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, PerNS};
50 use lint::builtin::{self, PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES};
51 use middle::cstore::CrateStore;
52 use rustc_data_structures::indexed_vec::IndexVec;
54 use util::common::FN_OUTPUT_NAME;
55 use util::nodemap::{DefIdMap, FxHashMap, NodeMap};
57 use std::collections::{BTreeMap, HashSet};
65 use syntax::ext::hygiene::{Mark, SyntaxContext};
66 use syntax::print::pprust;
68 use syntax::codemap::{self, respan, CompilerDesugaringKind, Spanned};
69 use syntax::std_inject;
70 use syntax::symbol::{keywords, Symbol};
71 use syntax::tokenstream::{Delimited, TokenStream, TokenTree};
72 use syntax::parse::token::Token;
73 use syntax::util::small_vector::SmallVector;
74 use syntax::visit::{self, Visitor};
77 const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF;
79 pub struct LoweringContext<'a> {
80 crate_root: Option<&'static str>,
82 // Use to assign ids to hir nodes that do not directly correspond to an ast node
85 cstore: &'a CrateStore,
87 resolver: &'a mut Resolver,
88 name_map: FxHashMap<Ident, Name>,
90 /// The items being lowered are collected here.
91 items: BTreeMap<NodeId, hir::Item>,
93 trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem>,
94 impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem>,
95 bodies: BTreeMap<hir::BodyId, hir::Body>,
96 exported_macros: Vec<hir::MacroDef>,
98 trait_impls: BTreeMap<DefId, Vec<NodeId>>,
99 trait_auto_impl: BTreeMap<DefId, NodeId>,
103 catch_scopes: Vec<NodeId>,
104 loop_scopes: Vec<NodeId>,
105 is_in_loop_condition: bool,
106 is_in_trait_impl: bool,
108 /// What to do when we encounter either an "anonymous lifetime
109 /// reference". The term "anonymous" is meant to encompass both
110 /// `'_` lifetimes as well as fully elided cases where nothing is
111 /// written at all (e.g., `&T` or `std::cell::Ref<T>`).
112 anonymous_lifetime_mode: AnonymousLifetimeMode,
114 // This is a list of in-band type definitions being generated by
115 // Argument-position `impl Trait`.
116 // When traversing a signature such as `fn foo(x: impl Trait)`,
117 // we record `impl Trait` as a new type parameter, then later
118 // add it on to `foo`s generics.
119 in_band_ty_params: Vec<hir::TyParam>,
121 // Used to create lifetime definitions from in-band lifetime usages.
122 // e.g. `fn foo(x: &'x u8) -> &'x u8` to `fn foo<'x>(x: &'x u8) -> &'x u8`
123 // When a named lifetime is encountered in a function or impl header and
124 // has not been defined
125 // (i.e. it doesn't appear in the in_scope_lifetimes list), it is added
126 // to this list. The results of this list are then added to the list of
127 // lifetime definitions in the corresponding impl or function generics.
128 lifetimes_to_define: Vec<(Span, hir::LifetimeName)>,
130 // Whether or not in-band lifetimes are being collected. This is used to
131 // indicate whether or not we're in a place where new lifetimes will result
132 // in in-band lifetime definitions, such a function or an impl header.
133 // This will always be false unless the `in_band_lifetimes` feature is
135 is_collecting_in_band_lifetimes: bool,
137 // Currently in-scope lifetimes defined in impl headers, fn headers, or HRTB.
138 // When `is_collectin_in_band_lifetimes` is true, each lifetime is checked
139 // against this list to see if it is already in-scope, or if a definition
140 // needs to be created for it.
141 in_scope_lifetimes: Vec<Name>,
143 type_def_lifetime_params: DefIdMap<usize>,
145 current_hir_id_owner: Vec<(DefIndex, u32)>,
146 item_local_id_counters: NodeMap<u32>,
147 node_id_to_hir_id: IndexVec<NodeId, hir::HirId>,
151 /// Resolve a hir path generated by the lowerer when expanding `for`, `if let`, etc.
152 fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool);
154 /// Obtain the resolution for a node id
155 fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution>;
157 /// Obtain the possible resolutions for the given `use` statement.
158 fn get_import(&mut self, id: NodeId) -> PerNS<Option<PathResolution>>;
160 /// We must keep the set of definitions up to date as we add nodes that weren't in the AST.
161 /// This should only return `None` during testing.
162 fn definitions(&mut self) -> &mut Definitions;
164 /// Given suffix ["b","c","d"], creates a HIR path for `[::crate_root]::b::c::d` and resolves
165 /// it based on `is_value`.
169 crate_root: Option<&str>,
175 #[derive(Clone, Copy, Debug)]
176 enum ImplTraitContext {
177 /// Treat `impl Trait` as shorthand for a new universal generic parameter.
178 /// Example: `fn foo(x: impl Debug)`, where `impl Debug` is conceptually
179 /// equivalent to a fresh universal parameter like `fn foo<T: Debug>(x: T)`.
181 /// We store a DefId here so we can look up necessary information later
184 /// Treat `impl Trait` as shorthand for a new universal existential parameter.
185 /// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually
186 /// equivalent to a fresh existential parameter like `abstract type T; fn foo() -> T`.
188 /// We store a DefId here so we can look up necessary information later
191 /// `impl Trait` is not accepted in this position.
198 dep_graph: &DepGraph,
200 resolver: &mut Resolver,
202 // We're constructing the HIR here; we don't care what we will
203 // read, since we haven't even constructed the *input* to
205 dep_graph.assert_ignored();
208 crate_root: std_inject::injected_crate_name(),
212 name_map: FxHashMap(),
213 items: BTreeMap::new(),
214 trait_items: BTreeMap::new(),
215 impl_items: BTreeMap::new(),
216 bodies: BTreeMap::new(),
217 trait_impls: BTreeMap::new(),
218 trait_auto_impl: BTreeMap::new(),
219 exported_macros: Vec::new(),
220 catch_scopes: Vec::new(),
221 loop_scopes: Vec::new(),
222 is_in_loop_condition: false,
223 anonymous_lifetime_mode: AnonymousLifetimeMode::PassThrough,
224 type_def_lifetime_params: DefIdMap(),
225 current_hir_id_owner: vec![(CRATE_DEF_INDEX, 0)],
226 item_local_id_counters: NodeMap(),
227 node_id_to_hir_id: IndexVec::new(),
229 is_in_trait_impl: false,
230 in_band_ty_params: Vec::new(),
231 lifetimes_to_define: Vec::new(),
232 is_collecting_in_band_lifetimes: false,
233 in_scope_lifetimes: Vec::new(),
237 #[derive(Copy, Clone, PartialEq, Eq)]
239 /// Any path in a type context.
241 /// The `module::Type` in `module::Type::method` in an expression.
