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::{DefKey, DefPathData, Definitions};
47 use hir::def_id::{DefId, DefIndex, DefIndexAddressSpace, CRATE_DEF_INDEX};
48 use hir::def::{Def, PathResolution};
49 use lint::builtin::{self, 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, CompilerDesugaringKind, Spanned};
67 use syntax::std_inject;
68 use syntax::symbol::{keywords, Symbol};
69 use syntax::tokenstream::{Delimited, TokenStream, TokenTree};
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 /// What to do when we encounter either an "anonymous lifetime
111 /// reference". The term "anonymous" is meant to encompass both
112 /// `'_` lifetimes as well as fully elided cases where nothing is
113 /// written at all (e.g., `&T` or `std::cell::Ref<T>`).
114 anonymous_lifetime_mode: AnonymousLifetimeMode,
116 // This is a list of in-band type definitions being generated by
117 // Argument-position `impl Trait`.
118 // When traversing a signature such as `fn foo(x: impl Trait)`,
119 // we record `impl Trait` as a new type parameter, then later
120 // add it on to `foo`s generics.
121 in_band_ty_params: Vec<hir::TyParam>,
123 // Used to create lifetime definitions from in-band lifetime usages.
124 // e.g. `fn foo(x: &'x u8) -> &'x u8` to `fn foo<'x>(x: &'x u8) -> &'x u8`
125 // When a named lifetime is encountered in a function or impl header and
126 // has not been defined
127 // (i.e. it doesn't appear in the in_scope_lifetimes list), it is added
128 // to this list. The results of this list are then added to the list of
129 // lifetime definitions in the corresponding impl or function generics.
130 lifetimes_to_define: Vec<(Span, hir::LifetimeName)>,
132 // Whether or not in-band lifetimes are being collected. This is used to
133 // indicate whether or not we're in a place where new lifetimes will result
134 // in in-band lifetime definitions, such a function or an impl header.
135 // This will always be false unless the `in_band_lifetimes` feature is
137 is_collecting_in_band_lifetimes: bool,
139 // Currently in-scope lifetimes defined in impl headers, fn headers, or HRTB.
140 // When `is_collectin_in_band_lifetimes` is true, each lifetime is checked
141 // against this list to see if it is already in-scope, or if a definition
142 // needs to be created for it.
143 in_scope_lifetimes: Vec<Name>,
145 type_def_lifetime_params: DefIdMap<usize>,
147 current_hir_id_owner: Vec<(DefIndex, u32)>,
148 item_local_id_counters: NodeMap<u32>,
149 node_id_to_hir_id: IndexVec<NodeId, hir::HirId>,
153 /// Resolve a hir path generated by the lowerer when expanding `for`, `if let`, etc.
154 fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool);
156 /// Obtain the resolution for a node id
157 fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution>;
159 /// We must keep the set of definitions up to date as we add nodes that weren't in the AST.
160 /// This should only return `None` during testing.
161 fn definitions(&mut self) -> &mut Definitions;
163 /// Given suffix ["b","c","d"], creates a HIR path for `[::crate_root]::b::c::d` and resolves
164 /// it based on `is_value`.
168 crate_root: Option<&str>,
174 #[derive(Clone, Copy, Debug)]
175 enum ImplTraitContext {
176 /// Treat `impl Trait` as shorthand for a new universal generic parameter.
177 /// Example: `fn foo(x: impl Debug)`, where `impl Debug` is conceptually
178 /// equivalent to a fresh universal parameter like `fn foo<T: Debug>(x: T)`.
180 /// We store a DefId here so we can look up necessary information later
183 /// Treat `impl Trait` as shorthand for a new universal existential parameter.
184 /// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually
185 /// equivalent to a fresh existential parameter like `abstract type T; fn foo() -> T`.
188 /// `impl Trait` is not accepted in this position.
195 dep_graph: &DepGraph,
197 resolver: &mut Resolver,
199 // We're constructing the HIR here; we don't care what we will
200 // read, since we haven't even constructed the *input* to
202 dep_graph.assert_ignored();
205 crate_root: std_inject::injected_crate_name(),
210 name_map: FxHashMap(),
211 items: BTreeMap::new(),
212 trait_items: BTreeMap::new(),
213 impl_items: BTreeMap::new(),
214 bodies: BTreeMap::new(),
215 trait_impls: BTreeMap::new(),
216 trait_auto_impl: BTreeMap::new(),
217 exported_macros: Vec::new(),
218 catch_scopes: Vec::new(),
219 loop_scopes: Vec::new(),
220 is_in_loop_condition: false,
221 anonymous_lifetime_mode: AnonymousLifetimeMode::PassThrough,
222 type_def_lifetime_params: DefIdMap(),
223 current_hir_id_owner: vec![(CRATE_DEF_INDEX, 0)],
224 item_local_id_counters: NodeMap(),
225 node_id_to_hir_id: IndexVec::new(),
227 is_in_trait_impl: false,
228 in_band_ty_params: Vec::new(),
229 lifetimes_to_define: Vec::new(),
230 is_collecting_in_band_lifetimes: false,
231 in_scope_lifetimes: Vec::new(),
235 #[derive(Copy, Clone, PartialEq, Eq)]
237 /// Any path in a type context.
239 /// The `module::Type` in `module::Type::method` in an expression.
243 struct LoweredNodeId {
248 enum ParenthesizedGenericArgs {
254 /// What to do when we encounter an **anonymous** lifetime
255 /// reference. Anonymous lifetime references come in two flavors. You
256 /// have implicit, or fully elided, references to lifetimes, like the
257 /// one in `&T` or `Ref<T>`, and you have `'_` lifetimes, like `&'_ T`
258 /// or `Ref<'_, T>`. These often behave the same, but not always:
260 /// - certain usages of implicit references are deprecated, like
261 /// `Ref<T>`, and we sometimes just give hard errors in those cases
263 /// - for object bounds there is a difference: `Box<dyn Foo>` is not
264 /// the same as `Box<dyn Foo + '_>`.
266 /// We describe the effects of the various modes in terms of three cases:
268 /// - **Modern** -- includes all uses of `'_`, but also the lifetime arg
269 /// of a `&` (e.g., the missing lifetime in something like `&T`)
270 /// - **Dyn Bound** -- if you have something like `Box<dyn Foo>`,
271 /// there is an elided lifetime bound (`Box<dyn Foo + 'X>`). These
272 /// elided bounds follow special rules. Note that this only covers
273 /// cases where *nothing* is written; the `'_` in `Box<dyn Foo +
274 /// '_>` is a case of "modern" elision.
275 /// - **Deprecated** -- this coverse cases like `Ref<T>`, where the lifetime
276 /// parameter to ref is completely elided. `Ref<'_, T>` would be the modern,
277 /// non-deprecated equivalent.
279 /// Currently, the handling of lifetime elision is somewhat spread out
280 /// between HIR lowering and -- as described below -- the
281 /// `resolve_lifetime` module. Often we "fallthrough" to that code by generating
282 /// an "elided" or "underscore" lifetime name. In the future, we probably want to move
283 /// everything into HIR lowering.
284 #[derive(Copy, Clone)]
285 enum AnonymousLifetimeMode {
286 /// For **Modern** cases, create a new anonymous region parameter
287 /// and reference that.
289 /// For **Dyn Bound** cases, pass responsibility to
290 /// `resolve_lifetime` code.
292 /// For **Deprecated** cases, report an error.
295 /// Pass responsibility to `resolve_lifetime` code for all cases.
299 impl<'a> LoweringContext<'a> {
300 fn lower_crate(mut self, c: &Crate) -> hir::Crate {
301 /// Full-crate AST visitor that inserts into a fresh
302 /// `LoweringContext` any information that may be
303 /// needed from arbitrary locations in the crate.
304 /// E.g. The number of lifetime generic parameters
305 /// declared for every type and trait definition.
306 struct MiscCollector<'lcx, 'interner: 'lcx> {
307 lctx: &'lcx mut LoweringContext<'interner>,
310 impl<'lcx, 'interner> Visitor<'lcx> for MiscCollector<'lcx, 'interner> {
311 fn visit_item(&mut self, item: &'lcx Item) {
312 self.lctx.allocate_hir_id_counter(item.id, item);
315 ItemKind::Struct(_, ref generics)
316 | ItemKind::Union(_, ref generics)
317 | ItemKind::Enum(_, ref generics)
318 | ItemKind::Ty(_, ref generics)
319 | ItemKind::Trait(_, _, ref generics, ..) => {
320 let def_id = self.lctx.resolver.definitions().local_def_id(item.id);
324 .filter(|param| param.is_lifetime_param())
326 self.lctx.type_def_lifetime_params.insert(def_id, count);
330 visit::walk_item(self, item);
333 fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
334 self.lctx.allocate_hir_id_counter(item.id, item);
335 visit::walk_trait_item(self, item);
338 fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
339 self.lctx.allocate_hir_id_counter(item.id, item);
340 visit::walk_impl_item(self, item);
344 struct ItemLowerer<'lcx, 'interner: 'lcx> {
345 lctx: &'lcx mut LoweringContext<'interner>,
348 impl<'lcx, 'interner> ItemLowerer<'lcx, 'interner> {
349 fn with_trait_impl_ref<F>(&mut self, trait_impl_ref: &Option<TraitRef>, f: F)
351 F: FnOnce(&mut Self),
353 let old = self.lctx.is_in_trait_impl;
354 self.lctx.is_in_trait_impl = if let &None = trait_impl_ref {
360 self.lctx.is_in_trait_impl = old;
364 impl<'lcx, 'interner> Visitor<'lcx> for ItemLowerer<'lcx, 'interner> {
365 fn visit_item(&mut self, item: &'lcx Item) {
366 let mut item_lowered = true;
367 self.lctx.with_hir_id_owner(item.id, |lctx| {
368 if let Some(hir_item) = lctx.lower_item(item) {
369 lctx.items.insert(item.id, hir_item);
371 item_lowered = false;
376 let item_lifetimes = match self.lctx.items.get(&item.id).unwrap().node {
377 hir::Item_::ItemImpl(_, _, _, ref generics, ..)
378 | hir::Item_::ItemTrait(_, _, ref generics, ..) => {
379 generics.lifetimes().cloned().collect::<Vec<_>>()
385 .with_parent_impl_lifetime_defs(&item_lifetimes, |this| {
386 let this = &mut ItemLowerer { lctx: this };
387 if let ItemKind::Impl(_, _, _, _, ref opt_trait_ref, _, _) = item.node {
388 this.with_trait_impl_ref(opt_trait_ref, |this| {
389 visit::walk_item(this, item)
392 visit::walk_item(this, item);
398 fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
399 self.lctx.with_hir_id_owner(item.id, |lctx| {
400 let id = hir::TraitItemId { node_id: item.id };
401 let hir_item = lctx.lower_trait_item(item);
402 lctx.trait_items.insert(id, hir_item);
405 visit::walk_trait_item(self, item);
408 fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
409 self.lctx.with_hir_id_owner(item.id, |lctx| {
410 let id = hir::ImplItemId { node_id: item.id };
411 let hir_item = lctx.lower_impl_item(item);
412 lctx.impl_items.insert(id, hir_item);
414 visit::walk_impl_item(self, item);
418 self.lower_node_id(CRATE_NODE_ID);
419 debug_assert!(self.node_id_to_hir_id[CRATE_NODE_ID] == hir::CRATE_HIR_ID);
421 visit::walk_crate(&mut MiscCollector { lctx: &mut self }, c);
422 visit::walk_crate(&mut ItemLowerer { lctx: &mut self }, c);
424 let module = self.lower_mod(&c.module);
425 let attrs = self.lower_attrs(&c.attrs);
426 let body_ids = body_ids(&self.bodies);
430 .init_node_id_to_hir_id_mapping(self.node_id_to_hir_id);
436 exported_macros: hir::HirVec::from(self.exported_macros),
438 trait_items: self.trait_items,
439 impl_items: self.impl_items,
442 trait_impls: self.trait_impls,
443 trait_auto_impl: self.trait_auto_impl,
447 fn allocate_hir_id_counter<T: Debug>(&mut self, owner: NodeId, debug: &T) {
448 if self.item_local_id_counters.insert(owner, 0).is_some() {
450 "Tried to allocate item_local_id_counter for {:?} twice",
454 // Always allocate the first HirId for the owner itself
455 self.lower_node_id_with_owner(owner, owner);
458 fn lower_node_id_generic<F>(&mut self, ast_node_id: NodeId, alloc_hir_id: F) -> LoweredNodeId
460 F: FnOnce(&mut Self) -> hir::HirId,
462 if ast_node_id == DUMMY_NODE_ID {
463 return LoweredNodeId {
464 node_id: DUMMY_NODE_ID,
465 hir_id: hir::DUMMY_HIR_ID,
469 let min_size = ast_node_id.as_usize() + 1;
471 if min_size > self.node_id_to_hir_id.len() {
472 self.node_id_to_hir_id.resize(min_size, hir::DUMMY_HIR_ID);
475 let existing_hir_id = self.node_id_to_hir_id[ast_node_id];
477 if existing_hir_id == hir::DUMMY_HIR_ID {
478 // Generate a new HirId
479 let hir_id = alloc_hir_id(self);
480 self.node_id_to_hir_id[ast_node_id] = hir_id;
482 node_id: ast_node_id,
487 node_id: ast_node_id,
488 hir_id: existing_hir_id,
493 fn with_hir_id_owner<F>(&mut self, owner: NodeId, f: F)
495 F: FnOnce(&mut Self),
497 let counter = self.item_local_id_counters
498 .insert(owner, HIR_ID_COUNTER_LOCKED)
500 let def_index = self.resolver.definitions().opt_def_index(owner).unwrap();
501 self.current_hir_id_owner.push((def_index, counter));
503 let (new_def_index, new_counter) = self.current_hir_id_owner.pop().unwrap();
505 debug_assert!(def_index == new_def_index);
506 debug_assert!(new_counter >= counter);
508 let prev = self.item_local_id_counters
509 .insert(owner, new_counter)
511 debug_assert!(prev == HIR_ID_COUNTER_LOCKED);
514 /// This method allocates a new HirId for the given NodeId and stores it in
515 /// the LoweringContext's NodeId => HirId map.
516 /// Take care not to call this method if the resulting HirId is then not
517 /// actually used in the HIR, as that would trigger an assertion in the
518 /// HirIdValidator later on, which makes sure that all NodeIds got mapped
519 /// properly. Calling the method twice with the same NodeId is fine though.
520 fn lower_node_id(&mut self, ast_node_id: NodeId) -> LoweredNodeId {
521 self.lower_node_id_generic(ast_node_id, |this| {
522 let &mut (def_index, ref mut local_id_counter) =
523 this.current_hir_id_owner.last_mut().unwrap();
524 let local_id = *local_id_counter;
525 *local_id_counter += 1;
528 local_id: hir::ItemLocalId(local_id),
533 fn lower_node_id_with_owner(&mut self, ast_node_id: NodeId, owner: NodeId) -> LoweredNodeId {
534 self.lower_node_id_generic(ast_node_id, |this| {
535 let local_id_counter = this.item_local_id_counters.get_mut(&owner).unwrap();
536 let local_id = *local_id_counter;
538 // We want to be sure not to modify the counter in the map while it
539 // is also on the stack. Otherwise we'll get lost updates when writing
540 // back from the stack to the map.
