1 // Copyright 2015 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 // Lowers the AST to the HIR.
13 // Since the AST and HIR are fairly similar, this is mostly a simple procedure,
14 // much like a fold. Where lowering involves a bit more work things get more
15 // interesting and there are some invariants you should know about. These mostly
16 // concern spans and ids.
18 // Spans are assigned to AST nodes during parsing and then are modified during
19 // expansion to indicate the origin of a node and the process it went through
20 // being expanded. Ids are assigned to AST nodes just before lowering.
22 // For the simpler lowering steps, ids and spans should be preserved. Unlike
23 // expansion we do not preserve the process of lowering in the spans, so spans
24 // should not be modified here. When creating a new node (as opposed to
25 // 'folding' an existing one), then you create a new id using `next_id()`.
27 // You must ensure that ids are unique. That means that you should only use the
28 // id from an AST node in a single HIR node (you can assume that AST node ids
29 // are unique). Every new node must have a unique id. Avoid cloning HIR nodes.
30 // If you do, you must then set the new node's id to a fresh one.
32 // Spans are used for error messages and for tools to map semantics back to
33 // source code. It is therefore not as important with spans as ids to be strict
34 // about use (you can't break the compiler by screwing up a span). Obviously, a
35 // HIR node can only have a single span. But multiple nodes can have the same
36 // span and spans don't need to be kept in order, etc. Where code is preserved
37 // by lowering, it should have the same span as in the AST. Where HIR nodes are
38 // new it is probably best to give a span for the whole AST node being lowered.
39 // All nodes should have real spans, don't use dummy spans. Tools are likely to
40 // get confused if the spans from leaf AST nodes occur in multiple places
41 // in the HIR, especially for multiple identifiers.
44 use hir::map::{Definitions, DefKey, REGULAR_SPACE};
45 use hir::map::definitions::DefPathData;
46 use hir::def_id::{DefIndex, DefId, CRATE_DEF_INDEX};
47 use hir::def::{Def, PathResolution};
48 use rustc_data_structures::indexed_vec::IndexVec;
50 use util::nodemap::{DefIdMap, NodeMap};
52 use std::collections::BTreeMap;
60 use syntax::ext::hygiene::{Mark, SyntaxContext};
62 use syntax::codemap::{self, respan, Spanned};
63 use syntax::std_inject;
64 use syntax::symbol::{Symbol, keywords};
65 use syntax::util::small_vector::SmallVector;
66 use syntax::visit::{self, Visitor};
69 const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF;
71 pub struct LoweringContext<'a> {
72 crate_root: Option<&'static str>,
73 // Use to assign ids to hir nodes that do not directly correspond to an ast node
75 // As we walk the AST we must keep track of the current 'parent' def id (in
76 // the form of a DefIndex) so that if we create a new node which introduces
77 // a definition, then we can properly create the def id.
78 parent_def: Option<DefIndex>,
79 resolver: &'a mut Resolver,
81 /// The items being lowered are collected here.
82 items: BTreeMap<NodeId, hir::Item>,
84 trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem>,
85 impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem>,
86 bodies: BTreeMap<hir::BodyId, hir::Body>,
87 exported_macros: Vec<hir::MacroDef>,
89 trait_impls: BTreeMap<DefId, Vec<NodeId>>,
90 trait_default_impl: BTreeMap<DefId, NodeId>,
92 catch_scopes: Vec<NodeId>,
93 loop_scopes: Vec<NodeId>,
94 is_in_loop_condition: bool,
96 type_def_lifetime_params: DefIdMap<usize>,
98 current_hir_id_owner: Vec<(DefIndex, u32)>,
99 item_local_id_counters: NodeMap<u32>,
100 node_id_to_hir_id: IndexVec<NodeId, hir::HirId>,
104 // Resolve a hir path generated by the lowerer when expanding `for`, `if let`, etc.
105 fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool);
107 // Obtain the resolution for a node id
108 fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution>;
110 // We must keep the set of definitions up to date as we add nodes that weren't in the AST.
111 // This should only return `None` during testing.
112 fn definitions(&mut self) -> &mut Definitions;
115 pub fn lower_crate(sess: &Session,
117 resolver: &mut Resolver)
119 // We're constructing the HIR here; we don't care what we will
120 // read, since we haven't even constructed the *input* to
122 let _ignore = sess.dep_graph.in_ignore();
125 crate_root: std_inject::injected_crate_name(krate),
129 items: BTreeMap::new(),
130 trait_items: BTreeMap::new(),
131 impl_items: BTreeMap::new(),
132 bodies: BTreeMap::new(),
133 trait_impls: BTreeMap::new(),
134 trait_default_impl: BTreeMap::new(),
135 exported_macros: Vec::new(),
136 catch_scopes: Vec::new(),
137 loop_scopes: Vec::new(),
138 is_in_loop_condition: false,
139 type_def_lifetime_params: DefIdMap(),
140 current_hir_id_owner: vec![(CRATE_DEF_INDEX, 0)],
141 item_local_id_counters: NodeMap(),
142 node_id_to_hir_id: IndexVec::new(),
146 #[derive(Copy, Clone, PartialEq, Eq)]
148 /// Any path in a type context.
150 /// The `module::Type` in `module::Type::method` in an expression.
154 impl<'a> LoweringContext<'a> {
155 fn lower_crate(mut self, c: &Crate) -> hir::Crate {
156 /// Full-crate AST visitor that inserts into a fresh
157 /// `LoweringContext` any information that may be
158 /// needed from arbitrary locations in the crate.
159 /// E.g. The number of lifetime generic parameters
160 /// declared for every type and trait definition.
161 struct MiscCollector<'lcx, 'interner: 'lcx> {
162 lctx: &'lcx mut LoweringContext<'interner>,
165 impl<'lcx, 'interner> Visitor<'lcx> for MiscCollector<'lcx, 'interner> {
166 fn visit_item(&mut self, item: &'lcx Item) {
167 self.lctx.allocate_hir_id_counter(item.id, item);
170 ItemKind::Struct(_, ref generics) |
171 ItemKind::Union(_, ref generics) |
172 ItemKind::Enum(_, ref generics) |
173 ItemKind::Ty(_, ref generics) |
174 ItemKind::Trait(_, ref generics, ..) => {
175 let def_id = self.lctx.resolver.definitions().local_def_id(item.id);
176 let count = generics.lifetimes.len();
177 self.lctx.type_def_lifetime_params.insert(def_id, count);
181 visit::walk_item(self, item);
184 fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
185 self.lctx.allocate_hir_id_counter(item.id, item);
186 visit::walk_trait_item(self, item);
189 fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
190 self.lctx.allocate_hir_id_counter(item.id, item);
191 visit::walk_impl_item(self, item);
195 struct ItemLowerer<'lcx, 'interner: 'lcx> {
196 lctx: &'lcx mut LoweringContext<'interner>,
199 impl<'lcx, 'interner> Visitor<'lcx> for ItemLowerer<'lcx, 'interner> {
200 fn visit_item(&mut self, item: &'lcx Item) {
201 let mut item_lowered = true;
202 self.lctx.with_hir_id_owner(item.id, |lctx| {
203 if let Some(hir_item) = lctx.lower_item(item) {
204 lctx.items.insert(item.id, hir_item);
206 item_lowered = false;
211 visit::walk_item(self, item);
215 fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
216 self.lctx.with_hir_id_owner(item.id, |lctx| {
217 let id = hir::TraitItemId { node_id: item.id };
218 let hir_item = lctx.lower_trait_item(item);
219 lctx.trait_items.insert(id, hir_item);
222 visit::walk_trait_item(self, item);
225 fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
226 self.lctx.with_hir_id_owner(item.id, |lctx| {
227 let id = hir::ImplItemId { node_id: item.id };
228 let hir_item = lctx.lower_impl_item(item);
229 lctx.impl_items.insert(id, hir_item);
231 visit::walk_impl_item(self, item);
235 self.lower_node_id(CRATE_NODE_ID);
236 debug_assert!(self.node_id_to_hir_id[CRATE_NODE_ID] == hir::CRATE_HIR_ID);
238 visit::walk_crate(&mut MiscCollector { lctx: &mut self }, c);
239 visit::walk_crate(&mut ItemLowerer { lctx: &mut self }, c);
241 let module = self.lower_mod(&c.module);
242 let attrs = self.lower_attrs(&c.attrs);
243 let body_ids = body_ids(&self.bodies);
247 .init_node_id_to_hir_id_mapping(self.node_id_to_hir_id);
253 exported_macros: hir::HirVec::from(self.exported_macros),
255 trait_items: self.trait_items,
256 impl_items: self.impl_items,
259 trait_impls: self.trait_impls,
260 trait_default_impl: self.trait_default_impl,
264 fn allocate_hir_id_counter<T: Debug>(&mut self,
267 if self.item_local_id_counters.insert(owner, 0).is_some() {
268 bug!("Tried to allocate item_local_id_counter for {:?} twice", debug);
270 // Always allocate the first HirId for the owner itself
271 self.lower_node_id_with_owner(owner, owner);
274 fn lower_node_id_generic<F>(&mut self,
278 where F: FnOnce(&mut Self) -> hir::HirId
280 if ast_node_id == DUMMY_NODE_ID {
284 let min_size = ast_node_id.as_usize() + 1;
286 if min_size > self.node_id_to_hir_id.len() {
287 self.node_id_to_hir_id.resize(min_size, hir::DUMMY_HIR_ID);
290 if self.node_id_to_hir_id[ast_node_id] == hir::DUMMY_HIR_ID {
291 // Generate a new HirId
292 self.node_id_to_hir_id[ast_node_id] = alloc_hir_id(self);
298 fn with_hir_id_owner<F>(&mut self, owner: NodeId, f: F)
299 where F: FnOnce(&mut Self)
301 let counter = self.item_local_id_counters
302 .insert(owner, HIR_ID_COUNTER_LOCKED)
304 let def_index = self.resolver.definitions().opt_def_index(owner).unwrap();
305 self.current_hir_id_owner.push((def_index, counter));
307 let (new_def_index, new_counter) = self.current_hir_id_owner.pop().unwrap();
309 debug_assert!(def_index == new_def_index);
310 debug_assert!(new_counter >= counter);
312 let prev = self.item_local_id_counters.insert(owner, new_counter).unwrap();
313 debug_assert!(prev == HIR_ID_COUNTER_LOCKED);
316 /// This method allocates a new HirId for the given NodeId and stores it in
317 /// the LoweringContext's NodeId => HirId map.
318 /// Take care not to call this method if the resulting HirId is then not
319 /// actually used in the HIR, as that would trigger an assertion in the
320 /// HirIdValidator later on, which makes sure that all NodeIds got mapped
321 /// properly. Calling the method twice with the same NodeId is fine though.
322 fn lower_node_id(&mut self, ast_node_id: NodeId) -> NodeId {
323 self.lower_node_id_generic(ast_node_id, |this| {
324 let &mut (def_index, ref mut local_id_counter) = this.current_hir_id_owner
327 let local_id = *local_id_counter;
328 *local_id_counter += 1;
331 local_id: hir::ItemLocalId(local_id),
336 fn lower_node_id_with_owner(&mut self,
340 self.lower_node_id_generic(ast_node_id, |this| {
341 let local_id_counter = this.item_local_id_counters
344 let local_id = *local_id_counter;
346 // We want to be sure not to modify the counter in the map while it
347 // is also on the stack. Otherwise we'll get lost updates when writing
348 // back from the stack to the map.