246 struct LoweredNodeId {
251 enum ParenthesizedGenericArgs {
257 /// What to do when we encounter an **anonymous** lifetime
258 /// reference. Anonymous lifetime references come in two flavors. You
259 /// have implicit, or fully elided, references to lifetimes, like the
260 /// one in `&T` or `Ref<T>`, and you have `'_` lifetimes, like `&'_ T`
261 /// or `Ref<'_, T>`. These often behave the same, but not always:
263 /// - certain usages of implicit references are deprecated, like
264 /// `Ref<T>`, and we sometimes just give hard errors in those cases
266 /// - for object bounds there is a difference: `Box<dyn Foo>` is not
267 /// the same as `Box<dyn Foo + '_>`.
269 /// We describe the effects of the various modes in terms of three cases:
271 /// - **Modern** -- includes all uses of `'_`, but also the lifetime arg
272 /// of a `&` (e.g., the missing lifetime in something like `&T`)
273 /// - **Dyn Bound** -- if you have something like `Box<dyn Foo>`,
274 /// there is an elided lifetime bound (`Box<dyn Foo + 'X>`). These
275 /// elided bounds follow special rules. Note that this only covers
276 /// cases where *nothing* is written; the `'_` in `Box<dyn Foo +
277 /// '_>` is a case of "modern" elision.
278 /// - **Deprecated** -- this coverse cases like `Ref<T>`, where the lifetime
279 /// parameter to ref is completely elided. `Ref<'_, T>` would be the modern,
280 /// non-deprecated equivalent.
282 /// Currently, the handling of lifetime elision is somewhat spread out
283 /// between HIR lowering and -- as described below -- the
284 /// `resolve_lifetime` module. Often we "fallthrough" to that code by generating
285 /// an "elided" or "underscore" lifetime name. In the future, we probably want to move
286 /// everything into HIR lowering.
287 #[derive(Copy, Clone)]
288 enum AnonymousLifetimeMode {
289 /// For **Modern** cases, create a new anonymous region parameter
290 /// and reference that.
292 /// For **Dyn Bound** cases, pass responsibility to
293 /// `resolve_lifetime` code.
295 /// For **Deprecated** cases, report an error.
298 /// Pass responsibility to `resolve_lifetime` code for all cases.
302 impl<'a> LoweringContext<'a> {
303 fn lower_crate(mut self, c: &Crate) -> hir::Crate {
304 /// Full-crate AST visitor that inserts into a fresh
305 /// `LoweringContext` any information that may be
306 /// needed from arbitrary locations in the crate.
307 /// E.g. The number of lifetime generic parameters
308 /// declared for every type and trait definition.
309 struct MiscCollector<'lcx, 'interner: 'lcx> {
310 lctx: &'lcx mut LoweringContext<'interner>,
313 impl<'lcx, 'interner> Visitor<'lcx> for MiscCollector<'lcx, 'interner> {
314 fn visit_item(&mut self, item: &'lcx Item) {
315 self.lctx.allocate_hir_id_counter(item.id, item);
318 ItemKind::Struct(_, ref generics)
319 | ItemKind::Union(_, ref generics)
320 | ItemKind::Enum(_, ref generics)
321 | ItemKind::Ty(_, ref generics)
322 | ItemKind::Trait(_, _, ref generics, ..) => {
323 let def_id = self.lctx.resolver.definitions().local_def_id(item.id);
327 .filter(|param| param.is_lifetime_param())
329 self.lctx.type_def_lifetime_params.insert(def_id, count);
333 visit::walk_item(self, item);
336 fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
337 self.lctx.allocate_hir_id_counter(item.id, item);
338 visit::walk_trait_item(self, item);
341 fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
342 self.lctx.allocate_hir_id_counter(item.id, item);
343 visit::walk_impl_item(self, item);
347 struct ItemLowerer<'lcx, 'interner: 'lcx> {
348 lctx: &'lcx mut LoweringContext<'interner>,
351 impl<'lcx, 'interner> ItemLowerer<'lcx, 'interner> {
352 fn with_trait_impl_ref<F>(&mut self, trait_impl_ref: &Option<TraitRef>, f: F)
354 F: FnOnce(&mut Self),
356 let old = self.lctx.is_in_trait_impl;
357 self.lctx.is_in_trait_impl = if let &None = trait_impl_ref {
363 self.lctx.is_in_trait_impl = old;
367 impl<'lcx, 'interner> Visitor<'lcx> for ItemLowerer<'lcx, 'interner> {
368 fn visit_item(&mut self, item: &'lcx Item) {
369 let mut item_lowered = true;
370 self.lctx.with_hir_id_owner(item.id, |lctx| {
371 if let Some(hir_item) = lctx.lower_item(item) {
372 lctx.items.insert(item.id, hir_item);
374 item_lowered = false;
379 let item_lifetimes = match self.lctx.items.get(&item.id).unwrap().node {
380 hir::Item_::ItemImpl(_, _, _, ref generics, ..)
381 | hir::Item_::ItemTrait(_, _, ref generics, ..) => {
382 generics.lifetimes().cloned().collect::<Vec<_>>()
388 .with_parent_impl_lifetime_defs(&item_lifetimes, |this| {
389 let this = &mut ItemLowerer { lctx: this };
390 if let ItemKind::Impl(_, _, _, _, ref opt_trait_ref, _, _) = item.node {
391 this.with_trait_impl_ref(opt_trait_ref, |this| {
392 visit::walk_item(this, item)
395 visit::walk_item(this, item);
401 fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
402 self.lctx.with_hir_id_owner(item.id, |lctx| {
403 let id = hir::TraitItemId { node_id: item.id };
404 let hir_item = lctx.lower_trait_item(item);
405 lctx.trait_items.insert(id, hir_item);
408 visit::walk_trait_item(self, item);
411 fn visit_impl_item(&mut self, item: &'lcx ImplItem) {
412 self.lctx.with_hir_id_owner(item.id, |lctx| {
413 let id = hir::ImplItemId { node_id: item.id };
414 let hir_item = lctx.lower_impl_item(item);
415 lctx.impl_items.insert(id, hir_item);
417 visit::walk_impl_item(self, item);
421 self.lower_node_id(CRATE_NODE_ID);
422 debug_assert!(self.node_id_to_hir_id[CRATE_NODE_ID] == hir::CRATE_HIR_ID);
424 visit::walk_crate(&mut MiscCollector { lctx: &mut self }, c);
425 visit::walk_crate(&mut ItemLowerer { lctx: &mut self }, c);
427 let module = self.lower_mod(&c.module);
428 let attrs = self.lower_attrs(&c.attrs);
429 let body_ids = body_ids(&self.bodies);
433 .init_node_id_to_hir_id_mapping(self.node_id_to_hir_id);
439 exported_macros: hir::HirVec::from(self.exported_macros),
441 trait_items: self.trait_items,
442 impl_items: self.impl_items,
445 trait_impls: self.trait_impls,
446 trait_auto_impl: self.trait_auto_impl,
450 fn allocate_hir_id_counter<T: Debug>(&mut self, owner: NodeId, debug: &T) {
451 if self.item_local_id_counters.insert(owner, 0).is_some() {
453 "Tried to allocate item_local_id_counter for {:?} twice",
457 // Always allocate the first HirId for the owner itself
458 self.lower_node_id_with_owner(owner, owner);
461 fn lower_node_id_generic<F>(&mut self, ast_node_id: NodeId, alloc_hir_id: F) -> LoweredNodeId
463 F: FnOnce(&mut Self) -> hir::HirId,
465 if ast_node_id == DUMMY_NODE_ID {
466 return LoweredNodeId {
467 node_id: DUMMY_NODE_ID,
468 hir_id: hir::DUMMY_HIR_ID,
472 let min_size = ast_node_id.as_usize() + 1;
474 if min_size > self.node_id_to_hir_id.len() {
475 self.node_id_to_hir_id.resize(min_size, hir::DUMMY_HIR_ID);
478 let existing_hir_id = self.node_id_to_hir_id[ast_node_id];
480 if existing_hir_id == hir::DUMMY_HIR_ID {
481 // Generate a new HirId
482 let hir_id = alloc_hir_id(self);
483 self.node_id_to_hir_id[ast_node_id] = hir_id;
485 node_id: ast_node_id,
490 node_id: ast_node_id,
491 hir_id: existing_hir_id,
496 fn with_hir_id_owner<F, T>(&mut self, owner: NodeId, f: F) -> T
498 F: FnOnce(&mut Self) -> T,
500 let counter = self.item_local_id_counters
501 .insert(owner, HIR_ID_COUNTER_LOCKED)
503 let def_index = self.resolver.definitions().opt_def_index(owner).unwrap();
504 self.current_hir_id_owner.push((def_index, counter));
506 let (new_def_index, new_counter) = self.current_hir_id_owner.pop().unwrap();
508 debug_assert!(def_index == new_def_index);
509 debug_assert!(new_counter >= counter);
511 let prev = self.item_local_id_counters
512 .insert(owner, new_counter)
514 debug_assert!(prev == HIR_ID_COUNTER_LOCKED);
518 /// This method allocates a new HirId for the given NodeId and stores it in
519 /// the LoweringContext's NodeId => HirId map.