541 debug_assert!(local_id != HIR_ID_COUNTER_LOCKED);
543 *local_id_counter += 1;
544 let def_index = this.resolver.definitions().opt_def_index(owner).unwrap();
548 local_id: hir::ItemLocalId(local_id),
553 fn record_body(&mut self, value: hir::Expr, decl: Option<&FnDecl>) -> hir::BodyId {
554 let body = hir::Body {
555 arguments: decl.map_or(hir_vec![], |decl| {
556 decl.inputs.iter().map(|x| self.lower_arg(x)).collect()
558 is_generator: self.is_generator,
562 self.bodies.insert(id, body);
566 fn next_id(&mut self) -> LoweredNodeId {
567 self.lower_node_id(self.sess.next_node_id())
570 fn expect_full_def(&mut self, id: NodeId) -> Def {
571 self.resolver.get_resolution(id).map_or(Def::Err, |pr| {
572 if pr.unresolved_segments() != 0 {
573 bug!("path not fully resolved: {:?}", pr);
579 fn diagnostic(&self) -> &errors::Handler {
580 self.sess.diagnostic()
583 fn str_to_ident(&self, s: &'static str) -> Name {
587 fn allow_internal_unstable(&self, reason: CompilerDesugaringKind, span: Span) -> Span {
588 let mark = Mark::fresh(Mark::root());
589 mark.set_expn_info(codemap::ExpnInfo {
591 callee: codemap::NameAndSpan {
592 format: codemap::CompilerDesugaring(reason),
594 allow_internal_unstable: true,
595 allow_internal_unsafe: false,
598 span.with_ctxt(SyntaxContext::empty().apply_mark(mark))
601 /// Creates a new hir::GenericParam for every new lifetime and
602 /// type parameter encountered while evaluating `f`. Definitions
603 /// are created with the parent provided. If no `parent_id` is
604 /// provided, no definitions will be returned.
606 /// Presuming that in-band lifetimes are enabled, then
607 /// `self.anonymous_lifetime_mode` will be updated to match the
608 /// argument while `f` is running (and restored afterwards).
609 fn collect_in_band_defs<T, F>(
612 anonymous_lifetime_mode: AnonymousLifetimeMode,
614 ) -> (Vec<hir::GenericParam>, T)
616 F: FnOnce(&mut LoweringContext) -> T,
618 assert!(!self.is_collecting_in_band_lifetimes);
619 assert!(self.lifetimes_to_define.is_empty());
620 let old_anonymous_lifetime_mode = self.anonymous_lifetime_mode;
622 self.is_collecting_in_band_lifetimes = self.sess.features_untracked().in_band_lifetimes;
623 if self.is_collecting_in_band_lifetimes {
624 self.anonymous_lifetime_mode = anonymous_lifetime_mode;
627 assert!(self.in_band_ty_params.is_empty());
630 self.is_collecting_in_band_lifetimes = false;
631 self.anonymous_lifetime_mode = old_anonymous_lifetime_mode;
633 let in_band_ty_params = self.in_band_ty_params.split_off(0);
634 let lifetimes_to_define = self.lifetimes_to_define.split_off(0);
636 let params = lifetimes_to_define
638 .map(|(span, hir_name)| {
639 let def_node_id = self.next_id().node_id;
641 // Get the name we'll use to make the def-path. Note
642 // that collisions are ok here and this shouldn't
643 // really show up for end-user.
644 let str_name = match hir_name {
645 hir::LifetimeName::Name(n) => n.as_str(),
646 hir::LifetimeName::Fresh(_) => keywords::UnderscoreLifetime.name().as_str(),
647 hir::LifetimeName::Implicit
648 | hir::LifetimeName::Underscore
649 | hir::LifetimeName::Static => {
650 span_bug!(span, "unexpected in-band lifetime name: {:?}", hir_name)
654 // Add a definition for the in-band lifetime def
655 self.resolver.definitions().create_def_with_parent(
658 DefPathData::LifetimeDef(str_name),
659 DefIndexAddressSpace::High,
664 hir::GenericParam::Lifetime(hir::LifetimeDef {
665 lifetime: hir::Lifetime {
670 bounds: Vec::new().into(),
671 pure_wrt_drop: false,
678 .map(|tp| hir::GenericParam::Type(tp)),
685 /// When there is a reference to some lifetime `'a`, and in-band
686 /// lifetimes are enabled, then we want to push that lifetime into
687 /// the vector of names to define later. In that case, it will get
688 /// added to the appropriate generics.
689 fn maybe_collect_in_band_lifetime(&mut self, span: Span, name: Name) {
690 if !self.is_collecting_in_band_lifetimes {
694 if self.in_scope_lifetimes.contains(&name) {
698 let hir_name = hir::LifetimeName::Name(name);
700 if self.lifetimes_to_define
702 .any(|(_, lt_name)| *lt_name == hir_name)
707 self.lifetimes_to_define.push((span, hir_name));
710 /// When we have either an elided or `'_` lifetime in an impl
711 /// header, we convert it to
712 fn collect_fresh_in_band_lifetime(&mut self, span: Span) -> hir::LifetimeName {
713 assert!(self.is_collecting_in_band_lifetimes);
714 let index = self.lifetimes_to_define.len();
715 let hir_name = hir::LifetimeName::Fresh(index);
716 self.lifetimes_to_define.push((span, hir_name));
720 // Evaluates `f` with the lifetimes in `lt_defs` in-scope.
721 // This is used to track which lifetimes have already been defined, and
722 // which are new in-band lifetimes that need to have a definition created
724 fn with_in_scope_lifetime_defs<'l, T, F>(
726 lt_defs: impl Iterator<Item = &'l LifetimeDef>,
730 F: FnOnce(&mut LoweringContext) -> T,
732 let old_len = self.in_scope_lifetimes.len();
733 let lt_def_names = lt_defs.map(|lt_def| lt_def.lifetime.ident.name);
734 self.in_scope_lifetimes.extend(lt_def_names);
738 self.in_scope_lifetimes.truncate(old_len);
742 // Same as the method above, but accepts `hir::LifetimeDef`s
743 // instead of `ast::LifetimeDef`s.
744 // This should only be used with generics that have already had their
745 // in-band lifetimes added. In practice, this means that this function is
746 // only used when lowering a child item of a trait or impl.
747 fn with_parent_impl_lifetime_defs<T, F>(&mut self, lt_defs: &[hir::LifetimeDef], f: F) -> T
749 F: FnOnce(&mut LoweringContext) -> T,
751 let old_len = self.in_scope_lifetimes.len();
752 let lt_def_names = lt_defs.iter().map(|lt_def| lt_def.lifetime.name.name());
753 self.in_scope_lifetimes.extend(lt_def_names);
757 self.in_scope_lifetimes.truncate(old_len);
761 /// Appends in-band lifetime defs and argument-position `impl
762 /// Trait` defs to the existing set of generics.
764 /// Presuming that in-band lifetimes are enabled, then
765 /// `self.anonymous_lifetime_mode` will be updated to match the
766 /// argument while `f` is running (and restored afterwards).
767 fn add_in_band_defs<F, T>(
771 anonymous_lifetime_mode: AnonymousLifetimeMode,
773 ) -> (hir::Generics, T)
775 F: FnOnce(&mut LoweringContext) -> T,
777 let (in_band_defs, (mut lowered_generics, res)) = self.with_in_scope_lifetime_defs(
778 generics.params.iter().filter_map(|p| match p {
779 GenericParam::Lifetime(ld) => Some(ld),
783 this.collect_in_band_defs(parent_id, anonymous_lifetime_mode, |this| {
784 (this.lower_generics(generics), f(this))
789 lowered_generics.params = lowered_generics
796 (lowered_generics, res)
799 fn with_catch_scope<T, F>(&mut self, catch_id: NodeId, f: F) -> T
801 F: FnOnce(&mut LoweringContext) -> T,
803 let len = self.catch_scopes.len();
804 self.catch_scopes.push(catch_id);
806 let result = f(self);
809 self.catch_scopes.len(),
810 "catch scopes should be added and removed in stack order"
813 self.catch_scopes.pop().unwrap();
818 fn lower_body<F>(&mut self, decl: Option<&FnDecl>, f: F) -> hir::BodyId
820 F: FnOnce(&mut LoweringContext) -> hir::Expr,
822 let prev = mem::replace(&mut self.is_generator, false);
823 let result = f(self);
824 let r = self.record_body(result, decl);
825 self.is_generator = prev;
829 fn with_loop_scope<T, F>(&mut self, loop_id: NodeId, f: F) -> T
831 F: FnOnce(&mut LoweringContext) -> T,
833 // We're no longer in the base loop's condition; we're in another loop.
834 let was_in_loop_condition = self.is_in_loop_condition;
835 self.is_in_loop_condition = false;
837 let len = self.loop_scopes.len();
838 self.loop_scopes.push(loop_id);
840 let result = f(self);
843 self.loop_scopes.len(),
844 "Loop scopes should be added and removed in stack order"
847 self.loop_scopes.pop().unwrap();
849 self.is_in_loop_condition = was_in_loop_condition;
854 fn with_loop_condition_scope<T, F>(&mut self, f: F) -> T
856 F: FnOnce(&mut LoweringContext) -> T,
858 let was_in_loop_condition = self.is_in_loop_condition;
859 self.is_in_loop_condition = true;
861 let result = f(self);
863 self.is_in_loop_condition = was_in_loop_condition;
868 fn with_new_scopes<T, F>(&mut self, f: F) -> T
870 F: FnOnce(&mut LoweringContext) -> T,
872 let was_in_loop_condition = self.is_in_loop_condition;
873 self.is_in_loop_condition = false;
875 let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new());
876 let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new());
877 let result = f(self);
878 self.catch_scopes = catch_scopes;
879 self.loop_scopes = loop_scopes;
881 self.is_in_loop_condition = was_in_loop_condition;
886 fn with_parent_def<T, F>(&mut self, parent_id: NodeId, f: F) -> T
888 F: FnOnce(&mut LoweringContext) -> T,
890 let old_def = self.parent_def;
892 let defs = self.resolver.definitions();
893 Some(defs.opt_def_index(parent_id).unwrap())
896 let result = f(self);
898 self.parent_def = old_def;
902 fn def_key(&mut self, id: DefId) -> DefKey {
904 self.resolver.definitions().def_key(id.index)
906 self.cstore.def_key(id)
910 fn lower_ident(&mut self, ident: Ident) -> Name {
911 let ident = ident.modern();
912 if ident.span.ctxt() == SyntaxContext::empty() {
917 .or_insert_with(|| Symbol::from_ident(ident))
920 fn lower_label(&mut self, label: Option<Label>) -> Option<hir::Label> {
921 label.map(|label| hir::Label {
922 name: label.ident.name,
923 span: label.ident.span,
927 fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination {
929 Some((id, label)) => {
930 let target = if let Def::Label(loop_id) = self.expect_full_def(id) {
931 hir::LoopIdResult::Ok(self.lower_node_id(loop_id).node_id)
933 hir::LoopIdResult::Err(hir::LoopIdError::UnresolvedLabel)
936 label: self.lower_label(Some(label)),
937 target_id: hir::ScopeTarget::Loop(target),
941 let loop_id = self.loop_scopes
943 .map(|innermost_loop_id| *innermost_loop_id);
947 target_id: hir::ScopeTarget::Loop(
949 .map(|id| Ok(self.lower_node_id(id).node_id))
950 .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
958 fn lower_attrs(&mut self, attrs: &[Attribute]) -> hir::HirVec<Attribute> {
961 .map(|a| self.lower_attr(a))
966 fn lower_attr(&mut self, attr: &Attribute) -> Attribute {
970 path: attr.path.clone(),
971 tokens: self.lower_token_stream(attr.tokens.clone()),
972 is_sugared_doc: attr.is_sugared_doc,
977 fn lower_token_stream(&mut self, tokens: TokenStream) -> TokenStream {
980 .flat_map(|tree| self.lower_token_tree(tree).into_trees())
984 fn lower_token_tree(&mut self, tree: TokenTree) -> TokenStream {
986 TokenTree::Token(span, token) => self.lower_token(token, span),
987 TokenTree::Delimited(span, delimited) => TokenTree::Delimited(
990 delim: delimited.delim,
991 tts: self.lower_token_stream(delimited.tts.into()).into(),
997 fn lower_token(&mut self, token: Token, span: Span) -> TokenStream {
999 Token::Interpolated(_) => {}
1000 other => return TokenTree::Token(span, other).into(),
1003 let tts = token.interpolated_to_tokenstream(&self.sess.parse_sess, span);
1004 self.lower_token_stream(tts)
1007 fn lower_arm(&mut self, arm: &Arm) -> hir::Arm {
1009 attrs: self.lower_attrs(&arm.attrs),
1010 pats: arm.pats.iter().map(|x| self.lower_pat(x)).collect(),
1011 guard: arm.guard.as_ref().map(|ref x| P(self.lower_expr(x))),
1012 body: P(self.lower_expr(&arm.body)),
1016 fn lower_ty_binding(&mut self, b: &TypeBinding, itctx: ImplTraitContext) -> hir::TypeBinding {
1018 id: self.lower_node_id(b.id).node_id,
1019 name: self.lower_ident(b.ident),
1020 ty: self.lower_ty(&b.ty, itctx),
1025 fn lower_ty(&mut self, t: &Ty, itctx: ImplTraitContext) -> P<hir::Ty> {
1026 let kind = match t.node {
1027 TyKind::Infer => hir::TyInfer,
1028 TyKind::Err => hir::TyErr,
1029 TyKind::Slice(ref ty) => hir::TySlice(self.lower_ty(ty, itctx)),
1030 TyKind::Ptr(ref mt) => hir::TyPtr(self.lower_mt(mt, itctx)),
1031 TyKind::Rptr(ref region, ref mt) => {
1032 let span = t.span.shrink_to_lo();
1033 let lifetime = match *region {
1034 Some(ref lt) => self.lower_lifetime(lt),
1035 None => self.elided_ref_lifetime(span),
1037 hir::TyRptr(lifetime, self.lower_mt(mt, itctx))
1039 TyKind::BareFn(ref f) => self.with_in_scope_lifetime_defs(
1040 f.generic_params.iter().filter_map(|p| match p {
1041 GenericParam::Lifetime(ld) => Some(ld),
1045 hir::TyBareFn(P(hir::BareFnTy {
1046 generic_params: this.lower_generic_params(&f.generic_params, &NodeMap()),
1047 unsafety: this.lower_unsafety(f.unsafety),
1049 decl: this.lower_fn_decl(&f.decl, None, false),
1050 arg_names: this.lower_fn_args_to_names(&f.decl),
1054 TyKind::Never => hir::TyNever,
1055 TyKind::Tup(ref tys) => {
1056 hir::TyTup(tys.iter().map(|ty| self.lower_ty(ty, itctx)).collect())
1058 TyKind::Paren(ref ty) => {
1059 return self.lower_ty(ty, itctx);
1061 TyKind::Path(ref qself, ref path) => {
1062 let id = self.lower_node_id(t.id);
1063 let qpath = self.lower_qpath(t.id, qself, path, ParamMode::Explicit, itctx);
1064 let ty = self.ty_path(id, t.span, qpath);
1065 if let hir::TyTraitObject(..) = ty.node {
1066 self.maybe_lint_bare_trait(t.span, t.id, qself.is_none() && path.is_global());
1070 TyKind::ImplicitSelf => hir::TyPath(hir::QPath::Resolved(
1073 def: self.expect_full_def(t.id),
1074 segments: hir_vec![hir::PathSegment::from_name(keywords::SelfType.name())],
1078 TyKind::Array(ref ty, ref length) => {
1079 let length = self.lower_body(None, |this| this.lower_expr(length));
1080 hir::TyArray(self.lower_ty(ty, itctx), length)
1082 TyKind::Typeof(ref expr) => {
1083 let expr = self.lower_body(None, |this| this.lower_expr(expr));
1086 TyKind::TraitObject(ref bounds, kind) => {
1087 let mut lifetime_bound = None;
1090 .filter_map(|bound| match *bound {
1091 TraitTyParamBound(ref ty, TraitBoundModifier::None) => {
1092 Some(self.lower_poly_trait_ref(ty, itctx))
1094 TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
1095 RegionTyParamBound(ref lifetime) => {
1096 if lifetime_bound.is_none() {
1097 lifetime_bound = Some(self.lower_lifetime(lifetime));
1103 let lifetime_bound =
1104 lifetime_bound.unwrap_or_else(|| self.elided_dyn_bound(t.span));
1105 if kind != TraitObjectSyntax::Dyn {
1106 self.maybe_lint_bare_trait(t.span, t.id, false);
1108 hir::TyTraitObject(bounds, lifetime_bound)
1110 TyKind::ImplTrait(ref bounds) => {
1113 ImplTraitContext::Existential => {
1114 let def_index = self.resolver.definitions().opt_def_index(t.id).unwrap();
1115 let hir_bounds = self.lower_bounds(bounds, itctx);
1116 let (lifetimes, lifetime_defs) =
1117 self.lifetimes_from_impl_trait_bounds(def_index, &hir_bounds);
1119 hir::TyImplTraitExistential(
1121 generics: hir::Generics {
1122 params: lifetime_defs,
1123 where_clause: hir::WhereClause {
1124 id: self.next_id().node_id,
1125 predicates: Vec::new().into(),
1134 ImplTraitContext::Universal(def_id) => {
1135 let def_node_id = self.next_id().node_id;
1137 // Add a definition for the in-band TyParam
1138 let def_index = self.resolver.definitions().create_def_with_parent(
1141 DefPathData::ImplTrait,
1142 DefIndexAddressSpace::High,
1147 let hir_bounds = self.lower_bounds(bounds, itctx);
1148 // Set the name to `impl Bound1 + Bound2`
1149 let name = Symbol::intern(&pprust::ty_to_string(t));
1150 self.in_band_ty_params.push(hir::TyParam {
1156 pure_wrt_drop: false,
1157 synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
1161 hir::TyPath(hir::QPath::Resolved(
1165 def: Def::TyParam(DefId::local(def_index)),
1166 segments: hir_vec![hir::PathSegment::from_name(name)],
1170 ImplTraitContext::Disallowed => {
1175 "`impl Trait` not allowed outside of function \
1176 and inherent method return types"
1182 TyKind::Mac(_) => panic!("TyMac should have been expanded by now."),
1185 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(t.id);
1194 fn lifetimes_from_impl_trait_bounds(
1196 parent_index: DefIndex,
1197 bounds: &hir::TyParamBounds,
1198 ) -> (HirVec<hir::Lifetime>, HirVec<hir::GenericParam>) {
1199 // This visitor walks over impl trait bounds and creates defs for all lifetimes which
1200 // appear in the bounds, excluding lifetimes that are created within the bounds.
