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.
43 use dep_graph::DepGraph;
46 use hir::map::{Definitions, DefKey, DefPathData};
47 use hir::def_id::{DefIndex, DefId, CRATE_DEF_INDEX, DefIndexAddressSpace};
48 use hir::def::{Def, PathResolution};
49 use lint::builtin::PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES;
50 use middle::cstore::CrateStore;
51 use rustc_data_structures::indexed_vec::IndexVec;
53 use util::common::FN_OUTPUT_NAME;
54 use util::nodemap::{DefIdMap, FxHashMap, NodeMap};
56 use std::collections::{BTreeMap, HashSet};
63 use syntax::ext::hygiene::{Mark, SyntaxContext};
64 use syntax::print::pprust;
66 use syntax::codemap::{self, respan, Spanned, CompilerDesugaringKind};
67 use syntax::std_inject;
68 use syntax::symbol::{Symbol, keywords};
69 use syntax::tokenstream::{TokenStream, TokenTree, Delimited};
70 use syntax::parse::token::Token;
71 use syntax::util::small_vector::SmallVector;
72 use syntax::visit::{self, Visitor};
75 const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF;
77 pub struct LoweringContext<'a> {
78 crate_root: Option<&'static str>,
80 // Use to assign ids to hir nodes that do not directly correspond to an ast node
83 cstore: &'a CrateStore,
85 // As we walk the AST we must keep track of the current 'parent' def id (in
86 // the form of a DefIndex) so that if we create a new node which introduces
87 // a definition, then we can properly create the def id.
88 parent_def: Option<DefIndex>,
89 resolver: &'a mut Resolver,
90 name_map: FxHashMap<Ident, Name>,
92 /// The items being lowered are collected here.
93 items: BTreeMap<NodeId, hir::Item>,
95 trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem>,
96 impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem>,
97 bodies: BTreeMap<hir::BodyId, hir::Body>,
98 exported_macros: Vec<hir::MacroDef>,
100 trait_impls: BTreeMap<DefId, Vec<NodeId>>,
101 trait_auto_impl: BTreeMap<DefId, NodeId>,
105 catch_scopes: Vec<NodeId>,
106 loop_scopes: Vec<NodeId>,
107 is_in_loop_condition: bool,
108 is_in_trait_impl: bool,
110 // This is a list of in-band type definitions being generated by
111 // Argument-position `impl Trait`.
112 // When traversing a signature such as `fn foo(x: impl Trait)`,
113 // we record `impl Trait` as a new type parameter, then later
114 // add it on to `foo`s generics.
115 in_band_ty_params: Vec<hir::TyParam>,
117 // Used to create lifetime definitions from in-band lifetime usages.
118 // e.g. `fn foo(x: &'x u8) -> &'x u8` to `fn foo<'x>(x: &'x u8) -> &'x u8`
119 // When a named lifetime is encountered in a function or impl header and
120 // has not been defined
121 // (i.e. it doesn't appear in the in_scope_lifetimes list), it is added
122 // to this list. The results of this list are then added to the list of
123 // lifetime definitions in the corresponding impl or function generics.
124 lifetimes_to_define: Vec<(Span, Name)>,
125 // Whether or not in-band lifetimes are being collected. This is used to
126 // indicate whether or not we're in a place where new lifetimes will result
127 // in in-band lifetime definitions, such a function or an impl header.
128 // This will always be false unless the `in_band_lifetimes` feature is
130 is_collecting_in_band_lifetimes: bool,
131 // Currently in-scope lifetimes defined in impl headers, fn headers, or HRTB.
132 // When `is_collectin_in_band_lifetimes` is true, each lifetime is checked
133 // against this list to see if it is already in-scope, or if a definition
134 // needs to be created for it.
135 in_scope_lifetimes: Vec<Name>,
137 type_def_lifetime_params: DefIdMap<usize>,
139 current_hir_id_owner: Vec<(DefIndex, u32)>,
140 item_local_id_counters: NodeMap<u32>,
141 node_id_to_hir_id: IndexVec<NodeId, hir::HirId>,
145 /// Resolve a hir path generated by the lowerer when expanding `for`, `if let`, etc.
146 fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool);
148 /// Obtain the resolution for a node id
149 fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution>;
151 /// We must keep the set of definitions up to date as we add nodes that weren't in the AST.
152 /// This should only return `None` during testing.
153 fn definitions(&mut self) -> &mut Definitions;
156 #[derive(Clone, Copy, Debug)]
157 enum ImplTraitContext {
158 /// Treat `impl Trait` as shorthand for a new universal generic parameter.
159 /// Example: `fn foo(x: impl Debug)`, where `impl Debug` is conceptually
160 /// equivalent to a fresh universal parameter like `fn foo<T: Debug>(x: T)`.
162 /// We store a DefId here so we can look up necessary information later
165 /// Treat `impl Trait` as shorthand for a new universal existential parameter.
166 /// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually
167 /// equivalent to a fresh existential parameter like `abstract type T; fn foo() -> T`.
170 /// `impl Trait` is not accepted in this position.
174 pub fn lower_crate(sess: &Session,
176 dep_graph: &DepGraph,
178 resolver: &mut Resolver)
180 // We're constructing the HIR here; we don't care what we will
181 // read, since we haven't even constructed the *input* to
183 dep_graph.assert_ignored();
186 crate_root: std_inject::injected_crate_name(),
191 name_map: FxHashMap(),
192 items: BTreeMap::new(),
193 trait_items: BTreeMap::new(),
194 impl_items: BTreeMap::new(),
195 bodies: BTreeMap::new(),
196 trait_impls: BTreeMap::new(),
197 trait_auto_impl: BTreeMap::new(),
198 exported_macros: Vec::new(),
199 catch_scopes: Vec::new(),
200 loop_scopes: Vec::new(),
201 is_in_loop_condition: false,
202 type_def_lifetime_params: DefIdMap(),
203 current_hir_id_owner: vec![(CRATE_DEF_INDEX, 0)],
204 item_local_id_counters: NodeMap(),
205 node_id_to_hir_id: IndexVec::new(),
207 is_in_trait_impl: false,
208 in_band_ty_params: Vec::new(),
209 lifetimes_to_define: Vec::new(),
210 is_collecting_in_band_lifetimes: false,
211 in_scope_lifetimes: Vec::new(),
215 #[derive(Copy, Clone, PartialEq, Eq)]
217 /// Any path in a type context.
219 /// The `module::Type` in `module::Type::method` in an expression.
223 struct LoweredNodeId {
228 enum ParenthesizedGenericArgs {
234 impl<'a> LoweringContext<'a> {
235 fn lower_crate(mut self, c: &Crate) -> hir::Crate {
236 /// Full-crate AST visitor that inserts into a fresh
237 /// `LoweringContext` any information that may be
238 /// needed from arbitrary locations in the crate.
239 /// E.g. The number of lifetime generic parameters
240 /// declared for every type and trait definition.
241 struct MiscCollector<'lcx, 'interner: 'lcx> {
242 lctx: &'lcx mut LoweringContext<'interner>,
245 impl<'lcx, 'interner> Visitor<'lcx> for MiscCollector<'lcx, 'interner> {
246 fn visit_item(&mut self, item: &'lcx Item) {
247 self.lctx.allocate_hir_id_counter(item.id, item);
250 ItemKind::Struct(_, ref generics) |
251 ItemKind::Union(_, ref generics) |
252 ItemKind::Enum(_, ref generics) |
253 ItemKind::Ty(_, ref generics) |
254 ItemKind::Trait(_, _, ref generics, ..) => {
255 let def_id = self.lctx.resolver.definitions().local_def_id(item.id);
256 let count = generics.params.iter()
257 .filter(|param| param.is_lifetime_param())
259 self.lctx.type_def_lifetime_params.insert(def_id, count);
263 visit::walk_item(self, item);
266 fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
267 self.lctx.allocate_hir_id_counter(item.id, item);
268 visit::walk_trait_item(self, item);
271 fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
272 self.lctx.allocate_hir_id_counter(item.id, item);
273 visit::walk_impl_item(self, item);
277 struct ItemLowerer<'lcx, 'interner: 'lcx> {
278 lctx: &'lcx mut LoweringContext<'interner>,
281 impl<'lcx, 'interner> ItemLowerer<'lcx, 'interner> {
282 fn with_trait_impl_ref<F>(&mut self, trait_impl_ref: &Option<TraitRef>, f: F)
283 where F: FnOnce(&mut Self)
285 let old = self.lctx.is_in_trait_impl;
286 self.lctx.is_in_trait_impl = if let &None = trait_impl_ref {
292 self.lctx.is_in_trait_impl = old;
296 impl<'lcx, 'interner> Visitor<'lcx> for ItemLowerer<'lcx, 'interner> {
297 fn visit_item(&mut self, item: &'lcx Item) {
298 let mut item_lowered = true;
299 self.lctx.with_hir_id_owner(item.id, |lctx| {
300 if let Some(hir_item) = lctx.lower_item(item) {
301 lctx.items.insert(item.id, hir_item);
303 item_lowered = false;
308 let item_lifetimes = match self.lctx.items.get(&item.id).unwrap().node {
309 hir::Item_::ItemImpl(_,_,_,ref generics,..) |
310 hir::Item_::ItemTrait(_,_,ref generics,..) =>
311 generics.lifetimes().cloned().collect::<Vec<_>>(),
315 self.lctx.with_parent_impl_lifetime_defs(&item_lifetimes, |this| {
316 let this = &mut ItemLowerer { lctx: this };
317 if let ItemKind::Impl(_,_,_,_,ref opt_trait_ref,_,_) = item.node {
318 this.with_trait_impl_ref(opt_trait_ref, |this| {
319 visit::walk_item(this, item)
322 visit::walk_item(this, item);
328 fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
329 self.lctx.with_hir_id_owner(item.id, |lctx| {
330 let id = hir::TraitItemId { node_id: item.id };
331 let hir_item = lctx.lower_trait_item(item);
332 lctx.trait_items.insert(id, hir_item);
335 visit::walk_trait_item(self, item);
338 fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
339 self.lctx.with_hir_id_owner(item.id, |lctx| {
340 let id = hir::ImplItemId { node_id: item.id };
341 let hir_item = lctx.lower_impl_item(item);
342 lctx.impl_items.insert(id, hir_item);
344 visit::walk_impl_item(self, item);
348 self.lower_node_id(CRATE_NODE_ID);
349 debug_assert!(self.node_id_to_hir_id[CRATE_NODE_ID] == hir::CRATE_HIR_ID);
351 visit::walk_crate(&mut MiscCollector { lctx: &mut self }, c);
352 visit::walk_crate(&mut ItemLowerer { lctx: &mut self }, c);
354 let module = self.lower_mod(&c.module);
355 let attrs = self.lower_attrs(&c.attrs);
356 let body_ids = body_ids(&self.bodies);
360 .init_node_id_to_hir_id_mapping(self.node_id_to_hir_id);
366 exported_macros: hir::HirVec::from(self.exported_macros),
368 trait_items: self.trait_items,
369 impl_items: self.impl_items,
372 trait_impls: self.trait_impls,
373 trait_auto_impl: self.trait_auto_impl,
377 fn allocate_hir_id_counter<T: Debug>(&mut self,
380 if self.item_local_id_counters.insert(owner, 0).is_some() {
381 bug!("Tried to allocate item_local_id_counter for {:?} twice", debug);
383 // Always allocate the first HirId for the owner itself
384 self.lower_node_id_with_owner(owner, owner);
387 fn lower_node_id_generic<F>(&mut self,
391 where F: FnOnce(&mut Self) -> hir::HirId
393 if ast_node_id == DUMMY_NODE_ID {
394 return LoweredNodeId {
395 node_id: DUMMY_NODE_ID,
396 hir_id: hir::DUMMY_HIR_ID,
400 let min_size = ast_node_id.as_usize() + 1;
402 if min_size > self.node_id_to_hir_id.len() {
403 self.node_id_to_hir_id.resize(min_size, hir::DUMMY_HIR_ID);
406 let existing_hir_id = self.node_id_to_hir_id[ast_node_id];
408 if existing_hir_id == hir::DUMMY_HIR_ID {
409 // Generate a new HirId
410 let hir_id = alloc_hir_id(self);
411 self.node_id_to_hir_id[ast_node_id] = hir_id;
413 node_id: ast_node_id,
418 node_id: ast_node_id,
419 hir_id: existing_hir_id,
424 fn with_hir_id_owner<F>(&mut self, owner: NodeId, f: F)
425 where F: FnOnce(&mut Self)
427 let counter = self.item_local_id_counters
428 .insert(owner, HIR_ID_COUNTER_LOCKED)
430 let def_index = self.resolver.definitions().opt_def_index(owner).unwrap();
431 self.current_hir_id_owner.push((def_index, counter));
433 let (new_def_index, new_counter) = self.current_hir_id_owner.pop().unwrap();
435 debug_assert!(def_index == new_def_index);
436 debug_assert!(new_counter >= counter);
438 let prev = self.item_local_id_counters.insert(owner, new_counter).unwrap();
439 debug_assert!(prev == HIR_ID_COUNTER_LOCKED);
442 /// This method allocates a new HirId for the given NodeId and stores it in
443 /// the LoweringContext's NodeId => HirId map.
444 /// Take care not to call this method if the resulting HirId is then not
445 /// actually used in the HIR, as that would trigger an assertion in the
446 /// HirIdValidator later on, which makes sure that all NodeIds got mapped
447 /// properly. Calling the method twice with the same NodeId is fine though.
448 fn lower_node_id(&mut self, ast_node_id: NodeId) -> LoweredNodeId {
449 self.lower_node_id_generic(ast_node_id, |this| {
450 let &mut (def_index, ref mut local_id_counter) = this.current_hir_id_owner
453 let local_id = *local_id_counter;
454 *local_id_counter += 1;
457 local_id: hir::ItemLocalId(local_id),
462 fn lower_node_id_with_owner(&mut self,
466 self.lower_node_id_generic(ast_node_id, |this| {
467 let local_id_counter = this.item_local_id_counters
470 let local_id = *local_id_counter;
472 // We want to be sure not to modify the counter in the map while it
473 // is also on the stack. Otherwise we'll get lost updates when writing
474 // back from the stack to the map.