520 /// Take care not to call this method if the resulting HirId is then not
521 /// actually used in the HIR, as that would trigger an assertion in the
522 /// HirIdValidator later on, which makes sure that all NodeIds got mapped
523 /// properly. Calling the method twice with the same NodeId is fine though.
524 fn lower_node_id(&mut self, ast_node_id: NodeId) -> LoweredNodeId {
525 self.lower_node_id_generic(ast_node_id, |this| {
526 let &mut (def_index, ref mut local_id_counter) =
527 this.current_hir_id_owner.last_mut().unwrap();
528 let local_id = *local_id_counter;
529 *local_id_counter += 1;
532 local_id: hir::ItemLocalId(local_id),
537 fn lower_node_id_with_owner(&mut self, ast_node_id: NodeId, owner: NodeId) -> LoweredNodeId {
538 self.lower_node_id_generic(ast_node_id, |this| {
539 let local_id_counter = this
540 .item_local_id_counters
542 .expect("called lower_node_id_with_owner before allocate_hir_id_counter");
543 let local_id = *local_id_counter;
545 // We want to be sure not to modify the counter in the map while it
546 // is also on the stack. Otherwise we'll get lost updates when writing
547 // back from the stack to the map.
548 debug_assert!(local_id != HIR_ID_COUNTER_LOCKED);
550 *local_id_counter += 1;
554 .opt_def_index(owner)
555 .expect("You forgot to call `create_def_with_parent` or are lowering node ids \
556 that do not belong to the current owner");
560 local_id: hir::ItemLocalId(local_id),
565 fn record_body(&mut self, value: hir::Expr, decl: Option<&FnDecl>) -> hir::BodyId {
566 let body = hir::Body {
567 arguments: decl.map_or(hir_vec![], |decl| {
568 decl.inputs.iter().map(|x| self.lower_arg(x)).collect()
570 is_generator: self.is_generator,
574 self.bodies.insert(id, body);
578 fn next_id(&mut self) -> LoweredNodeId {
579 self.lower_node_id(self.sess.next_node_id())
582 fn expect_full_def(&mut self, id: NodeId) -> Def {
583 self.resolver.get_resolution(id).map_or(Def::Err, |pr| {
584 if pr.unresolved_segments() != 0 {
585 bug!("path not fully resolved: {:?}", pr);
591 fn expect_full_def_from_use(&mut self, id: NodeId) -> impl Iterator<Item=Def> {
592 self.resolver.get_import(id).present_items().map(|pr| {
593 if pr.unresolved_segments() != 0 {
594 bug!("path not fully resolved: {:?}", pr);
600 fn diagnostic(&self) -> &errors::Handler {
601 self.sess.diagnostic()
604 fn str_to_ident(&self, s: &'static str) -> Name {
608 fn allow_internal_unstable(&self, reason: CompilerDesugaringKind, span: Span) -> Span {
609 let mark = Mark::fresh(Mark::root());
610 mark.set_expn_info(codemap::ExpnInfo {
612 callee: codemap::NameAndSpan {
613 format: codemap::CompilerDesugaring(reason),
615 allow_internal_unstable: true,
616 allow_internal_unsafe: false,
617 edition: codemap::hygiene::default_edition(),
620 span.with_ctxt(SyntaxContext::empty().apply_mark(mark))
623 fn with_anonymous_lifetime_mode<R>(
625 anonymous_lifetime_mode: AnonymousLifetimeMode,
626 op: impl FnOnce(&mut Self) -> R,
628 let old_anonymous_lifetime_mode = self.anonymous_lifetime_mode;
629 self.anonymous_lifetime_mode = anonymous_lifetime_mode;
630 let result = op(self);
631 self.anonymous_lifetime_mode = old_anonymous_lifetime_mode;
635 /// Creates a new hir::GenericParam for every new lifetime and
636 /// type parameter encountered while evaluating `f`. Definitions
637 /// are created with the parent provided. If no `parent_id` is
638 /// provided, no definitions will be returned.
640 /// Presuming that in-band lifetimes are enabled, then
641 /// `self.anonymous_lifetime_mode` will be updated to match the
642 /// argument while `f` is running (and restored afterwards).
643 fn collect_in_band_defs<T, F>(
646 anonymous_lifetime_mode: AnonymousLifetimeMode,
648 ) -> (Vec<hir::GenericParam>, T)
650 F: FnOnce(&mut LoweringContext) -> T,
652 assert!(!self.is_collecting_in_band_lifetimes);
653 assert!(self.lifetimes_to_define.is_empty());
654 let old_anonymous_lifetime_mode = self.anonymous_lifetime_mode;
656 self.is_collecting_in_band_lifetimes = self.sess.features_untracked().in_band_lifetimes;
657 if self.is_collecting_in_band_lifetimes {
658 self.anonymous_lifetime_mode = anonymous_lifetime_mode;
661 assert!(self.in_band_ty_params.is_empty());
664 self.is_collecting_in_band_lifetimes = false;
665 self.anonymous_lifetime_mode = old_anonymous_lifetime_mode;
667 let in_band_ty_params = self.in_band_ty_params.split_off(0);
668 let lifetimes_to_define = self.lifetimes_to_define.split_off(0);
670 let params = lifetimes_to_define
672 .map(|(span, hir_name)| {
673 let def_node_id = self.next_id().node_id;
675 // Get the name we'll use to make the def-path. Note
676 // that collisions are ok here and this shouldn't
677 // really show up for end-user.