1201 // e.g. 'a, 'b, but not 'c in `impl for<'c> SomeTrait<'a, 'b, 'c>`
1202 struct ImplTraitLifetimeCollector<'r, 'a: 'r> {
1203 context: &'r mut LoweringContext<'a>,
1205 collect_elided_lifetimes: bool,
1206 currently_bound_lifetimes: Vec<hir::LifetimeName>,
1207 already_defined_lifetimes: HashSet<hir::LifetimeName>,
1208 output_lifetimes: Vec<hir::Lifetime>,
1209 output_lifetime_params: Vec<hir::GenericParam>,
1212 impl<'r, 'a: 'r, 'v> hir::intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r, 'a> {
1213 fn nested_visit_map<'this>(
1215 ) -> hir::intravisit::NestedVisitorMap<'this, 'v> {
1216 hir::intravisit::NestedVisitorMap::None
1219 fn visit_path_parameters(&mut self, span: Span, parameters: &'v hir::PathParameters) {
1220 // Don't collect elided lifetimes used inside of `Fn()` syntax.
1221 if parameters.parenthesized {
1222 let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
1223 self.collect_elided_lifetimes = false;
1224 hir::intravisit::walk_path_parameters(self, span, parameters);
1225 self.collect_elided_lifetimes = old_collect_elided_lifetimes;
1227 hir::intravisit::walk_path_parameters(self, span, parameters);
1231 fn visit_ty(&mut self, t: &'v hir::Ty) {
1232 // Don't collect elided lifetimes used inside of `fn()` syntax
1233 if let &hir::Ty_::TyBareFn(_) = &t.node {
1234 let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
1235 self.collect_elided_lifetimes = false;
1236 hir::intravisit::walk_ty(self, t);
1237 self.collect_elided_lifetimes = old_collect_elided_lifetimes;
1239 hir::intravisit::walk_ty(self, t);
1243 fn visit_poly_trait_ref(
1245 polytr: &'v hir::PolyTraitRef,
1246 _: hir::TraitBoundModifier,
1248 let old_len = self.currently_bound_lifetimes.len();
1250 // Record the introduction of 'a in `for<'a> ...`
1251 for param in &polytr.bound_generic_params {
1252 if let hir::GenericParam::Lifetime(ref lt_def) = *param {
1253 // Introduce lifetimes one at a time so that we can handle
1254 // cases like `fn foo<'d>() -> impl for<'a, 'b: 'a, 'c: 'b + 'd>`
1255 self.currently_bound_lifetimes.push(lt_def.lifetime.name);
1257 // Visit the lifetime bounds
1258 for lt_bound in <_def.bounds {
1259 self.visit_lifetime(<_bound);
1264 hir::intravisit::walk_trait_ref(self, &polytr.trait_ref);
1266 self.currently_bound_lifetimes.truncate(old_len);
1269 fn visit_lifetime(&mut self, lifetime: &'v hir::Lifetime) {
1270 let name = match lifetime.name {
1271 hir::LifetimeName::Implicit | hir::LifetimeName::Underscore => {
1272 if self.collect_elided_lifetimes {
1273 // Use `'_` for both implicit and underscore lifetimes in
1274 // `abstract type Foo<'_>: SomeTrait<'_>;`
1275 hir::LifetimeName::Underscore
1280 name @ hir::LifetimeName::Fresh(_) => name,
1281 name @ hir::LifetimeName::Name(_) => name,
1282 hir::LifetimeName::Static => return,
1285 if !self.currently_bound_lifetimes.contains(&name)
1286 && !self.already_defined_lifetimes.contains(&name)
1288 self.already_defined_lifetimes.insert(name);
1290 self.output_lifetimes.push(hir::Lifetime {
1291 id: self.context.next_id().node_id,
1292 span: lifetime.span,
1296 let def_node_id = self.context.next_id().node_id;
1297 self.context.resolver.definitions().create_def_with_parent(
1300 DefPathData::LifetimeDef(name.name().as_str()),
1301 DefIndexAddressSpace::High,
1305 let def_lifetime = hir::Lifetime {
1307 span: lifetime.span,
1310 self.output_lifetime_params
1311 .push(hir::GenericParam::Lifetime(hir::LifetimeDef {
1312 lifetime: def_lifetime,
1313 bounds: Vec::new().into(),
1314 pure_wrt_drop: false,
1321 let mut lifetime_collector = ImplTraitLifetimeCollector {
1323 parent: parent_index,
1324 collect_elided_lifetimes: true,
1325 currently_bound_lifetimes: Vec::new(),
1326 already_defined_lifetimes: HashSet::new(),
1327 output_lifetimes: Vec::new(),
1328 output_lifetime_params: Vec::new(),
1331 for bound in bounds {
1332 hir::intravisit::walk_ty_param_bound(&mut lifetime_collector, &bound);
1336 lifetime_collector.output_lifetimes.into(),
1337 lifetime_collector.output_lifetime_params.into(),
1341 fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod {
1346 .map(|x| self.lower_foreign_item(x))
1351 fn lower_global_asm(&mut self, ga: &GlobalAsm) -> P<hir::GlobalAsm> {
1358 fn lower_variant(&mut self, v: &Variant) -> hir::Variant {
1360 node: hir::Variant_ {
1361 name: v.node.ident.name,
1362 attrs: self.lower_attrs(&v.node.attrs),
1363 data: self.lower_variant_data(&v.node.data),
1367 .map(|e| self.lower_body(None, |this| this.lower_expr(e))),
1376 qself: &Option<QSelf>,
1378 param_mode: ParamMode,
1379 itctx: ImplTraitContext,
1381 let qself_position = qself.as_ref().map(|q| q.position);
1382 let qself = qself.as_ref().map(|q| self.lower_ty(&q.ty, itctx));
1384 let resolution = self.resolver
1386 .unwrap_or(PathResolution::new(Def::Err));
1388 let proj_start = p.segments.len() - resolution.unresolved_segments();
1389 let path = P(hir::Path {
1390 def: resolution.base_def(),
1391 segments: p.segments[..proj_start]
1394 .map(|(i, segment)| {
1395 let param_mode = match (qself_position, param_mode) {
1396 (Some(j), ParamMode::Optional) if i < j => {
1397 // This segment is part of the trait path in a
1398 // qualified path - one of `a`, `b` or `Trait`
1399 // in `<X as a::b::Trait>::T::U::method`.
1405 // Figure out if this is a type/trait segment,
1406 // which may need lifetime elision performed.
1407 let parent_def_id = |this: &mut Self, def_id: DefId| DefId {
1408 krate: def_id.krate,
1409 index: this.def_key(def_id).parent.expect("missing parent"),
1411 let type_def_id = match resolution.base_def() {
1412 Def::AssociatedTy(def_id) if i + 2 == proj_start => {
1413 Some(parent_def_id(self, def_id))
1415 Def::Variant(def_id) if i + 1 == proj_start => {
1416 Some(parent_def_id(self, def_id))
1419 | Def::Union(def_id)
1421 | Def::TyAlias(def_id)
1422 | Def::Trait(def_id) if i + 1 == proj_start =>
1428 let parenthesized_generic_args = match resolution.base_def() {
1429 // `a::b::Trait(Args)`
1430 Def::Trait(..) if i + 1 == proj_start => ParenthesizedGenericArgs::Ok,
1431 // `a::b::Trait(Args)::TraitItem`
1432 Def::Method(..) | Def::AssociatedConst(..) | Def::AssociatedTy(..)
1433 if i + 2 == proj_start =>
1435 ParenthesizedGenericArgs::Ok
1437 // Avoid duplicated errors
1438 Def::Err => ParenthesizedGenericArgs::Ok,
1444 | Def::Variant(..) if i + 1 == proj_start =>
1446 ParenthesizedGenericArgs::Err
1448 // A warning for now, for compatibility reasons
1449 _ => ParenthesizedGenericArgs::Warn,
1452 let num_lifetimes = type_def_id.map_or(0, |def_id| {
1453 if let Some(&n) = self.type_def_lifetime_params.get(&def_id) {
1456 assert!(!def_id.is_local());
1458 .item_generics_cloned_untracked(def_id, self.sess)
1461 self.type_def_lifetime_params.insert(def_id, n);
1464 self.lower_path_segment(
1469 parenthesized_generic_args,
1477 // Simple case, either no projections, or only fully-qualified.
1478 // E.g. `std::mem::size_of` or `<I as Iterator>::Item`.
1479 if resolution.unresolved_segments() == 0 {
1480 return hir::QPath::Resolved(qself, path);
1483 // Create the innermost type that we're projecting from.
1484 let mut ty = if path.segments.is_empty() {
1485 // If the base path is empty that means there exists a
1486 // syntactical `Self`, e.g. `&i32` in `<&i32>::clone`.
1487 qself.expect("missing QSelf for <T>::...")
1489 // Otherwise, the base path is an implicit `Self` type path,
1490 // e.g. `Vec` in `Vec::new` or `<I as Iterator>::Item` in
1491 // `<I as Iterator>::Item::default`.
1492 let new_id = self.next_id();
1493 self.ty_path(new_id, p.span, hir::QPath::Resolved(qself, path))
1496 // Anything after the base path are associated "extensions",
1497 // out of which all but the last one are associated types,
1498 // e.g. for `std::vec::Vec::<T>::IntoIter::Item::clone`:
1499 // * base path is `std::vec::Vec<T>`
1500 // * "extensions" are `IntoIter`, `Item` and `clone`
1501 // * type nodes are:
1502 // 1. `std::vec::Vec<T>` (created above)
1503 // 2. `<std::vec::Vec<T>>::IntoIter`
1504 // 3. `<<std::vec::Vec<T>>::IntoIter>::Item`
1505 // * final path is `<<<std::vec::Vec<T>>::IntoIter>::Item>::clone`
1506 for (i, segment) in p.segments.iter().enumerate().skip(proj_start) {
1507 let segment = P(self.lower_path_segment(
1512 ParenthesizedGenericArgs::Warn,
1515 let qpath = hir::QPath::TypeRelative(ty, segment);
1517 // It's finished, return the extension of the right node type.
1518 if i == p.segments.len() - 1 {
1522 // Wrap the associated extension in another type node.
1523 let new_id = self.next_id();
1524 ty = self.ty_path(new_id, p.span, qpath);
1527 // Should've returned in the for loop above.