475 debug_assert!(local_id != HIR_ID_COUNTER_LOCKED);
477 *local_id_counter += 1;
478 let def_index = this.resolver.definitions().opt_def_index(owner).unwrap();
482 local_id: hir::ItemLocalId(local_id),
487 fn record_body(&mut self, value: hir::Expr, decl: Option<&FnDecl>)
489 let body = hir::Body {
490 arguments: decl.map_or(hir_vec![], |decl| {
491 decl.inputs.iter().map(|x| self.lower_arg(x)).collect()
493 is_generator: self.is_generator,
497 self.bodies.insert(id, body);
501 fn next_id(&mut self) -> LoweredNodeId {
502 self.lower_node_id(self.sess.next_node_id())
505 fn expect_full_def(&mut self, id: NodeId) -> Def {
506 self.resolver.get_resolution(id).map_or(Def::Err, |pr| {
507 if pr.unresolved_segments() != 0 {
508 bug!("path not fully resolved: {:?}", pr);
514 fn diagnostic(&self) -> &errors::Handler {
515 self.sess.diagnostic()
518 fn str_to_ident(&self, s: &'static str) -> Name {
522 fn allow_internal_unstable(&self, reason: CompilerDesugaringKind, span: Span) -> Span
524 let mark = Mark::fresh(Mark::root());
525 mark.set_expn_info(codemap::ExpnInfo {
527 callee: codemap::NameAndSpan {
528 format: codemap::CompilerDesugaring(reason),
530 allow_internal_unstable: true,
531 allow_internal_unsafe: false,
534 span.with_ctxt(SyntaxContext::empty().apply_mark(mark))
537 // Creates a new hir::GenericParam for every new lifetime and type parameter
538 // encountered while evaluating `f`. Definitions are created with the parent
539 // provided. If no `parent_id` is provided, no definitions will be returned.
540 fn collect_in_band_defs<T, F>(
542 parent_id: Option<DefId>,
544 ) -> (Vec<hir::GenericParam>, T) where F: FnOnce(&mut LoweringContext) -> T
546 assert!(!self.is_collecting_in_band_lifetimes);
547 assert!(self.lifetimes_to_define.is_empty());
548 self.is_collecting_in_band_lifetimes = self.sess.features.borrow().in_band_lifetimes;
550 assert!(self.in_band_ty_params.is_empty());
554 self.is_collecting_in_band_lifetimes = false;
556 let in_band_ty_params = self.in_band_ty_params.split_off(0);
557 let lifetimes_to_define = self.lifetimes_to_define.split_off(0);
559 let mut params = match parent_id {
560 Some(parent_id) => lifetimes_to_define.into_iter().map(|(span, name)| {
561 let def_node_id = self.next_id().node_id;
563 // Add a definition for the in-band lifetime def
564 self.resolver.definitions().create_def_with_parent(
567 DefPathData::LifetimeDef(name.as_str()),
568 DefIndexAddressSpace::High,
572 hir::GenericParam::Lifetime(hir::LifetimeDef {
573 lifetime: hir::Lifetime {
576 name: hir::LifetimeName::Name(name),
578 bounds: Vec::new().into(),
579 pure_wrt_drop: false,
586 params.extend(in_band_ty_params.into_iter().map(|tp| hir::GenericParam::Type(tp)));
591 // Evaluates `f` with the lifetimes in `lt_defs` in-scope.
592 // This is used to track which lifetimes have already been defined, and
593 // which are new in-band lifetimes that need to have a definition created
595 fn with_in_scope_lifetime_defs<T, F>(
597 lt_defs: &[LifetimeDef],
599 ) -> T where F: FnOnce(&mut LoweringContext) -> T
601 let old_len = self.in_scope_lifetimes.len();
602 let lt_def_names = lt_defs.iter().map(|lt_def| lt_def.lifetime.ident.name);
603 self.in_scope_lifetimes.extend(lt_def_names);
607 self.in_scope_lifetimes.truncate(old_len);
611 // Same as the method above, but accepts `hir::LifetimeDef`s
612 // instead of `ast::LifetimeDef`s.
613 // This should only be used with generics that have already had their
614 // in-band lifetimes added. In practice, this means that this function is
615 // only used when lowering a child item of a trait or impl.
616 fn with_parent_impl_lifetime_defs<T, F>(
618 lt_defs: &[hir::LifetimeDef],
620 ) -> T where F: FnOnce(&mut LoweringContext) -> T
622 let old_len = self.in_scope_lifetimes.len();
623 let lt_def_names = lt_defs.iter().map(|lt_def| lt_def.lifetime.name.name());
624 self.in_scope_lifetimes.extend(lt_def_names);
628 self.in_scope_lifetimes.truncate(old_len);
632 // Appends in-band lifetime defs and argument-position `impl Trait` defs
633 // to the existing set of generics.
634 fn add_in_band_defs<F, T>(
637 parent_id: Option<DefId>,
639 ) -> (hir::Generics, T)
640 where F: FnOnce(&mut LoweringContext) -> T
642 let (in_band_defs, (mut lowered_generics, res)) =
643 self.with_in_scope_lifetime_defs(
646 .filter_map(|p| match *p {
647 GenericParam::Lifetime(ref ld) => Some(ld.clone()),
650 .collect::<Vec<_>>(),
652 this.collect_in_band_defs(parent_id, |this| {
653 (this.lower_generics(generics), f(this))
658 lowered_generics.params =
659 lowered_generics.params.iter().cloned().chain(in_band_defs).collect();
661 (lowered_generics, res)
664 fn with_catch_scope<T, F>(&mut self, catch_id: NodeId, f: F) -> T
665 where F: FnOnce(&mut LoweringContext) -> T
667 let len = self.catch_scopes.len();
668 self.catch_scopes.push(catch_id);
670 let result = f(self);
671 assert_eq!(len + 1, self.catch_scopes.len(),
672 "catch scopes should be added and removed in stack order");
674 self.catch_scopes.pop().unwrap();
679 fn lower_body<F>(&mut self, decl: Option<&FnDecl>, f: F) -> hir::BodyId
680 where F: FnOnce(&mut LoweringContext) -> hir::Expr
682 let prev = mem::replace(&mut self.is_generator, false);
683 let result = f(self);
684 let r = self.record_body(result, decl);
685 self.is_generator = prev;
689 fn with_loop_scope<T, F>(&mut self, loop_id: NodeId, f: F) -> T
690 where F: FnOnce(&mut LoweringContext) -> T
692 // We're no longer in the base loop's condition; we're in another loop.
693 let was_in_loop_condition = self.is_in_loop_condition;
694 self.is_in_loop_condition = false;
696 let len = self.loop_scopes.len();
697 self.loop_scopes.push(loop_id);
699 let result = f(self);
700 assert_eq!(len + 1, self.loop_scopes.len(),
701 "Loop scopes should be added and removed in stack order");
703 self.loop_scopes.pop().unwrap();
705 self.is_in_loop_condition = was_in_loop_condition;
710 fn with_loop_condition_scope<T, F>(&mut self, f: F) -> T
711 where F: FnOnce(&mut LoweringContext) -> T
713 let was_in_loop_condition = self.is_in_loop_condition;
714 self.is_in_loop_condition = true;
716 let result = f(self);
718 self.is_in_loop_condition = was_in_loop_condition;
723 fn with_new_scopes<T, F>(&mut self, f: F) -> T
724 where F: FnOnce(&mut LoweringContext) -> T
726 let was_in_loop_condition = self.is_in_loop_condition;
727 self.is_in_loop_condition = false;
729 let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new());
730 let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new());
731 let result = f(self);
732 self.catch_scopes = catch_scopes;
733 self.loop_scopes = loop_scopes;
735 self.is_in_loop_condition = was_in_loop_condition;
740 fn with_parent_def<T, F>(&mut self, parent_id: NodeId, f: F) -> T
741 where F: FnOnce(&mut LoweringContext) -> T
743 let old_def = self.parent_def;
745 let defs = self.resolver.definitions();
746 Some(defs.opt_def_index(parent_id).unwrap())
749 let result = f(self);
751 self.parent_def = old_def;
755 fn def_key(&mut self, id: DefId) -> DefKey {
757 self.resolver.definitions().def_key(id.index)
759 self.cstore.def_key(id)
763 fn lower_ident(&mut self, ident: Ident) -> Name {
764 let ident = ident.modern();
765 if ident.ctxt == SyntaxContext::empty() {
768 *self.name_map.entry(ident).or_insert_with(|| Symbol::from_ident(ident))
771 fn lower_opt_sp_ident(&mut self, o_id: Option<Spanned<Ident>>) -> Option<Spanned<Name>> {
772 o_id.map(|sp_ident| respan(sp_ident.span, sp_ident.node.name))
775 fn lower_loop_destination(&mut self, destination: Option<(NodeId, Spanned<Ident>)>)
779 Some((id, label_ident)) => {
780 let target = if let Def::Label(loop_id) = self.expect_full_def(id) {
781 hir::LoopIdResult::Ok(self.lower_node_id(loop_id).node_id)
783 hir::LoopIdResult::Err(hir::LoopIdError::UnresolvedLabel)
786 ident: Some(label_ident),
787 target_id: hir::ScopeTarget::Loop(target),
791 let loop_id = self.loop_scopes
793 .map(|innermost_loop_id| *innermost_loop_id);
797 target_id: hir::ScopeTarget::Loop(
798 loop_id.map(|id| Ok(self.lower_node_id(id).node_id))
799 .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
806 fn lower_attrs(&mut self, attrs: &Vec<Attribute>) -> hir::HirVec<Attribute> {
807 attrs.iter().map(|a| self.lower_attr(a)).collect::<Vec<_>>().into()
810 fn lower_attr(&mut self, attr: &Attribute) -> Attribute {
814 path: attr.path.clone(),
815 tokens: self.lower_token_stream(attr.tokens.clone()),
816 is_sugared_doc: attr.is_sugared_doc,
821 fn lower_token_stream(&mut self, tokens: TokenStream) -> TokenStream {
823 .flat_map(|tree| self.lower_token_tree(tree).into_trees())
827 fn lower_token_tree(&mut self, tree: TokenTree) -> TokenStream {
829 TokenTree::Token(span, token) => {
830 self.lower_token(token, span)
832 TokenTree::Delimited(span, delimited) => {
833 TokenTree::Delimited(span, Delimited {
834 delim: delimited.delim,
835 tts: self.lower_token_stream(delimited.tts.into()).into(),
841 fn lower_token(&mut self, token: Token, span: Span) -> TokenStream {
843 Token::Interpolated(_) => {}
844 other => return TokenTree::Token(span, other).into(),
847 let tts = token.interpolated_to_tokenstream(&self.sess.parse_sess, span);
848 self.lower_token_stream(tts)
851 fn lower_arm(&mut self, arm: &Arm) -> hir::Arm {
853 attrs: self.lower_attrs(&arm.attrs),
854 pats: arm.pats.iter().map(|x| self.lower_pat(x)).collect(),
855 guard: arm.guard.as_ref().map(|ref x| P(self.lower_expr(x))),
856 body: P(self.lower_expr(&arm.body)),
860 fn lower_ty_binding(&mut self, b: &TypeBinding, itctx: ImplTraitContext) -> hir::TypeBinding {
862 id: self.lower_node_id(b.id).node_id,
863 name: self.lower_ident(b.ident),
864 ty: self.lower_ty(&b.ty, itctx),
869 fn lower_ty(&mut self, t: &Ty, itctx: ImplTraitContext) -> P<hir::Ty> {
870 let kind = match t.node {
871 TyKind::Infer => hir::TyInfer,
872 TyKind::Err => hir::TyErr,
873 TyKind::Slice(ref ty) => hir::TySlice(self.lower_ty(ty, itctx)),
874 TyKind::Ptr(ref mt) => hir::TyPtr(self.lower_mt(mt, itctx)),
875 TyKind::Rptr(ref region, ref mt) => {
876 let span = t.span.with_hi(t.span.lo());
877 let lifetime = match *region {
878 Some(ref lt) => self.lower_lifetime(lt),
879 None => self.elided_lifetime(span)
881 hir::TyRptr(lifetime, self.lower_mt(mt, itctx))
883 TyKind::BareFn(ref f) => {
884 self.with_in_scope_lifetime_defs(
887 .filter_map(|p| match *p {
888 GenericParam::Lifetime(ref ld) => Some(ld.clone()),
891 .collect::<Vec<_>>(),
892 |this| hir::TyBareFn(P(hir::BareFnTy {
893 generic_params: this.lower_generic_params(&f.generic_params, &NodeMap()),
894 unsafety: this.lower_unsafety(f.unsafety),
896 decl: this.lower_fn_decl(&f.decl, None, false),
897 arg_names: this.lower_fn_args_to_names(&f.decl),
900 TyKind::Never => hir::TyNever,
901 TyKind::Tup(ref tys) => {
902 hir::TyTup(tys.iter().map(|ty| self.lower_ty(ty, itctx)).collect())
904 TyKind::Paren(ref ty) => {
905 return self.lower_ty(ty, itctx);
907 TyKind::Path(ref qself, ref path) => {
908 let id = self.lower_node_id(t.id);
909 let qpath = self.lower_qpath(t.id, qself, path, ParamMode::Explicit, itctx);
910 return self.ty_path(id, t.span, qpath);
912 TyKind::ImplicitSelf => {
913 hir::TyPath(hir::QPath::Resolved(None, P(hir::Path {
914 def: self.expect_full_def(t.id),
916 hir::PathSegment::from_name(keywords::SelfType.name())
921 TyKind::Array(ref ty, ref length) => {
922 let length = self.lower_body(None, |this| this.lower_expr(length));
923 hir::TyArray(self.lower_ty(ty, itctx), length)
925 TyKind::Typeof(ref expr) => {
926 let expr = self.lower_body(None, |this| this.lower_expr(expr));
929 TyKind::TraitObject(ref bounds, ..) => {
930 let mut lifetime_bound = None;
931 let bounds = bounds.iter().filter_map(|bound| {
933 TraitTyParamBound(ref ty, TraitBoundModifier::None) => {
934 Some(self.lower_poly_trait_ref(ty, itctx))
936 TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
937 RegionTyParamBound(ref lifetime) => {
938 if lifetime_bound.is_none() {
939 lifetime_bound = Some(self.lower_lifetime(lifetime));
945 let lifetime_bound = lifetime_bound.unwrap_or_else(|| {
946 self.elided_lifetime(t.span)
948 hir::TyTraitObject(bounds, lifetime_bound)
950 TyKind::ImplTrait(ref bounds) => {
951 use syntax::feature_gate::{emit_feature_err, GateIssue};
954 ImplTraitContext::Existential => {
955 let has_feature = self.sess.features.borrow().conservative_impl_trait;
956 if !t.span.allows_unstable() && !has_feature {
957 emit_feature_err(&self.sess.parse_sess, "conservative_impl_trait",
958 t.span, GateIssue::Language,
959 "`impl Trait` in return position is experimental");
961 let def_index = self.resolver.definitions().opt_def_index(t.id).unwrap();
962 let hir_bounds = self.lower_bounds(bounds, itctx);
963 let (lifetimes, lifetime_defs) =
964 self.lifetimes_from_impl_trait_bounds(def_index, &hir_bounds);
966 hir::TyImplTraitExistential(hir::ExistTy {
967 generics: hir::Generics {
968 params: lifetime_defs,
969 where_clause: hir::WhereClause {
970 id: self.next_id().node_id,
971 predicates: Vec::new().into(),
978 ImplTraitContext::Universal(def_id) => {
979 let has_feature = self.sess.features.borrow().universal_impl_trait;
980 if !t.span.allows_unstable() && !has_feature {
981 emit_feature_err(&self.sess.parse_sess, "universal_impl_trait",
982 t.span, GateIssue::Language,
983 "`impl Trait` in argument position is experimental");
986 let def_node_id = self.next_id().node_id;
988 // Add a definition for the in-band TyParam
989 let def_index = self.resolver.definitions().create_def_with_parent(
992 DefPathData::ImplTrait,
993 DefIndexAddressSpace::High,
997 let hir_bounds = self.lower_bounds(bounds, itctx);
998 // Set the name to `impl Bound1 + Bound2`
999 let name = Symbol::intern(&pprust::ty_to_string(t));
1000 self.in_band_ty_params.push(hir::TyParam {
1006 pure_wrt_drop: false,
1007 synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
1010 hir::TyPath(hir::QPath::Resolved(None, P(hir::Path {
1012 def: Def::TyParam(DefId::local(def_index)),
1013 segments: hir_vec![hir::PathSegment::from_name(name)],
1016 ImplTraitContext::Disallowed => {
1017 span_err!(self.sess, t.span, E0562,
1018 "`impl Trait` not allowed outside of function \
1019 and inherent method return types");
1024 TyKind::Mac(_) => panic!("TyMac should have been expanded by now."),
1027 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(t.id);
1036 fn lifetimes_from_impl_trait_bounds(
1038 parent_index: DefIndex,
1039 bounds: &hir::TyParamBounds
1040 ) -> (HirVec<hir::Lifetime>, HirVec<hir::GenericParam>) {
1042 // This visitor walks over impl trait bounds and creates defs for all lifetimes which
1043 // appear in the bounds, excluding lifetimes that are created within the bounds.