678 let str_name = match hir_name {
679 hir::LifetimeName::Name(n) => n.as_str(),
680 hir::LifetimeName::Fresh(_) => keywords::UnderscoreLifetime.name().as_str(),
681 hir::LifetimeName::Implicit
682 | hir::LifetimeName::Underscore
683 | hir::LifetimeName::Static => {
684 span_bug!(span, "unexpected in-band lifetime name: {:?}", hir_name)
688 // Add a definition for the in-band lifetime def
689 self.resolver.definitions().create_def_with_parent(
692 DefPathData::LifetimeDef(str_name.as_interned_str()),
693 DefIndexAddressSpace::High,
698 hir::GenericParam::Lifetime(hir::LifetimeDef {
699 lifetime: hir::Lifetime {
704 bounds: Vec::new().into(),
705 pure_wrt_drop: false,
712 .map(|tp| hir::GenericParam::Type(tp)),
719 /// When there is a reference to some lifetime `'a`, and in-band
720 /// lifetimes are enabled, then we want to push that lifetime into
721 /// the vector of names to define later. In that case, it will get
722 /// added to the appropriate generics.
723 fn maybe_collect_in_band_lifetime(&mut self, span: Span, name: Name) {
724 if !self.is_collecting_in_band_lifetimes {
728 if self.in_scope_lifetimes.contains(&name) {
732 let hir_name = hir::LifetimeName::Name(name);
734 if self.lifetimes_to_define
736 .any(|(_, lt_name)| *lt_name == hir_name)
741 self.lifetimes_to_define.push((span, hir_name));
744 /// When we have either an elided or `'_` lifetime in an impl
745 /// header, we convert it to
746 fn collect_fresh_in_band_lifetime(&mut self, span: Span) -> hir::LifetimeName {
747 assert!(self.is_collecting_in_band_lifetimes);
748 let index = self.lifetimes_to_define.len();
749 let hir_name = hir::LifetimeName::Fresh(index);
750 self.lifetimes_to_define.push((span, hir_name));
754 // Evaluates `f` with the lifetimes in `lt_defs` in-scope.
755 // This is used to track which lifetimes have already been defined, and
756 // which are new in-band lifetimes that need to have a definition created
758 fn with_in_scope_lifetime_defs<'l, T, F>(
760 lt_defs: impl Iterator<Item = &'l LifetimeDef>,
764 F: FnOnce(&mut LoweringContext) -> T,
766 let old_len = self.in_scope_lifetimes.len();
767 let lt_def_names = lt_defs.map(|lt_def| lt_def.lifetime.ident.name);
768 self.in_scope_lifetimes.extend(lt_def_names);
772 self.in_scope_lifetimes.truncate(old_len);
776 // Same as the method above, but accepts `hir::LifetimeDef`s
777 // instead of `ast::LifetimeDef`s.
778 // This should only be used with generics that have already had their
779 // in-band lifetimes added. In practice, this means that this function is
780 // only used when lowering a child item of a trait or impl.
781 fn with_parent_impl_lifetime_defs<T, F>(&mut self, lt_defs: &[hir::LifetimeDef], f: F) -> T
783 F: FnOnce(&mut LoweringContext) -> T,
785 let old_len = self.in_scope_lifetimes.len();
786 let lt_def_names = lt_defs.iter().map(|lt_def| lt_def.lifetime.name.name());
787 self.in_scope_lifetimes.extend(lt_def_names);
791 self.in_scope_lifetimes.truncate(old_len);
795 /// Appends in-band lifetime defs and argument-position `impl
796 /// Trait` defs to the existing set of generics.
798 /// Presuming that in-band lifetimes are enabled, then
799 /// `self.anonymous_lifetime_mode` will be updated to match the
800 /// argument while `f` is running (and restored afterwards).
801 fn add_in_band_defs<F, T>(
805 anonymous_lifetime_mode: AnonymousLifetimeMode,
807 ) -> (hir::Generics, T)
809 F: FnOnce(&mut LoweringContext) -> T,
811 let (in_band_defs, (mut lowered_generics, res)) = self.with_in_scope_lifetime_defs(
812 generics.params.iter().filter_map(|p| match p {
813 GenericParam::Lifetime(ld) => Some(ld),
817 let itctx = ImplTraitContext::Universal(parent_id);
818 this.collect_in_band_defs(parent_id, anonymous_lifetime_mode, |this| {
819 (this.lower_generics(generics, itctx), f(this))
824 lowered_generics.params = lowered_generics
831 (lowered_generics, res)
834 fn with_catch_scope<T, F>(&mut self, catch_id: NodeId, f: F) -> T
836 F: FnOnce(&mut LoweringContext) -> T,
838 let len = self.catch_scopes.len();
839 self.catch_scopes.push(catch_id);
841 let result = f(self);
844 self.catch_scopes.len(),
845 "catch scopes should be added and removed in stack order"
848 self.catch_scopes.pop().unwrap();
853 fn lower_body<F>(&mut self, decl: Option<&FnDecl>, f: F) -> hir::BodyId
855 F: FnOnce(&mut LoweringContext) -> hir::Expr,
857 let prev = mem::replace(&mut self.is_generator, false);
858 let result = f(self);
859 let r = self.record_body(result, decl);
860 self.is_generator = prev;
864 fn with_loop_scope<T, F>(&mut self, loop_id: NodeId, f: F) -> T
866 F: FnOnce(&mut LoweringContext) -> T,
868 // We're no longer in the base loop's condition; we're in another loop.