349 debug_assert!(local_id != HIR_ID_COUNTER_LOCKED);
351 *local_id_counter += 1;
352 let def_index = this.resolver.definitions().opt_def_index(owner).unwrap();
356 local_id: hir::ItemLocalId(local_id),
361 fn record_body(&mut self, value: hir::Expr, decl: Option<&FnDecl>)
363 let body = hir::Body {
364 arguments: decl.map_or(hir_vec![], |decl| {
365 decl.inputs.iter().map(|x| self.lower_arg(x)).collect()
370 self.bodies.insert(id, body);
374 fn next_id(&mut self) -> NodeId {
375 self.lower_node_id(self.sess.next_node_id())
378 fn expect_full_def(&mut self, id: NodeId) -> Def {
379 self.resolver.get_resolution(id).map_or(Def::Err, |pr| {
380 if pr.unresolved_segments() != 0 {
381 bug!("path not fully resolved: {:?}", pr);
387 fn diagnostic(&self) -> &errors::Handler {
388 self.sess.diagnostic()
391 fn str_to_ident(&self, s: &'static str) -> Name {
395 fn allow_internal_unstable(&self, reason: &'static str, mut span: Span) -> Span {
396 let mark = Mark::fresh();
397 mark.set_expn_info(codemap::ExpnInfo {
399 callee: codemap::NameAndSpan {
400 format: codemap::CompilerDesugaring(Symbol::intern(reason)),
402 allow_internal_unstable: true,
405 span.ctxt = SyntaxContext::empty().apply_mark(mark);
409 fn with_catch_scope<T, F>(&mut self, catch_id: NodeId, f: F) -> T
410 where F: FnOnce(&mut LoweringContext) -> T
412 let len = self.catch_scopes.len();
413 self.catch_scopes.push(catch_id);
415 let result = f(self);
416 assert_eq!(len + 1, self.catch_scopes.len(),
417 "catch scopes should be added and removed in stack order");
419 self.catch_scopes.pop().unwrap();
424 fn with_loop_scope<T, F>(&mut self, loop_id: NodeId, f: F) -> T
425 where F: FnOnce(&mut LoweringContext) -> T
427 // We're no longer in the base loop's condition; we're in another loop.
428 let was_in_loop_condition = self.is_in_loop_condition;
429 self.is_in_loop_condition = false;
431 let len = self.loop_scopes.len();
432 self.loop_scopes.push(loop_id);
434 let result = f(self);
435 assert_eq!(len + 1, self.loop_scopes.len(),
436 "Loop scopes should be added and removed in stack order");
438 self.loop_scopes.pop().unwrap();
440 self.is_in_loop_condition = was_in_loop_condition;
445 fn with_loop_condition_scope<T, F>(&mut self, f: F) -> T
446 where F: FnOnce(&mut LoweringContext) -> T
448 let was_in_loop_condition = self.is_in_loop_condition;
449 self.is_in_loop_condition = true;
451 let result = f(self);
453 self.is_in_loop_condition = was_in_loop_condition;
458 fn with_new_scopes<T, F>(&mut self, f: F) -> T
459 where F: FnOnce(&mut LoweringContext) -> T
461 let was_in_loop_condition = self.is_in_loop_condition;
462 self.is_in_loop_condition = false;
464 let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new());
465 let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new());
466 let result = f(self);
467 self.catch_scopes = catch_scopes;
468 self.loop_scopes = loop_scopes;
470 self.is_in_loop_condition = was_in_loop_condition;
475 fn with_parent_def<T, F>(&mut self, parent_id: NodeId, f: F) -> T
476 where F: FnOnce(&mut LoweringContext) -> T
478 let old_def = self.parent_def;
480 let defs = self.resolver.definitions();
481 Some(defs.opt_def_index(parent_id).unwrap())
484 let result = f(self);
486 self.parent_def = old_def;
490 fn def_key(&mut self, id: DefId) -> DefKey {
492 self.resolver.definitions().def_key(id.index)
494 self.sess.cstore.def_key(id)
498 fn lower_opt_sp_ident(&mut self, o_id: Option<Spanned<Ident>>) -> Option<Spanned<Name>> {
499 o_id.map(|sp_ident| respan(sp_ident.span, sp_ident.node.name))
502 fn lower_loop_destination(&mut self, destination: Option<(NodeId, Spanned<Ident>)>)
506 Some((id, label_ident)) => {
507 let target = if let Def::Label(loop_id) = self.expect_full_def(id) {
508 hir::LoopIdResult::Ok(self.lower_node_id(loop_id))
510 hir::LoopIdResult::Err(hir::LoopIdError::UnresolvedLabel)
513 ident: Some(label_ident),
514 target_id: hir::ScopeTarget::Loop(target),
518 let loop_id = self.loop_scopes
520 .map(|innermost_loop_id| *innermost_loop_id);
524 target_id: hir::ScopeTarget::Loop(
525 loop_id.map(|id| Ok(self.lower_node_id(id)))
526 .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
533 fn lower_attrs(&mut self, attrs: &Vec<Attribute>) -> hir::HirVec<Attribute> {
537 fn lower_arm(&mut self, arm: &Arm) -> hir::Arm {
539 attrs: self.lower_attrs(&arm.attrs),
540 pats: arm.pats.iter().map(|x| self.lower_pat(x)).collect(),
541 guard: arm.guard.as_ref().map(|ref x| P(self.lower_expr(x))),
542 body: P(self.lower_expr(&arm.body)),
546 fn lower_ty_binding(&mut self, b: &TypeBinding) -> hir::TypeBinding {
548 id: self.lower_node_id(b.id),
550 ty: self.lower_ty(&b.ty),
555 fn lower_ty(&mut self, t: &Ty) -> P<hir::Ty> {
556 let kind = match t.node {
557 TyKind::Infer => hir::TyInfer,
558 TyKind::Err => hir::TyErr,
559 TyKind::Slice(ref ty) => hir::TySlice(self.lower_ty(ty)),
560 TyKind::Ptr(ref mt) => hir::TyPtr(self.lower_mt(mt)),
561 TyKind::Rptr(ref region, ref mt) => {
562 let span = Span { hi: t.span.lo, ..t.span };
563 let lifetime = match *region {
564 Some(ref lt) => self.lower_lifetime(lt),
565 None => self.elided_lifetime(span)
567 hir::TyRptr(lifetime, self.lower_mt(mt))
569 TyKind::BareFn(ref f) => {
570 hir::TyBareFn(P(hir::BareFnTy {
571 lifetimes: self.lower_lifetime_defs(&f.lifetimes),
572 unsafety: self.lower_unsafety(f.unsafety),
574 decl: self.lower_fn_decl(&f.decl),
577 TyKind::Never => hir::TyNever,
578 TyKind::Tup(ref tys) => {
579 hir::TyTup(tys.iter().map(|ty| self.lower_ty(ty)).collect())
581 TyKind::Paren(ref ty) => {
582 return self.lower_ty(ty);
584 TyKind::Path(ref qself, ref path) => {
585 let id = self.lower_node_id(t.id);
586 let qpath = self.lower_qpath(t.id, qself, path, ParamMode::Explicit);
587 return self.ty_path(id, t.span, qpath);
589 TyKind::ImplicitSelf => {
590 hir::TyPath(hir::QPath::Resolved(None, P(hir::Path {
591 def: self.expect_full_def(t.id),
592 segments: hir_vec![hir::PathSegment {
593 name: keywords::SelfType.name(),
594 parameters: hir::PathParameters::none()
599 TyKind::Array(ref ty, ref length) => {
600 let length = self.lower_expr(length);
601 hir::TyArray(self.lower_ty(ty),
602 self.record_body(length, None))
604 TyKind::Typeof(ref expr) => {
605 let expr = self.lower_expr(expr);
606 hir::TyTypeof(self.record_body(expr, None))
608 TyKind::TraitObject(ref bounds) => {
609 let mut lifetime_bound = None;
610 let bounds = bounds.iter().filter_map(|bound| {
612 TraitTyParamBound(ref ty, TraitBoundModifier::None) => {
613 Some(self.lower_poly_trait_ref(ty))
615 TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
616 RegionTyParamBound(ref lifetime) => {
617 if lifetime_bound.is_none() {
618 lifetime_bound = Some(self.lower_lifetime(lifetime));
624 let lifetime_bound = lifetime_bound.unwrap_or_else(|| {
625 self.elided_lifetime(t.span)
627 hir::TyTraitObject(bounds, lifetime_bound)
629 TyKind::ImplTrait(ref bounds) => {
630 hir::TyImplTrait(self.lower_bounds(bounds))
632 TyKind::Mac(_) => panic!("TyMac should have been expanded by now."),
636 id: self.lower_node_id(t.id),
642 fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod {
645 items: fm.items.iter().map(|x| self.lower_foreign_item(x)).collect(),
649 fn lower_global_asm(&mut self, ga: &GlobalAsm) -> P<hir::GlobalAsm> {
656 fn lower_variant(&mut self, v: &Variant) -> hir::Variant {
658 node: hir::Variant_ {
659 name: v.node.name.name,
660 attrs: self.lower_attrs(&v.node.attrs),
661 data: self.lower_variant_data(&v.node.data),
662 disr_expr: v.node.disr_expr.as_ref().map(|e| {
663 let e = self.lower_expr(e);
664 self.record_body(e, None)
671 fn lower_qpath(&mut self,
673 qself: &Option<QSelf>,
675 param_mode: ParamMode)
677 let qself_position = qself.as_ref().map(|q| q.position);
678 let qself = qself.as_ref().map(|q| self.lower_ty(&q.ty));
680 let resolution = self.resolver.get_resolution(id)
681 .unwrap_or(PathResolution::new(Def::Err));
683 let proj_start = p.segments.len() - resolution.unresolved_segments();
684 let path = P(hir::Path {
685 def: resolution.base_def(),
686 segments: p.segments[..proj_start].iter().enumerate().map(|(i, segment)| {
687 let param_mode = match (qself_position, param_mode) {
688 (Some(j), ParamMode::Optional) if i < j => {
689 // This segment is part of the trait path in a
690 // qualified path - one of `a`, `b` or `Trait`
691 // in `<X as a::b::Trait>::T::U::method`.
697 // Figure out if this is a type/trait segment,
698 // which may need lifetime elision performed.
699 let parent_def_id = |this: &mut Self, def_id: DefId| {
702 index: this.def_key(def_id).parent.expect("missing parent")
705 let type_def_id = match resolution.base_def() {
706 Def::AssociatedTy(def_id) if i + 2 == proj_start => {
707 Some(parent_def_id(self, def_id))
709 Def::Variant(def_id) if i + 1 == proj_start => {
710 Some(parent_def_id(self, def_id))
712 Def::Struct(def_id) |
715 Def::TyAlias(def_id) |
716 Def::Trait(def_id) if i + 1 == proj_start => Some(def_id),
720 let num_lifetimes = type_def_id.map_or(0, |def_id| {
721 if let Some(&n) = self.type_def_lifetime_params.get(&def_id) {
724 assert!(!def_id.is_local());
725 let n = self.sess.cstore.item_generics_cloned(def_id).regions.len();
726 self.type_def_lifetime_params.insert(def_id, n);
729 self.lower_path_segment(p.span, segment, param_mode, num_lifetimes)
734 // Simple case, either no projections, or only fully-qualified.