1530 "lower_qpath: no final extension segment in {}..{}",
1536 fn lower_path_extra(
1541 param_mode: ParamMode,
1544 def: self.expect_full_def(id),
1545 segments: p.segments
1548 self.lower_path_segment(
1553 ParenthesizedGenericArgs::Err,
1554 ImplTraitContext::Disallowed,
1557 .chain(name.map(|name| hir::PathSegment::from_name(name)))
1563 fn lower_path(&mut self, id: NodeId, p: &Path, param_mode: ParamMode) -> hir::Path {
1564 self.lower_path_extra(id, p, None, param_mode)
1567 fn lower_path_segment(
1570 segment: &PathSegment,
1571 param_mode: ParamMode,
1572 expected_lifetimes: usize,
1573 parenthesized_generic_args: ParenthesizedGenericArgs,
1574 itctx: ImplTraitContext,
1575 ) -> hir::PathSegment {
1576 let (mut parameters, infer_types) = if let Some(ref parameters) = segment.parameters {
1577 let msg = "parenthesized parameters may only be used with a trait";
1578 match **parameters {
1579 PathParameters::AngleBracketed(ref data) => {
1580 self.lower_angle_bracketed_parameter_data(data, param_mode, itctx)
1582 PathParameters::Parenthesized(ref data) => match parenthesized_generic_args {
1583 ParenthesizedGenericArgs::Ok => self.lower_parenthesized_parameter_data(data),
1584 ParenthesizedGenericArgs::Warn => {
1585 self.sess.buffer_lint(
1586 PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
1591 (hir::PathParameters::none(), true)
1593 ParenthesizedGenericArgs::Err => {
1594 struct_span_err!(self.sess, data.span, E0214, "{}", msg)
1595 .span_label(data.span, "only traits may use parentheses")
1597 (hir::PathParameters::none(), true)
1602 self.lower_angle_bracketed_parameter_data(&Default::default(), param_mode, itctx)
1605 if !parameters.parenthesized && parameters.lifetimes.is_empty() {
1606 parameters.lifetimes = self.elided_path_lifetimes(path_span, expected_lifetimes);
1609 hir::PathSegment::new(
1610 self.lower_ident(segment.ident),
1616 fn lower_angle_bracketed_parameter_data(
1618 data: &AngleBracketedParameterData,
1619 param_mode: ParamMode,
1620 itctx: ImplTraitContext,
1621 ) -> (hir::PathParameters, bool) {
1622 let &AngleBracketedParameterData {
1629 hir::PathParameters {
1630 lifetimes: self.lower_lifetimes(lifetimes),
1631 types: types.iter().map(|ty| self.lower_ty(ty, itctx)).collect(),
1634 .map(|b| self.lower_ty_binding(b, itctx))
1636 parenthesized: false,
1638 types.is_empty() && param_mode == ParamMode::Optional,
1642 fn lower_parenthesized_parameter_data(
1644 data: &ParenthesizedParameterData,
1645 ) -> (hir::PathParameters, bool) {
1646 const DISALLOWED: ImplTraitContext = ImplTraitContext::Disallowed;
1647 let &ParenthesizedParameterData {
1654 .map(|ty| self.lower_ty(ty, DISALLOWED))
1656 let mk_tup = |this: &mut Self, tys, span| {
1657 let LoweredNodeId { node_id, hir_id } = this.next_id();
1659 node: hir::TyTup(tys),
1667 hir::PathParameters {
1668 lifetimes: hir::HirVec::new(),
1669 types: hir_vec![mk_tup(self, inputs, span)],
1672 id: self.next_id().node_id,
1673 name: Symbol::intern(FN_OUTPUT_NAME),
1676 .map(|ty| self.lower_ty(&ty, DISALLOWED))
1677 .unwrap_or_else(|| mk_tup(self, hir::HirVec::new(), span)),
1678 span: output.as_ref().map_or(span, |ty| ty.span),
1681 parenthesized: true,
1687 fn lower_local(&mut self, l: &Local) -> P<hir::Local> {
1688 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(l.id);
1694 .map(|t| self.lower_ty(t, ImplTraitContext::Disallowed)),
1695 pat: self.lower_pat(&l.pat),
1696 init: l.init.as_ref().map(|e| P(self.lower_expr(e))),
1698 attrs: l.attrs.clone(),
1699 source: hir::LocalSource::Normal,
1703 fn lower_mutability(&mut self, m: Mutability) -> hir::Mutability {
1705 Mutability::Mutable => hir::MutMutable,
1706 Mutability::Immutable => hir::MutImmutable,
1710 fn lower_arg(&mut self, arg: &Arg) -> hir::Arg {
1711 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(arg.id);
1715 pat: self.lower_pat(&arg.pat),
1719 fn lower_fn_args_to_names(&mut self, decl: &FnDecl) -> hir::HirVec<Spanned<Name>> {
1722 .map(|arg| match arg.pat.node {
1723 PatKind::Ident(_, ident, None) => respan(ident.span, ident.name),
1724 _ => respan(arg.pat.span, keywords::Invalid.name()),
1732 fn_def_id: Option<DefId>,
1733 impl_trait_return_allow: bool,
1734 ) -> P<hir::FnDecl> {
1735 // NOTE: The two last parameters here have to do with impl Trait. If fn_def_id is Some,
1736 // then impl Trait arguments are lowered into generic parameters on the given
1737 // fn_def_id, otherwise impl Trait is disallowed. (for now)
1739 // Furthermore, if impl_trait_return_allow is true, then impl Trait may be used in
1740 // return positions as well. This guards against trait declarations and their impls
1741 // where impl Trait is disallowed. (again for now)
1746 if let Some(def_id) = fn_def_id {
1747 self.lower_ty(&arg.ty, ImplTraitContext::Universal(def_id))
1749 self.lower_ty(&arg.ty, ImplTraitContext::Disallowed)
1753 output: match decl.output {
1754 FunctionRetTy::Ty(ref ty) => match fn_def_id {
1755 Some(_) if impl_trait_return_allow => {
1756 hir::Return(self.lower_ty(ty, ImplTraitContext::Existential))
1758 _ => hir::Return(self.lower_ty(ty, ImplTraitContext::Disallowed)),
1760 FunctionRetTy::Default(span) => hir::DefaultReturn(span),
1762 variadic: decl.variadic,
1763 has_implicit_self: decl.inputs.get(0).map_or(false, |arg| match arg.ty.node {
1764 TyKind::ImplicitSelf => true,
1765 TyKind::Rptr(_, ref mt) => mt.ty.node == TyKind::ImplicitSelf,
1771 fn lower_ty_param_bound(
1774 itctx: ImplTraitContext,
1775 ) -> hir::TyParamBound {
1777 TraitTyParamBound(ref ty, modifier) => hir::TraitTyParamBound(
1778 self.lower_poly_trait_ref(ty, itctx),
1779 self.lower_trait_bound_modifier(modifier),
1781 RegionTyParamBound(ref lifetime) => {
1782 hir::RegionTyParamBound(self.lower_lifetime(lifetime))
1787 fn lower_ty_param(&mut self, tp: &TyParam, add_bounds: &[TyParamBound]) -> hir::TyParam {
1788 let mut name = self.lower_ident(tp.ident);
1790 // Don't expose `Self` (recovered "keyword used as ident" parse error).
1791 // `rustc::ty` expects `Self` to be only used for a trait's `Self`.
1792 // Instead, use gensym("Self") to create a distinct name that looks the same.
1793 if name == keywords::SelfType.name() {
1794 name = Symbol::gensym("Self");
1797 let itctx = ImplTraitContext::Universal(self.resolver.definitions().local_def_id(tp.id));
1798 let mut bounds = self.lower_bounds(&tp.bounds, itctx);
1799 if !add_bounds.is_empty() {
1802 .chain(self.lower_bounds(add_bounds, itctx).into_iter())
1807 id: self.lower_node_id(tp.id).node_id,
1812 .map(|x| self.lower_ty(x, ImplTraitContext::Disallowed)),
1813 span: tp.ident.span,
1814 pure_wrt_drop: attr::contains_name(&tp.attrs, "may_dangle"),
1817 .filter(|attr| attr.check_name("rustc_synthetic"))
1818 .map(|_| hir::SyntheticTyParamKind::ImplTrait)
1820 attrs: self.lower_attrs(&tp.attrs),
1824 fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime {
1825 let span = l.ident.span;
1826 match self.lower_ident(l.ident) {
1827 x if x == "'static" => self.new_named_lifetime(l.id, span, hir::LifetimeName::Static),
1828 x if x == "'_" => match self.anonymous_lifetime_mode {
1829 AnonymousLifetimeMode::CreateParameter => {
1830 let fresh_name = self.collect_fresh_in_band_lifetime(span);
1831 self.new_named_lifetime(l.id, span, fresh_name)
1834 AnonymousLifetimeMode::PassThrough => {
1835 self.new_named_lifetime(l.id, span, hir::LifetimeName::Underscore)
1839 self.maybe_collect_in_band_lifetime(span, name);
1840 self.new_named_lifetime(l.id, span, hir::LifetimeName::Name(name))
1845 fn new_named_lifetime(
1849 name: hir::LifetimeName,
1850 ) -> hir::Lifetime {
1852 id: self.lower_node_id(id).node_id,
1858 fn lower_lifetime_def(&mut self, l: &LifetimeDef) -> hir::LifetimeDef {
1859 let was_collecting_in_band = self.is_collecting_in_band_lifetimes;
1860 self.is_collecting_in_band_lifetimes = false;
1862 let def = hir::LifetimeDef {
1863 lifetime: self.lower_lifetime(&l.lifetime),
1864 bounds: self.lower_lifetimes(&l.bounds),
1865 pure_wrt_drop: attr::contains_name(&l.attrs, "may_dangle"),
1869 self.is_collecting_in_band_lifetimes = was_collecting_in_band;
1874 fn lower_lifetimes(&mut self, lts: &Vec<Lifetime>) -> hir::HirVec<hir::Lifetime> {
1875 lts.iter().map(|l| self.lower_lifetime(l)).collect()
1878 fn lower_generic_params(
1880 params: &Vec<GenericParam>,
1881 add_bounds: &NodeMap<Vec<TyParamBound>>,
1882 ) -> hir::HirVec<hir::GenericParam> {
1885 .map(|param| match *param {
1886 GenericParam::Lifetime(ref lifetime_def) => {
1887 hir::GenericParam::Lifetime(self.lower_lifetime_def(lifetime_def))
1889 GenericParam::Type(ref ty_param) => hir::GenericParam::Type(self.lower_ty_param(
1891 add_bounds.get(&ty_param.id).map_or(&[][..], |x| &x),
1897 fn lower_generics(&mut self, g: &Generics) -> hir::Generics {
1898 // Collect `?Trait` bounds in where clause and move them to parameter definitions.
1899 // FIXME: This could probably be done with less rightward drift. Also looks like two control
1900 // paths where report_error is called are also the only paths that advance to after
1901 // the match statement, so the error reporting could probably just be moved there.
1902 let mut add_bounds = NodeMap();
1903 for pred in &g.where_clause.predicates {
1904 if let WherePredicate::BoundPredicate(ref bound_pred) = *pred {
1905 'next_bound: for bound in &bound_pred.bounds {
1906 if let TraitTyParamBound(_, TraitBoundModifier::Maybe) = *bound {
1907 let report_error = |this: &mut Self| {
1908 this.diagnostic().span_err(
1909 bound_pred.bounded_ty.span,
1910 "`?Trait` bounds are only permitted at the \
1911 point where a type parameter is declared",
1914 // Check if the where clause type is a plain type parameter.
1915 match bound_pred.bounded_ty.node {
1916 TyKind::Path(None, ref path)
1917 if path.segments.len() == 1
1918 && bound_pred.bound_generic_params.is_empty() =>
1920 if let Some(Def::TyParam(def_id)) = self.resolver
1921 .get_resolution(bound_pred.bounded_ty.id)
1922 .map(|d| d.base_def())
1924 if let Some(node_id) =
1925 self.resolver.definitions().as_local_node_id(def_id)
1927 for param in &g.params {
1928 if let GenericParam::Type(ref ty_param) = *param {
1929 if node_id == ty_param.id {
1932 .or_insert(Vec::new())
1933 .push(bound.clone());
1934 continue 'next_bound;
1942 _ => report_error(self),
1950 params: self.lower_generic_params(&g.params, &add_bounds),
1951 where_clause: self.lower_where_clause(&g.where_clause),
1956 fn lower_where_clause(&mut self, wc: &WhereClause) -> hir::WhereClause {
1958 id: self.lower_node_id(wc.id).node_id,
1959 predicates: wc.predicates
1961 .map(|predicate| self.lower_where_predicate(predicate))
1966 fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate {
1968 WherePredicate::BoundPredicate(WhereBoundPredicate {
1969 ref bound_generic_params,
1974 self.with_in_scope_lifetime_defs(
1975 bound_generic_params.iter().filter_map(|p| match p {
1976 GenericParam::Lifetime(ld) => Some(ld),
1980 hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
1981 bound_generic_params: this.lower_generic_params(
1982 bound_generic_params,
1985 bounded_ty: this.lower_ty(bounded_ty, ImplTraitContext::Disallowed),
1988 .filter_map(|bound| match *bound {
1989 // Ignore `?Trait` bounds.
1990 // Tthey were copied into type parameters already.