869 let was_in_loop_condition = self.is_in_loop_condition;
870 self.is_in_loop_condition = false;
872 let len = self.loop_scopes.len();
873 self.loop_scopes.push(loop_id);
875 let result = f(self);
878 self.loop_scopes.len(),
879 "Loop scopes should be added and removed in stack order"
882 self.loop_scopes.pop().unwrap();
884 self.is_in_loop_condition = was_in_loop_condition;
889 fn with_loop_condition_scope<T, F>(&mut self, f: F) -> T
891 F: FnOnce(&mut LoweringContext) -> T,
893 let was_in_loop_condition = self.is_in_loop_condition;
894 self.is_in_loop_condition = true;
896 let result = f(self);
898 self.is_in_loop_condition = was_in_loop_condition;
903 fn with_new_scopes<T, F>(&mut self, f: F) -> T
905 F: FnOnce(&mut LoweringContext) -> T,
907 let was_in_loop_condition = self.is_in_loop_condition;
908 self.is_in_loop_condition = false;
910 let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new());
911 let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new());
912 let result = f(self);
913 self.catch_scopes = catch_scopes;
914 self.loop_scopes = loop_scopes;
916 self.is_in_loop_condition = was_in_loop_condition;
921 fn def_key(&mut self, id: DefId) -> DefKey {
923 self.resolver.definitions().def_key(id.index)
925 self.cstore.def_key(id)
929 fn lower_ident(&mut self, ident: Ident) -> Name {
930 let ident = ident.modern();
931 if ident.span.ctxt() == SyntaxContext::empty() {
936 .or_insert_with(|| Symbol::from_ident(ident))
939 fn lower_label(&mut self, label: Option<Label>) -> Option<hir::Label> {
940 label.map(|label| hir::Label {
941 name: label.ident.name,
942 span: label.ident.span,
946 fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination {
948 Some((id, label)) => {
949 let target_id = if let Def::Label(loop_id) = self.expect_full_def(id) {
950 Ok(self.lower_node_id(loop_id).node_id)
952 Err(hir::LoopIdError::UnresolvedLabel)
955 label: self.lower_label(Some(label)),
960 let target_id = self.loop_scopes
962 .map(|innermost_loop_id| *innermost_loop_id)
963 .map(|id| Ok(self.lower_node_id(id).node_id))
964 .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
975 fn lower_attrs(&mut self, attrs: &[Attribute]) -> hir::HirVec<Attribute> {
978 .map(|a| self.lower_attr(a))
983 fn lower_attr(&mut self, attr: &Attribute) -> Attribute {
987 path: attr.path.clone(),
988 tokens: self.lower_token_stream(attr.tokens.clone()),
989 is_sugared_doc: attr.is_sugared_doc,
994 fn lower_token_stream(&mut self, tokens: TokenStream) -> TokenStream {
997 .flat_map(|tree| self.lower_token_tree(tree).into_trees())
1001 fn lower_token_tree(&mut self, tree: TokenTree) -> TokenStream {
1003 TokenTree::Token(span, token) => self.lower_token(token, span),
1004 TokenTree::Delimited(span, delimited) => TokenTree::Delimited(
1007 delim: delimited.delim,
1008 tts: self.lower_token_stream(delimited.tts.into()).into(),
1014 fn lower_token(&mut self, token: Token, span: Span) -> TokenStream {
1016 Token::Interpolated(_) => {}
1017 other => return TokenTree::Token(span, other).into(),
1020 let tts = token.interpolated_to_tokenstream(&self.sess.parse_sess, span);
1021 self.lower_token_stream(tts)
1024 fn lower_arm(&mut self, arm: &Arm) -> hir::Arm {
1026 attrs: self.lower_attrs(&arm.attrs),
1027 pats: arm.pats.iter().map(|x| self.lower_pat(x)).collect(),
1028 guard: arm.guard.as_ref().map(|ref x| P(self.lower_expr(x))),
1029 body: P(self.lower_expr(&arm.body)),
1033 fn lower_ty_binding(&mut self, b: &TypeBinding, itctx: ImplTraitContext) -> hir::TypeBinding {
1035 id: self.lower_node_id(b.id).node_id,
1036 name: self.lower_ident(b.ident),
1037 ty: self.lower_ty(&b.ty, itctx),
1042 fn lower_generic_arg(&mut self,
1043 p: &ast::GenericArg,
1044 itctx: ImplTraitContext)
1045 -> hir::GenericArg {
1047 ast::GenericArg::Lifetime(lt) => {
1048 GenericArg::Lifetime(self.lower_lifetime(<))
1050 ast::GenericArg::Type(ty) => {
1051 GenericArg::Type(self.lower_ty(&ty, itctx))
1056 fn lower_ty(&mut self, t: &Ty, itctx: ImplTraitContext) -> P<hir::Ty> {
1057 let kind = match t.node {
1058 TyKind::Infer => hir::TyInfer,
1059 TyKind::Err => hir::TyErr,
1060 TyKind::Slice(ref ty) => hir::TySlice(self.lower_ty(ty, itctx)),
1061 TyKind::Ptr(ref mt) => hir::TyPtr(self.lower_mt(mt, itctx)),
1062 TyKind::Rptr(ref region, ref mt) => {
1063 let span = t.span.shrink_to_lo();
1064 let lifetime = match *region {
1065 Some(ref lt) => self.lower_lifetime(lt),
1066 None => self.elided_ref_lifetime(span),
1068 hir::TyRptr(lifetime, self.lower_mt(mt, itctx))
1070 TyKind::BareFn(ref f) => self.with_in_scope_lifetime_defs(
1071 f.generic_params.iter().filter_map(|p| match p {
1072 GenericParam::Lifetime(ld) => Some(ld),
1076 this.with_anonymous_lifetime_mode(
1077 AnonymousLifetimeMode::PassThrough,
1079 hir::TyBareFn(P(hir::BareFnTy {
1080 generic_params: this.lower_generic_params(
1083 ImplTraitContext::Disallowed,
1085 unsafety: this.lower_unsafety(f.unsafety),
1087 decl: this.lower_fn_decl(&f.decl, None, false),
1088 arg_names: this.lower_fn_args_to_names(&f.decl),
1094 TyKind::Never => hir::TyNever,
1095 TyKind::Tup(ref tys) => {
1096 hir::TyTup(tys.iter().map(|ty| self.lower_ty(ty, itctx)).collect())
1098 TyKind::Paren(ref ty) => {
1099 return self.lower_ty(ty, itctx);
1101 TyKind::Path(ref qself, ref path) => {
1102 let id = self.lower_node_id(t.id);
1103 let qpath = self.lower_qpath(t.id, qself, path, ParamMode::Explicit, itctx);
1104 let ty = self.ty_path(id, t.span, qpath);
1105 if let hir::TyTraitObject(..) = ty.node {
1106 self.maybe_lint_bare_trait(t.span, t.id, qself.is_none() && path.is_global());
1110 TyKind::ImplicitSelf => hir::TyPath(hir::QPath::Resolved(
1113 def: self.expect_full_def(t.id),
1114 segments: hir_vec![hir::PathSegment::from_name(keywords::SelfType.name())],
1118 TyKind::Array(ref ty, ref length) => {
1119 hir::TyArray(self.lower_ty(ty, itctx), self.lower_anon_const(length))
1121 TyKind::Typeof(ref expr) => {
1122 hir::TyTypeof(self.lower_anon_const(expr))
1124 TyKind::TraitObject(ref bounds, kind) => {
1125 let mut lifetime_bound = None;
1128 .filter_map(|bound| match *bound {
1129 TraitTyParamBound(ref ty, TraitBoundModifier::None) => {
1130 Some(self.lower_poly_trait_ref(ty, itctx))
1132 TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
1133 RegionTyParamBound(ref lifetime) => {
1134 if lifetime_bound.is_none() {
1135 lifetime_bound = Some(self.lower_lifetime(lifetime));
1141 let lifetime_bound =
1142 lifetime_bound.unwrap_or_else(|| self.elided_dyn_bound(t.span));
1143 if kind != TraitObjectSyntax::Dyn {
1144 self.maybe_lint_bare_trait(t.span, t.id, false);
1146 hir::TyTraitObject(bounds, lifetime_bound)
1148 TyKind::ImplTrait(ref bounds) => {
1151 ImplTraitContext::Existential(fn_def_id) => {
1153 // We need to manually repeat the code of `next_id` because the lowering
1154 // needs to happen while the owner_id is pointing to the item itself,
1155 // because items are their own owners
1156 let exist_ty_node_id = self.sess.next_node_id();
1158 // Make sure we know that some funky desugaring has been going on here.