735 // E.g. `std::mem::size_of` or `<I as Iterator>::Item`.
736 if resolution.unresolved_segments() == 0 {
737 return hir::QPath::Resolved(qself, path);
740 // Create the innermost type that we're projecting from.
741 let mut ty = if path.segments.is_empty() {
742 // If the base path is empty that means there exists a
743 // syntactical `Self`, e.g. `&i32` in `<&i32>::clone`.
744 qself.expect("missing QSelf for <T>::...")
746 // Otherwise, the base path is an implicit `Self` type path,
747 // e.g. `Vec` in `Vec::new` or `<I as Iterator>::Item` in
748 // `<I as Iterator>::Item::default`.
749 let new_id = self.next_id();
750 self.ty_path(new_id, p.span, hir::QPath::Resolved(qself, path))
753 // Anything after the base path are associated "extensions",
754 // out of which all but the last one are associated types,
755 // e.g. for `std::vec::Vec::<T>::IntoIter::Item::clone`:
756 // * base path is `std::vec::Vec<T>`
757 // * "extensions" are `IntoIter`, `Item` and `clone`
759 // 1. `std::vec::Vec<T>` (created above)
760 // 2. `<std::vec::Vec<T>>::IntoIter`
761 // 3. `<<std::vec::Vec<T>>::IntoIter>::Item`
762 // * final path is `<<<std::vec::Vec<T>>::IntoIter>::Item>::clone`
763 for (i, segment) in p.segments.iter().enumerate().skip(proj_start) {
764 let segment = P(self.lower_path_segment(p.span, segment, param_mode, 0));
765 let qpath = hir::QPath::TypeRelative(ty, segment);
767 // It's finished, return the extension of the right node type.
768 if i == p.segments.len() - 1 {
772 // Wrap the associated extension in another type node.
773 let new_id = self.next_id();
774 ty = self.ty_path(new_id, p.span, qpath);
777 // Should've returned in the for loop above.
778 span_bug!(p.span, "lower_qpath: no final extension segment in {}..{}",
779 proj_start, p.segments.len())
782 fn lower_path_extra(&mut self,
786 param_mode: ParamMode,
787 defaults_to_global: bool)
789 let mut segments = p.segments.iter();
790 if defaults_to_global && p.is_global() {
795 def: self.expect_full_def(id),
796 segments: segments.map(|segment| {
797 self.lower_path_segment(p.span, segment, param_mode, 0)
798 }).chain(name.map(|name| {
801 parameters: hir::PathParameters::none()
808 fn lower_path(&mut self,
811 param_mode: ParamMode,
812 defaults_to_global: bool)
814 self.lower_path_extra(id, p, None, param_mode, defaults_to_global)
817 fn lower_path_segment(&mut self,
819 segment: &PathSegment,
820 param_mode: ParamMode,
821 expected_lifetimes: usize)
822 -> hir::PathSegment {
823 let mut parameters = if let Some(ref parameters) = segment.parameters {
825 PathParameters::AngleBracketed(ref data) => {
826 let data = self.lower_angle_bracketed_parameter_data(data, param_mode);
827 hir::AngleBracketedParameters(data)
829 PathParameters::Parenthesized(ref data) => {
830 hir::ParenthesizedParameters(self.lower_parenthesized_parameter_data(data))
834 let data = self.lower_angle_bracketed_parameter_data(&Default::default(), param_mode);
835 hir::AngleBracketedParameters(data)
838 if let hir::AngleBracketedParameters(ref mut data) = parameters {
839 if data.lifetimes.is_empty() {
840 data.lifetimes = (0..expected_lifetimes).map(|_| {
841 self.elided_lifetime(path_span)
847 name: segment.identifier.name,
848 parameters: parameters,
852 fn lower_angle_bracketed_parameter_data(&mut self,
853 data: &AngleBracketedParameterData,
854 param_mode: ParamMode)
855 -> hir::AngleBracketedParameterData {
856 let &AngleBracketedParameterData { ref lifetimes, ref types, ref bindings } = data;
857 hir::AngleBracketedParameterData {
858 lifetimes: self.lower_lifetimes(lifetimes),
859 types: types.iter().map(|ty| self.lower_ty(ty)).collect(),
860 infer_types: types.is_empty() && param_mode == ParamMode::Optional,
861 bindings: bindings.iter().map(|b| self.lower_ty_binding(b)).collect(),
865 fn lower_parenthesized_parameter_data(&mut self,
866 data: &ParenthesizedParameterData)
867 -> hir::ParenthesizedParameterData {
868 let &ParenthesizedParameterData { ref inputs, ref output, span } = data;
869 hir::ParenthesizedParameterData {
870 inputs: inputs.iter().map(|ty| self.lower_ty(ty)).collect(),
871 output: output.as_ref().map(|ty| self.lower_ty(ty)),
876 fn lower_local(&mut self, l: &Local) -> P<hir::Local> {
878 id: self.lower_node_id(l.id),
879 ty: l.ty.as_ref().map(|t| self.lower_ty(t)),
880 pat: self.lower_pat(&l.pat),
881 init: l.init.as_ref().map(|e| P(self.lower_expr(e))),
883 attrs: l.attrs.clone(),
887 fn lower_mutability(&mut self, m: Mutability) -> hir::Mutability {
889 Mutability::Mutable => hir::MutMutable,
890 Mutability::Immutable => hir::MutImmutable,
894 fn lower_arg(&mut self, arg: &Arg) -> hir::Arg {
896 id: self.lower_node_id(arg.id),
897 pat: self.lower_pat(&arg.pat),
901 fn lower_fn_args_to_names(&mut self, decl: &FnDecl)
902 -> hir::HirVec<Spanned<Name>> {
903 decl.inputs.iter().map(|arg| {
905 PatKind::Ident(_, ident, None) => {
906 respan(ident.span, ident.node.name)
908 _ => respan(arg.pat.span, keywords::Invalid.name()),
913 fn lower_fn_decl(&mut self, decl: &FnDecl) -> P<hir::FnDecl> {
915 inputs: decl.inputs.iter().map(|arg| self.lower_ty(&arg.ty)).collect(),
916 output: match decl.output {
917 FunctionRetTy::Ty(ref ty) => hir::Return(self.lower_ty(ty)),
918 FunctionRetTy::Default(span) => hir::DefaultReturn(span),
920 variadic: decl.variadic,
921 has_implicit_self: decl.inputs.get(0).map_or(false, |arg| {
923 TyKind::ImplicitSelf => true,
924 TyKind::Rptr(_, ref mt) => mt.ty.node == TyKind::ImplicitSelf,
931 fn lower_ty_param_bound(&mut self, tpb: &TyParamBound) -> hir::TyParamBound {
933 TraitTyParamBound(ref ty, modifier) => {
934 hir::TraitTyParamBound(self.lower_poly_trait_ref(ty),
935 self.lower_trait_bound_modifier(modifier))
937 RegionTyParamBound(ref lifetime) => {
938 hir::RegionTyParamBound(self.lower_lifetime(lifetime))
943 fn lower_ty_param(&mut self, tp: &TyParam, add_bounds: &[TyParamBound]) -> hir::TyParam {
944 let mut name = tp.ident.name;
946 // Don't expose `Self` (recovered "keyword used as ident" parse error).
947 // `rustc::ty` expects `Self` to be only used for a trait's `Self`.
948 // Instead, use gensym("Self") to create a distinct name that looks the same.
949 if name == keywords::SelfType.name() {
950 name = Symbol::gensym("Self");
953 let mut bounds = self.lower_bounds(&tp.bounds);
954 if !add_bounds.is_empty() {
955 bounds = bounds.into_iter().chain(self.lower_bounds(add_bounds).into_iter()).collect();
959 id: self.lower_node_id(tp.id),
962 default: tp.default.as_ref().map(|x| self.lower_ty(x)),
964 pure_wrt_drop: tp.attrs.iter().any(|attr| attr.check_name("may_dangle")),
968 fn lower_ty_params(&mut self, tps: &Vec<TyParam>, add_bounds: &NodeMap<Vec<TyParamBound>>)
969 -> hir::HirVec<hir::TyParam> {
970 tps.iter().map(|tp| {
971 self.lower_ty_param(tp, add_bounds.get(&tp.id).map_or(&[][..], |x| &x))
975 fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime {
977 id: self.lower_node_id(l.id),
983 fn lower_lifetime_def(&mut self, l: &LifetimeDef) -> hir::LifetimeDef {
985 lifetime: self.lower_lifetime(&l.lifetime),
986 bounds: self.lower_lifetimes(&l.bounds),
987 pure_wrt_drop: l.attrs.iter().any(|attr| attr.check_name("may_dangle")),
991 fn lower_lifetimes(&mut self, lts: &Vec<Lifetime>) -> hir::HirVec<hir::Lifetime> {
992 lts.iter().map(|l| self.lower_lifetime(l)).collect()
995 fn lower_lifetime_defs(&mut self, lts: &Vec<LifetimeDef>) -> hir::HirVec<hir::LifetimeDef> {
996 lts.iter().map(|l| self.lower_lifetime_def(l)).collect()
999 fn lower_generics(&mut self, g: &Generics) -> hir::Generics {
1000 // Collect `?Trait` bounds in where clause and move them to parameter definitions.
1001 let mut add_bounds = NodeMap();
1002 for pred in &g.where_clause.predicates {
1003 if let WherePredicate::BoundPredicate(ref bound_pred) = *pred {
1004 'next_bound: for bound in &bound_pred.bounds {
1005 if let TraitTyParamBound(_, TraitBoundModifier::Maybe) = *bound {
1006 let report_error = |this: &mut Self| {
1007 this.diagnostic().span_err(bound_pred.bounded_ty.span,
1008 "`?Trait` bounds are only permitted at the \
1009 point where a type parameter is declared");
1011 // Check if the where clause type is a plain type parameter.
1012 match bound_pred.bounded_ty.node {
1013 TyKind::Path(None, ref path)
1014 if path.segments.len() == 1 &&
1015 bound_pred.bound_lifetimes.is_empty() => {
1016 if let Some(Def::TyParam(def_id)) =
1017 self.resolver.get_resolution(bound_pred.bounded_ty.id)
1018 .map(|d| d.base_def()) {
1019 if let Some(node_id) =
1020 self.resolver.definitions().as_local_node_id(def_id) {
1021 for ty_param in &g.ty_params {
1022 if node_id == ty_param.id {
1023 add_bounds.entry(ty_param.id).or_insert(Vec::new())
1024 .push(bound.clone());
1025 continue 'next_bound;
1032 _ => report_error(self)
1040 ty_params: self.lower_ty_params(&g.ty_params, &add_bounds),
1041 lifetimes: self.lower_lifetime_defs(&g.lifetimes),
1042 where_clause: self.lower_where_clause(&g.where_clause),
1047 fn lower_where_clause(&mut self, wc: &WhereClause) -> hir::WhereClause {
1049 id: self.lower_node_id(wc.id),
1050 predicates: wc.predicates
1052 .map(|predicate| self.lower_where_predicate(predicate))
1057 fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate {
1059 WherePredicate::BoundPredicate(WhereBoundPredicate{ ref bound_lifetimes,
1063 hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
1064 bound_lifetimes: self.lower_lifetime_defs(bound_lifetimes),
1065 bounded_ty: self.lower_ty(bounded_ty),
1066 bounds: bounds.iter().filter_map(|bound| match *bound {
1067 // Ignore `?Trait` bounds, they were copied into type parameters already.