1044 // e.g. 'a, 'b, but not 'c in `impl for<'c> SomeTrait<'a, 'b, 'c>`
1045 struct ImplTraitLifetimeCollector<'r, 'a: 'r> {
1046 context: &'r mut LoweringContext<'a>,
1048 collect_elided_lifetimes: bool,
1049 currently_bound_lifetimes: Vec<hir::LifetimeName>,
1050 already_defined_lifetimes: HashSet<hir::LifetimeName>,
1051 output_lifetimes: Vec<hir::Lifetime>,
1052 output_lifetime_params: Vec<hir::GenericParam>,
1055 impl<'r, 'a: 'r, 'v> hir::intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r, 'a> {
1056 fn nested_visit_map<'this>(&'this mut self)
1057 -> hir::intravisit::NestedVisitorMap<'this, 'v> {
1058 hir::intravisit::NestedVisitorMap::None
1061 fn visit_path_parameters(&mut self, span: Span, parameters: &'v hir::PathParameters) {
1062 // Don't collect elided lifetimes used inside of `Fn()` syntax.
1063 if parameters.parenthesized {
1064 let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
1065 self.collect_elided_lifetimes = false;
1066 hir::intravisit::walk_path_parameters(self, span, parameters);
1067 self.collect_elided_lifetimes = old_collect_elided_lifetimes;
1069 hir::intravisit::walk_path_parameters(self, span, parameters);
1073 fn visit_ty(&mut self, t: &'v hir::Ty) {
1074 // Don't collect elided lifetimes used inside of `fn()` syntax
1075 if let &hir::Ty_::TyBareFn(_) = &t.node {
1076 let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
1077 self.collect_elided_lifetimes = false;
1078 hir::intravisit::walk_ty(self, t);
1079 self.collect_elided_lifetimes = old_collect_elided_lifetimes;
1081 hir::intravisit::walk_ty(self, t);
1085 fn visit_poly_trait_ref(&mut self,
1086 polytr: &'v hir::PolyTraitRef,
1087 _: hir::TraitBoundModifier) {
1088 let old_len = self.currently_bound_lifetimes.len();
1090 // Record the introduction of 'a in `for<'a> ...`
1091 for param in &polytr.bound_generic_params {
1092 if let hir::GenericParam::Lifetime(ref lt_def) = *param {
1093 // Introduce lifetimes one at a time so that we can handle
1094 // cases like `fn foo<'d>() -> impl for<'a, 'b: 'a, 'c: 'b + 'd>`
1095 self.currently_bound_lifetimes.push(lt_def.lifetime.name);
1097 // Visit the lifetime bounds
1098 for lt_bound in <_def.bounds {
1099 self.visit_lifetime(<_bound);
1104 hir::intravisit::walk_trait_ref(self, &polytr.trait_ref);
1106 self.currently_bound_lifetimes.truncate(old_len);
1109 fn visit_lifetime(&mut self, lifetime: &'v hir::Lifetime) {
1110 let name = match lifetime.name {
1111 hir::LifetimeName::Implicit |
1112 hir::LifetimeName::Underscore =>
1113 if self.collect_elided_lifetimes {
1114 // Use `'_` for both implicit and underscore lifetimes in
1115 // `abstract type Foo<'_>: SomeTrait<'_>;`
1116 hir::LifetimeName::Underscore
1120 name @ hir::LifetimeName::Name(_) => name,
1121 hir::LifetimeName::Static => return,
1124 if !self.currently_bound_lifetimes.contains(&name) &&
1125 !self.already_defined_lifetimes.contains(&name)
1127 self.already_defined_lifetimes.insert(name);
1129 self.output_lifetimes.push(hir::Lifetime {
1130 id: self.context.next_id().node_id,
1131 span: lifetime.span,
1135 let def_node_id = self.context.next_id().node_id;
1136 self.context.resolver.definitions().create_def_with_parent(
1139 DefPathData::LifetimeDef(name.name().as_str()),
1140 DefIndexAddressSpace::High,
1143 let def_lifetime = hir::Lifetime {
1145 span: lifetime.span,
1148 self.output_lifetime_params.push(hir::GenericParam::Lifetime(hir::LifetimeDef {
1149 lifetime: def_lifetime,
1150 bounds: Vec::new().into(),
1151 pure_wrt_drop: false,
1158 let mut lifetime_collector = ImplTraitLifetimeCollector {
1160 parent: parent_index,
1161 collect_elided_lifetimes: true,
1162 currently_bound_lifetimes: Vec::new(),
1163 already_defined_lifetimes: HashSet::new(),
1164 output_lifetimes: Vec::new(),
1165 output_lifetime_params: Vec::new(),
1168 for bound in bounds {
1169 hir::intravisit::walk_ty_param_bound(&mut lifetime_collector, &bound);
1173 lifetime_collector.output_lifetimes.into(),
1174 lifetime_collector.output_lifetime_params.into()
1178 fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod {
1181 items: fm.items.iter().map(|x| self.lower_foreign_item(x)).collect(),
1185 fn lower_global_asm(&mut self, ga: &GlobalAsm) -> P<hir::GlobalAsm> {
1192 fn lower_variant(&mut self, v: &Variant) -> hir::Variant {
1194 node: hir::Variant_ {
1195 name: v.node.name.name,
1196 attrs: self.lower_attrs(&v.node.attrs),
1197 data: self.lower_variant_data(&v.node.data),
1198 disr_expr: v.node.disr_expr.as_ref().map(|e| {
1199 self.lower_body(None, |this| this.lower_expr(e))
1206 fn lower_qpath(&mut self,
1208 qself: &Option<QSelf>,
1210 param_mode: ParamMode,
1211 itctx: ImplTraitContext)
1213 let qself_position = qself.as_ref().map(|q| q.position);
1214 let qself = qself.as_ref().map(|q| self.lower_ty(&q.ty, itctx));
1216 let resolution = self.resolver.get_resolution(id)
1217 .unwrap_or(PathResolution::new(Def::Err));
1219 let proj_start = p.segments.len() - resolution.unresolved_segments();
1220 let path = P(hir::Path {
1221 def: resolution.base_def(),
1222 segments: p.segments[..proj_start].iter().enumerate().map(|(i, segment)| {
1223 let param_mode = match (qself_position, param_mode) {
1224 (Some(j), ParamMode::Optional) if i < j => {
1225 // This segment is part of the trait path in a
1226 // qualified path - one of `a`, `b` or `Trait`
1227 // in `<X as a::b::Trait>::T::U::method`.
1233 // Figure out if this is a type/trait segment,
1234 // which may need lifetime elision performed.
1235 let parent_def_id = |this: &mut Self, def_id: DefId| {
1237 krate: def_id.krate,
1238 index: this.def_key(def_id).parent.expect("missing parent")
1241 let type_def_id = match resolution.base_def() {
1242 Def::AssociatedTy(def_id) if i + 2 == proj_start => {
1243 Some(parent_def_id(self, def_id))
1245 Def::Variant(def_id) if i + 1 == proj_start => {
1246 Some(parent_def_id(self, def_id))
1248 Def::Struct(def_id) |
1249 Def::Union(def_id) |
1251 Def::TyAlias(def_id) |
1252 Def::Trait(def_id) if i + 1 == proj_start => Some(def_id),
1255 let parenthesized_generic_args = match resolution.base_def() {
1256 // `a::b::Trait(Args)`
1257 Def::Trait(..) if i + 1 == proj_start => ParenthesizedGenericArgs::Ok,
1258 // `a::b::Trait(Args)::TraitItem`
1260 Def::AssociatedConst(..) |
1261 Def::AssociatedTy(..) if i + 2 == proj_start => ParenthesizedGenericArgs::Ok,
1262 // Avoid duplicated errors
1263 Def::Err => ParenthesizedGenericArgs::Ok,
1265 Def::Struct(..) | Def::Enum(..) | Def::Union(..) | Def::TyAlias(..) |
1266 Def::Variant(..) if i + 1 == proj_start => ParenthesizedGenericArgs::Err,
1267 // A warning for now, for compatibility reasons
1268 _ => ParenthesizedGenericArgs::Warn,
1271 let num_lifetimes = type_def_id.map_or(0, |def_id| {
1272 if let Some(&n) = self.type_def_lifetime_params.get(&def_id) {
1275 assert!(!def_id.is_local());
1277 .item_generics_cloned_untracked(def_id, self.sess)
1280 self.type_def_lifetime_params.insert(def_id, n);
1283 self.lower_path_segment(p.span, segment, param_mode, num_lifetimes,
1284 parenthesized_generic_args, itctx)
1289 // Simple case, either no projections, or only fully-qualified.
1290 // E.g. `std::mem::size_of` or `<I as Iterator>::Item`.
1291 if resolution.unresolved_segments() == 0 {
1292 return hir::QPath::Resolved(qself, path);
1295 // Create the innermost type that we're projecting from.
1296 let mut ty = if path.segments.is_empty() {
1297 // If the base path is empty that means there exists a
1298 // syntactical `Self`, e.g. `&i32` in `<&i32>::clone`.
1299 qself.expect("missing QSelf for <T>::...")
1301 // Otherwise, the base path is an implicit `Self` type path,
1302 // e.g. `Vec` in `Vec::new` or `<I as Iterator>::Item` in
1303 // `<I as Iterator>::Item::default`.
1304 let new_id = self.next_id();
1305 self.ty_path(new_id, p.span, hir::QPath::Resolved(qself, path))
1308 // Anything after the base path are associated "extensions",
1309 // out of which all but the last one are associated types,
1310 // e.g. for `std::vec::Vec::<T>::IntoIter::Item::clone`:
1311 // * base path is `std::vec::Vec<T>`
1312 // * "extensions" are `IntoIter`, `Item` and `clone`
1313 // * type nodes are:
1314 // 1. `std::vec::Vec<T>` (created above)
1315 // 2. `<std::vec::Vec<T>>::IntoIter`
1316 // 3. `<<std::vec::Vec<T>>::IntoIter>::Item`
1317 // * final path is `<<<std::vec::Vec<T>>::IntoIter>::Item>::clone`
1318 for (i, segment) in p.segments.iter().enumerate().skip(proj_start) {
1319 let segment = P(self.lower_path_segment(p.span, segment, param_mode, 0,
1320 ParenthesizedGenericArgs::Warn,
1322 let qpath = hir::QPath::TypeRelative(ty, segment);
1324 // It's finished, return the extension of the right node type.
1325 if i == p.segments.len() - 1 {
1329 // Wrap the associated extension in another type node.
1330 let new_id = self.next_id();
1331 ty = self.ty_path(new_id, p.span, qpath);
1334 // Should've returned in the for loop above.