1159 // This is a first: there is code in other places like for loop
1160 // desugaring that explicitly states that we don't want to track that.
1161 // Not tracking it makes lints in rustc and clippy very fragile as
1162 // frequently opened issues show.
1163 let exist_ty_span = self.allow_internal_unstable(
1164 CompilerDesugaringKind::ExistentialReturnType,
1168 // Pull a new definition from the ether
1169 let exist_ty_def_index = self
1172 .create_def_with_parent(
1175 DefPathData::ExistentialImplTrait,
1176 DefIndexAddressSpace::High,
1181 // the `t` is just for printing debug messages
1182 self.allocate_hir_id_counter(exist_ty_node_id, t);
1184 let hir_bounds = self.with_hir_id_owner(exist_ty_node_id, |lctx| {
1185 lctx.lower_bounds(bounds, itctx)
1188 let (lifetimes, lifetime_defs) = self.lifetimes_from_impl_trait_bounds(
1194 self.with_hir_id_owner(exist_ty_node_id, |lctx| {
1195 let exist_ty_item_kind = hir::ItemExistential(hir::ExistTy {
1196 generics: hir::Generics {
1197 params: lifetime_defs,
1198 where_clause: hir::WhereClause {
1199 id: lctx.next_id().node_id,
1200 predicates: Vec::new().into(),
1205 impl_trait_fn: Some(fn_def_id),
1207 let exist_ty_id = lctx.lower_node_id(exist_ty_node_id);
1208 // Generate an `existential type Foo: Trait;` declaration
1209 trace!("creating existential type with id {:#?}", exist_ty_id);
1210 // Set the name to `impl Bound1 + Bound2`
1211 let exist_ty_name = Symbol::intern(&pprust::ty_to_string(t));
1213 trace!("exist ty def index: {:#?}", exist_ty_def_index);
1214 let exist_ty_item = hir::Item {
1215 id: exist_ty_id.node_id,
1216 hir_id: exist_ty_id.hir_id,
1217 name: exist_ty_name,
1218 attrs: Default::default(),
1219 node: exist_ty_item_kind,
1220 vis: hir::Visibility::Inherited,
1221 span: exist_ty_span,
1224 // Insert the item into the global list. This usually happens
1225 // automatically for all AST items. But this existential type item
1226 // does not actually exist in the AST.
1227 lctx.items.insert(exist_ty_id.node_id, exist_ty_item);
1229 // `impl Trait` now just becomes `Foo<'a, 'b, ..>`
1230 hir::TyImplTraitExistential(
1232 id: exist_ty_id.node_id
1234 DefId::local(exist_ty_def_index),
1239 ImplTraitContext::Universal(def_id) => {
1240 let def_node_id = self.next_id().node_id;
1242 // Add a definition for the in-band TyParam
1243 let def_index = self.resolver.definitions().create_def_with_parent(
1246 DefPathData::UniversalImplTrait,
1247 DefIndexAddressSpace::High,
1252 let hir_bounds = self.lower_bounds(bounds, itctx);
1253 // Set the name to `impl Bound1 + Bound2`
1254 let name = Symbol::intern(&pprust::ty_to_string(t));
1255 self.in_band_ty_params.push(hir::TyParam {
1261 pure_wrt_drop: false,
1262 synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
1266 hir::TyPath(hir::QPath::Resolved(
1270 def: Def::TyParam(DefId::local(def_index)),
1271 segments: hir_vec![hir::PathSegment::from_name(name)],
1275 ImplTraitContext::Disallowed => {
1280 "`impl Trait` not allowed outside of function \
1281 and inherent method return types"
1287 TyKind::Mac(_) => panic!("TyMac should have been expanded by now."),
1290 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(t.id);
1299 fn lifetimes_from_impl_trait_bounds(
1301 exist_ty_id: NodeId,
1302 parent_index: DefIndex,
1303 bounds: &hir::TyParamBounds,
1304 ) -> (HirVec<hir::Lifetime>, HirVec<hir::GenericParam>) {
1305 // This visitor walks over impl trait bounds and creates defs for all lifetimes which
1306 // appear in the bounds, excluding lifetimes that are created within the bounds.
1307 // e.g. 'a, 'b, but not 'c in `impl for<'c> SomeTrait<'a, 'b, 'c>`
1308 struct ImplTraitLifetimeCollector<'r, 'a: 'r> {
1309 context: &'r mut LoweringContext<'a>,
1311 exist_ty_id: NodeId,
1312 collect_elided_lifetimes: bool,
1313 currently_bound_lifetimes: Vec<hir::LifetimeName>,
1314 already_defined_lifetimes: HashSet<hir::LifetimeName>,
1315 output_lifetimes: Vec<hir::Lifetime>,
1316 output_lifetime_params: Vec<hir::GenericParam>,
1319 impl<'r, 'a: 'r, 'v> hir::intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r, 'a> {
1320 fn nested_visit_map<'this>(
1322 ) -> hir::intravisit::NestedVisitorMap<'this, 'v> {
1323 hir::intravisit::NestedVisitorMap::None
1326 fn visit_generic_args(&mut self, span: Span, parameters: &'v hir::GenericArgs) {
1327 // Don't collect elided lifetimes used inside of `Fn()` syntax.
1328 if parameters.parenthesized {
1329 let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
1330 self.collect_elided_lifetimes = false;
1331 hir::intravisit::walk_generic_args(self, span, parameters);
1332 self.collect_elided_lifetimes = old_collect_elided_lifetimes;
1334 hir::intravisit::walk_generic_args(self, span, parameters);
1338 fn visit_ty(&mut self, t: &'v hir::Ty) {
1339 // Don't collect elided lifetimes used inside of `fn()` syntax
1340 if let &hir::Ty_::TyBareFn(_) = &t.node {
1341 let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
1342 self.collect_elided_lifetimes = false;
1344 // Record the "stack height" of `for<'a>` lifetime bindings
1345 // to be able to later fully undo their introduction.
1346 let old_len = self.currently_bound_lifetimes.len();
1347 hir::intravisit::walk_ty(self, t);
1348 self.currently_bound_lifetimes.truncate(old_len);
1350 self.collect_elided_lifetimes = old_collect_elided_lifetimes;
1352 hir::intravisit::walk_ty(self, t);
1356 fn visit_poly_trait_ref(
1358 trait_ref: &'v hir::PolyTraitRef,
1359 modifier: hir::TraitBoundModifier,
1361 // Record the "stack height" of `for<'a>` lifetime bindings
1362 // to be able to later fully undo their introduction.