1068 TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
1069 _ => Some(self.lower_ty_param_bound(bound))
1074 WherePredicate::RegionPredicate(WhereRegionPredicate{ ref lifetime,
1077 hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
1079 lifetime: self.lower_lifetime(lifetime),
1080 bounds: bounds.iter().map(|bound| self.lower_lifetime(bound)).collect(),
1083 WherePredicate::EqPredicate(WhereEqPredicate{ id,
1087 hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
1088 id: self.lower_node_id(id),
1089 lhs_ty: self.lower_ty(lhs_ty),
1090 rhs_ty: self.lower_ty(rhs_ty),
1097 fn lower_variant_data(&mut self, vdata: &VariantData) -> hir::VariantData {
1099 VariantData::Struct(ref fields, id) => {
1100 hir::VariantData::Struct(fields.iter()
1102 .map(|f| self.lower_struct_field(f))
1104 self.lower_node_id(id))
1106 VariantData::Tuple(ref fields, id) => {
1107 hir::VariantData::Tuple(fields.iter()
1109 .map(|f| self.lower_struct_field(f))
1111 self.lower_node_id(id))
1113 VariantData::Unit(id) => hir::VariantData::Unit(self.lower_node_id(id)),
1117 fn lower_trait_ref(&mut self, p: &TraitRef) -> hir::TraitRef {
1118 let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit) {
1119 hir::QPath::Resolved(None, path) => path.and_then(|path| path),
1120 qpath => bug!("lower_trait_ref: unexpected QPath `{:?}`", qpath)
1124 ref_id: self.lower_node_id(p.ref_id),
1128 fn lower_poly_trait_ref(&mut self, p: &PolyTraitRef) -> hir::PolyTraitRef {
1130 bound_lifetimes: self.lower_lifetime_defs(&p.bound_lifetimes),
1131 trait_ref: self.lower_trait_ref(&p.trait_ref),
1136 fn lower_struct_field(&mut self, (index, f): (usize, &StructField)) -> hir::StructField {
1139 id: self.lower_node_id(f.id),
1140 name: f.ident.map(|ident| ident.name).unwrap_or(Symbol::intern(&index.to_string())),
1141 vis: self.lower_visibility(&f.vis, None),
1142 ty: self.lower_ty(&f.ty),
1143 attrs: self.lower_attrs(&f.attrs),
1147 fn lower_field(&mut self, f: &Field) -> hir::Field {
1149 name: respan(f.ident.span, f.ident.node.name),
1150 expr: P(self.lower_expr(&f.expr)),
1152 is_shorthand: f.is_shorthand,
1156 fn lower_mt(&mut self, mt: &MutTy) -> hir::MutTy {
1158 ty: self.lower_ty(&mt.ty),
1159 mutbl: self.lower_mutability(mt.mutbl),
1163 fn lower_bounds(&mut self, bounds: &[TyParamBound]) -> hir::TyParamBounds {
1164 bounds.iter().map(|bound| self.lower_ty_param_bound(bound)).collect()
1167 fn lower_block(&mut self, b: &Block, targeted_by_break: bool) -> P<hir::Block> {
1168 let mut expr = None;
1170 let mut stmts = vec![];
1172 for (index, stmt) in b.stmts.iter().enumerate() {
1173 if index == b.stmts.len() - 1 {
1174 if let StmtKind::Expr(ref e) = stmt.node {
1175 expr = Some(P(self.lower_expr(e)));
1177 stmts.extend(self.lower_stmt(stmt));
1180 stmts.extend(self.lower_stmt(stmt));
1185 id: self.lower_node_id(b.id),
1186 stmts: stmts.into(),
1188 rules: self.lower_block_check_mode(&b.rules),
1190 targeted_by_break: targeted_by_break,
1194 fn lower_item_kind(&mut self,
1197 attrs: &hir::HirVec<Attribute>,
1198 vis: &mut hir::Visibility,
1202 ItemKind::ExternCrate(string) => hir::ItemExternCrate(string),
1203 ItemKind::Use(ref view_path) => {
1204 let path = match view_path.node {
1205 ViewPathSimple(_, ref path) => path,
1206 ViewPathGlob(ref path) => path,
1207 ViewPathList(ref path, ref path_list_idents) => {
1208 for &Spanned { node: ref import, span } in path_list_idents {
1209 // `use a::{self as x, b as y};` lowers to
1210 // `use a as x; use a::b as y;`
1211 let mut ident = import.name;
1212 let suffix = if ident.name == keywords::SelfValue.name() {
1213 if let Some(last) = path.segments.last() {
1214 ident = last.identifier;
1221 let mut path = self.lower_path_extra(import.id, path, suffix,
1222 ParamMode::Explicit, true);
1225 self.allocate_hir_id_counter(import.id, import);
1226 self.with_hir_id_owner(import.id, |this| {
1227 let vis = match *vis {
1228 hir::Visibility::Public => hir::Visibility::Public,
1229 hir::Visibility::Crate => hir::Visibility::Crate,
1230 hir::Visibility::Inherited => hir::Visibility::Inherited,
1231 hir::Visibility::Restricted { ref path, id: _ } => {
1232 hir::Visibility::Restricted {
1234 // We are allocating a new NodeId here
1240 this.items.insert(import.id, hir::Item {
1242 name: import.rename.unwrap_or(ident).name,
1243 attrs: attrs.clone(),
1244 node: hir::ItemUse(P(path), hir::UseKind::Single),
1253 let path = P(self.lower_path(id, path, ParamMode::Explicit, true));
1254 let kind = match view_path.node {
1255 ViewPathSimple(ident, _) => {
1257 hir::UseKind::Single
1259 ViewPathGlob(_) => {
1262 ViewPathList(..) => {
1263 // Privatize the degenerate import base, used only to check
1264 // the stability of `use a::{};`, to avoid it showing up as
1265 // a reexport by accident when `pub`, e.g. in documentation.
1266 *vis = hir::Inherited;
1267 hir::UseKind::ListStem
1270 hir::ItemUse(path, kind)
1272 ItemKind::Static(ref t, m, ref e) => {
1273 let value = self.lower_expr(e);
1274 hir::ItemStatic(self.lower_ty(t),
1275 self.lower_mutability(m),
1276 self.record_body(value, None))
1278 ItemKind::Const(ref t, ref e) => {
1279 let value = self.lower_expr(e);
1280 hir::ItemConst(self.lower_ty(t),
1281 self.record_body(value, None))
1283 ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
1284 self.with_new_scopes(|this| {
1285 let body = this.lower_block(body, false);
1286 let body = this.expr_block(body, ThinVec::new());
1287 let body_id = this.record_body(body, Some(decl));
1288 hir::ItemFn(this.lower_fn_decl(decl),
1289 this.lower_unsafety(unsafety),
1290 this.lower_constness(constness),
1292 this.lower_generics(generics),
1296 ItemKind::Mod(ref m) => hir::ItemMod(self.lower_mod(m)),
1297 ItemKind::ForeignMod(ref nm) => hir::ItemForeignMod(self.lower_foreign_mod(nm)),
1298 ItemKind::GlobalAsm(ref ga) => hir::ItemGlobalAsm(self.lower_global_asm(ga)),
1299 ItemKind::Ty(ref t, ref generics) => {
1300 hir::ItemTy(self.lower_ty(t), self.lower_generics(generics))
1302 ItemKind::Enum(ref enum_definition, ref generics) => {
1303 hir::ItemEnum(hir::EnumDef {
1304 variants: enum_definition.variants
1306 .map(|x| self.lower_variant(x))
1309 self.lower_generics(generics))
1311 ItemKind::Struct(ref struct_def, ref generics) => {
1312 let struct_def = self.lower_variant_data(struct_def);
1313 hir::ItemStruct(struct_def, self.lower_generics(generics))
1315 ItemKind::Union(ref vdata, ref generics) => {
1316 let vdata = self.lower_variant_data(vdata);
1317 hir::ItemUnion(vdata, self.lower_generics(generics))
1319 ItemKind::DefaultImpl(unsafety, ref trait_ref) => {
1320 let trait_ref = self.lower_trait_ref(trait_ref);
1322 if let Def::Trait(def_id) = trait_ref.path.def {
1323 self.trait_default_impl.insert(def_id, id);
1326 hir::ItemDefaultImpl(self.lower_unsafety(unsafety),
1329 ItemKind::Impl(unsafety,
1335 ref impl_items) => {
1336 let new_impl_items = impl_items.iter()
1337 .map(|item| self.lower_impl_item_ref(item))
1339 let ifce = ifce.as_ref().map(|trait_ref| self.lower_trait_ref(trait_ref));
1341 if let Some(ref trait_ref) = ifce {
1342 if let Def::Trait(def_id) = trait_ref.path.def {
1343 self.trait_impls.entry(def_id).or_insert(vec![]).push(id);
1347 hir::ItemImpl(self.lower_unsafety(unsafety),
1348 self.lower_impl_polarity(polarity),
1349 self.lower_defaultness(defaultness, true /* [1] */),
1350 self.lower_generics(generics),
1355 ItemKind::Trait(unsafety, ref generics, ref bounds, ref items) => {
1356 let bounds = self.lower_bounds(bounds);
1357 let items = items.iter().map(|item| self.lower_trait_item_ref(item)).collect();
1358 hir::ItemTrait(self.lower_unsafety(unsafety),
1359 self.lower_generics(generics),
1363 ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"),
1366 // [1] `defaultness.has_value()` is never called for an `impl`, always `true` in order to
1367 // not cause an assertion failure inside the `lower_defaultness` function
1370 fn lower_trait_item(&mut self, i: &TraitItem) -> hir::TraitItem {
1371 self.with_parent_def(i.id, |this| {
1373 id: this.lower_node_id(i.id),
1375 attrs: this.lower_attrs(&i.attrs),
1376 node: match i.node {
1377 TraitItemKind::Const(ref ty, ref default) => {
1378 hir::TraitItemKind::Const(this.lower_ty(ty),
1379 default.as_ref().map(|x| {
1380 let value = this.lower_expr(x);
1381 this.record_body(value, None)
1384 TraitItemKind::Method(ref sig, None) => {
1385 let names = this.lower_fn_args_to_names(&sig.decl);
1386 hir::TraitItemKind::Method(this.lower_method_sig(sig),
1387 hir::TraitMethod::Required(names))
1389 TraitItemKind::Method(ref sig, Some(ref body)) => {
1390 let body = this.lower_block(body, false);
1391 let expr = this.expr_block(body, ThinVec::new());
1392 let body_id = this.record_body(expr, Some(&sig.decl));
1393 hir::TraitItemKind::Method(this.lower_method_sig(sig),