1991 TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
1992 _ => Some(this.lower_ty_param_bound(
1994 ImplTraitContext::Disallowed,
2003 WherePredicate::RegionPredicate(WhereRegionPredicate {
2007 }) => hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
2009 lifetime: self.lower_lifetime(lifetime),
2012 .map(|bound| self.lower_lifetime(bound))
2015 WherePredicate::EqPredicate(WhereEqPredicate {
2020 }) => hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
2021 id: self.lower_node_id(id).node_id,
2022 lhs_ty: self.lower_ty(lhs_ty, ImplTraitContext::Disallowed),
2023 rhs_ty: self.lower_ty(rhs_ty, ImplTraitContext::Disallowed),
2029 fn lower_variant_data(&mut self, vdata: &VariantData) -> hir::VariantData {
2031 VariantData::Struct(ref fields, id) => hir::VariantData::Struct(
2035 .map(|f| self.lower_struct_field(f))
2037 self.lower_node_id(id).node_id,
2039 VariantData::Tuple(ref fields, id) => hir::VariantData::Tuple(
2043 .map(|f| self.lower_struct_field(f))
2045 self.lower_node_id(id).node_id,
2047 VariantData::Unit(id) => hir::VariantData::Unit(self.lower_node_id(id).node_id),
2051 fn lower_trait_ref(&mut self, p: &TraitRef, itctx: ImplTraitContext) -> hir::TraitRef {
2052 let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit, itctx) {
2053 hir::QPath::Resolved(None, path) => path.and_then(|path| path),
2054 qpath => bug!("lower_trait_ref: unexpected QPath `{:?}`", qpath),
2058 ref_id: self.lower_node_id(p.ref_id).node_id,
2062 fn lower_poly_trait_ref(
2065 itctx: ImplTraitContext,
2066 ) -> hir::PolyTraitRef {
2067 let bound_generic_params = self.lower_generic_params(&p.bound_generic_params, &NodeMap());
2068 let trait_ref = self.with_parent_impl_lifetime_defs(
2069 &bound_generic_params
2071 .filter_map(|p| match *p {
2072 hir::GenericParam::Lifetime(ref ld) => Some(ld.clone()),
2075 .collect::<Vec<_>>(),
2076 |this| this.lower_trait_ref(&p.trait_ref, itctx),
2080 bound_generic_params,
2086 fn lower_struct_field(&mut self, (index, f): (usize, &StructField)) -> hir::StructField {
2089 id: self.lower_node_id(f.id).node_id,
2090 name: self.lower_ident(match f.ident {
2091 Some(ident) => ident,
2092 // FIXME(jseyfried) positional field hygiene
2093 None => Ident::new(Symbol::intern(&index.to_string()), f.span),
2095 vis: self.lower_visibility(&f.vis, None),
2096 ty: self.lower_ty(&f.ty, ImplTraitContext::Disallowed),
2097 attrs: self.lower_attrs(&f.attrs),
2101 fn lower_field(&mut self, f: &Field) -> hir::Field {
2103 name: respan(f.ident.span, self.lower_ident(f.ident)),
2104 expr: P(self.lower_expr(&f.expr)),
2106 is_shorthand: f.is_shorthand,
2110 fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext) -> hir::MutTy {
2112 ty: self.lower_ty(&mt.ty, itctx),
2113 mutbl: self.lower_mutability(mt.mutbl),
2119 bounds: &[TyParamBound],
2120 itctx: ImplTraitContext,
2121 ) -> hir::TyParamBounds {
2124 .map(|bound| self.lower_ty_param_bound(bound, itctx))
2128 fn lower_block(&mut self, b: &Block, targeted_by_break: bool) -> P<hir::Block> {
2129 let mut expr = None;
2131 let mut stmts = vec![];
2133 for (index, stmt) in b.stmts.iter().enumerate() {
2134 if index == b.stmts.len() - 1 {
2135 if let StmtKind::Expr(ref e) = stmt.node {
2136 expr = Some(P(self.lower_expr(e)));
2138 stmts.extend(self.lower_stmt(stmt));
2141 stmts.extend(self.lower_stmt(stmt));
2145 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(b.id);
2150 stmts: stmts.into(),
2152 rules: self.lower_block_check_mode(&b.rules),
2155 recovered: b.recovered,
2163 attrs: &hir::HirVec<Attribute>,
2164 vis: &mut hir::Visibility,
2168 ItemKind::ExternCrate(orig_name) => hir::ItemExternCrate(orig_name),
2169 ItemKind::Use(ref use_tree) => {
2170 // Start with an empty prefix
2173 span: use_tree.span,
2176 self.lower_use_tree(use_tree, &prefix, id, vis, name, attrs)
2178 ItemKind::Static(ref t, m, ref e) => {
2179 let value = self.lower_body(None, |this| this.lower_expr(e));
2181 self.lower_ty(t, ImplTraitContext::Disallowed),
2182 self.lower_mutability(m),
2186 ItemKind::Const(ref t, ref e) => {
2187 let value = self.lower_body(None, |this| this.lower_expr(e));
2188 hir::ItemConst(self.lower_ty(t, ImplTraitContext::Disallowed), value)
2190 ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
2191 let fn_def_id = self.resolver.definitions().local_def_id(id);
2192 self.with_new_scopes(|this| {
2193 let body_id = this.lower_body(Some(decl), |this| {
2194 let body = this.lower_block(body, false);
2195 this.expr_block(body, ThinVec::new())
2197 let (generics, fn_decl) = this.add_in_band_defs(
2200 AnonymousLifetimeMode::PassThrough,
2201 |this| this.lower_fn_decl(decl, Some(fn_def_id), true),
2206 this.lower_unsafety(unsafety),
2207 this.lower_constness(constness),
2214 ItemKind::Mod(ref m) => hir::ItemMod(self.lower_mod(m)),
2215 ItemKind::ForeignMod(ref nm) => hir::ItemForeignMod(self.lower_foreign_mod(nm)),
2216 ItemKind::GlobalAsm(ref ga) => hir::ItemGlobalAsm(self.lower_global_asm(ga)),
2217 ItemKind::Ty(ref t, ref generics) => hir::ItemTy(
2218 self.lower_ty(t, ImplTraitContext::Disallowed),
2219 self.lower_generics(generics),
2221 ItemKind::Enum(ref enum_definition, ref generics) => hir::ItemEnum(
2223 variants: enum_definition
2226 .map(|x| self.lower_variant(x))
2229 self.lower_generics(generics),
2231 ItemKind::Struct(ref struct_def, ref generics) => {
2232 let struct_def = self.lower_variant_data(struct_def);
2233 hir::ItemStruct(struct_def, self.lower_generics(generics))
2235 ItemKind::Union(ref vdata, ref generics) => {
2236 let vdata = self.lower_variant_data(vdata);
2237 hir::ItemUnion(vdata, self.lower_generics(generics))
2248 let def_id = self.resolver.definitions().local_def_id(id);
2250 // Lower the "impl header" first. This ordering is important
2251 // for in-band lifetimes! Consider `'a` here:
2253 // impl Foo<'a> for u32 {
2254 // fn method(&'a self) { .. }
2257 // Because we start by lowering the `Foo<'a> for u32`
2258 // part, we will add `'a` to the list of generics on
2259 // the impl. When we then encounter it later in the
2260 // method, it will not be considered an in-band
2261 // lifetime to be added, but rather a reference to a
2263 let (generics, (trait_ref, lowered_ty)) = self.add_in_band_defs(
2266 AnonymousLifetimeMode::CreateParameter,
2268 let trait_ref = trait_ref.as_ref().map(|trait_ref| {
2269 this.lower_trait_ref(trait_ref, ImplTraitContext::Disallowed)
2272 if let Some(ref trait_ref) = trait_ref {
2273 if let Def::Trait(def_id) = trait_ref.path.def {
2274 this.trait_impls.entry(def_id).or_insert(vec![]).push(id);
2278 let lowered_ty = this.lower_ty(ty, ImplTraitContext::Disallowed);
2280 (trait_ref, lowered_ty)
2284 let new_impl_items = self.with_in_scope_lifetime_defs(
2285 ast_generics.params.iter().filter_map(|p| match p {
2286 GenericParam::Lifetime(ld) => Some(ld),
2292 .map(|item| this.lower_impl_item_ref(item))
2298 self.lower_unsafety(unsafety),
2299 self.lower_impl_polarity(polarity),
2300 self.lower_defaultness(defaultness, true /* [1] */),
2307 ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref items) => {
2308 let bounds = self.lower_bounds(bounds, ImplTraitContext::Disallowed);
2311 .map(|item| self.lower_trait_item_ref(item))
2314 self.lower_is_auto(is_auto),
2315 self.lower_unsafety(unsafety),
2316 self.lower_generics(generics),
2321 ItemKind::TraitAlias(ref generics, ref bounds) => hir::ItemTraitAlias(
2322 self.lower_generics(generics),
2323 self.lower_bounds(bounds, ImplTraitContext::Disallowed),
2325 ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"),
2328 // [1] `defaultness.has_value()` is never called for an `impl`, always `true` in order to
2329 // not cause an assertion failure inside the `lower_defaultness` function
2337 vis: &mut hir::Visibility,
2339 attrs: &hir::HirVec<Attribute>,
2341 let path = &tree.prefix;
2344 UseTreeKind::Simple(rename) => {
2345 *name = tree.ident().name;
2347 // First apply the prefix to the path
2348 let mut path = Path {
2352 .chain(path.segments.iter())
2358 // Correctly resolve `self` imports
2359 if path.segments.len() > 1
2360 && path.segments.last().unwrap().ident.name == keywords::SelfValue.name()
2362 let _ = path.segments.pop();
2363 if rename.is_none() {
2364 *name = path.segments.last().unwrap().ident.name;
2368 let path = P(self.lower_path(id, &path, ParamMode::Explicit));
2369 hir::ItemUse(path, hir::UseKind::Single)
2371 UseTreeKind::Glob => {
2372 let path = P(self.lower_path(
2378 .chain(path.segments.iter())
2383 ParamMode::Explicit,
2385 hir::ItemUse(path, hir::UseKind::Glob)
2387 UseTreeKind::Nested(ref trees) => {
2392 .chain(path.segments.iter())
2395 span: prefix.span.to(path.span),
2398 // Add all the nested PathListItems in the HIR
2399 for &(ref use_tree, id) in trees {
2400 self.allocate_hir_id_counter(id, &use_tree);
2404 } = self.lower_node_id(id);
2406 let mut vis = vis.clone();
2407 let mut name = name.clone();
2409 self.lower_use_tree(use_tree, &prefix, new_id, &mut vis, &mut name, &attrs);
2411 self.with_hir_id_owner(new_id, |this| {
2412 let vis = match vis {
2413 hir::Visibility::Public => hir::Visibility::Public,
2414 hir::Visibility::Crate => hir::Visibility::Crate,
2415 hir::Visibility::Inherited => hir::Visibility::Inherited,
2416 hir::Visibility::Restricted { ref path, id: _ } => {
2417 hir::Visibility::Restricted {
2419 // We are allocating a new NodeId here
2420 id: this.next_id().node_id,
2431 attrs: attrs.clone(),
2434 span: use_tree.span,
2440 // Privatize the degenerate import base, used only to check
2441 // the stability of `use a::{};`, to avoid it showing up as
2442 // a re-export by accident when `pub`, e.g. in documentation.
2443 let path = P(self.lower_path(id, &prefix, ParamMode::Explicit));
2444 *vis = hir::Inherited;
2445 hir::ItemUse(path, hir::UseKind::ListStem)
2450 fn lower_trait_item(&mut self, i: &TraitItem) -> hir::TraitItem {
2451 self.with_parent_def(i.id, |this| {
2452 let LoweredNodeId { node_id, hir_id } = this.lower_node_id(i.id);
2453 let trait_item_def_id = this.resolver.definitions().local_def_id(node_id);
2455 let (generics, node) = match i.node {
2456 TraitItemKind::Const(ref ty, ref default) => (
2457 this.lower_generics(&i.generics),
2458 hir::TraitItemKind::Const(
2459 this.lower_ty(ty, ImplTraitContext::Disallowed),
2462 .map(|x| this.lower_body(None, |this| this.lower_expr(x))),
2465 TraitItemKind::Method(ref sig, None) => {
2466 let names = this.lower_fn_args_to_names(&sig.decl);
2467 this.add_in_band_defs(
2470 AnonymousLifetimeMode::PassThrough,
2472 hir::TraitItemKind::Method(
2473 this.lower_method_sig(sig, trait_item_def_id, false),
2474 hir::TraitMethod::Required(names),
2479 TraitItemKind::Method(ref sig, Some(ref body)) => {
2480 let body_id = this.lower_body(Some(&sig.decl), |this| {
2481 let body = this.lower_block(body, false);
2482 this.expr_block(body, ThinVec::new())
2485 this.add_in_band_defs(
2488 AnonymousLifetimeMode::PassThrough,
2490 hir::TraitItemKind::Method(
2491 this.lower_method_sig(sig, trait_item_def_id, false),
2492 hir::TraitMethod::Provided(body_id),
2497 TraitItemKind::Type(ref bounds, ref default) => (
2498 this.lower_generics(&i.generics),
2499 hir::TraitItemKind::Type(
2500 this.lower_bounds(bounds, ImplTraitContext::Disallowed),
2503 .map(|x| this.lower_ty(x, ImplTraitContext::Disallowed)),
2506 TraitItemKind::Macro(..) => panic!("Shouldn't exist any more"),
2512 name: this.lower_ident(i.ident),