1363 let old_len = self.currently_bound_lifetimes.len();
1364 hir::intravisit::walk_poly_trait_ref(self, trait_ref, modifier);
1365 self.currently_bound_lifetimes.truncate(old_len);
1368 fn visit_generic_param(&mut self, param: &'v hir::GenericParam) {
1369 // Record the introduction of 'a in `for<'a> ...`
1370 if let hir::GenericParam::Lifetime(ref lt_def) = *param {
1371 // Introduce lifetimes one at a time so that we can handle
1372 // cases like `fn foo<'d>() -> impl for<'a, 'b: 'a, 'c: 'b + 'd>`
1373 self.currently_bound_lifetimes.push(lt_def.lifetime.name);
1376 hir::intravisit::walk_generic_param(self, param);
1379 fn visit_lifetime(&mut self, lifetime: &'v hir::Lifetime) {
1380 let name = match lifetime.name {
1381 hir::LifetimeName::Implicit | hir::LifetimeName::Underscore => {
1382 if self.collect_elided_lifetimes {
1383 // Use `'_` for both implicit and underscore lifetimes in
1384 // `abstract type Foo<'_>: SomeTrait<'_>;`
1385 hir::LifetimeName::Underscore
1390 name @ hir::LifetimeName::Fresh(_) => name,
1391 name @ hir::LifetimeName::Name(_) => name,
1392 hir::LifetimeName::Static => return,
1395 if !self.currently_bound_lifetimes.contains(&name)
1396 && !self.already_defined_lifetimes.contains(&name)
1398 self.already_defined_lifetimes.insert(name);
1400 self.output_lifetimes.push(hir::Lifetime {
1401 id: self.context.next_id().node_id,
1402 span: lifetime.span,
1406 // We need to manually create the ids here, because the
1407 // definitions will go into the explicit `existential type`
1408 // declaration and thus need to have their owner set to that item
1409 let def_node_id = self.context.sess.next_node_id();
1410 let _ = self.context.lower_node_id_with_owner(def_node_id, self.exist_ty_id);
1411 self.context.resolver.definitions().create_def_with_parent(
1414 DefPathData::LifetimeDef(name.name().as_interned_str()),
1415 DefIndexAddressSpace::High,
1419 let def_lifetime = hir::Lifetime {
1421 span: lifetime.span,
1424 self.output_lifetime_params
1425 .push(hir::GenericParam::Lifetime(hir::LifetimeDef {
1426 lifetime: def_lifetime,
1427 bounds: Vec::new().into(),
1428 pure_wrt_drop: false,
1435 let mut lifetime_collector = ImplTraitLifetimeCollector {
1437 parent: parent_index,
1439 collect_elided_lifetimes: true,
1440 currently_bound_lifetimes: Vec::new(),
1441 already_defined_lifetimes: HashSet::new(),
1442 output_lifetimes: Vec::new(),
1443 output_lifetime_params: Vec::new(),
1446 for bound in bounds {
1447 hir::intravisit::walk_ty_param_bound(&mut lifetime_collector, &bound);
1451 lifetime_collector.output_lifetimes.into(),
1452 lifetime_collector.output_lifetime_params.into(),
1456 fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod {
1461 .map(|x| self.lower_foreign_item(x))
1466 fn lower_global_asm(&mut self, ga: &GlobalAsm) -> P<hir::GlobalAsm> {
1473 fn lower_variant(&mut self, v: &Variant) -> hir::Variant {
1475 node: hir::Variant_ {
1476 name: v.node.ident.name,
1477 attrs: self.lower_attrs(&v.node.attrs),
1478 data: self.lower_variant_data(&v.node.data),
1479 disr_expr: v.node.disr_expr.as_ref().map(|e| self.lower_anon_const(e)),
1488 qself: &Option<QSelf>,
1490 param_mode: ParamMode,
1491 itctx: ImplTraitContext,
1493 let qself_position = qself.as_ref().map(|q| q.position);
1494 let qself = qself.as_ref().map(|q| self.lower_ty(&q.ty, itctx));
1496 let resolution = self.resolver
1498 .unwrap_or(PathResolution::new(Def::Err));
1500 let proj_start = p.segments.len() - resolution.unresolved_segments();
1501 let path = P(hir::Path {
1502 def: resolution.base_def(),
1503 segments: p.segments[..proj_start]
1506 .map(|(i, segment)| {
1507 let param_mode = match (qself_position, param_mode) {
1508 (Some(j), ParamMode::Optional) if i < j => {
1509 // This segment is part of the trait path in a
1510 // qualified path - one of `a`, `b` or `Trait`
1511 // in `<X as a::b::Trait>::T::U::method`.
1517 // Figure out if this is a type/trait segment,
1518 // which may need lifetime elision performed.
1519 let parent_def_id = |this: &mut Self, def_id: DefId| DefId {
1520 krate: def_id.krate,
1521 index: this.def_key(def_id).parent.expect("missing parent"),
1523 let type_def_id = match resolution.base_def() {
1524 Def::AssociatedTy(def_id) if i + 2 == proj_start => {
1525 Some(parent_def_id(self, def_id))
1527 Def::Variant(def_id) if i + 1 == proj_start => {
1528 Some(parent_def_id(self, def_id))
1531 | Def::Union(def_id)
1533 | Def::TyAlias(def_id)
1534 | Def::Trait(def_id) if i + 1 == proj_start =>
1540 let parenthesized_generic_args = match resolution.base_def() {
1541 // `a::b::Trait(Args)`
1542 Def::Trait(..) if i + 1 == proj_start => ParenthesizedGenericArgs::Ok,
1543 // `a::b::Trait(Args)::TraitItem`
1544 Def::Method(..) | Def::AssociatedConst(..) | Def::AssociatedTy(..)
1545 if i + 2 == proj_start =>
1547 ParenthesizedGenericArgs::Ok
1549 // Avoid duplicated errors
1550 Def::Err => ParenthesizedGenericArgs::Ok,
1556 | Def::Variant(..) if i + 1 == proj_start =>
1558 ParenthesizedGenericArgs::Err
1560 // A warning for now, for compatibility reasons
1561 _ => ParenthesizedGenericArgs::Warn,
1564 let num_lifetimes = type_def_id.map_or(0, |def_id| {
1565 if let Some(&n) = self.type_def_lifetime_params.get(&def_id) {
1568 assert!(!def_id.is_local());
1570 self.cstore.item_generics_cloned_untracked(def_id, self.sess);
1571 let n = item_generics.own_counts().lifetimes;
1572 self.type_def_lifetime_params.insert(def_id, n);
1575 self.lower_path_segment(
1580 parenthesized_generic_args,
1588 // Simple case, either no projections, or only fully-qualified.
1589 // E.g. `std::mem::size_of` or `<I as Iterator>::Item`.
1590 if resolution.unresolved_segments() == 0 {
1591 return hir::QPath::Resolved(qself, path);
1594 // Create the innermost type that we're projecting from.
1595 let mut ty = if path.segments.is_empty() {
1596 // If the base path is empty that means there exists a
1597 // syntactical `Self`, e.g. `&i32` in `<&i32>::clone`.
1598 qself.expect("missing QSelf for <T>::...")