1335 span_bug!(p.span, "lower_qpath: no final extension segment in {}..{}",
1336 proj_start, p.segments.len())
1339 fn lower_path_extra(&mut self,
1343 param_mode: ParamMode,
1344 defaults_to_global: bool)
1346 let mut segments = p.segments.iter();
1347 if defaults_to_global && p.is_global() {
1352 def: self.expect_full_def(id),
1353 segments: segments.map(|segment| {
1354 self.lower_path_segment(p.span, segment, param_mode, 0,
1355 ParenthesizedGenericArgs::Err,
1356 ImplTraitContext::Disallowed)
1357 }).chain(name.map(|name| hir::PathSegment::from_name(name)))
1363 fn lower_path(&mut self,
1366 param_mode: ParamMode,
1367 defaults_to_global: bool)
1369 self.lower_path_extra(id, p, None, param_mode, defaults_to_global)
1372 fn lower_path_segment(&mut self,
1374 segment: &PathSegment,
1375 param_mode: ParamMode,
1376 expected_lifetimes: usize,
1377 parenthesized_generic_args: ParenthesizedGenericArgs,
1378 itctx: ImplTraitContext)
1379 -> hir::PathSegment {
1380 let (mut parameters, infer_types) = if let Some(ref parameters) = segment.parameters {
1381 let msg = "parenthesized parameters may only be used with a trait";
1382 match **parameters {
1383 PathParameters::AngleBracketed(ref data) => {
1384 self.lower_angle_bracketed_parameter_data(data, param_mode, itctx)
1386 PathParameters::Parenthesized(ref data) => match parenthesized_generic_args {
1387 ParenthesizedGenericArgs::Ok =>
1388 self.lower_parenthesized_parameter_data(data),
1389 ParenthesizedGenericArgs::Warn => {
1390 self.sess.buffer_lint(PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
1391 CRATE_NODE_ID, data.span, msg.into());
1392 (hir::PathParameters::none(), true)
1394 ParenthesizedGenericArgs::Err => {
1395 struct_span_err!(self.sess, data.span, E0214, "{}", msg)
1396 .span_label(data.span, "only traits may use parentheses").emit();
1397 (hir::PathParameters::none(), true)
1402 self.lower_angle_bracketed_parameter_data(&Default::default(), param_mode, itctx)
1405 if !parameters.parenthesized && parameters.lifetimes.is_empty() {
1406 parameters.lifetimes = (0..expected_lifetimes).map(|_| {
1407 self.elided_lifetime(path_span)
1411 hir::PathSegment::new(
1412 self.lower_ident(segment.identifier),
1418 fn lower_angle_bracketed_parameter_data(&mut self,
1419 data: &AngleBracketedParameterData,
1420 param_mode: ParamMode,
1421 itctx: ImplTraitContext)
1422 -> (hir::PathParameters, bool) {
1423 let &AngleBracketedParameterData { ref lifetimes, ref types, ref bindings, .. } = data;
1424 (hir::PathParameters {
1425 lifetimes: self.lower_lifetimes(lifetimes),
1426 types: types.iter().map(|ty| self.lower_ty(ty, itctx)).collect(),
1427 bindings: bindings.iter().map(|b| self.lower_ty_binding(b, itctx)).collect(),
1428 parenthesized: false,
1429 }, types.is_empty() && param_mode == ParamMode::Optional)
1432 fn lower_parenthesized_parameter_data(&mut self,
1433 data: &ParenthesizedParameterData)
1434 -> (hir::PathParameters, bool) {
1435 const DISALLOWED: ImplTraitContext = ImplTraitContext::Disallowed;
1436 let &ParenthesizedParameterData { ref inputs, ref output, span } = data;
1437 let inputs = inputs.iter().map(|ty| self.lower_ty(ty, DISALLOWED)).collect();
1438 let mk_tup = |this: &mut Self, tys, span| {
1439 let LoweredNodeId { node_id, hir_id } = this.next_id();
1440 P(hir::Ty { node: hir::TyTup(tys), id: node_id, hir_id, span })
1443 (hir::PathParameters {
1444 lifetimes: hir::HirVec::new(),
1445 types: hir_vec![mk_tup(self, inputs, span)],
1446 bindings: hir_vec![hir::TypeBinding {
1447 id: self.next_id().node_id,
1448 name: Symbol::intern(FN_OUTPUT_NAME),
1449 ty: output.as_ref().map(|ty| self.lower_ty(&ty, DISALLOWED))
1450 .unwrap_or_else(|| mk_tup(self, hir::HirVec::new(), span)),
1451 span: output.as_ref().map_or(span, |ty| ty.span),
1453 parenthesized: true,
1457 fn lower_local(&mut self, l: &Local) -> P<hir::Local> {
1458 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(l.id);
1462 ty: l.ty.as_ref().map(|t| self.lower_ty(t, ImplTraitContext::Disallowed)),
1463 pat: self.lower_pat(&l.pat),
1464 init: l.init.as_ref().map(|e| P(self.lower_expr(e))),
1466 attrs: l.attrs.clone(),
1467 source: hir::LocalSource::Normal,
1471 fn lower_mutability(&mut self, m: Mutability) -> hir::Mutability {
1473 Mutability::Mutable => hir::MutMutable,
1474 Mutability::Immutable => hir::MutImmutable,
1478 fn lower_arg(&mut self, arg: &Arg) -> hir::Arg {
1479 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(arg.id);
1483 pat: self.lower_pat(&arg.pat),
1487 fn lower_fn_args_to_names(&mut self, decl: &FnDecl)
1488 -> hir::HirVec<Spanned<Name>> {
1489 decl.inputs.iter().map(|arg| {
1490 match arg.pat.node {
1491 PatKind::Ident(_, ident, None) => {
1492 respan(ident.span, ident.node.name)
1494 _ => respan(arg.pat.span, keywords::Invalid.name()),
1500 fn lower_fn_decl(&mut self,
1502 fn_def_id: Option<DefId>,
1503 impl_trait_return_allow: bool)
1505 // NOTE: The two last paramters here have to do with impl Trait. If fn_def_id is Some,
1506 // then impl Trait arguments are lowered into generic paramters on the given
1507 // fn_def_id, otherwise impl Trait is disallowed. (for now)
1509 // Furthermore, if impl_trait_return_allow is true, then impl Trait may be used in
1510 // return positions as well. This guards against trait declarations and their impls
1511 // where impl Trait is disallowed. (again for now)
1513 inputs: decl.inputs.iter()
1514 .map(|arg| if let Some(def_id) = fn_def_id {
1515 self.lower_ty(&arg.ty, ImplTraitContext::Universal(def_id))
1517 self.lower_ty(&arg.ty, ImplTraitContext::Disallowed)
1519 output: match decl.output {
1520 FunctionRetTy::Ty(ref ty) => match fn_def_id {
1521 Some(_) if impl_trait_return_allow =>
1522 hir::Return(self.lower_ty(ty, ImplTraitContext::Existential)),
1523 _ => hir::Return(self.lower_ty(ty, ImplTraitContext::Disallowed)),
1525 FunctionRetTy::Default(span) => hir::DefaultReturn(span),
1527 variadic: decl.variadic,
1528 has_implicit_self: decl.inputs.get(0).map_or(false, |arg| {
1530 TyKind::ImplicitSelf => true,
1531 TyKind::Rptr(_, ref mt) => mt.ty.node == TyKind::ImplicitSelf,
1538 fn lower_ty_param_bound(&mut self, tpb: &TyParamBound, itctx: ImplTraitContext)
1539 -> hir::TyParamBound {
1541 TraitTyParamBound(ref ty, modifier) => {
1542 hir::TraitTyParamBound(self.lower_poly_trait_ref(ty, itctx),
1543 self.lower_trait_bound_modifier(modifier))
1545 RegionTyParamBound(ref lifetime) => {
1546 hir::RegionTyParamBound(self.lower_lifetime(lifetime))
1551 fn lower_ty_param(&mut self, tp: &TyParam, add_bounds: &[TyParamBound]) -> hir::TyParam {
1552 let mut name = self.lower_ident(tp.ident);
1554 // Don't expose `Self` (recovered "keyword used as ident" parse error).
1555 // `rustc::ty` expects `Self` to be only used for a trait's `Self`.
1556 // Instead, use gensym("Self") to create a distinct name that looks the same.
1557 if name == keywords::SelfType.name() {
1558 name = Symbol::gensym("Self");
1561 let itctx = ImplTraitContext::Universal(self.resolver.definitions().local_def_id(tp.id));
1562 let mut bounds = self.lower_bounds(&tp.bounds, itctx);
1563 if !add_bounds.is_empty() {
1564 bounds = bounds.into_iter().chain(
1565 self.lower_bounds(add_bounds, itctx).into_iter()
1570 id: self.lower_node_id(tp.id).node_id,
1573 default: tp.default.as_ref().map(|x| self.lower_ty(x, ImplTraitContext::Disallowed)),
1575 pure_wrt_drop: attr::contains_name(&tp.attrs, "may_dangle"),
1576 synthetic: tp.attrs.iter()
1577 .filter(|attr| attr.check_name("rustc_synthetic"))
1578 .map(|_| hir::SyntheticTyParamKind::ImplTrait)
1583 fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime {
1584 let name = match self.lower_ident(l.ident) {
1585 x if x == "'_" => hir::LifetimeName::Underscore,
1586 x if x == "'static" => hir::LifetimeName::Static,
1588 if self.is_collecting_in_band_lifetimes &&
1589 !self.in_scope_lifetimes.contains(&name) &&
1590 self.lifetimes_to_define.iter()
1591 .find(|&&(_, lt_name)| lt_name == name)
1594 self.lifetimes_to_define.push((l.span, name));
1597 hir::LifetimeName::Name(name)
1602 id: self.lower_node_id(l.id).node_id,
1608 fn lower_lifetime_def(&mut self, l: &LifetimeDef) -> hir::LifetimeDef {
1609 let was_collecting_in_band = self.is_collecting_in_band_lifetimes;
1610 self.is_collecting_in_band_lifetimes = false;
1612 let def = hir::LifetimeDef {
1613 lifetime: self.lower_lifetime(&l.lifetime),
1614 bounds: self.lower_lifetimes(&l.bounds),
1615 pure_wrt_drop: attr::contains_name(&l.attrs, "may_dangle"),
1619 self.is_collecting_in_band_lifetimes = was_collecting_in_band;
1624 fn lower_lifetimes(&mut self, lts: &Vec<Lifetime>) -> hir::HirVec<hir::Lifetime> {
1625 lts.iter().map(|l| self.lower_lifetime(l)).collect()
1628 fn lower_generic_params(
1630 params: &Vec<GenericParam>,
1631 add_bounds: &NodeMap<Vec<TyParamBound>>,
1632 ) -> hir::HirVec<hir::GenericParam> {
1634 .map(|param| match *param {
1635 GenericParam::Lifetime(ref lifetime_def) => {
1636 hir::GenericParam::Lifetime(self.lower_lifetime_def(lifetime_def))
1638 GenericParam::Type(ref ty_param) => {
1639 hir::GenericParam::Type(self.lower_ty_param(
1641 add_bounds.get(&ty_param.id).map_or(&[][..], |x| &x)
1648 fn lower_generics(&mut self, g: &Generics) -> hir::Generics {
1649 // Collect `?Trait` bounds in where clause and move them to parameter definitions.
1650 // FIXME: This could probably be done with less rightward drift. Also looks like two control
1651 // paths where report_error is called are also the only paths that advance to after
1652 // the match statement, so the error reporting could probably just be moved there.
1653 let mut add_bounds = NodeMap();
1654 for pred in &g.where_clause.predicates {
1655 if let WherePredicate::BoundPredicate(ref bound_pred) = *pred {
1656 'next_bound: for bound in &bound_pred.bounds {
1657 if let TraitTyParamBound(_, TraitBoundModifier::Maybe) = *bound {
1658 let report_error = |this: &mut Self| {
1659 this.diagnostic().span_err(bound_pred.bounded_ty.span,
1660 "`?Trait` bounds are only permitted at the \
1661 point where a type parameter is declared");
1663 // Check if the where clause type is a plain type parameter.
1664 match bound_pred.bounded_ty.node {
1665 TyKind::Path(None, ref path)
1666 if path.segments.len() == 1 &&
1667 bound_pred.bound_generic_params.is_empty() => {
1668 if let Some(Def::TyParam(def_id)) =
1669 self.resolver.get_resolution(bound_pred.bounded_ty.id)
1670 .map(|d| d.base_def()) {
1671 if let Some(node_id) =
1672 self.resolver.definitions().as_local_node_id(def_id) {
1673 for param in &g.params {
1674 if let GenericParam::Type(ref ty_param) = *param {
1675 if node_id == ty_param.id {
1676 add_bounds.entry(ty_param.id)
1677 .or_insert(Vec::new())
1678 .push(bound.clone());
1679 continue 'next_bound;
1687 _ => report_error(self)
1695 params: self.lower_generic_params(&g.params, &add_bounds),
1696 where_clause: self.lower_where_clause(&g.where_clause),
1701 fn lower_where_clause(&mut self, wc: &WhereClause) -> hir::WhereClause {
1703 id: self.lower_node_id(wc.id).node_id,
1704 predicates: wc.predicates
1706 .map(|predicate| self.lower_where_predicate(predicate))
1711 fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate {
1713 WherePredicate::BoundPredicate(WhereBoundPredicate{ ref bound_generic_params,
1717 self.with_in_scope_lifetime_defs(
1718 &bound_generic_params.iter()
1719 .filter_map(|p| match *p {
1720 GenericParam::Lifetime(ref ld) => Some(ld.clone()),
1723 .collect::<Vec<_>>(),
1725 hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
1726 bound_generic_params:
1727 this.lower_generic_params(bound_generic_params, &NodeMap()),
1728 bounded_ty: this.lower_ty(bounded_ty, ImplTraitContext::Disallowed),
1729 bounds: bounds.iter().filter_map(|bound| match *bound {
1730 // Ignore `?Trait` bounds.
1731 // Tthey were copied into type parameters already.