2513 attrs: this.lower_attrs(&i.attrs),
2521 fn lower_trait_item_ref(&mut self, i: &TraitItem) -> hir::TraitItemRef {
2522 let (kind, has_default) = match i.node {
2523 TraitItemKind::Const(_, ref default) => {
2524 (hir::AssociatedItemKind::Const, default.is_some())
2526 TraitItemKind::Type(_, ref default) => {
2527 (hir::AssociatedItemKind::Type, default.is_some())
2529 TraitItemKind::Method(ref sig, ref default) => (
2530 hir::AssociatedItemKind::Method {
2531 has_self: sig.decl.has_self(),
2535 TraitItemKind::Macro(..) => unimplemented!(),
2538 id: hir::TraitItemId { node_id: i.id },
2539 name: self.lower_ident(i.ident),
2541 defaultness: self.lower_defaultness(Defaultness::Default, has_default),
2546 fn lower_impl_item(&mut self, i: &ImplItem) -> hir::ImplItem {
2547 self.with_parent_def(i.id, |this| {
2548 let LoweredNodeId { node_id, hir_id } = this.lower_node_id(i.id);
2549 let impl_item_def_id = this.resolver.definitions().local_def_id(node_id);
2551 let (generics, node) = match i.node {
2552 ImplItemKind::Const(ref ty, ref expr) => {
2553 let body_id = this.lower_body(None, |this| this.lower_expr(expr));
2555 this.lower_generics(&i.generics),
2556 hir::ImplItemKind::Const(
2557 this.lower_ty(ty, ImplTraitContext::Disallowed),
2562 ImplItemKind::Method(ref sig, ref body) => {
2563 let body_id = this.lower_body(Some(&sig.decl), |this| {
2564 let body = this.lower_block(body, false);
2565 this.expr_block(body, ThinVec::new())
2567 let impl_trait_return_allow = !this.is_in_trait_impl;
2569 this.add_in_band_defs(
2572 AnonymousLifetimeMode::PassThrough,
2574 hir::ImplItemKind::Method(
2575 this.lower_method_sig(
2578 impl_trait_return_allow,
2585 ImplItemKind::Type(ref ty) => (
2586 this.lower_generics(&i.generics),
2587 hir::ImplItemKind::Type(this.lower_ty(ty, ImplTraitContext::Disallowed)),
2589 ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"),
2595 name: this.lower_ident(i.ident),
2596 attrs: this.lower_attrs(&i.attrs),
2598 vis: this.lower_visibility(&i.vis, None),
2599 defaultness: this.lower_defaultness(i.defaultness, true /* [1] */),
2605 // [1] since `default impl` is not yet implemented, this is always true in impls
2608 fn lower_impl_item_ref(&mut self, i: &ImplItem) -> hir::ImplItemRef {
2610 id: hir::ImplItemId { node_id: i.id },
2611 name: self.lower_ident(i.ident),
2613 vis: self.lower_visibility(&i.vis, Some(i.id)),
2614 defaultness: self.lower_defaultness(i.defaultness, true /* [1] */),
2615 kind: match i.node {
2616 ImplItemKind::Const(..) => hir::AssociatedItemKind::Const,
2617 ImplItemKind::Type(..) => hir::AssociatedItemKind::Type,
2618 ImplItemKind::Method(ref sig, _) => hir::AssociatedItemKind::Method {
2619 has_self: sig.decl.has_self(),
2621 ImplItemKind::Macro(..) => unimplemented!(),
2625 // [1] since `default impl` is not yet implemented, this is always true in impls
2628 fn lower_mod(&mut self, m: &Mod) -> hir::Mod {
2631 item_ids: m.items.iter().flat_map(|x| self.lower_item_id(x)).collect(),
2635 fn lower_item_id(&mut self, i: &Item) -> SmallVector<hir::ItemId> {
2637 ItemKind::Use(ref use_tree) => {
2638 let mut vec = SmallVector::one(hir::ItemId { id: i.id });
2639 self.lower_item_id_use_tree(use_tree, &mut vec);
2642 ItemKind::MacroDef(..) => return SmallVector::new(),
2645 SmallVector::one(hir::ItemId { id: i.id })
2648 fn lower_item_id_use_tree(&self, tree: &UseTree, vec: &mut SmallVector<hir::ItemId>) {
2650 UseTreeKind::Nested(ref nested_vec) => for &(ref nested, id) in nested_vec {
2651 vec.push(hir::ItemId { id });
2652 self.lower_item_id_use_tree(nested, vec);
2654 UseTreeKind::Glob => {}
2655 UseTreeKind::Simple(..) => {}
2659 pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> {
2660 let mut name = i.ident.name;
2661 let mut vis = self.lower_visibility(&i.vis, None);
2662 let attrs = self.lower_attrs(&i.attrs);
2663 if let ItemKind::MacroDef(ref def) = i.node {
2664 if !def.legacy || attr::contains_name(&i.attrs, "macro_export") {
2665 let body = self.lower_token_stream(def.stream());
2666 self.exported_macros.push(hir::MacroDef {
2679 let node = self.with_parent_def(i.id, |this| {
2680 this.lower_item_kind(i.id, &mut name, &attrs, &mut vis, &i.node)
2683 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id);
2696 fn lower_foreign_item(&mut self, i: &ForeignItem) -> hir::ForeignItem {
2697 self.with_parent_def(i.id, |this| {
2698 let node_id = this.lower_node_id(i.id).node_id;
2699 let def_id = this.resolver.definitions().local_def_id(node_id);
2703 attrs: this.lower_attrs(&i.attrs),
2704 node: match i.node {
2705 ForeignItemKind::Fn(ref fdec, ref generics) => {
2706 let (generics, (fn_dec, fn_args)) = this.add_in_band_defs(
2709 AnonymousLifetimeMode::PassThrough,
2712 // Disallow impl Trait in foreign items
2713 this.lower_fn_decl(fdec, None, false),
2714 this.lower_fn_args_to_names(fdec),
2719 hir::ForeignItemFn(fn_dec, fn_args, generics)
2721 ForeignItemKind::Static(ref t, m) => {
2722 hir::ForeignItemStatic(this.lower_ty(t, ImplTraitContext::Disallowed), m)
2724 ForeignItemKind::Ty => hir::ForeignItemType,
2725 ForeignItemKind::Macro(_) => panic!("shouldn't exist here"),
2727 vis: this.lower_visibility(&i.vis, None),
2733 fn lower_method_sig(
2737 impl_trait_return_allow: bool,
2738 ) -> hir::MethodSig {
2741 unsafety: self.lower_unsafety(sig.unsafety),
2742 constness: self.lower_constness(sig.constness),
2743 decl: self.lower_fn_decl(&sig.decl, Some(fn_def_id), impl_trait_return_allow),
2747 fn lower_is_auto(&mut self, a: IsAuto) -> hir::IsAuto {
2749 IsAuto::Yes => hir::IsAuto::Yes,
2750 IsAuto::No => hir::IsAuto::No,
2754 fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety {
2756 Unsafety::Unsafe => hir::Unsafety::Unsafe,
2757 Unsafety::Normal => hir::Unsafety::Normal,
2761 fn lower_constness(&mut self, c: Spanned<Constness>) -> hir::Constness {
2763 Constness::Const => hir::Constness::Const,
2764 Constness::NotConst => hir::Constness::NotConst,
2768 fn lower_unop(&mut self, u: UnOp) -> hir::UnOp {
2770 UnOp::Deref => hir::UnDeref,
2771 UnOp::Not => hir::UnNot,
2772 UnOp::Neg => hir::UnNeg,
2776 fn lower_binop(&mut self, b: BinOp) -> hir::BinOp {
2778 node: match b.node {
2779 BinOpKind::Add => hir::BiAdd,
2780 BinOpKind::Sub => hir::BiSub,
2781 BinOpKind::Mul => hir::BiMul,
2782 BinOpKind::Div => hir::BiDiv,
2783 BinOpKind::Rem => hir::BiRem,
2784 BinOpKind::And => hir::BiAnd,
2785 BinOpKind::Or => hir::BiOr,
2786 BinOpKind::BitXor => hir::BiBitXor,
2787 BinOpKind::BitAnd => hir::BiBitAnd,
2788 BinOpKind::BitOr => hir::BiBitOr,
2789 BinOpKind::Shl => hir::BiShl,
2790 BinOpKind::Shr => hir::BiShr,
2791 BinOpKind::Eq => hir::BiEq,
2792 BinOpKind::Lt => hir::BiLt,
2793 BinOpKind::Le => hir::BiLe,
2794 BinOpKind::Ne => hir::BiNe,
2795 BinOpKind::Ge => hir::BiGe,
2796 BinOpKind::Gt => hir::BiGt,
2802 fn lower_pat(&mut self, p: &Pat) -> P<hir::Pat> {
2803 let node = match p.node {
2804 PatKind::Wild => hir::PatKind::Wild,
2805 PatKind::Ident(ref binding_mode, ident, ref sub) => {
2806 match self.resolver.get_resolution(p.id).map(|d| d.base_def()) {
2807 // `None` can occur in body-less function signatures
2808 def @ None | def @ Some(Def::Local(_)) => {
2809 let canonical_id = match def {
2810 Some(Def::Local(id)) => id,
2813 hir::PatKind::Binding(
2814 self.lower_binding_mode(binding_mode),
2816 respan(ident.span, ident.name),
2817 sub.as_ref().map(|x| self.lower_pat(x)),
2820 Some(def) => hir::PatKind::Path(hir::QPath::Resolved(
2825 segments: hir_vec![hir::PathSegment::from_name(ident.name)],
2830 PatKind::Lit(ref e) => hir::PatKind::Lit(P(self.lower_expr(e))),
2831 PatKind::TupleStruct(ref path, ref pats, ddpos) => {
2832 let qpath = self.lower_qpath(
2836 ParamMode::Optional,
2837 ImplTraitContext::Disallowed,
2839 hir::PatKind::TupleStruct(
2841 pats.iter().map(|x| self.lower_pat(x)).collect(),
2845 PatKind::Path(ref qself, ref path) => hir::PatKind::Path(self.lower_qpath(
2849 ParamMode::Optional,
2850 ImplTraitContext::Disallowed,
2852 PatKind::Struct(ref path, ref fields, etc) => {
2853 let qpath = self.lower_qpath(
2857 ParamMode::Optional,
2858 ImplTraitContext::Disallowed,
2865 node: hir::FieldPat {
2866 name: self.lower_ident(f.node.ident),
2867 pat: self.lower_pat(&f.node.pat),
2868 is_shorthand: f.node.is_shorthand,
2872 hir::PatKind::Struct(qpath, fs, etc)
2874 PatKind::Tuple(ref elts, ddpos) => {
2875 hir::PatKind::Tuple(elts.iter().map(|x| self.lower_pat(x)).collect(), ddpos)
2877 PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)),
2878 PatKind::Ref(ref inner, mutbl) => {
2879 hir::PatKind::Ref(self.lower_pat(inner), self.lower_mutability(mutbl))
2881 PatKind::Range(ref e1, ref e2, ref end) => hir::PatKind::Range(
2882 P(self.lower_expr(e1)),
2883 P(self.lower_expr(e2)),
2884 self.lower_range_end(end),
2886 PatKind::Slice(ref before, ref slice, ref after) => hir::PatKind::Slice(
2887 before.iter().map(|x| self.lower_pat(x)).collect(),
2888 slice.as_ref().map(|x| self.lower_pat(x)),
2889 after.iter().map(|x| self.lower_pat(x)).collect(),
2891 PatKind::Paren(ref inner) => return self.lower_pat(inner),
2892 PatKind::Mac(_) => panic!("Shouldn't exist here"),
2895 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(p.id);
2904 fn lower_range_end(&mut self, e: &RangeEnd) -> hir::RangeEnd {
2906 RangeEnd::Included(_) => hir::RangeEnd::Included,
2907 RangeEnd::Excluded => hir::RangeEnd::Excluded,
2911 fn lower_expr(&mut self, e: &Expr) -> hir::Expr {
2912 let kind = match e.node {
2913 ExprKind::Box(ref inner) => hir::ExprBox(P(self.lower_expr(inner))),
2915 ExprKind::Array(ref exprs) => {
2916 hir::ExprArray(exprs.iter().map(|x| self.lower_expr(x)).collect())
2918 ExprKind::Repeat(ref expr, ref count) => {
2919 let expr = P(self.lower_expr(expr));
2920 let count = self.lower_body(None, |this| this.lower_expr(count));
2921 hir::ExprRepeat(expr, count)
2923 ExprKind::Tup(ref elts) => {
2924 hir::ExprTup(elts.iter().map(|x| self.lower_expr(x)).collect())
2926 ExprKind::Call(ref f, ref args) => {
2927 let f = P(self.lower_expr(f));
2928 hir::ExprCall(f, args.iter().map(|x| self.lower_expr(x)).collect())
2930 ExprKind::MethodCall(ref seg, ref args) => {
2931 let hir_seg = self.lower_path_segment(
2934 ParamMode::Optional,
2936 ParenthesizedGenericArgs::Err,
2937 ImplTraitContext::Disallowed,
2939 let args = args.iter().map(|x| self.lower_expr(x)).collect();
2940 hir::ExprMethodCall(hir_seg, seg.ident.span, args)
2942 ExprKind::Binary(binop, ref lhs, ref rhs) => {
2943 let binop = self.lower_binop(binop);
2944 let lhs = P(self.lower_expr(lhs));
2945 let rhs = P(self.lower_expr(rhs));
2946 hir::ExprBinary(binop, lhs, rhs)
2948 ExprKind::Unary(op, ref ohs) => {
2949 let op = self.lower_unop(op);
2950 let ohs = P(self.lower_expr(ohs));
2951 hir::ExprUnary(op, ohs)
2953 ExprKind::Lit(ref l) => hir::ExprLit(P((**l).clone())),
2954 ExprKind::Cast(ref expr, ref ty) => {
2955 let expr = P(self.lower_expr(expr));
2956 hir::ExprCast(expr, self.lower_ty(ty, ImplTraitContext::Disallowed))
2958 ExprKind::Type(ref expr, ref ty) => {
2959 let expr = P(self.lower_expr(expr));
2960 hir::ExprType(expr, self.lower_ty(ty, ImplTraitContext::Disallowed))
2962 ExprKind::AddrOf(m, ref ohs) => {
2963 let m = self.lower_mutability(m);
2964 let ohs = P(self.lower_expr(ohs));
2965 hir::ExprAddrOf(m, ohs)
2967 // More complicated than you might expect because the else branch
2968 // might be `if let`.
