fn;
334 U128MulFnLangItem, "u128_mul", u128_mul_fn;
335 I128DivFnLangItem, "i128_div", i128_div_fn;
336 U128DivFnLangItem, "u128_div", u128_div_fn;
337 I128RemFnLangItem, "i128_rem", i128_rem_fn;
338 U128RemFnLangItem, "u128_rem", u128_rem_fn;
339 I128ShlFnLangItem, "i128_shl", i128_shl_fn;
340 U128ShlFnLangItem, "u128_shl", u128_shl_fn;
341 I128ShrFnLangItem, "i128_shr", i128_shr_fn;
342 U128ShrFnLangItem, "u128_shr", u128_shr_fn;
343 // And overflow versions for the operators that are checkable.
344 // While MIR calls these Checked*, they return (T,bool), not Option<T>.
345 I128AddoFnLangItem, "i128_addo", i128_addo_fn;
346 U128AddoFnLangItem, "u128_addo", u128_addo_fn;
347 I128SuboFnLangItem, "i128_subo", i128_subo_fn;
348 U128SuboFnLangItem, "u128_subo", u128_subo_fn;
349 I128MuloFnLangItem, "i128_mulo", i128_mulo_fn;
350 U128MuloFnLangItem, "u128_mulo", u128_mulo_fn;
351 I128ShloFnLangItem, "i128_shlo", i128_shlo_fn;
352 U128ShloFnLangItem, "u128_shlo", u128_shlo_fn;
353 I128ShroFnLangItem, "i128_shro", i128_shro_fn;
354 U128ShroFnLangItem, "u128_shro", u128_shro_fn;
356 // Align offset for stride != 1, must not panic.
357 AlignOffsetLangItem, "align_offset", align_offset_fn;
359 TerminationTraitLangItem, "termination", termination;
365 impl<'a, 'tcx, 'gcx> TyCtxt<'a, 'tcx, 'gcx> {
366 pub fn require_lang_item(&self, lang_item: LangItem) -> DefId {
367 self.lang_items().require(lang_item).unwrap_or_else(|msg| {
368 self.sess.fatal(&msg)