1732 TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
1733 _ => Some(this.lower_ty_param_bound(
1734 bound, ImplTraitContext::Disallowed))
1741 WherePredicate::RegionPredicate(WhereRegionPredicate{ ref lifetime,
1744 hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
1746 lifetime: self.lower_lifetime(lifetime),
1747 bounds: bounds.iter().map(|bound| self.lower_lifetime(bound)).collect(),
1750 WherePredicate::EqPredicate(WhereEqPredicate{ id,
1754 hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
1755 id: self.lower_node_id(id).node_id,
1756 lhs_ty: self.lower_ty(lhs_ty, ImplTraitContext::Disallowed),
1757 rhs_ty: self.lower_ty(rhs_ty, ImplTraitContext::Disallowed),
1764 fn lower_variant_data(&mut self, vdata: &VariantData) -> hir::VariantData {
1766 VariantData::Struct(ref fields, id) => {
1767 hir::VariantData::Struct(fields.iter()
1769 .map(|f| self.lower_struct_field(f))
1771 self.lower_node_id(id).node_id)
1773 VariantData::Tuple(ref fields, id) => {
1774 hir::VariantData::Tuple(fields.iter()
1776 .map(|f| self.lower_struct_field(f))
1778 self.lower_node_id(id).node_id)
1780 VariantData::Unit(id) => hir::VariantData::Unit(self.lower_node_id(id).node_id),
1784 fn lower_trait_ref(&mut self, p: &TraitRef, itctx: ImplTraitContext) -> hir::TraitRef {
1785 let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit, itctx) {
1786 hir::QPath::Resolved(None, path) => path.and_then(|path| path),
1787 qpath => bug!("lower_trait_ref: unexpected QPath `{:?}`", qpath)
1791 ref_id: self.lower_node_id(p.ref_id).node_id,
1795 fn lower_poly_trait_ref(&mut self,
1797 itctx: ImplTraitContext)
1798 -> hir::PolyTraitRef {
1799 let bound_generic_params = self.lower_generic_params(&p.bound_generic_params, &NodeMap());
1800 let trait_ref = self.with_parent_impl_lifetime_defs(
1801 &bound_generic_params.iter()
1802 .filter_map(|p| match *p {
1803 hir::GenericParam::Lifetime(ref ld) => Some(ld.clone()),
1806 .collect::<Vec<_>>(),
1807 |this| this.lower_trait_ref(&p.trait_ref, itctx),
1811 bound_generic_params,
1817 fn lower_struct_field(&mut self, (index, f): (usize, &StructField)) -> hir::StructField {
1820 id: self.lower_node_id(f.id).node_id,
1821 name: self.lower_ident(match f.ident {
1822 Some(ident) => ident,
1823 // FIXME(jseyfried) positional field hygiene
1824 None => Ident { name: Symbol::intern(&index.to_string()), ctxt: f.span.ctxt() },
1826 vis: self.lower_visibility(&f.vis, None),
1827 ty: self.lower_ty(&f.ty, ImplTraitContext::Disallowed),
1828 attrs: self.lower_attrs(&f.attrs),
1832 fn lower_field(&mut self, f: &Field) -> hir::Field {
1834 name: respan(f.ident.span, self.lower_ident(f.ident.node)),
1835 expr: P(self.lower_expr(&f.expr)),
1837 is_shorthand: f.is_shorthand,
1841 fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext) -> hir::MutTy {
1843 ty: self.lower_ty(&mt.ty, itctx),
1844 mutbl: self.lower_mutability(mt.mutbl),
1848 fn lower_bounds(&mut self, bounds: &[TyParamBound], itctx: ImplTraitContext)
1849 -> hir::TyParamBounds {
1850 bounds.iter().map(|bound| self.lower_ty_param_bound(bound, itctx)).collect()
1853 fn lower_block(&mut self, b: &Block, targeted_by_break: bool) -> P<hir::Block> {
1854 let mut expr = None;
1856 let mut stmts = vec![];
1858 for (index, stmt) in b.stmts.iter().enumerate() {
1859 if index == b.stmts.len() - 1 {
1860 if let StmtKind::Expr(ref e) = stmt.node {
1861 expr = Some(P(self.lower_expr(e)));
1863 stmts.extend(self.lower_stmt(stmt));
1866 stmts.extend(self.lower_stmt(stmt));
1870 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(b.id);
1875 stmts: stmts.into(),
1877 rules: self.lower_block_check_mode(&b.rules),
1880 recovered: b.recovered,
1884 fn lower_item_kind(&mut self,
1887 attrs: &hir::HirVec<Attribute>,
1888 vis: &mut hir::Visibility,
1892 ItemKind::ExternCrate(string) => hir::ItemExternCrate(string),
1893 ItemKind::Use(ref use_tree) => {
1894 // Start with an empty prefix
1897 span: use_tree.span,
1900 self.lower_use_tree(use_tree, &prefix, id, vis, name, attrs)
1902 ItemKind::Static(ref t, m, ref e) => {
1903 let value = self.lower_body(None, |this| this.lower_expr(e));
1904 hir::ItemStatic(self.lower_ty(t, ImplTraitContext::Disallowed),
1905 self.lower_mutability(m),
1908 ItemKind::Const(ref t, ref e) => {
1909 let value = self.lower_body(None, |this| this.lower_expr(e));
1910 hir::ItemConst(self.lower_ty(t, ImplTraitContext::Disallowed), value)
1912 ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
1913 let fn_def_id = self.resolver.definitions().opt_local_def_id(id);
1914 self.with_new_scopes(|this| {
1915 let body_id = this.lower_body(Some(decl), |this| {
1916 let body = this.lower_block(body, false);
1917 this.expr_block(body, ThinVec::new())
1919 let (generics, fn_decl) =
1920 this.add_in_band_defs(generics, fn_def_id, |this|
1921 this.lower_fn_decl(decl, fn_def_id, true));
1923 hir::ItemFn(fn_decl,
1924 this.lower_unsafety(unsafety),
1925 this.lower_constness(constness),
1931 ItemKind::Mod(ref m) => hir::ItemMod(self.lower_mod(m)),
1932 ItemKind::ForeignMod(ref nm) => hir::ItemForeignMod(self.lower_foreign_mod(nm)),
1933 ItemKind::GlobalAsm(ref ga) => hir::ItemGlobalAsm(self.lower_global_asm(ga)),
1934 ItemKind::Ty(ref t, ref generics) => {
1935 hir::ItemTy(self.lower_ty(t, ImplTraitContext::Disallowed),
1936 self.lower_generics(generics))
1938 ItemKind::Enum(ref enum_definition, ref generics) => {
1939 hir::ItemEnum(hir::EnumDef {
1940 variants: enum_definition.variants
1942 .map(|x| self.lower_variant(x))
1945 self.lower_generics(generics))
1947 ItemKind::Struct(ref struct_def, ref generics) => {
1948 let struct_def = self.lower_variant_data(struct_def);
1949 hir::ItemStruct(struct_def, self.lower_generics(generics))
1951 ItemKind::Union(ref vdata, ref generics) => {
1952 let vdata = self.lower_variant_data(vdata);
1953 hir::ItemUnion(vdata, self.lower_generics(generics))
1955 ItemKind::AutoImpl(unsafety, ref trait_ref) => {
1956 let trait_ref = self.lower_trait_ref(trait_ref, ImplTraitContext::Disallowed);
1958 if let Def::Trait(def_id) = trait_ref.path.def {
1959 self.trait_auto_impl.insert(def_id, id);
1962 hir::ItemAutoImpl(self.lower_unsafety(unsafety),
1965 ItemKind::Impl(unsafety,
1971 ref impl_items) => {
1972 let def_id = self.resolver.definitions().opt_local_def_id(id);
1973 let (generics, (ifce, lowered_ty)) =
1974 self.add_in_band_defs(ast_generics, def_id, |this| {
1975 let ifce = ifce.as_ref().map(|trait_ref| {
1976 this.lower_trait_ref(trait_ref, ImplTraitContext::Disallowed)
1979 if let Some(ref trait_ref) = ifce {
1980 if let Def::Trait(def_id) = trait_ref.path.def {
1981 this.trait_impls.entry(def_id).or_insert(vec![]).push(id);
1985 let lowered_ty = this.lower_ty(ty, ImplTraitContext::Disallowed);
1990 let new_impl_items = self.with_in_scope_lifetime_defs(
1991 &ast_generics.params
1993 .filter_map(|p| match *p {
1994 GenericParam::Lifetime(ref ld) => Some(ld.clone()),
1997 .collect::<Vec<_>>(),
2000 .map(|item| this.lower_impl_item_ref(item))
2006 hir::ItemImpl(self.lower_unsafety(unsafety),
2007 self.lower_impl_polarity(polarity),
2008 self.lower_defaultness(defaultness, true /* [1] */),
2014 ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref items) => {
2015 let bounds = self.lower_bounds(bounds, ImplTraitContext::Disallowed);
2016 let items = items.iter().map(|item| self.lower_trait_item_ref(item)).collect();
2017 hir::ItemTrait(self.lower_is_auto(is_auto),
2018 self.lower_unsafety(unsafety),
2019 self.lower_generics(generics),
2023 ItemKind::TraitAlias(ref generics, ref bounds) => {
2024 hir::ItemTraitAlias(self.lower_generics(generics),
2025 self.lower_bounds(bounds, ImplTraitContext::Disallowed))
2027 ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"),
2030 // [1] `defaultness.has_value()` is never called for an `impl`, always `true` in order to
2031 // not cause an assertion failure inside the `lower_defaultness` function
2034 fn lower_use_tree(&mut self,
2038 vis: &mut hir::Visibility,
2040 attrs: &hir::HirVec<Attribute>)
2042 let path = &tree.prefix;
2045 UseTreeKind::Simple(ident) => {
2048 // First apply the prefix to the path
2049 let mut path = Path {
2050 segments: prefix.segments
2052 .chain(path.segments.iter())
2058 // Correctly resolve `self` imports
2059 if path.segments.last().unwrap().identifier.name == keywords::SelfValue.name() {
2060 let _ = path.segments.pop();
2061 if ident.name == keywords::SelfValue.name() {
2062 *name = path.segments.last().unwrap().identifier.name;
2066 let path = P(self.lower_path(id, &path, ParamMode::Explicit, true));
2067 hir::ItemUse(path, hir::UseKind::Single)
2069 UseTreeKind::Glob => {
2070 let path = P(self.lower_path(id, &Path {
2071 segments: prefix.segments
2073 .chain(path.segments.iter())
2077 }, ParamMode::Explicit, true));
2078 hir::ItemUse(path, hir::UseKind::Glob)
2080 UseTreeKind::Nested(ref trees) => {
2082 segments: prefix.segments
2084 .chain(path.segments.iter())
2087 span: prefix.span.to(path.span),
2090 // Add all the nested PathListItems in the HIR
2091 for &(ref use_tree, id) in trees {
2092 self.allocate_hir_id_counter(id, &use_tree);
2096 } = self.lower_node_id(id);
2098 let mut vis = vis.clone();
2099 let mut name = name.clone();
2100 let item = self.lower_use_tree(
2101 use_tree, &prefix, new_id, &mut vis, &mut name, &attrs,
2104 self.with_hir_id_owner(new_id, |this| {
2105 let vis = match vis {
2106 hir::Visibility::Public => hir::Visibility::Public,
2107 hir::Visibility::Crate => hir::Visibility::Crate,
2108 hir::Visibility::Inherited => hir::Visibility::Inherited,
2109 hir::Visibility::Restricted { ref path, id: _ } => {
2110 hir::Visibility::Restricted {
2112 // We are allocating a new NodeId here
2113 id: this.next_id().node_id,
2118 this.items.insert(new_id, hir::Item {
2122 attrs: attrs.clone(),
2125 span: use_tree.span,
2130 // Privatize the degenerate import base, used only to check
2131 // the stability of `use a::{};`, to avoid it showing up as
2132 // a reexport by accident when `pub`, e.g. in documentation.
2133 let path = P(self.lower_path(id, &prefix, ParamMode::Explicit, true));
2134 *vis = hir::Inherited;
2135 hir::ItemUse(path, hir::UseKind::ListStem)
2140 fn lower_trait_item(&mut self, i: &TraitItem) -> hir::TraitItem {
2141 self.with_parent_def(i.id, |this| {
2142 let LoweredNodeId { node_id, hir_id } = this.lower_node_id(i.id);
2143 let fn_def_id = this.resolver.definitions().opt_local_def_id(node_id);
2145 let (generics, node) = match i.node {
2146 TraitItemKind::Const(ref ty, ref default) => {
2148 this.lower_generics(&i.generics),
2149 hir::TraitItemKind::Const(
2150 this.lower_ty(ty, ImplTraitContext::Disallowed),
2151 default.as_ref().map(|x| {
2152 this.lower_body(None, |this| this.lower_expr(x))
2156 TraitItemKind::Method(ref sig, None) => {
2157 let names = this.lower_fn_args_to_names(&sig.decl);
2158 this.add_in_band_defs(&i.generics, fn_def_id, |this|
2159 hir::TraitItemKind::Method(
2160 this.lower_method_sig(sig, fn_def_id, false),
2161 hir::TraitMethod::Required(names)))
2163 TraitItemKind::Method(ref sig, Some(ref body)) => {
2164 let body_id = this.lower_body(Some(&sig.decl), |this| {
2165 let body = this.lower_block(body, false);
2166 this.expr_block(body, ThinVec::new())
2169 this.add_in_band_defs(&i.generics, fn_def_id, |this|
2170 hir::TraitItemKind::Method(
2171 this.lower_method_sig(sig, fn_def_id, false),
2172 hir::TraitMethod::Provided(body_id)))
2174 TraitItemKind::Type(ref bounds, ref default) => {
2176 this.lower_generics(&i.generics),
2177 hir::TraitItemKind::Type(
2178 this.lower_bounds(bounds, ImplTraitContext::Disallowed),
2179 default.as_ref().map(|x| {
2180 this.lower_ty(x, ImplTraitContext::Disallowed)
2184 TraitItemKind::Macro(..) => panic!("Shouldn't exist any more"),
2190 name: this.lower_ident(i.ident),
2191 attrs: this.lower_attrs(&i.attrs),
2199 fn lower_trait_item_ref(&mut self, i: &TraitItem) -> hir::TraitItemRef {
2200 let (kind, has_default) = match i.node {
2201 TraitItemKind::Const(_, ref default) => {
2202 (hir::AssociatedItemKind::Const, default.is_some())
2204 TraitItemKind::Type(_, ref default) => {
2205 (hir::AssociatedItemKind::Type, default.is_some())
2207 TraitItemKind::Method(ref sig, ref default) => {
2208 (hir::AssociatedItemKind::Method {
2209 has_self: sig.decl.has_self(),
2210 }, default.is_some())
2212 TraitItemKind::Macro(..) => unimplemented!(),
2215 id: hir::TraitItemId { node_id: i.id },
2216 name: self.lower_ident(i.ident),
2218 defaultness: self.lower_defaultness(Defaultness::Default, has_default),
2223 fn lower_impl_item(&mut self, i: &ImplItem) -> hir::ImplItem {
2224 self.with_parent_def(i.id, |this| {
2225 let LoweredNodeId { node_id, hir_id } = this.lower_node_id(i.id);
2226 let fn_def_id = this.resolver.definitions().opt_local_def_id(node_id);
2228 let (generics, node) = match i.node {
2229 ImplItemKind::Const(ref ty, ref expr) => {
2230 let body_id = this.lower_body(None, |this| this.lower_expr(expr));
2232 this.lower_generics(&i.generics),
2233 hir::ImplItemKind::Const(
2234 this.lower_ty(ty, ImplTraitContext::Disallowed),
2239 ImplItemKind::Method(ref sig, ref body) => {
2240 let body_id = this.lower_body(Some(&sig.decl), |this| {