2969 ExprKind::If(ref cond, ref blk, ref else_opt) => {
2970 let else_opt = else_opt.as_ref().map(|els| {
2972 ExprKind::IfLet(..) => {
2973 // wrap the if-let expr in a block
2974 let span = els.span;
2975 let els = P(self.lower_expr(els));
2976 let LoweredNodeId { node_id, hir_id } = self.next_id();
2977 let blk = P(hir::Block {
2982 rules: hir::DefaultBlock,
2984 targeted_by_break: false,
2985 recovered: blk.recovered,
2987 P(self.expr_block(blk, ThinVec::new()))
2989 _ => P(self.lower_expr(els)),
2993 let then_blk = self.lower_block(blk, false);
2994 let then_expr = self.expr_block(then_blk, ThinVec::new());
2996 hir::ExprIf(P(self.lower_expr(cond)), P(then_expr), else_opt)
2998 ExprKind::While(ref cond, ref body, opt_label) => self.with_loop_scope(e.id, |this| {
3000 this.with_loop_condition_scope(|this| P(this.lower_expr(cond))),
3001 this.lower_block(body, false),
3002 this.lower_label(opt_label),
3005 ExprKind::Loop(ref body, opt_label) => self.with_loop_scope(e.id, |this| {
3007 this.lower_block(body, false),
3008 this.lower_label(opt_label),
3009 hir::LoopSource::Loop,
3012 ExprKind::Catch(ref body) => {
3013 self.with_catch_scope(body.id, |this| hir::ExprBlock(this.lower_block(body, true)))
3015 ExprKind::Match(ref expr, ref arms) => hir::ExprMatch(
3016 P(self.lower_expr(expr)),
3017 arms.iter().map(|x| self.lower_arm(x)).collect(),
3018 hir::MatchSource::Normal,
3020 ExprKind::Closure(capture_clause, movability, ref decl, ref body, fn_decl_span) => {
3021 self.with_new_scopes(|this| {
3022 this.with_parent_def(e.id, |this| {
3023 let mut is_generator = false;
3024 let body_id = this.lower_body(Some(decl), |this| {
3025 let e = this.lower_expr(body);
3026 is_generator = this.is_generator;
3029 let generator_option = if is_generator {
3030 if !decl.inputs.is_empty() {
3035 "generators cannot have explicit arguments"
3037 this.sess.abort_if_errors();
3039 Some(match movability {
3040 Movability::Movable => hir::GeneratorMovability::Movable,
3041 Movability::Static => hir::GeneratorMovability::Static,
3044 if movability == Movability::Static {
3049 "closures cannot be static"
3055 this.lower_capture_clause(capture_clause),
3056 this.lower_fn_decl(decl, None, false),
3064 ExprKind::Block(ref blk) => hir::ExprBlock(self.lower_block(blk, false)),
3065 ExprKind::Assign(ref el, ref er) => {
3066 hir::ExprAssign(P(self.lower_expr(el)), P(self.lower_expr(er)))
3068 ExprKind::AssignOp(op, ref el, ref er) => hir::ExprAssignOp(
3069 self.lower_binop(op),
3070 P(self.lower_expr(el)),
3071 P(self.lower_expr(er)),
3073 ExprKind::Field(ref el, ident) => hir::ExprField(
3074 P(self.lower_expr(el)),
3075 respan(ident.span, self.lower_ident(ident)),
3077 ExprKind::TupField(ref el, ident) => hir::ExprTupField(P(self.lower_expr(el)), ident),
3078 ExprKind::Index(ref el, ref er) => {
3079 hir::ExprIndex(P(self.lower_expr(el)), P(self.lower_expr(er)))
3081 ExprKind::Range(ref e1, ref e2, lims) => {
3082 use syntax::ast::RangeLimits::*;
3084 let path = match (e1, e2, lims) {
3085 (&None, &None, HalfOpen) => "RangeFull",
3086 (&Some(..), &None, HalfOpen) => "RangeFrom",
3087 (&None, &Some(..), HalfOpen) => "RangeTo",
3088 (&Some(..), &Some(..), HalfOpen) => "Range",
3089 (&None, &Some(..), Closed) => "RangeToInclusive",
3090 (&Some(..), &Some(..), Closed) => "RangeInclusive",
3091 (_, &None, Closed) => self.diagnostic()
3092 .span_fatal(e.span, "inclusive range with no end")
3096 let fields = e1.iter()
3097 .map(|e| ("start", e))
3098 .chain(e2.iter().map(|e| ("end", e)))
3100 let expr = P(self.lower_expr(&e));
3102 self.allow_internal_unstable(CompilerDesugaringKind::DotFill, e.span);
3103 self.field(Symbol::intern(s), expr, unstable_span)
3105 .collect::<P<[hir::Field]>>();
3107 let is_unit = fields.is_empty();
3109 self.allow_internal_unstable(CompilerDesugaringKind::DotFill, e.span);
3110 let struct_path = iter::once("ops")
3111 .chain(iter::once(path))
3112 .collect::<Vec<_>>();
3113 let struct_path = self.std_path(unstable_span, &struct_path, is_unit);
3114 let struct_path = hir::QPath::Resolved(None, P(struct_path));
3116 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
3122 hir::ExprPath(struct_path)
3124 hir::ExprStruct(struct_path, fields, None)
3126 span: unstable_span,
3127 attrs: e.attrs.clone(),
3130 ExprKind::Path(ref qself, ref path) => hir::ExprPath(self.lower_qpath(
3134 ParamMode::Optional,
3135 ImplTraitContext::Disallowed,
3137 ExprKind::Break(opt_label, ref opt_expr) => {
3138 let destination = if self.is_in_loop_condition && opt_label.is_none() {
3141 target_id: hir::ScopeTarget::Loop(
3142 Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into(),
3146 self.lower_loop_destination(opt_label.map(|label| (e.id, label)))
3150 opt_expr.as_ref().map(|x| P(self.lower_expr(x))),
3153 ExprKind::Continue(opt_label) => {
3154 hir::ExprAgain(if self.is_in_loop_condition && opt_label.is_none() {
3157 target_id: hir::ScopeTarget::Loop(
3158 Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into(),
3162 self.lower_loop_destination(opt_label.map(|label| (e.id, label)))
3165 ExprKind::Ret(ref e) => hir::ExprRet(e.as_ref().map(|x| P(self.lower_expr(x)))),
3166 ExprKind::InlineAsm(ref asm) => {
3167 let hir_asm = hir::InlineAsm {
3168 inputs: asm.inputs.iter().map(|&(ref c, _)| c.clone()).collect(),
3169 outputs: asm.outputs
3171 .map(|out| hir::InlineAsmOutput {
3172 constraint: out.constraint.clone(),
3174 is_indirect: out.is_indirect,
3177 asm: asm.asm.clone(),
3178 asm_str_style: asm.asm_str_style,
3179 clobbers: asm.clobbers.clone().into(),
3180 volatile: asm.volatile,
3181 alignstack: asm.alignstack,
3182 dialect: asm.dialect,
3185 let outputs = asm.outputs
3187 .map(|out| self.lower_expr(&out.expr))
3189 let inputs = asm.inputs
3191 .map(|&(_, ref input)| self.lower_expr(input))
3193 hir::ExprInlineAsm(P(hir_asm), outputs, inputs)
3195 ExprKind::Struct(ref path, ref fields, ref maybe_expr) => hir::ExprStruct(
3200 ParamMode::Optional,
3201 ImplTraitContext::Disallowed,
3203 fields.iter().map(|x| self.lower_field(x)).collect(),
3204 maybe_expr.as_ref().map(|x| P(self.lower_expr(x))),
3206 ExprKind::Paren(ref ex) => {
3207 let mut ex = self.lower_expr(ex);
3208 // include parens in span, but only if it is a super-span.
3209 if e.span.contains(ex.span) {
3212 // merge attributes into the inner expression.
3213 let mut attrs = e.attrs.clone();
3214 attrs.extend::<Vec<_>>(ex.attrs.into());
3219 ExprKind::Yield(ref opt_expr) => {
3220 self.is_generator = true;
3223 .map(|x| self.lower_expr(x))
3224 .unwrap_or_else(|| self.expr(e.span, hir::ExprTup(hir_vec![]), ThinVec::new()));
3225 hir::ExprYield(P(expr))
3228 // Desugar ExprIfLet
3229 // From: `if let <pat> = <sub_expr> <body> [<else_opt>]`
3230 ExprKind::IfLet(ref pats, ref sub_expr, ref body, ref else_opt) => {
3233 // match <sub_expr> {
3235 // _ => [<else_opt> | ()]
3238 let mut arms = vec![];
3240 // `<pat> => <body>`
3242 let body = self.lower_block(body, false);
3243 let body_expr = P(self.expr_block(body, ThinVec::new()));
3244 let pats = pats.iter().map(|pat| self.lower_pat(pat)).collect();
3245 arms.push(self.arm(pats, body_expr));
3248 // _ => [<else_opt>|()]
3250 let wildcard_arm: Option<&Expr> = else_opt.as_ref().map(|p| &**p);
3251 let wildcard_pattern = self.pat_wild(e.span);
3252 let body = if let Some(else_expr) = wildcard_arm {
3253 P(self.lower_expr(else_expr))
3255 self.expr_tuple(e.span, hir_vec![])
3257 arms.push(self.arm(hir_vec![wildcard_pattern], body));
3260 let contains_else_clause = else_opt.is_some();
3262 let sub_expr = P(self.lower_expr(sub_expr));
3267 hir::MatchSource::IfLetDesugar {
3268 contains_else_clause,
3273 // Desugar ExprWhileLet
3274 // From: `[opt_ident]: while let <pat> = <sub_expr> <body>`
3275 ExprKind::WhileLet(ref pats, ref sub_expr, ref body, opt_label) => {
3278 // [opt_ident]: loop {
3279 // match <sub_expr> {
3285 // Note that the block AND the condition are evaluated in the loop scope.
3286 // This is done to allow `break` from inside the condition of the loop.
3287 let (body, break_expr, sub_expr) = self.with_loop_scope(e.id, |this| {
3289 this.lower_block(body, false),
3290 this.expr_break(e.span, ThinVec::new()),
3291 this.with_loop_condition_scope(|this| P(this.lower_expr(sub_expr))),
3295 // `<pat> => <body>`
3297 let body_expr = P(self.expr_block(body, ThinVec::new()));
3298 let pats = pats.iter().map(|pat| self.lower_pat(pat)).collect();
3299 self.arm(pats, body_expr)
3304 let pat_under = self.pat_wild(e.span);
3305 self.arm(hir_vec![pat_under], break_expr)
3308 // `match <sub_expr> { ... }`
3309 let arms = hir_vec![pat_arm, break_arm];
3310 let match_expr = self.expr(
3312 hir::ExprMatch(sub_expr, arms, hir::MatchSource::WhileLetDesugar),
3316 // `[opt_ident]: loop { ... }`
3317 let loop_block = P(self.block_expr(P(match_expr)));
3318 let loop_expr = hir::ExprLoop(
3320 self.lower_label(opt_label),
3321 hir::LoopSource::WhileLet,
3323 // add attributes to the outer returned expr node
3327 // Desugar ExprForLoop
3328 // From: `[opt_ident]: for <pat> in <head> <body>`
3329 ExprKind::ForLoop(ref pat, ref head, ref body, opt_label) => {
3333 // let result = match ::std::iter::IntoIterator::into_iter(<head>) {
3335 // [opt_ident]: loop {
3337 // match ::std::iter::Iterator::next(&mut iter) {
3338 // ::std::option::Option::Some(val) => __next = val,
3339 // ::std::option::Option::None => break
3341 // let <pat> = __next;
3342 // StmtExpr(<body>);
3350 let head = self.lower_expr(head);
3351 let head_sp = head.span;
3353 let iter = self.str_to_ident("iter");
3355 let next_ident = self.str_to_ident("__next");
3356 let next_pat = self.pat_ident_binding_mode(
3359 hir::BindingAnnotation::Mutable,
3362 // `::std::option::Option::Some(val) => next = val`
3364 let val_ident = self.str_to_ident("val");
3365 let val_pat = self.pat_ident(pat.span, val_ident);
3366 let val_expr = P(self.expr_ident(pat.span, val_ident, val_pat.id));
3367 let next_expr = P(self.expr_ident(pat.span, next_ident, next_pat.id));
3368 let assign = P(self.expr(
3370 hir::ExprAssign(next_expr, val_expr),
3373 let some_pat = self.pat_some(pat.span, val_pat);
3374 self.arm(hir_vec![some_pat], assign)
3377 // `::std::option::Option::None => break`
3380 self.with_loop_scope(e.id, |this| this.expr_break(e.span, ThinVec::new()));
3381 let pat = self.pat_none(e.span);
3382 self.arm(hir_vec![pat], break_expr)
3387 self.pat_ident_binding_mode(head_sp, iter, hir::BindingAnnotation::Mutable);
3389 // `match ::std::iter::Iterator::next(&mut iter) { ... }`
3391 let iter = P(self.expr_ident(head_sp, iter, iter_pat.id));
3392 let ref_mut_iter = self.expr_mut_addr_of(head_sp, iter);
3393 let next_path = &["iter", "Iterator", "next"];
3394 let next_path = P(self.expr_std_path(head_sp, next_path, ThinVec::new()));
3395 let next_expr = P(self.expr_call(head_sp, next_path, hir_vec![ref_mut_iter]));
3396 let arms = hir_vec![pat_arm, break_arm];
3400 hir::ExprMatch(next_expr, arms, hir::MatchSource::ForLoopDesugar),
3404 let match_stmt = respan(head_sp, hir::StmtExpr(match_expr, self.next_id().node_id));
3406 let next_expr = P(self.expr_ident(head_sp, next_ident, next_pat.id));
3410 self.stmt_let_pat(head_sp, None, next_pat, hir::LocalSource::ForLoopDesugar);
3412 // `let <pat> = __next`
3413 let pat = self.lower_pat(pat);
3414 let pat_let = self.stmt_let_pat(
3418 hir::LocalSource::ForLoopDesugar,
3421 let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false));
3422 let body_expr = P(self.expr_block(body_block, ThinVec::new()));
3423 let body_stmt = respan(body.span, hir::StmtExpr(body_expr, self.next_id().node_id));
3425 let loop_block = P(self.block_all(
3427 hir_vec![next_let, match_stmt, pat_let, body_stmt],
3431 // `[opt_ident]: loop { ... }`
3432 let loop_expr = hir::ExprLoop(
3434 self.lower_label(opt_label),
3435 hir::LoopSource::ForLoop,
3437 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
3438 let loop_expr = P(hir::Expr {
3443 attrs: ThinVec::new(),
3446 // `mut iter => { ... }`
3447 let iter_arm = self.arm(hir_vec![iter_pat], loop_expr);
3449 // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }`
3450 let into_iter_expr = {
3451 let into_iter_path = &["iter", "IntoIterator", "into_iter"];
3452 let into_iter = P(self.expr_std_path(head_sp, into_iter_path, ThinVec::new()));
3453 P(self.expr_call(head_sp, into_iter, hir_vec![head]))
3456 let match_expr = P(self.expr_match(
3460 hir::MatchSource::ForLoopDesugar,
3463 // `{ let _result = ...; _result }`
3464 // underscore prevents an unused_variables lint if the head diverges
3465 let result_ident = self.str_to_ident("_result");
3466 let (let_stmt, let_stmt_binding) =
3467 self.stmt_let(e.span, false, result_ident, match_expr);
3469 let result = P(self.expr_ident(e.span, result_ident, let_stmt_binding));
3470 let block = P(self.block_all(e.span, hir_vec![let_stmt], Some(result)));
3471 // add the attributes to the outer returned expr node
3472 return self.expr_block(block, e.attrs.clone());
3475 // Desugar ExprKind::Try
3477 ExprKind::Try(ref sub_expr) => {
3480 // match Try::into_result(<expr>) {
3481 // Ok(val) => #[allow(unreachable_code)] val,
3482 // Err(err) => #[allow(unreachable_code)]
3483 // // If there is an enclosing `catch {...}`
3484 // break 'catch_target Try::from_error(From::from(err)),
3486 // return Try::from_error(From::from(err)),
3490 self.allow_internal_unstable(CompilerDesugaringKind::QuestionMark, e.span);
3492 // Try::into_result(<expr>)
3495 let sub_expr = self.lower_expr(sub_expr);
3497 let path = &["ops", "Try", "into_result"];
3498 let path = P(self.expr_std_path(unstable_span, path, ThinVec::new()));
3499 P(self.expr_call(e.span, path, hir_vec![sub_expr]))
3502 // #[allow(unreachable_code)]
3504 // allow(unreachable_code)
3506 let allow_ident = Ident::from_str("allow").with_span_pos(e.span);
3507 let uc_ident = Ident::from_str("unreachable_code").with_span_pos(e.span);
3508 let uc_nested = attr::mk_nested_word_item(uc_ident);
3509 attr::mk_list_item(e.span, allow_ident, vec![uc_nested])
3511 attr::mk_spanned_attr_outer(e.span, attr::mk_attr_id(), allow)
3513 let attrs = vec![attr];
3515 // Ok(val) => #[allow(unreachable_code)] val,
3517 let val_ident = self.str_to_ident("val");
3518 let val_pat = self.pat_ident(e.span, val_ident);
3519 let val_expr = P(self.expr_ident_with_attrs(
3523 ThinVec::from(attrs.clone()),
3525 let ok_pat = self.pat_ok(e.span, val_pat);
3527 self.arm(hir_vec![ok_pat], val_expr)
3530 // Err(err) => #[allow(unreachable_code)]
3531 // return Try::from_error(From::from(err)),
3533 let err_ident = self.str_to_ident("err");
3534 let err_local = self.pat_ident(e.span, err_ident);
3536 let path = &["convert", "From", "from"];
3537 let from = P(self.expr_std_path(e.span, path, ThinVec::new()));
3538 let err_expr = self.expr_ident(e.span, err_ident, err_local.id);
3540 self.expr_call(e.span, from, hir_vec![err_expr])
3542 let from_err_expr = {
3543 let path = &["ops", "Try", "from_error"];
3544 let from_err = P(self.expr_std_path(unstable_span, path, ThinVec::new()));
3545 P(self.expr_call(e.span, from_err, hir_vec![from_expr]))
3548 let thin_attrs = ThinVec::from(attrs);
3549 let catch_scope = self.catch_scopes.last().map(|x| *x);
3550 let ret_expr = if let Some(catch_node) = catch_scope {
3556 target_id: hir::ScopeTarget::Block(catch_node),
3558 Some(from_err_expr),
3563 P(self.expr(e.span, hir::Expr_::ExprRet(Some(from_err_expr)), thin_attrs))
3566 let err_pat = self.pat_err(e.span, err_local);
3567 self.arm(hir_vec![err_pat], ret_expr)
3572 hir_vec![err_arm, ok_arm],
3573 hir::MatchSource::TryDesugar,
3577 ExprKind::Mac(_) => panic!("Shouldn't exist here"),
3580 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
3587 attrs: e.attrs.clone(),
3591 fn lower_stmt(&mut self, s: &Stmt) -> SmallVector<hir::Stmt> {
3592 SmallVector::one(match s.node {
3593 StmtKind::Local(ref l) => Spanned {
3594 node: hir::StmtDecl(
3596 node: hir::DeclLocal(self.lower_local(l)),
3599 self.lower_node_id(s.id).node_id,
3603 StmtKind::Item(ref it) => {
3604 // Can only use the ID once.