1394 hir::TraitMethod::Provided(body_id))
1396 TraitItemKind::Type(ref bounds, ref default) => {
1397 hir::TraitItemKind::Type(this.lower_bounds(bounds),
1398 default.as_ref().map(|x| this.lower_ty(x)))
1400 TraitItemKind::Macro(..) => panic!("Shouldn't exist any more"),
1407 fn lower_trait_item_ref(&mut self, i: &TraitItem) -> hir::TraitItemRef {
1408 let (kind, has_default) = match i.node {
1409 TraitItemKind::Const(_, ref default) => {
1410 (hir::AssociatedItemKind::Const, default.is_some())
1412 TraitItemKind::Type(_, ref default) => {
1413 (hir::AssociatedItemKind::Type, default.is_some())
1415 TraitItemKind::Method(ref sig, ref default) => {
1416 (hir::AssociatedItemKind::Method {
1417 has_self: sig.decl.has_self(),
1418 }, default.is_some())
1420 TraitItemKind::Macro(..) => unimplemented!(),
1423 id: hir::TraitItemId { node_id: i.id },
1426 defaultness: self.lower_defaultness(Defaultness::Default, has_default),
1431 fn lower_impl_item(&mut self, i: &ImplItem) -> hir::ImplItem {
1432 self.with_parent_def(i.id, |this| {
1434 id: this.lower_node_id(i.id),
1436 attrs: this.lower_attrs(&i.attrs),
1437 vis: this.lower_visibility(&i.vis, None),
1438 defaultness: this.lower_defaultness(i.defaultness, true /* [1] */),
1439 node: match i.node {
1440 ImplItemKind::Const(ref ty, ref expr) => {
1441 let value = this.lower_expr(expr);
1442 let body_id = this.record_body(value, None);
1443 hir::ImplItemKind::Const(this.lower_ty(ty), body_id)
1445 ImplItemKind::Method(ref sig, ref body) => {
1446 let body = this.lower_block(body, false);
1447 let expr = this.expr_block(body, ThinVec::new());
1448 let body_id = this.record_body(expr, Some(&sig.decl));
1449 hir::ImplItemKind::Method(this.lower_method_sig(sig), body_id)
1451 ImplItemKind::Type(ref ty) => hir::ImplItemKind::Type(this.lower_ty(ty)),
1452 ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"),
1458 // [1] since `default impl` is not yet implemented, this is always true in impls
1461 fn lower_impl_item_ref(&mut self, i: &ImplItem) -> hir::ImplItemRef {
1463 id: hir::ImplItemId { node_id: i.id },
1466 vis: self.lower_visibility(&i.vis, Some(i.id)),
1467 defaultness: self.lower_defaultness(i.defaultness, true /* [1] */),
1468 kind: match i.node {
1469 ImplItemKind::Const(..) => hir::AssociatedItemKind::Const,
1470 ImplItemKind::Type(..) => hir::AssociatedItemKind::Type,
1471 ImplItemKind::Method(ref sig, _) => hir::AssociatedItemKind::Method {
1472 has_self: sig.decl.has_self(),
1474 ImplItemKind::Macro(..) => unimplemented!(),
1478 // [1] since `default impl` is not yet implemented, this is always true in impls
1481 fn lower_mod(&mut self, m: &Mod) -> hir::Mod {
1484 item_ids: m.items.iter().flat_map(|x| self.lower_item_id(x)).collect(),
1488 fn lower_item_id(&mut self, i: &Item) -> SmallVector<hir::ItemId> {
1490 ItemKind::Use(ref view_path) => {
1491 if let ViewPathList(_, ref imports) = view_path.node {
1492 return iter::once(i.id).chain(imports.iter().map(|import| import.node.id))
1493 .map(|id| hir::ItemId { id: id }).collect();
1496 ItemKind::MacroDef(..) => return SmallVector::new(),
1499 SmallVector::one(hir::ItemId { id: i.id })
1502 pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> {
1503 let mut name = i.ident.name;
1504 let attrs = self.lower_attrs(&i.attrs);
1505 if let ItemKind::MacroDef(ref tts) = i.node {
1506 if i.attrs.iter().any(|attr| attr.path == "macro_export") {
1507 self.exported_macros.push(hir::MacroDef {
1508 name: name, attrs: attrs, id: i.id, span: i.span, body: tts.clone().into(),
1514 let mut vis = self.lower_visibility(&i.vis, None);
1515 let node = self.with_parent_def(i.id, |this| {
1516 this.lower_item_kind(i.id, &mut name, &attrs, &mut vis, &i.node)
1520 id: self.lower_node_id(i.id),
1529 fn lower_foreign_item(&mut self, i: &ForeignItem) -> hir::ForeignItem {
1530 self.with_parent_def(i.id, |this| {
1532 id: this.lower_node_id(i.id),
1534 attrs: this.lower_attrs(&i.attrs),
1535 node: match i.node {
1536 ForeignItemKind::Fn(ref fdec, ref generics) => {
1537 hir::ForeignItemFn(this.lower_fn_decl(fdec),
1538 this.lower_fn_args_to_names(fdec),
1539 this.lower_generics(generics))
1541 ForeignItemKind::Static(ref t, m) => {
1542 hir::ForeignItemStatic(this.lower_ty(t), m)
1545 vis: this.lower_visibility(&i.vis, None),
1551 fn lower_method_sig(&mut self, sig: &MethodSig) -> hir::MethodSig {
1553 generics: self.lower_generics(&sig.generics),
1555 unsafety: self.lower_unsafety(sig.unsafety),
1556 constness: self.lower_constness(sig.constness),
1557 decl: self.lower_fn_decl(&sig.decl),
1561 fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety {
1563 Unsafety::Unsafe => hir::Unsafety::Unsafe,
1564 Unsafety::Normal => hir::Unsafety::Normal,
1568 fn lower_constness(&mut self, c: Spanned<Constness>) -> hir::Constness {
1570 Constness::Const => hir::Constness::Const,
1571 Constness::NotConst => hir::Constness::NotConst,
1575 fn lower_unop(&mut self, u: UnOp) -> hir::UnOp {
1577 UnOp::Deref => hir::UnDeref,
1578 UnOp::Not => hir::UnNot,
1579 UnOp::Neg => hir::UnNeg,
1583 fn lower_binop(&mut self, b: BinOp) -> hir::BinOp {
1585 node: match b.node {
1586 BinOpKind::Add => hir::BiAdd,
1587 BinOpKind::Sub => hir::BiSub,
1588 BinOpKind::Mul => hir::BiMul,
1589 BinOpKind::Div => hir::BiDiv,
1590 BinOpKind::Rem => hir::BiRem,
1591 BinOpKind::And => hir::BiAnd,
1592 BinOpKind::Or => hir::BiOr,
1593 BinOpKind::BitXor => hir::BiBitXor,
1594 BinOpKind::BitAnd => hir::BiBitAnd,
1595 BinOpKind::BitOr => hir::BiBitOr,
1596 BinOpKind::Shl => hir::BiShl,
1597 BinOpKind::Shr => hir::BiShr,
1598 BinOpKind::Eq => hir::BiEq,
1599 BinOpKind::Lt => hir::BiLt,
1600 BinOpKind::Le => hir::BiLe,
1601 BinOpKind::Ne => hir::BiNe,
1602 BinOpKind::Ge => hir::BiGe,
1603 BinOpKind::Gt => hir::BiGt,
1609 fn lower_pat(&mut self, p: &Pat) -> P<hir::Pat> {
1611 id: self.lower_node_id(p.id),
1612 node: match p.node {
1613 PatKind::Wild => hir::PatKind::Wild,
1614 PatKind::Ident(ref binding_mode, pth1, ref sub) => {
1615 self.with_parent_def(p.id, |this| {
1616 match this.resolver.get_resolution(p.id).map(|d| d.base_def()) {
1617 // `None` can occur in body-less function signatures
1618 def @ None | def @ Some(Def::Local(_)) => {
1619 let def_id = def.map(|d| d.def_id()).unwrap_or_else(|| {
1620 this.resolver.definitions().local_def_id(p.id)
1622 hir::PatKind::Binding(this.lower_binding_mode(binding_mode),
1624 respan(pth1.span, pth1.node.name),
1625 sub.as_ref().map(|x| this.lower_pat(x)))
1628 hir::PatKind::Path(hir::QPath::Resolved(None, P(hir::Path {
1632 hir::PathSegment::from_name(pth1.node.name)
1639 PatKind::Lit(ref e) => hir::PatKind::Lit(P(self.lower_expr(e))),
1640 PatKind::TupleStruct(ref path, ref pats, ddpos) => {
1641 let qpath = self.lower_qpath(p.id, &None, path, ParamMode::Optional);
1642 hir::PatKind::TupleStruct(qpath,
1643 pats.iter().map(|x| self.lower_pat(x)).collect(),
1646 PatKind::Path(ref qself, ref path) => {
1647 hir::PatKind::Path(self.lower_qpath(p.id, qself, path, ParamMode::Optional))
1649 PatKind::Struct(ref path, ref fields, etc) => {
1650 let qpath = self.lower_qpath(p.id, &None, path, ParamMode::Optional);
1652 let fs = fields.iter()
1656 node: hir::FieldPat {
1657 name: f.node.ident.name,
1658 pat: self.lower_pat(&f.node.pat),
1659 is_shorthand: f.node.is_shorthand,
1664 hir::PatKind::Struct(qpath, fs, etc)
1666 PatKind::Tuple(ref elts, ddpos) => {
1667 hir::PatKind::Tuple(elts.iter().map(|x| self.lower_pat(x)).collect(), ddpos)
1669 PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)),
1670 PatKind::Ref(ref inner, mutbl) => {
1671 hir::PatKind::Ref(self.lower_pat(inner), self.lower_mutability(mutbl))
1673 PatKind::Range(ref e1, ref e2, ref end) => {
1674 hir::PatKind::Range(P(self.lower_expr(e1)),
1675 P(self.lower_expr(e2)),
1676 self.lower_range_end(end))
1678 PatKind::Slice(ref before, ref slice, ref after) => {
1679 hir::PatKind::Slice(before.iter().map(|x| self.lower_pat(x)).collect(),
1680 slice.as_ref().map(|x| self.lower_pat(x)),
1681 after.iter().map(|x| self.lower_pat(x)).collect())
1683 PatKind::Mac(_) => panic!("Shouldn't exist here"),
1689 fn lower_range_end(&mut self, e: &RangeEnd) -> hir::RangeEnd {
1691 RangeEnd::Included => hir::RangeEnd::Included,
1692 RangeEnd::Excluded => hir::RangeEnd::Excluded,
1696 fn lower_expr(&mut self, e: &Expr) -> hir::Expr {
1697 let kind = match e.node {
1699 // Eventually a desugaring for `box EXPR`
1700 // (similar to the desugaring above for `in PLACE BLOCK`)
1701 // should go here, desugaring
1705 // let mut place = BoxPlace::make_place();
1706 // let raw_place = Place::pointer(&mut place);
1707 // let value = $value;
1709 // ::std::ptr::write(raw_place, value);
1710 // Boxed::finalize(place)
1713 // But for now there are type-inference issues doing that.