2241 let body = this.lower_block(body, false);
2242 this.expr_block(body, ThinVec::new())
2244 let impl_trait_return_allow = !this.is_in_trait_impl;
2246 this.add_in_band_defs(&i.generics, fn_def_id, |this|
2247 hir::ImplItemKind::Method(
2248 this.lower_method_sig(sig, fn_def_id, impl_trait_return_allow),
2251 ImplItemKind::Type(ref ty) => (
2252 this.lower_generics(&i.generics),
2253 hir::ImplItemKind::Type(
2254 this.lower_ty(ty, ImplTraitContext::Disallowed)),
2256 ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"),
2262 name: this.lower_ident(i.ident),
2263 attrs: this.lower_attrs(&i.attrs),
2265 vis: this.lower_visibility(&i.vis, None),
2266 defaultness: this.lower_defaultness(i.defaultness, true /* [1] */),
2272 // [1] since `default impl` is not yet implemented, this is always true in impls
2275 fn lower_impl_item_ref(&mut self, i: &ImplItem) -> hir::ImplItemRef {
2277 id: hir::ImplItemId { node_id: i.id },
2278 name: self.lower_ident(i.ident),
2280 vis: self.lower_visibility(&i.vis, Some(i.id)),
2281 defaultness: self.lower_defaultness(i.defaultness, true /* [1] */),
2282 kind: match i.node {
2283 ImplItemKind::Const(..) => hir::AssociatedItemKind::Const,
2284 ImplItemKind::Type(..) => hir::AssociatedItemKind::Type,
2285 ImplItemKind::Method(ref sig, _) => {
2286 hir::AssociatedItemKind::Method {
2287 has_self: sig.decl.has_self(),
2290 ImplItemKind::Macro(..) => unimplemented!(),
2294 // [1] since `default impl` is not yet implemented, this is always true in impls
2297 fn lower_mod(&mut self, m: &Mod) -> hir::Mod {
2300 item_ids: m.items.iter().flat_map(|x| self.lower_item_id(x)).collect(),
2304 fn lower_item_id(&mut self, i: &Item) -> SmallVector<hir::ItemId> {
2306 ItemKind::Use(ref use_tree) => {
2307 let mut vec = SmallVector::one(hir::ItemId { id: i.id });
2308 self.lower_item_id_use_tree(use_tree, &mut vec);
2311 ItemKind::MacroDef(..) => return SmallVector::new(),
2314 SmallVector::one(hir::ItemId { id: i.id })
2317 fn lower_item_id_use_tree(&self, tree: &UseTree, vec: &mut SmallVector<hir::ItemId>) {
2319 UseTreeKind::Nested(ref nested_vec) => {
2320 for &(ref nested, id) in nested_vec {
2321 vec.push(hir::ItemId { id, });
2322 self.lower_item_id_use_tree(nested, vec);
2325 UseTreeKind::Glob => {}
2326 UseTreeKind::Simple(..) => {}
2330 pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> {
2331 let mut name = i.ident.name;
2332 let mut vis = self.lower_visibility(&i.vis, None);
2333 let attrs = self.lower_attrs(&i.attrs);
2334 if let ItemKind::MacroDef(ref def) = i.node {
2335 if !def.legacy || attr::contains_name(&i.attrs, "macro_export") {
2336 let body = self.lower_token_stream(def.stream());
2337 self.exported_macros.push(hir::MacroDef {
2350 let node = self.with_parent_def(i.id, |this| {
2351 this.lower_item_kind(i.id, &mut name, &attrs, &mut vis, &i.node)
2354 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id);
2367 fn lower_foreign_item(&mut self, i: &ForeignItem) -> hir::ForeignItem {
2368 self.with_parent_def(i.id, |this| {
2369 let node_id = this.lower_node_id(i.id).node_id;
2370 let def_id = this.resolver.definitions().local_def_id(node_id);
2374 attrs: this.lower_attrs(&i.attrs),
2375 node: match i.node {
2376 ForeignItemKind::Fn(ref fdec, ref generics) => {
2377 // Disallow impl Trait in foreign items
2378 let (generics, (fn_dec, fn_args)) =
2379 this.add_in_band_defs(
2383 this.lower_fn_decl(fdec, None, false),
2384 this.lower_fn_args_to_names(fdec)
2388 hir::ForeignItemFn(fn_dec, fn_args, generics)
2390 ForeignItemKind::Static(ref t, m) => {
2391 hir::ForeignItemStatic(this.lower_ty(t, ImplTraitContext::Disallowed), m)
2393 ForeignItemKind::Ty => {
2394 hir::ForeignItemType
2397 vis: this.lower_visibility(&i.vis, None),
2403 fn lower_method_sig(&mut self,
2405 fn_def_id: Option<DefId>,
2406 impl_trait_return_allow: bool)
2410 unsafety: self.lower_unsafety(sig.unsafety),
2411 constness: self.lower_constness(sig.constness),
2412 decl: self.lower_fn_decl(&sig.decl, fn_def_id, impl_trait_return_allow),
2416 fn lower_is_auto(&mut self, a: IsAuto) -> hir::IsAuto {
2418 IsAuto::Yes => hir::IsAuto::Yes,
2419 IsAuto::No => hir::IsAuto::No,
2423 fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety {
2425 Unsafety::Unsafe => hir::Unsafety::Unsafe,
2426 Unsafety::Normal => hir::Unsafety::Normal,
2430 fn lower_constness(&mut self, c: Spanned<Constness>) -> hir::Constness {
2432 Constness::Const => hir::Constness::Const,
2433 Constness::NotConst => hir::Constness::NotConst,
2437 fn lower_unop(&mut self, u: UnOp) -> hir::UnOp {
2439 UnOp::Deref => hir::UnDeref,
2440 UnOp::Not => hir::UnNot,
2441 UnOp::Neg => hir::UnNeg,
2445 fn lower_binop(&mut self, b: BinOp) -> hir::BinOp {
2447 node: match b.node {
2448 BinOpKind::Add => hir::BiAdd,
2449 BinOpKind::Sub => hir::BiSub,
2450 BinOpKind::Mul => hir::BiMul,
2451 BinOpKind::Div => hir::BiDiv,
2452 BinOpKind::Rem => hir::BiRem,
2453 BinOpKind::And => hir::BiAnd,
2454 BinOpKind::Or => hir::BiOr,
2455 BinOpKind::BitXor => hir::BiBitXor,
2456 BinOpKind::BitAnd => hir::BiBitAnd,
2457 BinOpKind::BitOr => hir::BiBitOr,
2458 BinOpKind::Shl => hir::BiShl,
2459 BinOpKind::Shr => hir::BiShr,
2460 BinOpKind::Eq => hir::BiEq,
2461 BinOpKind::Lt => hir::BiLt,
2462 BinOpKind::Le => hir::BiLe,
2463 BinOpKind::Ne => hir::BiNe,
2464 BinOpKind::Ge => hir::BiGe,
2465 BinOpKind::Gt => hir::BiGt,
2471 fn lower_pat(&mut self, p: &Pat) -> P<hir::Pat> {
2472 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(p.id);
2477 node: match p.node {
2478 PatKind::Wild => hir::PatKind::Wild,
2479 PatKind::Ident(ref binding_mode, pth1, ref sub) => {
2480 match self.resolver.get_resolution(p.id).map(|d| d.base_def()) {
2481 // `None` can occur in body-less function signatures
2482 def @ None | def @ Some(Def::Local(_)) => {
2483 let canonical_id = match def {
2484 Some(Def::Local(id)) => id,
2487 hir::PatKind::Binding(self.lower_binding_mode(binding_mode),
2489 respan(pth1.span, pth1.node.name),
2490 sub.as_ref().map(|x| self.lower_pat(x)))
2493 hir::PatKind::Path(hir::QPath::Resolved(None, P(hir::Path {
2497 hir::PathSegment::from_name(pth1.node.name)
2503 PatKind::Lit(ref e) => hir::PatKind::Lit(P(self.lower_expr(e))),
2504 PatKind::TupleStruct(ref path, ref pats, ddpos) => {
2505 let qpath = self.lower_qpath(p.id, &None, path, ParamMode::Optional,
2506 ImplTraitContext::Disallowed);
2507 hir::PatKind::TupleStruct(qpath,
2508 pats.iter().map(|x| self.lower_pat(x)).collect(),
2511 PatKind::Path(ref qself, ref path) => {
2512 hir::PatKind::Path(self.lower_qpath(p.id, qself, path, ParamMode::Optional,
2513 ImplTraitContext::Disallowed))
2515 PatKind::Struct(ref path, ref fields, etc) => {
2516 let qpath = self.lower_qpath(p.id, &None, path, ParamMode::Optional,
2517 ImplTraitContext::Disallowed);
2519 let fs = fields.iter()
2523 node: hir::FieldPat {
2524 name: self.lower_ident(f.node.ident),
2525 pat: self.lower_pat(&f.node.pat),
2526 is_shorthand: f.node.is_shorthand,
2531 hir::PatKind::Struct(qpath, fs, etc)
2533 PatKind::Tuple(ref elts, ddpos) => {
2534 hir::PatKind::Tuple(elts.iter().map(|x| self.lower_pat(x)).collect(), ddpos)
2536 PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)),
2537 PatKind::Ref(ref inner, mutbl) => {
2538 hir::PatKind::Ref(self.lower_pat(inner), self.lower_mutability(mutbl))
2540 PatKind::Range(ref e1, ref e2, ref end) => {
2541 hir::PatKind::Range(P(self.lower_expr(e1)),
2542 P(self.lower_expr(e2)),
2543 self.lower_range_end(end))
2545 PatKind::Slice(ref before, ref slice, ref after) => {
2546 hir::PatKind::Slice(before.iter().map(|x| self.lower_pat(x)).collect(),
2547 slice.as_ref().map(|x| self.lower_pat(x)),
2548 after.iter().map(|x| self.lower_pat(x)).collect())
2550 PatKind::Mac(_) => panic!("Shouldn't exist here"),
2556 fn lower_range_end(&mut self, e: &RangeEnd) -> hir::RangeEnd {
2558 RangeEnd::Included(_) => hir::RangeEnd::Included,
2559 RangeEnd::Excluded => hir::RangeEnd::Excluded,
2563 fn lower_expr(&mut self, e: &Expr) -> hir::Expr {
2564 let kind = match e.node {
2566 // Eventually a desugaring for `box EXPR`
2567 // (similar to the desugaring above for `in PLACE BLOCK`)
2568 // should go here, desugaring
2572 // let mut place = BoxPlace::make_place();
2573 // let raw_place = Place::pointer(&mut place);
2574 // let value = $value;
2576 // ::std::ptr::write(raw_place, value);
2577 // Boxed::finalize(place)
2580 // But for now there are type-inference issues doing that.
2581 ExprKind::Box(ref inner) => {
2582 hir::ExprBox(P(self.lower_expr(inner)))
2585 // Desugar ExprBox: `in (PLACE) EXPR`
2586 ExprKind::InPlace(ref placer, ref value_expr) => {
2590 // let mut place = Placer::make_place(p);
2591 // let raw_place = Place::pointer(&mut place);
2593 // std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
2594 // InPlace::finalize(place)
2596 let placer_expr = P(self.lower_expr(placer));
2597 let value_expr = P(self.lower_expr(value_expr));
2599 let placer_ident = self.str_to_ident("placer");
2600 let place_ident = self.str_to_ident("place");
2601 let p_ptr_ident = self.str_to_ident("p_ptr");
2603 let make_place = ["ops", "Placer", "make_place"];
2604 let place_pointer = ["ops", "Place", "pointer"];
2605 let move_val_init = ["intrinsics", "move_val_init"];
2606 let inplace_finalize = ["ops", "InPlace", "finalize"];
2609 self.allow_internal_unstable(CompilerDesugaringKind::BackArrow, e.span);
2610 let make_call = |this: &mut LoweringContext, p, args| {
2611 let path = P(this.expr_std_path(unstable_span, p, ThinVec::new()));
2612 P(this.expr_call(e.span, path, args))
2615 let mk_stmt_let = |this: &mut LoweringContext, bind, expr| {
2616 this.stmt_let(e.span, false, bind, expr)
2619 let mk_stmt_let_mut = |this: &mut LoweringContext, bind, expr| {
2620 this.stmt_let(e.span, true, bind, expr)
2623 // let placer = <placer_expr> ;
2624 let (s1, placer_binding) = {
2625 mk_stmt_let(self, placer_ident, placer_expr)
2628 // let mut place = Placer::make_place(placer);
2629 let (s2, place_binding) = {
2630 let placer = self.expr_ident(e.span, placer_ident, placer_binding);
2631 let call = make_call(self, &make_place, hir_vec![placer]);
2632 mk_stmt_let_mut(self, place_ident, call)
2635 // let p_ptr = Place::pointer(&mut place);
2636 let (s3, p_ptr_binding) = {
2637 let agent = P(self.expr_ident(e.span, place_ident, place_binding));
2638 let args = hir_vec![self.expr_mut_addr_of(e.span, agent)];
2639 let call = make_call(self, &place_pointer, args);
2640 mk_stmt_let(self, p_ptr_ident, call)
2643 // pop_unsafe!(EXPR));
2644 let pop_unsafe_expr = {
2645 self.signal_block_expr(hir_vec![],
2648 hir::PopUnsafeBlock(hir::CompilerGenerated),
2653 // std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
2654 // InPlace::finalize(place)
2657 let ptr = self.expr_ident(e.span, p_ptr_ident, p_ptr_binding);
2658 let call_move_val_init =
2660 make_call(self, &move_val_init, hir_vec![ptr, pop_unsafe_expr]),
2661 self.next_id().node_id);
2662 let call_move_val_init = respan(e.span, call_move_val_init);
2664 let place = self.expr_ident(e.span, place_ident, place_binding);
2665 let call = make_call(self, &inplace_finalize, hir_vec![place]);
2666 P(self.signal_block_expr(hir_vec![call_move_val_init],
2669 hir::PushUnsafeBlock(hir::CompilerGenerated),
2673 let block = self.block_all(e.span, hir_vec![s1, s2, s3], Some(expr));
2674 hir::ExprBlock(P(block))
2677 ExprKind::Array(ref exprs) => {
2678 hir::ExprArray(exprs.iter().map(|x| self.lower_expr(x)).collect())
2680 ExprKind::Repeat(ref expr, ref count) => {
2681 let expr = P(self.lower_expr(expr));
2682 let count = self.lower_body(None, |this| this.lower_expr(count));
2683 hir::ExprRepeat(expr, count)
2685 ExprKind::Tup(ref elts) => {
2686 hir::ExprTup(elts.iter().map(|x| self.lower_expr(x)).collect())
2688 ExprKind::Call(ref f, ref args) => {
2689 let f = P(self.lower_expr(f));
2690 hir::ExprCall(f, args.iter().map(|x| self.lower_expr(x)).collect())
2692 ExprKind::MethodCall(ref seg, ref args) => {
2693 let hir_seg = self.lower_path_segment(e.span, seg, ParamMode::Optional, 0,
2694 ParenthesizedGenericArgs::Err,
2695 ImplTraitContext::Disallowed);
2696 let args = args.iter().map(|x| self.lower_expr(x)).collect();
2697 hir::ExprMethodCall(hir_seg, seg.span, args)
2699 ExprKind::Binary(binop, ref lhs, ref rhs) => {
2700 let binop = self.lower_binop(binop);
2701 let lhs = P(self.lower_expr(lhs));
2702 let rhs = P(self.lower_expr(rhs));
2703 hir::ExprBinary(binop, lhs, rhs)
2705 ExprKind::Unary(op, ref ohs) => {
2706 let op = self.lower_unop(op);
2707 let ohs = P(self.lower_expr(ohs));
2708 hir::ExprUnary(op, ohs)
2710 ExprKind::Lit(ref l) => hir::ExprLit(P((**l).clone())),
2711 ExprKind::Cast(ref expr, ref ty) => {
2712 let expr = P(self.lower_expr(expr));
2713 hir::ExprCast(expr, self.lower_ty(ty, ImplTraitContext::Disallowed))
2715 ExprKind::Type(ref expr, ref ty) => {
2716 let expr = P(self.lower_expr(expr));
2717 hir::ExprType(expr, self.lower_ty(ty, ImplTraitContext::Disallowed))
2719 ExprKind::AddrOf(m, ref ohs) => {
2720 let m = self.lower_mutability(m);
2721 let ohs = P(self.lower_expr(ohs));
2722 hir::ExprAddrOf(m, ohs)
2724 // More complicated than you might expect because the else branch
2725 // might be `if let`.