3605 let mut id = Some(s.id);
3606 return self.lower_item_id(it)
3608 .map(|item_id| Spanned {
3609 node: hir::StmtDecl(
3611 node: hir::DeclItem(item_id),
3615 .map(|id| self.lower_node_id(id).node_id)
3616 .unwrap_or_else(|| self.next_id().node_id),
3622 StmtKind::Expr(ref e) => Spanned {
3623 node: hir::StmtExpr(P(self.lower_expr(e)), self.lower_node_id(s.id).node_id),
3626 StmtKind::Semi(ref e) => Spanned {
3627 node: hir::StmtSemi(P(self.lower_expr(e)), self.lower_node_id(s.id).node_id),
3630 StmtKind::Mac(..) => panic!("Shouldn't exist here"),
3634 fn lower_capture_clause(&mut self, c: CaptureBy) -> hir::CaptureClause {
3636 CaptureBy::Value => hir::CaptureByValue,
3637 CaptureBy::Ref => hir::CaptureByRef,
3641 /// If an `explicit_owner` is given, this method allocates the `HirId` in
3642 /// the address space of that item instead of the item currently being
3643 /// lowered. This can happen during `lower_impl_item_ref()` where we need to
3644 /// lower a `Visibility` value although we haven't lowered the owning
3645 /// `ImplItem` in question yet.
3646 fn lower_visibility(
3649 explicit_owner: Option<NodeId>,
3650 ) -> hir::Visibility {
3652 VisibilityKind::Public => hir::Public,
3653 VisibilityKind::Crate(..) => hir::Visibility::Crate,
3654 VisibilityKind::Restricted { ref path, id, .. } => hir::Visibility::Restricted {
3655 path: P(self.lower_path(id, path, ParamMode::Explicit)),
3656 id: if let Some(owner) = explicit_owner {
3657 self.lower_node_id_with_owner(id, owner).node_id
3659 self.lower_node_id(id).node_id
3662 VisibilityKind::Inherited => hir::Inherited,
3666 fn lower_defaultness(&mut self, d: Defaultness, has_value: bool) -> hir::Defaultness {
3668 Defaultness::Default => hir::Defaultness::Default {
3669 has_value: has_value,
3671 Defaultness::Final => {
3673 hir::Defaultness::Final
3678 fn lower_block_check_mode(&mut self, b: &BlockCheckMode) -> hir::BlockCheckMode {
3680 BlockCheckMode::Default => hir::DefaultBlock,
3681 BlockCheckMode::Unsafe(u) => hir::UnsafeBlock(self.lower_unsafe_source(u)),
3685 fn lower_binding_mode(&mut self, b: &BindingMode) -> hir::BindingAnnotation {
3687 BindingMode::ByValue(Mutability::Immutable) => hir::BindingAnnotation::Unannotated,
3688 BindingMode::ByRef(Mutability::Immutable) => hir::BindingAnnotation::Ref,
3689 BindingMode::ByValue(Mutability::Mutable) => hir::BindingAnnotation::Mutable,
3690 BindingMode::ByRef(Mutability::Mutable) => hir::BindingAnnotation::RefMut,
3694 fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
3696 CompilerGenerated => hir::CompilerGenerated,
3697 UserProvided => hir::UserProvided,
3701 fn lower_impl_polarity(&mut self, i: ImplPolarity) -> hir::ImplPolarity {
3703 ImplPolarity::Positive => hir::ImplPolarity::Positive,
3704 ImplPolarity::Negative => hir::ImplPolarity::Negative,
3708 fn lower_trait_bound_modifier(&mut self, f: TraitBoundModifier) -> hir::TraitBoundModifier {
3710 TraitBoundModifier::None => hir::TraitBoundModifier::None,
3711 TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe,
3715 // Helper methods for building HIR.
3717 fn arm(&mut self, pats: hir::HirVec<P<hir::Pat>>, expr: P<hir::Expr>) -> hir::Arm {
3726 fn field(&mut self, name: Name, expr: P<hir::Expr>, span: Span) -> hir::Field {
3728 name: Spanned { node: name, span },
3731 is_shorthand: false,
3735 fn expr_break(&mut self, span: Span, attrs: ThinVec<Attribute>) -> P<hir::Expr> {
3736 let expr_break = hir::ExprBreak(self.lower_loop_destination(None), None);
3737 P(self.expr(span, expr_break, attrs))
3744 args: hir::HirVec<hir::Expr>,
3746 self.expr(span, hir::ExprCall(e, args), ThinVec::new())
3749 fn expr_ident(&mut self, span: Span, id: Name, binding: NodeId) -> hir::Expr {
3750 self.expr_ident_with_attrs(span, id, binding, ThinVec::new())
3753 fn expr_ident_with_attrs(
3758 attrs: ThinVec<Attribute>,
3760 let expr_path = hir::ExprPath(hir::QPath::Resolved(
3764 def: Def::Local(binding),
3765 segments: hir_vec![hir::PathSegment::from_name(id)],
3769 self.expr(span, expr_path, attrs)
3772 fn expr_mut_addr_of(&mut self, span: Span, e: P<hir::Expr>) -> hir::Expr {
3773 self.expr(span, hir::ExprAddrOf(hir::MutMutable, e), ThinVec::new())
3779 components: &[&str],
3780 attrs: ThinVec<Attribute>,
3782 let path = self.std_path(span, components, true);
3785 hir::ExprPath(hir::QPath::Resolved(None, P(path))),
3794 arms: hir::HirVec<hir::Arm>,
3795 source: hir::MatchSource,
3797 self.expr(span, hir::ExprMatch(arg, arms, source), ThinVec::new())
3800 fn expr_block(&mut self, b: P<hir::Block>, attrs: ThinVec<Attribute>) -> hir::Expr {
3801 self.expr(b.span, hir::ExprBlock(b), attrs)
3804 fn expr_tuple(&mut self, sp: Span, exprs: hir::HirVec<hir::Expr>) -> P<hir::Expr> {
3805 P(self.expr(sp, hir::ExprTup(exprs), ThinVec::new()))
3808 fn expr(&mut self, span: Span, node: hir::Expr_, attrs: ThinVec<Attribute>) -> hir::Expr {
3809 let LoweredNodeId { node_id, hir_id } = self.next_id();
3822 ex: Option<P<hir::Expr>>,
3824 source: hir::LocalSource,
3826 let LoweredNodeId { node_id, hir_id } = self.next_id();
3828 let local = P(hir::Local {
3835 attrs: ThinVec::new(),
3838 let decl = respan(sp, hir::DeclLocal(local));
3839 respan(sp, hir::StmtDecl(P(decl), self.next_id().node_id))
3848 ) -> (hir::Stmt, NodeId) {
3849 let pat = if mutbl {
3850 self.pat_ident_binding_mode(sp, ident, hir::BindingAnnotation::Mutable)
3852 self.pat_ident(sp, ident)
3854 let pat_id = pat.id;
3856 self.stmt_let_pat(sp, Some(ex), pat, hir::LocalSource::Normal),
3861 fn block_expr(&mut self, expr: P<hir::Expr>) -> hir::Block {
3862 self.block_all(expr.span, hir::HirVec::new(), Some(expr))
3868 stmts: hir::HirVec<hir::Stmt>,
3869 expr: Option<P<hir::Expr>>,
3871 let LoweredNodeId { node_id, hir_id } = self.next_id();
3878 rules: hir::DefaultBlock,
3880 targeted_by_break: false,
3885 fn pat_ok(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
3886 self.pat_std_enum(span, &["result", "Result", "Ok"], hir_vec![pat])
3889 fn pat_err(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
3890 self.pat_std_enum(span, &["result", "Result", "Err"], hir_vec![pat])
3893 fn pat_some(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
3894 self.pat_std_enum(span, &["option", "Option", "Some"], hir_vec![pat])
3897 fn pat_none(&mut self, span: Span) -> P<hir::Pat> {
3898 self.pat_std_enum(span, &["option", "Option", "None"], hir_vec![])
3904 components: &[&str],
3905 subpats: hir::HirVec<P<hir::Pat>>,
3907 let path = self.std_path(span, components, true);
3908 let qpath = hir::QPath::Resolved(None, P(path));
3909 let pt = if subpats.is_empty() {
3910 hir::PatKind::Path(qpath)
3912 hir::PatKind::TupleStruct(qpath, subpats, None)
3917 fn pat_ident(&mut self, span: Span, name: Name) -> P<hir::Pat> {
3918 self.pat_ident_binding_mode(span, name, hir::BindingAnnotation::Unannotated)
3921 fn pat_ident_binding_mode(
3925 bm: hir::BindingAnnotation,
3927 let LoweredNodeId { node_id, hir_id } = self.next_id();
3932 node: hir::PatKind::Binding(bm, node_id, Spanned { span, node: name }, None),
3937 fn pat_wild(&mut self, span: Span) -> P<hir::Pat> {
3938 self.pat(span, hir::PatKind::Wild)
3941 fn pat(&mut self, span: Span, pat: hir::PatKind) -> P<hir::Pat> {
3942 let LoweredNodeId { node_id, hir_id } = self.next_id();
3951 /// Given suffix ["b","c","d"], returns path `::std::b::c::d` when
3952 /// `fld.cx.use_std`, and `::core::b::c::d` otherwise.
3953 /// The path is also resolved according to `is_value`.
3954 fn std_path(&mut self, span: Span, components: &[&str], is_value: bool) -> hir::Path {
3956 .resolve_str_path(span, self.crate_root, components, is_value)
3959 fn ty_path(&mut self, id: LoweredNodeId, span: Span, qpath: hir::QPath) -> P<hir::Ty> {
3961 let node = match qpath {
3962 hir::QPath::Resolved(None, path) => {
3963 // Turn trait object paths into `TyTraitObject` instead.
3964 if let Def::Trait(_) = path.def {
3965 let principal = hir::PolyTraitRef {
3966 bound_generic_params: hir::HirVec::new(),
3967 trait_ref: hir::TraitRef {
3968 path: path.and_then(|path| path),
3974 // The original ID is taken by the `PolyTraitRef`,
3975 // so the `Ty` itself needs a different one.
3976 id = self.next_id();
3977 hir::TyTraitObject(hir_vec![principal], self.elided_dyn_bound(span))
3979 hir::TyPath(hir::QPath::Resolved(None, path))
3982 _ => hir::TyPath(qpath),
3992 /// Invoked to create the lifetime argument for a type `&T`
3993 /// with no explicit lifetime.
3994 fn elided_ref_lifetime(&mut self, span: Span) -> hir::Lifetime {
3995 match self.anonymous_lifetime_mode {
3996 // Intercept when we are in an impl header and introduce an in-band lifetime.
3997 // Hence `impl Foo for &u32` becomes `impl<'f> Foo for &'f u32` for some fresh
3999 AnonymousLifetimeMode::CreateParameter => {
4000 let fresh_name = self.collect_fresh_in_band_lifetime(span);
4002 id: self.next_id().node_id,
4008 AnonymousLifetimeMode::PassThrough => self.new_implicit_lifetime(span),
4012 /// Invoked to create the lifetime argument(s) for a path like
4013 /// `std::cell::Ref<T>`; note that implicit lifetimes in these
4014 /// sorts of cases are deprecated. This may therefore report a warning or an
4015 /// error, depending on the mode.
4016 fn elided_path_lifetimes(&mut self, span: Span, count: usize) -> P<[hir::Lifetime]> {
4017 match self.anonymous_lifetime_mode {
4018 // NB. We intentionally ignore the create-parameter mode here
4019 // and instead "pass through" to resolve-lifetimes, which will then
4020 // report an error. This is because we don't want to support
4021 // impl elision for deprecated forms like
4023 // impl Foo for std::cell::Ref<u32> // note lack of '_
4024 AnonymousLifetimeMode::CreateParameter => {}
4026 // This is the normal case.
4027 AnonymousLifetimeMode::PassThrough => {}
4031 .map(|_| self.new_implicit_lifetime(span))
4035 /// Invoked to create the lifetime argument(s) for an elided trait object
4036 /// bound, like the bound in `Box<dyn Debug>`. This method is not invoked
4037 /// when the bound is written, even if it is written with `'_` like in
4038 /// `Box<dyn Debug + '_>`. In those cases, `lower_lifetime` is invoked.
4039 fn elided_dyn_bound(&mut self, span: Span) -> hir::Lifetime {
4040 match self.anonymous_lifetime_mode {
4041 // NB. We intentionally ignore the create-parameter mode here.
4042 // and instead "pass through" to resolve-lifetimes, which will apply
4043 // the object-lifetime-defaulting rules. Elided object lifetime defaults
4044 // do not act like other elided lifetimes. In other words, given this:
4046 // impl Foo for Box<dyn Debug>
4048 // we do not introduce a fresh `'_` to serve as the bound, but instead
4049 // ultimately translate to the equivalent of:
4051 // impl Foo for Box<dyn Debug + 'static>
4053 // `resolve_lifetime` has the code to make that happen.
4054 AnonymousLifetimeMode::CreateParameter => {}
4056 // This is the normal case.
4057 AnonymousLifetimeMode::PassThrough => {}
4060 self.new_implicit_lifetime(span)
4063 fn new_implicit_lifetime(&mut self, span: Span) -> hir::Lifetime {
4065 id: self.next_id().node_id,
4067 name: hir::LifetimeName::Implicit,
4071 fn maybe_lint_bare_trait(&self, span: Span, id: NodeId, is_global: bool) {
4072 if self.sess.features_untracked().dyn_trait {
4073 self.sess.buffer_lint_with_diagnostic(
4074 builtin::BARE_TRAIT_OBJECT,
4077 "trait objects without an explicit `dyn` are deprecated",
4078 builtin::BuiltinLintDiagnostics::BareTraitObject(span, is_global),
4084 fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
4085 // Sorting by span ensures that we get things in order within a
4086 // file, and also puts the files in a sensible order.
4087 let mut body_ids: Vec<_> = bodies.keys().cloned().collect();
4088 body_ids.sort_by_key(|b| bodies[b].value.span);