1714 ExprKind::Box(ref inner) => {
1715 hir::ExprBox(P(self.lower_expr(inner)))
1718 // Desugar ExprBox: `in (PLACE) EXPR`
1719 ExprKind::InPlace(ref placer, ref value_expr) => {
1723 // let mut place = Placer::make_place(p);
1724 // let raw_place = Place::pointer(&mut place);
1726 // std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
1727 // InPlace::finalize(place)
1729 let placer_expr = P(self.lower_expr(placer));
1730 let value_expr = P(self.lower_expr(value_expr));
1732 let placer_ident = self.str_to_ident("placer");
1733 let place_ident = self.str_to_ident("place");
1734 let p_ptr_ident = self.str_to_ident("p_ptr");
1736 let make_place = ["ops", "Placer", "make_place"];
1737 let place_pointer = ["ops", "Place", "pointer"];
1738 let move_val_init = ["intrinsics", "move_val_init"];
1739 let inplace_finalize = ["ops", "InPlace", "finalize"];
1741 let unstable_span = self.allow_internal_unstable("<-", e.span);
1742 let make_call = |this: &mut LoweringContext, p, args| {
1743 let path = P(this.expr_std_path(unstable_span, p, ThinVec::new()));
1744 P(this.expr_call(e.span, path, args))
1747 let mk_stmt_let = |this: &mut LoweringContext, bind, expr| {
1748 this.stmt_let(e.span, false, bind, expr)
1751 let mk_stmt_let_mut = |this: &mut LoweringContext, bind, expr| {
1752 this.stmt_let(e.span, true, bind, expr)
1755 // let placer = <placer_expr> ;
1756 let (s1, placer_binding) = {
1757 mk_stmt_let(self, placer_ident, placer_expr)
1760 // let mut place = Placer::make_place(placer);
1761 let (s2, place_binding) = {
1762 let placer = self.expr_ident(e.span, placer_ident, placer_binding);
1763 let call = make_call(self, &make_place, hir_vec![placer]);
1764 mk_stmt_let_mut(self, place_ident, call)
1767 // let p_ptr = Place::pointer(&mut place);
1768 let (s3, p_ptr_binding) = {
1769 let agent = P(self.expr_ident(e.span, place_ident, place_binding));
1770 let args = hir_vec![self.expr_mut_addr_of(e.span, agent)];
1771 let call = make_call(self, &place_pointer, args);
1772 mk_stmt_let(self, p_ptr_ident, call)
1775 // pop_unsafe!(EXPR));
1776 let pop_unsafe_expr = {
1777 self.signal_block_expr(hir_vec![],
1780 hir::PopUnsafeBlock(hir::CompilerGenerated),
1785 // std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
1786 // InPlace::finalize(place)
1789 let ptr = self.expr_ident(e.span, p_ptr_ident, p_ptr_binding);
1790 let call_move_val_init =
1792 make_call(self, &move_val_init, hir_vec![ptr, pop_unsafe_expr]),
1794 let call_move_val_init = respan(e.span, call_move_val_init);
1796 let place = self.expr_ident(e.span, place_ident, place_binding);
1797 let call = make_call(self, &inplace_finalize, hir_vec![place]);
1798 P(self.signal_block_expr(hir_vec![call_move_val_init],
1801 hir::PushUnsafeBlock(hir::CompilerGenerated),
1805 let block = self.block_all(e.span, hir_vec![s1, s2, s3], Some(expr));
1806 hir::ExprBlock(P(block))
1809 ExprKind::Array(ref exprs) => {
1810 hir::ExprArray(exprs.iter().map(|x| self.lower_expr(x)).collect())
1812 ExprKind::Repeat(ref expr, ref count) => {
1813 let expr = P(self.lower_expr(expr));
1814 let count = self.lower_expr(count);
1815 hir::ExprRepeat(expr, self.record_body(count, None))
1817 ExprKind::Tup(ref elts) => {
1818 hir::ExprTup(elts.iter().map(|x| self.lower_expr(x)).collect())
1820 ExprKind::Call(ref f, ref args) => {
1821 let f = P(self.lower_expr(f));
1822 hir::ExprCall(f, args.iter().map(|x| self.lower_expr(x)).collect())
1824 ExprKind::MethodCall(i, ref tps, ref args) => {
1825 let tps = tps.iter().map(|x| self.lower_ty(x)).collect();
1826 let args = args.iter().map(|x| self.lower_expr(x)).collect();
1827 hir::ExprMethodCall(respan(i.span, i.node.name), tps, args)
1829 ExprKind::Binary(binop, ref lhs, ref rhs) => {
1830 let binop = self.lower_binop(binop);
1831 let lhs = P(self.lower_expr(lhs));
1832 let rhs = P(self.lower_expr(rhs));
1833 hir::ExprBinary(binop, lhs, rhs)
1835 ExprKind::Unary(op, ref ohs) => {
1836 let op = self.lower_unop(op);
1837 let ohs = P(self.lower_expr(ohs));
1838 hir::ExprUnary(op, ohs)
1840 ExprKind::Lit(ref l) => hir::ExprLit(P((**l).clone())),
1841 ExprKind::Cast(ref expr, ref ty) => {
1842 let expr = P(self.lower_expr(expr));
1843 hir::ExprCast(expr, self.lower_ty(ty))
1845 ExprKind::Type(ref expr, ref ty) => {
1846 let expr = P(self.lower_expr(expr));
1847 hir::ExprType(expr, self.lower_ty(ty))
1849 ExprKind::AddrOf(m, ref ohs) => {
1850 let m = self.lower_mutability(m);
1851 let ohs = P(self.lower_expr(ohs));
1852 hir::ExprAddrOf(m, ohs)
1854 // More complicated than you might expect because the else branch
1855 // might be `if let`.
1856 ExprKind::If(ref cond, ref blk, ref else_opt) => {
1857 let else_opt = else_opt.as_ref().map(|els| {
1859 ExprKind::IfLet(..) => {
1860 // wrap the if-let expr in a block
1861 let span = els.span;
1862 let els = P(self.lower_expr(els));
1863 let id = self.next_id();
1864 let blk = P(hir::Block {
1868 rules: hir::DefaultBlock,
1870 targeted_by_break: false,
1872 P(self.expr_block(blk, ThinVec::new()))
1874 _ => P(self.lower_expr(els)),
1878 let then_blk = self.lower_block(blk, false);
1879 let then_expr = self.expr_block(then_blk, ThinVec::new());
1881 hir::ExprIf(P(self.lower_expr(cond)), P(then_expr), else_opt)
1883 ExprKind::While(ref cond, ref body, opt_ident) => {
1884 self.with_loop_scope(e.id, |this|
1886 this.with_loop_condition_scope(|this| P(this.lower_expr(cond))),
1887 this.lower_block(body, false),
1888 this.lower_opt_sp_ident(opt_ident)))
1890 ExprKind::Loop(ref body, opt_ident) => {
1891 self.with_loop_scope(e.id, |this|
1892 hir::ExprLoop(this.lower_block(body, false),
1893 this.lower_opt_sp_ident(opt_ident),
1894 hir::LoopSource::Loop))
1896 ExprKind::Catch(ref body) => {
1897 self.with_catch_scope(body.id, |this|
1898 hir::ExprBlock(this.lower_block(body, true)))
1900 ExprKind::Match(ref expr, ref arms) => {
1901 hir::ExprMatch(P(self.lower_expr(expr)),
1902 arms.iter().map(|x| self.lower_arm(x)).collect(),
1903 hir::MatchSource::Normal)
1905 ExprKind::Closure(capture_clause, ref decl, ref body, fn_decl_span) => {
1906 self.with_new_scopes(|this| {
1907 this.with_parent_def(e.id, |this| {
1908 let expr = this.lower_expr(body);
1909 hir::ExprClosure(this.lower_capture_clause(capture_clause),
1910 this.lower_fn_decl(decl),
1911 this.record_body(expr, Some(decl)),
1916 ExprKind::Block(ref blk) => hir::ExprBlock(self.lower_block(blk, false)),
1917 ExprKind::Assign(ref el, ref er) => {
1918 hir::ExprAssign(P(self.lower_expr(el)), P(self.lower_expr(er)))
1920 ExprKind::AssignOp(op, ref el, ref er) => {
1921 hir::ExprAssignOp(self.lower_binop(op),
1922 P(self.lower_expr(el)),
1923 P(self.lower_expr(er)))
1925 ExprKind::Field(ref el, ident) => {
1926 hir::ExprField(P(self.lower_expr(el)), respan(ident.span, ident.node.name))
1928 ExprKind::TupField(ref el, ident) => {
1929 hir::ExprTupField(P(self.lower_expr(el)), ident)
1931 ExprKind::Index(ref el, ref er) => {
1932 hir::ExprIndex(P(self.lower_expr(el)), P(self.lower_expr(er)))
1934 ExprKind::Range(ref e1, ref e2, lims) => {
1935 use syntax::ast::RangeLimits::*;
1937 let (path, variant) = match (e1, e2, lims) {
1938 (&None, &None, HalfOpen) => ("RangeFull", None),
1939 (&Some(..), &None, HalfOpen) => ("RangeFrom", None),
1940 (&None, &Some(..), HalfOpen) => ("RangeTo", None),
1941 (&Some(..), &Some(..), HalfOpen) => ("Range", None),
1942 (&None, &Some(..), Closed) => ("RangeToInclusive", None),
1943 (&Some(..), &Some(..), Closed) => ("RangeInclusive", Some("NonEmpty")),
1944 (_, &None, Closed) =>
1945 panic!(self.diagnostic().span_fatal(
1946 e.span, "inclusive range with no end")),
1950 e1.iter().map(|e| ("start", e)).chain(e2.iter().map(|e| ("end", e)))
1952 let expr = P(self.lower_expr(&e));
1953 let unstable_span = self.allow_internal_unstable("...", e.span);
1954 self.field(Symbol::intern(s), expr, unstable_span)
1955 }).collect::<P<[hir::Field]>>();
1957 let is_unit = fields.is_empty();
1958 let unstable_span = self.allow_internal_unstable("...", e.span);
1960 iter::once("ops").chain(iter::once(path)).chain(variant)
1961 .collect::<Vec<_>>();
1962 let struct_path = self.std_path(unstable_span, &struct_path, is_unit);
1963 let struct_path = hir::QPath::Resolved(None, P(struct_path));
1966 id: self.lower_node_id(e.id),
1968 hir::ExprPath(struct_path)
1970 hir::ExprStruct(struct_path, fields, None)
1972 span: unstable_span,
1973 attrs: e.attrs.clone(),
1976 ExprKind::Path(ref qself, ref path) => {
1977 hir::ExprPath(self.lower_qpath(e.id, qself, path, ParamMode::Optional))
1979 ExprKind::Break(opt_ident, ref opt_expr) => {
1980 let label_result = if self.is_in_loop_condition && opt_ident.is_none() {
1983 target_id: hir::ScopeTarget::Loop(
1984 Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into()),
1987 self.lower_loop_destination(opt_ident.map(|ident| (e.id, ident)))
1991 opt_expr.as_ref().map(|x| P(self.lower_expr(x))))
1993 ExprKind::Continue(opt_ident) =>
1995 if self.is_in_loop_condition && opt_ident.is_none() {
1998 target_id: hir::ScopeTarget::Loop(Err(
1999 hir::LoopIdError::UnlabeledCfInWhileCondition).into()),
2002 self.lower_loop_destination(opt_ident.map( |ident| (e.id, ident)))
2004 ExprKind::Ret(ref e) => hir::ExprRet(e.as_ref().map(|x| P(self.lower_expr(x)))),
2005 ExprKind::InlineAsm(ref asm) => {
2006 let hir_asm = hir::InlineAsm {
2007 inputs: asm.inputs.iter().map(|&(ref c, _)| c.clone()).collect(),
2008 outputs: asm.outputs.iter().map(|out| {
2009 hir::InlineAsmOutput {
2010 constraint: out.constraint.clone(),
2012 is_indirect: out.is_indirect,
2015 asm: asm.asm.clone(),
2016 asm_str_style: asm.asm_str_style,
2017 clobbers: asm.clobbers.clone().into(),
2018 volatile: asm.volatile,
2019 alignstack: asm.alignstack,
2020 dialect: asm.dialect,
2024 asm.outputs.iter().map(|out| self.lower_expr(&out.expr)).collect();
2026 asm.inputs.iter().map(|&(_, ref input)| self.lower_expr(input)).collect();
2027 hir::ExprInlineAsm(P(hir_asm), outputs, inputs)
2029 ExprKind::Struct(ref path, ref fields, ref maybe_expr) => {
2030 hir::ExprStruct(self.lower_qpath(e.id, &None, path, ParamMode::Optional),
2031 fields.iter().map(|x| self.lower_field(x)).collect(),
2032 maybe_expr.as_ref().map(|x| P(self.lower_expr(x))))
2034 ExprKind::Paren(ref ex) => {
2035 let mut ex = self.lower_expr(ex);
2036 // include parens in span, but only if it is a super-span.