2726 ExprKind::If(ref cond, ref blk, ref else_opt) => {
2727 let else_opt = else_opt.as_ref().map(|els| {
2729 ExprKind::IfLet(..) => {
2730 // wrap the if-let expr in a block
2731 let span = els.span;
2732 let els = P(self.lower_expr(els));
2737 let blk = P(hir::Block {
2742 rules: hir::DefaultBlock,
2744 targeted_by_break: false,
2745 recovered: blk.recovered,
2747 P(self.expr_block(blk, ThinVec::new()))
2749 _ => P(self.lower_expr(els)),
2753 let then_blk = self.lower_block(blk, false);
2754 let then_expr = self.expr_block(then_blk, ThinVec::new());
2756 hir::ExprIf(P(self.lower_expr(cond)), P(then_expr), else_opt)
2758 ExprKind::While(ref cond, ref body, opt_ident) => {
2759 self.with_loop_scope(e.id, |this|
2761 this.with_loop_condition_scope(|this| P(this.lower_expr(cond))),
2762 this.lower_block(body, false),
2763 this.lower_opt_sp_ident(opt_ident)))
2765 ExprKind::Loop(ref body, opt_ident) => {
2766 self.with_loop_scope(e.id, |this|
2767 hir::ExprLoop(this.lower_block(body, false),
2768 this.lower_opt_sp_ident(opt_ident),
2769 hir::LoopSource::Loop))
2771 ExprKind::Catch(ref body) => {
2772 self.with_catch_scope(body.id, |this|
2773 hir::ExprBlock(this.lower_block(body, true)))
2775 ExprKind::Match(ref expr, ref arms) => {
2776 hir::ExprMatch(P(self.lower_expr(expr)),
2777 arms.iter().map(|x| self.lower_arm(x)).collect(),
2778 hir::MatchSource::Normal)
2780 ExprKind::Closure(capture_clause, ref decl, ref body, fn_decl_span) => {
2781 self.with_new_scopes(|this| {
2782 this.with_parent_def(e.id, |this| {
2783 let mut is_generator = false;
2784 let body_id = this.lower_body(Some(decl), |this| {
2785 let e = this.lower_expr(body);
2786 is_generator = this.is_generator;
2789 if is_generator && !decl.inputs.is_empty() {
2790 span_err!(this.sess, fn_decl_span, E0628,
2791 "generators cannot have explicit arguments");
2792 this.sess.abort_if_errors();
2794 hir::ExprClosure(this.lower_capture_clause(capture_clause),
2795 this.lower_fn_decl(decl, None, false),
2802 ExprKind::Block(ref blk) => hir::ExprBlock(self.lower_block(blk, false)),
2803 ExprKind::Assign(ref el, ref er) => {
2804 hir::ExprAssign(P(self.lower_expr(el)), P(self.lower_expr(er)))
2806 ExprKind::AssignOp(op, ref el, ref er) => {
2807 hir::ExprAssignOp(self.lower_binop(op),
2808 P(self.lower_expr(el)),
2809 P(self.lower_expr(er)))
2811 ExprKind::Field(ref el, ident) => {
2812 hir::ExprField(P(self.lower_expr(el)),
2813 respan(ident.span, self.lower_ident(ident.node)))
2815 ExprKind::TupField(ref el, ident) => {
2816 hir::ExprTupField(P(self.lower_expr(el)), ident)
2818 ExprKind::Index(ref el, ref er) => {
2819 hir::ExprIndex(P(self.lower_expr(el)), P(self.lower_expr(er)))
2821 ExprKind::Range(ref e1, ref e2, lims) => {
2822 use syntax::ast::RangeLimits::*;
2824 let path = match (e1, e2, lims) {
2825 (&None, &None, HalfOpen) => "RangeFull",
2826 (&Some(..), &None, HalfOpen) => "RangeFrom",
2827 (&None, &Some(..), HalfOpen) => "RangeTo",
2828 (&Some(..), &Some(..), HalfOpen) => "Range",
2829 (&None, &Some(..), Closed) => "RangeToInclusive",
2830 (&Some(..), &Some(..), Closed) => "RangeInclusive",
2831 (_, &None, Closed) =>
2832 panic!(self.diagnostic().span_fatal(
2833 e.span, "inclusive range with no end")),
2837 e1.iter().map(|e| ("start", e)).chain(e2.iter().map(|e| ("end", e)))
2839 let expr = P(self.lower_expr(&e));
2841 self.allow_internal_unstable(CompilerDesugaringKind::DotFill, e.span);
2842 self.field(Symbol::intern(s), expr, unstable_span)
2843 }).collect::<P<[hir::Field]>>();
2845 let is_unit = fields.is_empty();
2847 self.allow_internal_unstable(CompilerDesugaringKind::DotFill, e.span);
2849 iter::once("ops").chain(iter::once(path))
2850 .collect::<Vec<_>>();
2851 let struct_path = self.std_path(unstable_span, &struct_path, is_unit);
2852 let struct_path = hir::QPath::Resolved(None, P(struct_path));
2854 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
2860 hir::ExprPath(struct_path)
2862 hir::ExprStruct(struct_path, fields, None)
2864 span: unstable_span,
2865 attrs: e.attrs.clone(),
2868 ExprKind::Path(ref qself, ref path) => {
2869 hir::ExprPath(self.lower_qpath(e.id, qself, path, ParamMode::Optional,
2870 ImplTraitContext::Disallowed))
2872 ExprKind::Break(opt_ident, ref opt_expr) => {
2873 let label_result = if self.is_in_loop_condition && opt_ident.is_none() {
2876 target_id: hir::ScopeTarget::Loop(
2877 Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into()),
2880 self.lower_loop_destination(opt_ident.map(|ident| (e.id, ident)))
2884 opt_expr.as_ref().map(|x| P(self.lower_expr(x))))
2886 ExprKind::Continue(opt_ident) =>
2888 if self.is_in_loop_condition && opt_ident.is_none() {
2891 target_id: hir::ScopeTarget::Loop(Err(
2892 hir::LoopIdError::UnlabeledCfInWhileCondition).into()),
2895 self.lower_loop_destination(opt_ident.map( |ident| (e.id, ident)))
2897 ExprKind::Ret(ref e) => hir::ExprRet(e.as_ref().map(|x| P(self.lower_expr(x)))),
2898 ExprKind::InlineAsm(ref asm) => {
2899 let hir_asm = hir::InlineAsm {
2900 inputs: asm.inputs.iter().map(|&(ref c, _)| c.clone()).collect(),
2901 outputs: asm.outputs.iter().map(|out| {
2902 hir::InlineAsmOutput {
2903 constraint: out.constraint.clone(),
2905 is_indirect: out.is_indirect,
2908 asm: asm.asm.clone(),
2909 asm_str_style: asm.asm_str_style,
2910 clobbers: asm.clobbers.clone().into(),
2911 volatile: asm.volatile,
2912 alignstack: asm.alignstack,
2913 dialect: asm.dialect,
2917 asm.outputs.iter().map(|out| self.lower_expr(&out.expr)).collect();
2919 asm.inputs.iter().map(|&(_, ref input)| self.lower_expr(input)).collect();
2920 hir::ExprInlineAsm(P(hir_asm), outputs, inputs)
2922 ExprKind::Struct(ref path, ref fields, ref maybe_expr) => {
2923 hir::ExprStruct(self.lower_qpath(e.id, &None, path, ParamMode::Optional,
2924 ImplTraitContext::Disallowed),
2925 fields.iter().map(|x| self.lower_field(x)).collect(),
2926 maybe_expr.as_ref().map(|x| P(self.lower_expr(x))))
2928 ExprKind::Paren(ref ex) => {
2929 let mut ex = self.lower_expr(ex);
2930 // include parens in span, but only if it is a super-span.
2931 if e.span.contains(ex.span) {
2934 // merge attributes into the inner expression.
2935 let mut attrs = e.attrs.clone();
2936 attrs.extend::<Vec<_>>(ex.attrs.into());
2941 ExprKind::Yield(ref opt_expr) => {
2942 self.is_generator = true;
2943 let expr = opt_expr.as_ref().map(|x| self.lower_expr(x)).unwrap_or_else(|| {
2944 self.expr(e.span, hir::ExprTup(hir_vec![]), ThinVec::new())
2946 hir::ExprYield(P(expr))
2949 // Desugar ExprIfLet
2950 // From: `if let <pat> = <sub_expr> <body> [<else_opt>]`
2951 ExprKind::IfLet(ref pat, ref sub_expr, ref body, ref else_opt) => {
2954 // match <sub_expr> {
2956 // _ => [<else_opt> | ()]
2959 let mut arms = vec![];
2961 // `<pat> => <body>`
2963 let body = self.lower_block(body, false);
2964 let body_expr = P(self.expr_block(body, ThinVec::new()));
2965 let pat = self.lower_pat(pat);
2966 arms.push(self.arm(hir_vec![pat], body_expr));
2969 // _ => [<else_opt>|()]
2971 let wildcard_arm: Option<&Expr> = else_opt.as_ref().map(|p| &**p);
2972 let wildcard_pattern = self.pat_wild(e.span);
2973 let body = if let Some(else_expr) = wildcard_arm {
2974 P(self.lower_expr(else_expr))
2976 self.expr_tuple(e.span, hir_vec![])
2978 arms.push(self.arm(hir_vec![wildcard_pattern], body));
2981 let contains_else_clause = else_opt.is_some();
2983 let sub_expr = P(self.lower_expr(sub_expr));
2988 hir::MatchSource::IfLetDesugar {
2989 contains_else_clause,
2993 // Desugar ExprWhileLet
2994 // From: `[opt_ident]: while let <pat> = <sub_expr> <body>`
2995 ExprKind::WhileLet(ref pat, ref sub_expr, ref body, opt_ident) => {
2998 // [opt_ident]: loop {
2999 // match <sub_expr> {
3005 // Note that the block AND the condition are evaluated in the loop scope.
3006 // This is done to allow `break` from inside the condition of the loop.
3007 let (body, break_expr, sub_expr) = self.with_loop_scope(e.id, |this| (
3008 this.lower_block(body, false),
3009 this.expr_break(e.span, ThinVec::new()),
3010 this.with_loop_condition_scope(|this| P(this.lower_expr(sub_expr))),
3013 // `<pat> => <body>`
3015 let body_expr = P(self.expr_block(body, ThinVec::new()));
3016 let pat = self.lower_pat(pat);
3017 self.arm(hir_vec![pat], body_expr)
3022 let pat_under = self.pat_wild(e.span);
3023 self.arm(hir_vec![pat_under], break_expr)
3026 // `match <sub_expr> { ... }`
3027 let arms = hir_vec![pat_arm, break_arm];
3028 let match_expr = self.expr(e.span,
3029 hir::ExprMatch(sub_expr,
3031 hir::MatchSource::WhileLetDesugar),
3034 // `[opt_ident]: loop { ... }`
3035 let loop_block = P(self.block_expr(P(match_expr)));
3036 let loop_expr = hir::ExprLoop(loop_block, self.lower_opt_sp_ident(opt_ident),
3037 hir::LoopSource::WhileLet);
3038 // add attributes to the outer returned expr node
3042 // Desugar ExprForLoop
3043 // From: `[opt_ident]: for <pat> in <head> <body>`
3044 ExprKind::ForLoop(ref pat, ref head, ref body, opt_ident) => {
3048 // let result = match ::std::iter::IntoIterator::into_iter(<head>) {
3050 // [opt_ident]: loop {
3052 // match ::std::iter::Iterator::next(&mut iter) {
3053 // ::std::option::Option::Some(val) => __next = val,
3054 // ::std::option::Option::None => break
3056 // let <pat> = __next;
3057 // StmtExpr(<body>);
3065 let head = self.lower_expr(head);
3067 let iter = self.str_to_ident("iter");
3069 let next_ident = self.str_to_ident("__next");
3070 let next_pat = self.pat_ident_binding_mode(e.span,
3072 hir::BindingAnnotation::Mutable);
3074 // `::std::option::Option::Some(val) => next = val`
3076 let val_ident = self.str_to_ident("val");
3077 let val_pat = self.pat_ident(e.span, val_ident);
3078 let val_expr = P(self.expr_ident(e.span, val_ident, val_pat.id));
3079 let next_expr = P(self.expr_ident(e.span, next_ident, next_pat.id));
3080 let assign = P(self.expr(e.span,
3081 hir::ExprAssign(next_expr, val_expr),
3083 let some_pat = self.pat_some(e.span, val_pat);
3084 self.arm(hir_vec![some_pat], assign)
3087 // `::std::option::Option::None => break`
3089 let break_expr = self.with_loop_scope(e.id, |this|
3090 this.expr_break(e.span, ThinVec::new()));
3091 let pat = self.pat_none(e.span);
3092 self.arm(hir_vec![pat], break_expr)
3096 let iter_pat = self.pat_ident_binding_mode(e.span,
3098 hir::BindingAnnotation::Mutable);
3100 // `match ::std::iter::Iterator::next(&mut iter) { ... }`
3102 let iter = P(self.expr_ident(e.span, iter, iter_pat.id));
3103 let ref_mut_iter = self.expr_mut_addr_of(e.span, iter);
3104 let next_path = &["iter", "Iterator", "next"];
3105 let next_path = P(self.expr_std_path(e.span, next_path, ThinVec::new()));
3106 let next_expr = P(self.expr_call(e.span, next_path,
3107 hir_vec![ref_mut_iter]));
3108 let arms = hir_vec![pat_arm, break_arm];
3111 hir::ExprMatch(next_expr, arms,
3112 hir::MatchSource::ForLoopDesugar),
3115 let match_stmt = respan(e.span, hir::StmtExpr(match_expr, self.next_id().node_id));
3117 let next_expr = P(self.expr_ident(e.span, next_ident, next_pat.id));
3120 let next_let = self.stmt_let_pat(e.span,
3123 hir::LocalSource::ForLoopDesugar);
3125 // `let <pat> = __next`
3126 let pat = self.lower_pat(pat);
3127 let pat_let = self.stmt_let_pat(e.span,
3130 hir::LocalSource::ForLoopDesugar);
3132 let body_block = self.with_loop_scope(e.id,
3133 |this| this.lower_block(body, false));
3134 let body_expr = P(self.expr_block(body_block, ThinVec::new()));
3135 let body_stmt = respan(e.span, hir::StmtExpr(body_expr, self.next_id().node_id));
3137 let loop_block = P(self.block_all(e.span,
3144 // `[opt_ident]: loop { ... }`
3145 let loop_expr = hir::ExprLoop(loop_block, self.lower_opt_sp_ident(opt_ident),
3146 hir::LoopSource::ForLoop);
3147 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
3148 let loop_expr = P(hir::Expr {
3153 attrs: ThinVec::new(),
3156 // `mut iter => { ... }`
3157 let iter_arm = self.arm(hir_vec![iter_pat], loop_expr);
3159 // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }`
3160 let into_iter_expr = {
3161 let into_iter_path = &["iter", "IntoIterator", "into_iter"];
3162 let into_iter = P(self.expr_std_path(e.span, into_iter_path,
3164 P(self.expr_call(e.span, into_iter, hir_vec![head]))
3167 let match_expr = P(self.expr_match(e.span,
3170 hir::MatchSource::ForLoopDesugar));
3172 // `{ let _result = ...; _result }`
3173 // underscore prevents an unused_variables lint if the head diverges
3174 let result_ident = self.str_to_ident("_result");
3175 let (let_stmt, let_stmt_binding) =
3176 self.stmt_let(e.span, false, result_ident, match_expr);
3178 let result = P(self.expr_ident(e.span, result_ident, let_stmt_binding));
3179 let block = P(self.block_all(e.span, hir_vec![let_stmt], Some(result)));
3180 // add the attributes to the outer returned expr node
3181 return self.expr_block(block, e.attrs.clone());
3184 // Desugar ExprKind::Try
3186 ExprKind::Try(ref sub_expr) => {
3189 // match Try::into_result(<expr>) {
3190 // Ok(val) => #[allow(unreachable_code)] val,
3191 // Err(err) => #[allow(unreachable_code)]
3192 // // If there is an enclosing `catch {...}`
3193 // break 'catch_target Try::from_error(From::from(err)),
3195 // return Try::from_error(From::from(err)),
3199 self.allow_internal_unstable(CompilerDesugaringKind::QuestionMark, e.span);
3201 // Try::into_result(<expr>)
3204 let sub_expr = self.lower_expr(sub_expr);
3206 let path = &["ops", "Try", "into_result"];
3207 let path = P(self.expr_std_path(unstable_span, path, ThinVec::new()));
3208 P(self.expr_call(e.span, path, hir_vec![sub_expr]))
3211 // #[allow(unreachable_code)]
3213 // allow(unreachable_code)
3215 let allow_ident = self.str_to_ident("allow");
3216 let uc_ident = self.str_to_ident("unreachable_code");
3217 let uc_meta_item = attr::mk_spanned_word_item(e.span, uc_ident);
3218 let uc_nested = NestedMetaItemKind::MetaItem(uc_meta_item);
3219 let uc_spanned = respan(e.span, uc_nested);
3220 attr::mk_spanned_list_item(e.span, allow_ident, vec![uc_spanned])
3222 attr::mk_spanned_attr_outer(e.span, attr::mk_attr_id(), allow)
3224 let attrs = vec![attr];
3226 // Ok(val) => #[allow(unreachable_code)] val,
3228 let val_ident = self.str_to_ident("val");
3229 let val_pat = self.pat_ident(e.span, val_ident);
3230 let val_expr = P(self.expr_ident_with_attrs(e.span,
3233 ThinVec::from(attrs.clone())));
3234 let ok_pat = self.pat_ok(e.span, val_pat);
3236 self.arm(hir_vec![ok_pat], val_expr)
3239 // Err(err) => #[allow(unreachable_code)]
3240 // return Try::from_error(From::from(err)),
3242 let err_ident = self.str_to_ident("err");
3243 let err_local = self.pat_ident(e.span, err_ident);
3245 let path = &["convert", "From", "from"];
3246 let from = P(self.expr_std_path(e.span, path, ThinVec::new()));
3247 let err_expr = self.expr_ident(e.span, err_ident, err_local.id);
3249 self.expr_call(e.span, from, hir_vec![err_expr])
3251 let from_err_expr = {
3252 let path = &["ops", "Try", "from_error"];
3253 let from_err = P(self.expr_std_path(unstable_span, path,
3255 P(self.expr_call(e.span, from_err, hir_vec![from_expr]))
3258 let thin_attrs = ThinVec::from(attrs);
3259 let catch_scope = self.catch_scopes.last().map(|x| *x);
3260 let ret_expr = if let Some(catch_node) = catch_scope {
3266 target_id: hir::ScopeTarget::Block(catch_node),
3273 hir::Expr_::ExprRet(Some(from_err_expr)),
3278 let err_pat = self.pat_err(e.span, err_local);
3279 self.arm(hir_vec![err_pat], ret_expr)
3282 hir::ExprMatch(discr,
3283 hir_vec![err_arm, ok_arm],
3284 hir::MatchSource::TryDesugar)
3287 ExprKind::Mac(_) => panic!("Shouldn't exist here"),
3290 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
3297 attrs: e.attrs.clone(),
3301 fn lower_stmt(&mut self, s: &Stmt) -> SmallVector<hir::Stmt> {
3302 SmallVector::one(match s.node {
3303 StmtKind::Local(ref l) => Spanned {
3304 node: hir::StmtDecl(P(Spanned {
3305 node: hir::DeclLocal(self.lower_local(l)),
3307 }), self.lower_node_id(s.id).node_id),
3310 StmtKind::Item(ref it) => {
3311 // Can only use the ID once.
3312 let mut id = Some(s.id);
3313 return self.lower_item_id(it).into_iter().map(|item_id| Spanned {
3314 node: hir::StmtDecl(P(Spanned {
3315 node: hir::DeclItem(item_id),
3318 .map(|id| self.lower_node_id(id).node_id)
3319 .unwrap_or_else(|| self.next_id().node_id)),
3323 StmtKind::Expr(ref e) => {
3325 node: hir::StmtExpr(P(self.lower_expr(e)),
3326 self.lower_node_id(s.id).node_id),
3330 StmtKind::Semi(ref e) => {
3332 node: hir::StmtSemi(P(self.lower_expr(e)),
3333 self.lower_node_id(s.id).node_id),
3337 StmtKind::Mac(..) => panic!("Shouldn't exist here"),
3341 fn lower_capture_clause(&mut self, c: CaptureBy) -> hir::CaptureClause {
3343 CaptureBy::Value => hir::CaptureByValue,
3344 CaptureBy::Ref => hir::CaptureByRef,
3348 /// If an `explicit_owner` is given, this method allocates the `HirId` in
3349 /// the address space of that item instead of the item currently being
3350 /// lowered. This can happen during `lower_impl_item_ref()` where we need to
3351 /// lower a `Visibility` value although we haven't lowered the owning
3352 /// `ImplItem` in question yet.
3353 fn lower_visibility(&mut self,
3355 explicit_owner: Option<NodeId>)
3356 -> hir::Visibility {
3358 Visibility::Public => hir::Public,
3359 Visibility::Crate(..) => hir::Visibility::Crate,
3360 Visibility::Restricted { ref path, id } => {
3361 hir::Visibility::Restricted {
3362 path: P(self.lower_path(id, path, ParamMode::Explicit, true)),
3363 id: if let Some(owner) = explicit_owner {
3364 self.lower_node_id_with_owner(id, owner).node_id
3366 self.lower_node_id(id).node_id
3370 Visibility::Inherited => hir::Inherited,
3374 fn lower_defaultness(&mut self, d: Defaultness, has_value: bool) -> hir::Defaultness {
3376 Defaultness::Default => hir::Defaultness::Default { has_value: has_value },
3377 Defaultness::Final => {
3379 hir::Defaultness::Final
3384 fn lower_block_check_mode(&mut self, b: &BlockCheckMode) -> hir::BlockCheckMode {
3386 BlockCheckMode::Default => hir::DefaultBlock,
3387 BlockCheckMode::Unsafe(u) => hir::UnsafeBlock(self.lower_unsafe_source(u)),
3391 fn lower_binding_mode(&mut self, b: &BindingMode) -> hir::BindingAnnotation {
3393 BindingMode::ByValue(Mutability::Immutable) =>
3394 hir::BindingAnnotation::Unannotated,
3395 BindingMode::ByRef(Mutability::Immutable) => hir::BindingAnnotation::Ref,
3396 BindingMode::ByValue(Mutability::Mutable) => hir::BindingAnnotation::Mutable,
3397 BindingMode::ByRef(Mutability::Mutable) => hir::BindingAnnotation::RefMut,
3401 fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
3403 CompilerGenerated => hir::CompilerGenerated,
3404 UserProvided => hir::UserProvided,
3408 fn lower_impl_polarity(&mut self, i: ImplPolarity) -> hir::ImplPolarity {
3410 ImplPolarity::Positive => hir::ImplPolarity::Positive,
3411 ImplPolarity::Negative => hir::ImplPolarity::Negative,
3415 fn lower_trait_bound_modifier(&mut self, f: TraitBoundModifier) -> hir::TraitBoundModifier {
3417 TraitBoundModifier::None => hir::TraitBoundModifier::None,
3418 TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe,
3422 // Helper methods for building HIR.
3424 fn arm(&mut self, pats: hir::HirVec<P<hir::Pat>>, expr: P<hir::Expr>) -> hir::Arm {
3433 fn field(&mut self, name: Name, expr: P<hir::Expr>, span: Span) -> hir::Field {
3441 is_shorthand: false,
3445 fn expr_break(&mut self, span: Span, attrs: ThinVec<Attribute>) -> P<hir::Expr> {
3446 let expr_break = hir::ExprBreak(self.lower_loop_destination(None), None);
3447 P(self.expr(span, expr_break, attrs))
3450 fn expr_call(&mut self, span: Span, e: P<hir::Expr>, args: hir::HirVec<hir::Expr>)
3452 self.expr(span, hir::ExprCall(e, args), ThinVec::new())
3455 fn expr_ident(&mut self, span: Span, id: Name, binding: NodeId) -> hir::Expr {
3456 self.expr_ident_with_attrs(span, id, binding, ThinVec::new())
3459 fn expr_ident_with_attrs(&mut self, span: Span,
3462 attrs: ThinVec<Attribute>) -> hir::Expr {
3463 let expr_path = hir::ExprPath(hir::QPath::Resolved(None, P(hir::Path {
3465 def: Def::Local(binding),
3466 segments: hir_vec![hir::PathSegment::from_name(id)],
3469 self.expr(span, expr_path, attrs)
3472 fn expr_mut_addr_of(&mut self, span: Span, e: P<hir::Expr>) -> hir::Expr {
3473 self.expr(span, hir::ExprAddrOf(hir::MutMutable, e), ThinVec::new())
3476 fn expr_std_path(&mut self,
3478 components: &[&str],
3479 attrs: ThinVec<Attribute>)
3481 let path = self.std_path(span, components, true);
3482 self.expr(span, hir::ExprPath(hir::QPath::Resolved(None, P(path))), attrs)
3485 fn expr_match(&mut self,
3488 arms: hir::HirVec<hir::Arm>,
3489 source: hir::MatchSource)
3491 self.expr(span, hir::ExprMatch(arg, arms, source), ThinVec::new())
3494 fn expr_block(&mut self, b: P<hir::Block>, attrs: ThinVec<Attribute>) -> hir::Expr {
3495 self.expr(b.span, hir::ExprBlock(b), attrs)
3498 fn expr_tuple(&mut self, sp: Span, exprs: hir::HirVec<hir::Expr>) -> P<hir::Expr> {
3499 P(self.expr(sp, hir::ExprTup(exprs), ThinVec::new()))
3502 fn expr(&mut self, span: Span, node: hir::Expr_, attrs: ThinVec<Attribute>) -> hir::Expr {
3503 let LoweredNodeId { node_id, hir_id } = self.next_id();
3513 fn stmt_let_pat(&mut self,
3515 ex: Option<P<hir::Expr>>,
3517 source: hir::LocalSource)
3519 let LoweredNodeId { node_id, hir_id } = self.next_id();
3521 let local = P(hir::Local {
3528 attrs: ThinVec::new(),
3531 let decl = respan(sp, hir::DeclLocal(local));
3532 respan(sp, hir::StmtDecl(P(decl), self.next_id().node_id))
3535 fn stmt_let(&mut self, sp: Span, mutbl: bool, ident: Name, ex: P<hir::Expr>)
3536 -> (hir::Stmt, NodeId) {
3537 let pat = if mutbl {
3538 self.pat_ident_binding_mode(sp, ident, hir::BindingAnnotation::Mutable)
3540 self.pat_ident(sp, ident)
3542 let pat_id = pat.id;
3543 (self.stmt_let_pat(sp, Some(ex), pat, hir::LocalSource::Normal), pat_id)
3546 fn block_expr(&mut self, expr: P<hir::Expr>) -> hir::Block {
3547 self.block_all(expr.span, hir::HirVec::new(), Some(expr))
3550 fn block_all(&mut self, span: Span, stmts: hir::HirVec<hir::Stmt>, expr: Option<P<hir::Expr>>)
3552 let LoweredNodeId { node_id, hir_id } = self.next_id();
3559 rules: hir::DefaultBlock,
3561 targeted_by_break: false,
3566 fn pat_ok(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
3567 self.pat_std_enum(span, &["result", "Result", "Ok"], hir_vec![pat])
3570 fn pat_err(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
3571 self.pat_std_enum(span, &["result", "Result", "Err"], hir_vec![pat])
3574 fn pat_some(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
3575 self.pat_std_enum(span, &["option", "Option", "Some"], hir_vec![pat])
3578 fn pat_none(&mut self, span: Span) -> P<hir::Pat> {
3579 self.pat_std_enum(span, &["option", "Option", "None"], hir_vec![])
3582 fn pat_std_enum(&mut self,
3584 components: &[&str],
3585 subpats: hir::HirVec<P<hir::Pat>>)
3587 let path = self.std_path(span, components, true);
3588 let qpath = hir::QPath::Resolved(None, P(path));
3589 let pt = if subpats.is_empty() {
3590 hir::PatKind::Path(qpath)
3592 hir::PatKind::TupleStruct(qpath, subpats, None)
3597 fn pat_ident(&mut self, span: Span, name: Name) -> P<hir::Pat> {
3598 self.pat_ident_binding_mode(span, name, hir::BindingAnnotation::Unannotated)
3601 fn pat_ident_binding_mode(&mut self, span: Span, name: Name, bm: hir::BindingAnnotation)
3603 let LoweredNodeId { node_id, hir_id } = self.next_id();
3608 node: hir::PatKind::Binding(bm,
3619 fn pat_wild(&mut self, span: Span) -> P<hir::Pat> {
3620 self.pat(span, hir::PatKind::Wild)
3623 fn pat(&mut self, span: Span, pat: hir::PatKind) -> P<hir::Pat> {
3624 let LoweredNodeId { node_id, hir_id } = self.next_id();
3633 /// Given suffix ["b","c","d"], returns path `::std::b::c::d` when
3634 /// `fld.cx.use_std`, and `::core::b::c::d` otherwise.
3635 /// The path is also resolved according to `is_value`.
3636 fn std_path(&mut self, span: Span, components: &[&str], is_value: bool) -> hir::Path {
3637 let mut path = hir::Path {
3640 segments: iter::once(keywords::CrateRoot.name()).chain({
3641 self.crate_root.into_iter().chain(components.iter().cloned()).map(Symbol::intern)
3642 }).map(hir::PathSegment::from_name).collect(),
3645 self.resolver.resolve_hir_path(&mut path, is_value);
3649 fn signal_block_expr(&mut self,
3650 stmts: hir::HirVec<hir::Stmt>,
3653 rule: hir::BlockCheckMode,
3654 attrs: ThinVec<Attribute>)
3656 let LoweredNodeId { node_id, hir_id } = self.next_id();
3658 let block = P(hir::Block {
3665 targeted_by_break: false,
3668 self.expr_block(block, attrs)
3671 fn ty_path(&mut self, id: LoweredNodeId, span: Span, qpath: hir::QPath) -> P<hir::Ty> {
3673 let node = match qpath {
3674 hir::QPath::Resolved(None, path) => {
3675 // Turn trait object paths into `TyTraitObject` instead.
3676 if let Def::Trait(_) = path.def {
3677 let principal = hir::PolyTraitRef {
3678 bound_generic_params: hir::HirVec::new(),
3679 trait_ref: hir::TraitRef {
3680 path: path.and_then(|path| path),
3686 // The original ID is taken by the `PolyTraitRef`,
3687 // so the `Ty` itself needs a different one.
3688 id = self.next_id();
3690 hir::TyTraitObject(hir_vec![principal], self.elided_lifetime(span))
3692 hir::TyPath(hir::QPath::Resolved(None, path))
3695 _ => hir::TyPath(qpath)
3697 P(hir::Ty { id: id.node_id, hir_id: id.hir_id, node, span })
3700 fn elided_lifetime(&mut self, span: Span) -> hir::Lifetime {
3702 id: self.next_id().node_id,
3704 name: hir::LifetimeName::Implicit,
3709 fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
3710 // Sorting by span ensures that we get things in order within a
3711 // file, and also puts the files in a sensible order.
3712 let mut body_ids: Vec<_> = bodies.keys().cloned().collect();
3713 body_ids.sort_by_key(|b| bodies[b].value.span);