2037 if e.span.contains(ex.span) {
2040 // merge attributes into the inner expression.
2041 let mut attrs = e.attrs.clone();
2042 attrs.extend::<Vec<_>>(ex.attrs.into());
2047 // Desugar ExprIfLet
2048 // From: `if let <pat> = <sub_expr> <body> [<else_opt>]`
2049 ExprKind::IfLet(ref pat, ref sub_expr, ref body, ref else_opt) => {
2052 // match <sub_expr> {
2054 // _ => [<else_opt> | ()]
2057 let mut arms = vec![];
2059 // `<pat> => <body>`
2061 let body = self.lower_block(body, false);
2062 let body_expr = P(self.expr_block(body, ThinVec::new()));
2063 let pat = self.lower_pat(pat);
2064 arms.push(self.arm(hir_vec![pat], body_expr));
2067 // _ => [<else_opt>|()]
2069 let wildcard_arm: Option<&Expr> = else_opt.as_ref().map(|p| &**p);
2070 let wildcard_pattern = self.pat_wild(e.span);
2071 let body = if let Some(else_expr) = wildcard_arm {
2072 P(self.lower_expr(else_expr))
2074 self.expr_tuple(e.span, hir_vec![])
2076 arms.push(self.arm(hir_vec![wildcard_pattern], body));
2079 let contains_else_clause = else_opt.is_some();
2081 let sub_expr = P(self.lower_expr(sub_expr));
2086 hir::MatchSource::IfLetDesugar {
2087 contains_else_clause: contains_else_clause,
2091 // Desugar ExprWhileLet
2092 // From: `[opt_ident]: while let <pat> = <sub_expr> <body>`
2093 ExprKind::WhileLet(ref pat, ref sub_expr, ref body, opt_ident) => {
2096 // [opt_ident]: loop {
2097 // match <sub_expr> {
2103 // Note that the block AND the condition are evaluated in the loop scope.
2104 // This is done to allow `break` from inside the condition of the loop.
2105 let (body, break_expr, sub_expr) = self.with_loop_scope(e.id, |this| (
2106 this.lower_block(body, false),
2107 this.expr_break(e.span, ThinVec::new()),
2108 this.with_loop_condition_scope(|this| P(this.lower_expr(sub_expr))),
2111 // `<pat> => <body>`
2113 let body_expr = P(self.expr_block(body, ThinVec::new()));
2114 let pat = self.lower_pat(pat);
2115 self.arm(hir_vec![pat], body_expr)
2120 let pat_under = self.pat_wild(e.span);
2121 self.arm(hir_vec![pat_under], break_expr)
2124 // `match <sub_expr> { ... }`
2125 let arms = hir_vec![pat_arm, break_arm];
2126 let match_expr = self.expr(e.span,
2127 hir::ExprMatch(sub_expr,
2129 hir::MatchSource::WhileLetDesugar),
2132 // `[opt_ident]: loop { ... }`
2133 let loop_block = P(self.block_expr(P(match_expr)));
2134 let loop_expr = hir::ExprLoop(loop_block, self.lower_opt_sp_ident(opt_ident),
2135 hir::LoopSource::WhileLet);
2136 // add attributes to the outer returned expr node
2140 // Desugar ExprForLoop
2141 // From: `[opt_ident]: for <pat> in <head> <body>`
2142 ExprKind::ForLoop(ref pat, ref head, ref body, opt_ident) => {
2146 // let result = match ::std::iter::IntoIterator::into_iter(<head>) {
2148 // [opt_ident]: loop {
2149 // match ::std::iter::Iterator::next(&mut iter) {
2150 // ::std::option::Option::Some(<pat>) => <body>,
2151 // ::std::option::Option::None => break
2160 let head = self.lower_expr(head);
2162 let iter = self.str_to_ident("iter");
2164 // `::std::option::Option::Some(<pat>) => <body>`
2166 let body_block = self.with_loop_scope(e.id,
2167 |this| this.lower_block(body, false));
2168 let body_expr = P(self.expr_block(body_block, ThinVec::new()));
2169 let pat = self.lower_pat(pat);
2170 let some_pat = self.pat_some(e.span, pat);
2172 self.arm(hir_vec![some_pat], body_expr)
2175 // `::std::option::Option::None => break`
2177 let break_expr = self.with_loop_scope(e.id, |this|
2178 this.expr_break(e.span, ThinVec::new()));
2179 let pat = self.pat_none(e.span);
2180 self.arm(hir_vec![pat], break_expr)
2184 let iter_pat = self.pat_ident_binding_mode(e.span, iter,
2185 hir::BindByValue(hir::MutMutable));
2187 // `match ::std::iter::Iterator::next(&mut iter) { ... }`
2189 let iter = P(self.expr_ident(e.span, iter, iter_pat.id));
2190 let ref_mut_iter = self.expr_mut_addr_of(e.span, iter);
2191 let next_path = &["iter", "Iterator", "next"];
2192 let next_path = P(self.expr_std_path(e.span, next_path, ThinVec::new()));
2193 let next_expr = P(self.expr_call(e.span, next_path,
2194 hir_vec![ref_mut_iter]));
2195 let arms = hir_vec![pat_arm, break_arm];
2198 hir::ExprMatch(next_expr, arms,
2199 hir::MatchSource::ForLoopDesugar),
2203 // `[opt_ident]: loop { ... }`
2204 let loop_block = P(self.block_expr(match_expr));
2205 let loop_expr = hir::ExprLoop(loop_block, self.lower_opt_sp_ident(opt_ident),
2206 hir::LoopSource::ForLoop);
2207 let loop_expr = P(hir::Expr {
2208 id: self.lower_node_id(e.id),
2211 attrs: ThinVec::new(),
2214 // `mut iter => { ... }`
2215 let iter_arm = self.arm(hir_vec![iter_pat], loop_expr);
2217 // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }`
2218 let into_iter_expr = {
2219 let into_iter_path = &["iter", "IntoIterator", "into_iter"];
2220 let into_iter = P(self.expr_std_path(e.span, into_iter_path,
2222 P(self.expr_call(e.span, into_iter, hir_vec![head]))
2225 let match_expr = P(self.expr_match(e.span,
2228 hir::MatchSource::ForLoopDesugar));
2230 // `{ let _result = ...; _result }`
2231 // underscore prevents an unused_variables lint if the head diverges
2232 let result_ident = self.str_to_ident("_result");
2233 let (let_stmt, let_stmt_binding) =
2234 self.stmt_let(e.span, false, result_ident, match_expr);
2236 let result = P(self.expr_ident(e.span, result_ident, let_stmt_binding));
2237 let block = P(self.block_all(e.span, hir_vec![let_stmt], Some(result)));
2238 // add the attributes to the outer returned expr node
2239 return self.expr_block(block, e.attrs.clone());
2242 // Desugar ExprKind::Try
2244 ExprKind::Try(ref sub_expr) => {
2247 // match Carrier::translate(<expr>) {
2248 // Ok(val) => #[allow(unreachable_code)] val,
2249 // Err(err) => #[allow(unreachable_code)]
2250 // // If there is an enclosing `catch {...}`
2251 // break 'catch_target Carrier::from_error(From::from(err)),
2253 // return Carrier::from_error(From::from(err)),
2256 let unstable_span = self.allow_internal_unstable("?", e.span);
2258 // Carrier::translate(<expr>)
2261 let sub_expr = self.lower_expr(sub_expr);
2263 let path = &["ops", "Carrier", "translate"];
2264 let path = P(self.expr_std_path(unstable_span, path, ThinVec::new()));
2265 P(self.expr_call(e.span, path, hir_vec![sub_expr]))
2268 // #[allow(unreachable_code)]
2270 // allow(unreachable_code)
2272 let allow_ident = self.str_to_ident("allow");
2273 let uc_ident = self.str_to_ident("unreachable_code");
2274 let uc_meta_item = attr::mk_spanned_word_item(e.span, uc_ident);
2275 let uc_nested = NestedMetaItemKind::MetaItem(uc_meta_item);
2276 let uc_spanned = respan(e.span, uc_nested);
2277 attr::mk_spanned_list_item(e.span, allow_ident, vec![uc_spanned])
2279 attr::mk_spanned_attr_outer(e.span, attr::mk_attr_id(), allow)
2281 let attrs = vec![attr];
2283 // Ok(val) => #[allow(unreachable_code)] val,
2285 let val_ident = self.str_to_ident("val");
2286 let val_pat = self.pat_ident(e.span, val_ident);
2287 let val_expr = P(self.expr_ident_with_attrs(e.span,
2290 ThinVec::from(attrs.clone())));
2291 let ok_pat = self.pat_ok(e.span, val_pat);
2293 self.arm(hir_vec![ok_pat], val_expr)
2296 // Err(err) => #[allow(unreachable_code)]
2297 // return Carrier::from_error(From::from(err)),
2299 let err_ident = self.str_to_ident("err");
2300 let err_local = self.pat_ident(e.span, err_ident);
2302 let path = &["convert", "From", "from"];
2303 let from = P(self.expr_std_path(e.span, path, ThinVec::new()));
2304 let err_expr = self.expr_ident(e.span, err_ident, err_local.id);
2306 self.expr_call(e.span, from, hir_vec![err_expr])
2308 let from_err_expr = {
2309 let path = &["ops", "Carrier", "from_error"];
2310 let from_err = P(self.expr_std_path(unstable_span, path,
2312 P(self.expr_call(e.span, from_err, hir_vec![from_expr]))
2315 let thin_attrs = ThinVec::from(attrs);
2316 let catch_scope = self.catch_scopes.last().map(|x| *x);
2317 let ret_expr = if let Some(catch_node) = catch_scope {
2323 target_id: hir::ScopeTarget::Block(catch_node),
2330 hir::Expr_::ExprRet(Some(from_err_expr)),
2335 let err_pat = self.pat_err(e.span, err_local);
2336 self.arm(hir_vec![err_pat], ret_expr)
2339 hir::ExprMatch(discr,
2340 hir_vec![err_arm, ok_arm],
2341 hir::MatchSource::TryDesugar)
2344 ExprKind::Mac(_) => panic!("Shouldn't exist here"),
2348 id: self.lower_node_id(e.id),
2351 attrs: e.attrs.clone(),
2355 fn lower_stmt(&mut self, s: &Stmt) -> SmallVector<hir::Stmt> {
2356 SmallVector::one(match s.node {
2357 StmtKind::Local(ref l) => Spanned {
2358 node: hir::StmtDecl(P(Spanned {
2359 node: hir::DeclLocal(self.lower_local(l)),
2361 }), self.lower_node_id(s.id)),
2364 StmtKind::Item(ref it) => {
2365 // Can only use the ID once.
2366 let mut id = Some(s.id);
2367 return self.lower_item_id(it).into_iter().map(|item_id| Spanned {
2368 node: hir::StmtDecl(P(Spanned {
2369 node: hir::DeclItem(item_id),
2372 .map(|id| self.lower_node_id(id))
2373 .unwrap_or_else(|| self.next_id())),
2377 StmtKind::Expr(ref e) => {
2379 node: hir::StmtExpr(P(self.lower_expr(e)),
2380 self.lower_node_id(s.id)),
2384 StmtKind::Semi(ref e) => {
2386 node: hir::StmtSemi(P(self.lower_expr(e)),
2387 self.lower_node_id(s.id)),
2391 StmtKind::Mac(..) => panic!("Shouldn't exist here"),
2395 fn lower_capture_clause(&mut self, c: CaptureBy) -> hir::CaptureClause {
2397 CaptureBy::Value => hir::CaptureByValue,
2398 CaptureBy::Ref => hir::CaptureByRef,
2402 /// If an `explicit_owner` is given, this method allocates the `HirId` in
2403 /// the address space of that item instead of the item currently being
2404 /// lowered. This can happen during `lower_impl_item_ref()` where we need to
2405 /// lower a `Visibility` value although we haven't lowered the owning
2406 /// `ImplItem` in question yet.
2407 fn lower_visibility(&mut self,
2409 explicit_owner: Option<NodeId>)
2410 -> hir::Visibility {
2412 Visibility::Public => hir::Public,
2413 Visibility::Crate(_) => hir::Visibility::Crate,
2414 Visibility::Restricted { ref path, id } => {
2415 hir::Visibility::Restricted {
2416 path: P(self.lower_path(id, path, ParamMode::Explicit, true)),
2417 id: if let Some(owner) = explicit_owner {
2418 self.lower_node_id_with_owner(id, owner)
2420 self.lower_node_id(id)
2424 Visibility::Inherited => hir::Inherited,
2428 fn lower_defaultness(&mut self, d: Defaultness, has_value: bool) -> hir::Defaultness {
2430 Defaultness::Default => hir::Defaultness::Default { has_value: has_value },
2431 Defaultness::Final => {
2433 hir::Defaultness::Final
2438 fn lower_block_check_mode(&mut self, b: &BlockCheckMode) -> hir::BlockCheckMode {
2440 BlockCheckMode::Default => hir::DefaultBlock,
2441 BlockCheckMode::Unsafe(u) => hir::UnsafeBlock(self.lower_unsafe_source(u)),
2445 fn lower_binding_mode(&mut self, b: &BindingMode) -> hir::BindingMode {
2447 BindingMode::ByRef(m) => hir::BindByRef(self.lower_mutability(m)),
2448 BindingMode::ByValue(m) => hir::BindByValue(self.lower_mutability(m)),
2452 fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
2454 CompilerGenerated => hir::CompilerGenerated,
2455 UserProvided => hir::UserProvided,
2459 fn lower_impl_polarity(&mut self, i: ImplPolarity) -> hir::ImplPolarity {
2461 ImplPolarity::Positive => hir::ImplPolarity::Positive,
2462 ImplPolarity::Negative => hir::ImplPolarity::Negative,
2466 fn lower_trait_bound_modifier(&mut self, f: TraitBoundModifier) -> hir::TraitBoundModifier {
2468 TraitBoundModifier::None => hir::TraitBoundModifier::None,
2469 TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe,
2473 // Helper methods for building HIR.
2475 fn arm(&mut self, pats: hir::HirVec<P<hir::Pat>>, expr: P<hir::Expr>) -> hir::Arm {
2484 fn field(&mut self, name: Name, expr: P<hir::Expr>, span: Span) -> hir::Field {
2492 is_shorthand: false,
2496 fn expr_break(&mut self, span: Span, attrs: ThinVec<Attribute>) -> P<hir::Expr> {
2497 let expr_break = hir::ExprBreak(self.lower_loop_destination(None), None);
2498 P(self.expr(span, expr_break, attrs))
2501 fn expr_call(&mut self, span: Span, e: P<hir::Expr>, args: hir::HirVec<hir::Expr>)
2503 self.expr(span, hir::ExprCall(e, args), ThinVec::new())
2506 fn expr_ident(&mut self, span: Span, id: Name, binding: NodeId) -> hir::Expr {
2507 self.expr_ident_with_attrs(span, id, binding, ThinVec::new())
2510 fn expr_ident_with_attrs(&mut self, span: Span,
2513 attrs: ThinVec<Attribute>) -> hir::Expr {
2515 let defs = self.resolver.definitions();
2516 Def::Local(defs.local_def_id(binding))
2519 let expr_path = hir::ExprPath(hir::QPath::Resolved(None, P(hir::Path {
2522 segments: hir_vec![hir::PathSegment::from_name(id)],
2525 self.expr(span, expr_path, attrs)
2528 fn expr_mut_addr_of(&mut self, span: Span, e: P<hir::Expr>) -> hir::Expr {
2529 self.expr(span, hir::ExprAddrOf(hir::MutMutable, e), ThinVec::new())
2532 fn expr_std_path(&mut self,
2534 components: &[&str],
2535 attrs: ThinVec<Attribute>)
2537 let path = self.std_path(span, components, true);
2538 self.expr(span, hir::ExprPath(hir::QPath::Resolved(None, P(path))), attrs)
2541 fn expr_match(&mut self,
2544 arms: hir::HirVec<hir::Arm>,
2545 source: hir::MatchSource)
2547 self.expr(span, hir::ExprMatch(arg, arms, source), ThinVec::new())
2550 fn expr_block(&mut self, b: P<hir::Block>, attrs: ThinVec<Attribute>) -> hir::Expr {
2551 self.expr(b.span, hir::ExprBlock(b), attrs)
2554 fn expr_tuple(&mut self, sp: Span, exprs: hir::HirVec<hir::Expr>) -> P<hir::Expr> {
2555 P(self.expr(sp, hir::ExprTup(exprs), ThinVec::new()))
2558 fn expr(&mut self, span: Span, node: hir::Expr_, attrs: ThinVec<Attribute>) -> hir::Expr {
2567 fn stmt_let(&mut self, sp: Span, mutbl: bool, ident: Name, ex: P<hir::Expr>)
2568 -> (hir::Stmt, NodeId) {
2569 let pat = if mutbl {
2570 self.pat_ident_binding_mode(sp, ident, hir::BindByValue(hir::MutMutable))
2572 self.pat_ident(sp, ident)
2574 let pat_id = pat.id;
2575 let local = P(hir::Local {
2581 attrs: ThinVec::new(),
2583 let decl = respan(sp, hir::DeclLocal(local));
2584 (respan(sp, hir::StmtDecl(P(decl), self.next_id())), pat_id)
2587 fn block_expr(&mut self, expr: P<hir::Expr>) -> hir::Block {
2588 self.block_all(expr.span, hir::HirVec::new(), Some(expr))
2591 fn block_all(&mut self, span: Span, stmts: hir::HirVec<hir::Stmt>, expr: Option<P<hir::Expr>>)
2597 rules: hir::DefaultBlock,
2599 targeted_by_break: false,
2603 fn pat_ok(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
2604 self.pat_std_enum(span, &["result", "Result", "Ok"], hir_vec![pat])
2607 fn pat_err(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
2608 self.pat_std_enum(span, &["result", "Result", "Err"], hir_vec![pat])
2611 fn pat_some(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
2612 self.pat_std_enum(span, &["option", "Option", "Some"], hir_vec![pat])
2615 fn pat_none(&mut self, span: Span) -> P<hir::Pat> {
2616 self.pat_std_enum(span, &["option", "Option", "None"], hir_vec![])
2619 fn pat_std_enum(&mut self,
2621 components: &[&str],
2622 subpats: hir::HirVec<P<hir::Pat>>)
2624 let path = self.std_path(span, components, true);
2625 let qpath = hir::QPath::Resolved(None, P(path));
2626 let pt = if subpats.is_empty() {
2627 hir::PatKind::Path(qpath)
2629 hir::PatKind::TupleStruct(qpath, subpats, None)
2634 fn pat_ident(&mut self, span: Span, name: Name) -> P<hir::Pat> {
2635 self.pat_ident_binding_mode(span, name, hir::BindByValue(hir::MutImmutable))
2638 fn pat_ident_binding_mode(&mut self, span: Span, name: Name, bm: hir::BindingMode)
2640 let id = self.next_id();
2641 let parent_def = self.parent_def.unwrap();
2643 let defs = self.resolver.definitions();
2644 let def_path_data = DefPathData::Binding(name.as_str());
2645 let def_index = defs.create_def_with_parent(parent_def,
2649 DefId::local(def_index)
2654 node: hir::PatKind::Binding(bm,
2665 fn pat_wild(&mut self, span: Span) -> P<hir::Pat> {
2666 self.pat(span, hir::PatKind::Wild)
2669 fn pat(&mut self, span: Span, pat: hir::PatKind) -> P<hir::Pat> {
2677 /// Given suffix ["b","c","d"], returns path `::std::b::c::d` when
2678 /// `fld.cx.use_std`, and `::core::b::c::d` otherwise.
2679 /// The path is also resolved according to `is_value`.
2680 fn std_path(&mut self, span: Span, components: &[&str], is_value: bool) -> hir::Path {
2681 let mut path = hir::Path {
2684 segments: iter::once(keywords::CrateRoot.name()).chain({
2685 self.crate_root.into_iter().chain(components.iter().cloned()).map(Symbol::intern)
2686 }).map(hir::PathSegment::from_name).collect(),
2689 self.resolver.resolve_hir_path(&mut path, is_value);
2693 fn signal_block_expr(&mut self,
2694 stmts: hir::HirVec<hir::Stmt>,
2697 rule: hir::BlockCheckMode,
2698 attrs: ThinVec<Attribute>)
2700 let id = self.next_id();
2701 let block = P(hir::Block {
2707 targeted_by_break: false,
2709 self.expr_block(block, attrs)
2712 fn ty_path(&mut self, id: NodeId, span: Span, qpath: hir::QPath) -> P<hir::Ty> {
2714 let node = match qpath {
2715 hir::QPath::Resolved(None, path) => {
2716 // Turn trait object paths into `TyTraitObject` instead.
2717 if let Def::Trait(_) = path.def {
2718 let principal = hir::PolyTraitRef {
2719 bound_lifetimes: hir_vec![],
2720 trait_ref: hir::TraitRef {
2721 path: path.and_then(|path| path),
2727 // The original ID is taken by the `PolyTraitRef`,
2728 // so the `Ty` itself needs a different one.
2729 id = self.next_id();
2731 hir::TyTraitObject(hir_vec![principal], self.elided_lifetime(span))
2733 hir::TyPath(hir::QPath::Resolved(None, path))
2736 _ => hir::TyPath(qpath)
2738 P(hir::Ty { id, node, span })
2741 fn elided_lifetime(&mut self, span: Span) -> hir::Lifetime {
2745 name: keywords::Invalid.name()
2750 fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
2751 // Sorting by span ensures that we get things in order within a
2752 // file, and also puts the files in a sensible order.
2753 let mut body_ids: Vec<_> = bodies.keys().cloned().collect();
2754 body_ids.sort_by_key(|b| bodies[b].value.span);