1600 // Otherwise, the base path is an implicit `Self` type path,
1601 // e.g. `Vec` in `Vec::new` or `<I as Iterator>::Item` in
1602 // `<I as Iterator>::Item::default`.
1603 let new_id = self.next_id();
1604 self.ty_path(new_id, p.span, hir::QPath::Resolved(qself, path))
1607 // Anything after the base path are associated "extensions",
1608 // out of which all but the last one are associated types,
1609 // e.g. for `std::vec::Vec::<T>::IntoIter::Item::clone`:
1610 // * base path is `std::vec::Vec<T>`
1611 // * "extensions" are `IntoIter`, `Item` and `clone`
1612 // * type nodes are:
1613 // 1. `std::vec::Vec<T>` (created above)
1614 // 2. `<std::vec::Vec<T>>::IntoIter`
1615 // 3. `<<std::vec::Vec<T>>::IntoIter>::Item`
1616 // * final path is `<<<std::vec::Vec<T>>::IntoIter>::Item>::clone`
1617 for (i, segment) in p.segments.iter().enumerate().skip(proj_start) {
1618 let segment = P(self.lower_path_segment(
1623 ParenthesizedGenericArgs::Warn,
1626 let qpath = hir::QPath::TypeRelative(ty, segment);
1628 // It's finished, return the extension of the right node type.
1629 if i == p.segments.len() - 1 {
1633 // Wrap the associated extension in another type node.
1634 let new_id = self.next_id();
1635 ty = self.ty_path(new_id, p.span, qpath);
1638 // Should've returned in the for loop above.
1641 "lower_qpath: no final extension segment in {}..{}",
1647 fn lower_path_extra(
1652 param_mode: ParamMode,
1656 segments: p.segments
1659 self.lower_path_segment(
1664 ParenthesizedGenericArgs::Err,
1665 ImplTraitContext::Disallowed,
1668 .chain(name.map(|name| hir::PathSegment::from_name(name)))
1674 fn lower_path(&mut self, id: NodeId, p: &Path, param_mode: ParamMode) -> hir::Path {
1675 let def = self.expect_full_def(id);
1676 self.lower_path_extra(def, p, None, param_mode)
1679 fn lower_path_segment(
1682 segment: &PathSegment,
1683 param_mode: ParamMode,
1684 expected_lifetimes: usize,
1685 parenthesized_generic_args: ParenthesizedGenericArgs,
1686 itctx: ImplTraitContext,
1687 ) -> hir::PathSegment {
1688 let (mut generic_args, infer_types) = if let Some(ref generic_args) = segment.args {
1689 let msg = "parenthesized parameters may only be used with a trait";
1690 match **generic_args {
1691 GenericArgs::AngleBracketed(ref data) => {
1692 self.lower_angle_bracketed_parameter_data(data, param_mode, itctx)
1694 GenericArgs::Parenthesized(ref data) => match parenthesized_generic_args {
1695 ParenthesizedGenericArgs::Ok => self.lower_parenthesized_parameter_data(data),
1696 ParenthesizedGenericArgs::Warn => {
1697 self.sess.buffer_lint(
1698 PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
1703 (hir::GenericArgs::none(), true)
1705 ParenthesizedGenericArgs::Err => {
1706 struct_span_err!(self.sess, data.span, E0214, "{}", msg)
1707 .span_label(data.span, "only traits may use parentheses")
1709 (hir::GenericArgs::none(), true)
1714 self.lower_angle_bracketed_parameter_data(&Default::default(), param_mode, itctx)
1717 if !generic_args.parenthesized && generic_args.lifetimes().count() == 0 {
1719 self.elided_path_lifetimes(path_span, expected_lifetimes)
1721 .map(|lt| GenericArg::Lifetime(lt))
1722 .chain(generic_args.args.into_iter())
1726 hir::PathSegment::new(
1727 self.lower_ident(segment.ident),
1733 fn lower_angle_bracketed_parameter_data(
1735 data: &AngleBracketedArgs,
1736 param_mode: ParamMode,
1737 itctx: ImplTraitContext,
1738 ) -> (hir::GenericArgs, bool) {
1739 let &AngleBracketedArgs { ref args, ref bindings, .. } = data;
1741 args: args.iter().map(|p| self.lower_generic_arg(p, itctx)).collect(),
1742 bindings: bindings.iter().map(|b| self.lower_ty_binding(b, itctx)).collect(),
1743 parenthesized: false,
1745 data.types().count() == 0 && param_mode == ParamMode::Optional)
1748 fn lower_parenthesized_parameter_data(
1750 data: &ParenthesizedParameterData,
1751 ) -> (hir::PathParameters, bool) {
1752 // Switch to `PassThrough` mode for anonymous lifetimes: this
1753 // means that we permit things like `&Ref<T>`, where `Ref` has
1754 // a hidden lifetime parameter. This is needed for backwards
1755 // compatibility, even in contexts like an impl header where
1756 // we generally don't permit such things (see #51008).
1757 self.with_anonymous_lifetime_mode(
1758 AnonymousLifetimeMode::PassThrough,
1760 const DISALLOWED: ImplTraitContext = ImplTraitContext::Disallowed;
1761 let &ParenthesizedParameterData { ref inputs, ref output, span } = data;
1762 let inputs = inputs.iter().map(|ty| this.lower_ty(ty, DISALLOWED)).collect();
1763 let mk_tup = |this: &mut Self, tys, span| {
1764 let LoweredNodeId { node_id, hir_id } = this.next_id();
1765 P(hir::Ty { node: hir::TyTup(tys), id: node_id, hir_id, span })
1770 parameters: hir_vec![GenericArg::Type(mk_tup(this, inputs, span))],
1773 id: this.next_id().node_id,
1774 name: Symbol::intern(FN_OUTPUT_NAME),
1777 .map(|ty| this.lower_ty(&ty, DISALLOWED))
1778 .unwrap_or_else(|| mk_tup(this, hir::HirVec::new(), span)),
1779 span: output.as_ref().map_or(span, |ty| ty.span),
1782 parenthesized: true,
1790 fn lower_local(&mut self, l: &Local) -> P<hir::Local> {
1791 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(l.id);
1797 .map(|t| self.lower_ty(t, ImplTraitContext::Disallowed)),
1798 pat: self.lower_pat(&l.pat),
1799 init: l.init.as_ref().map(|e| P(self.lower_expr(e))),
1801 attrs: l.attrs.clone(),
1802 source: hir::LocalSource::Normal,
1806 fn lower_mutability(&mut self, m: Mutability) -> hir::Mutability {
1808 Mutability::Mutable => hir::MutMutable,
1809 Mutability::Immutable => hir::MutImmutable,
1813 fn lower_arg(&mut self, arg: &Arg) -> hir::Arg {
1814 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(arg.id);
1818 pat: self.lower_pat(&arg.pat),
1822 fn lower_fn_args_to_names(&mut self, decl: &FnDecl) -> hir::HirVec<Spanned<Name>> {
1825 .map(|arg| match arg.pat.node {
1826 PatKind::Ident(_, ident, None) => respan(ident.span, ident.name),
1827 _ => respan(arg.pat.span, keywords::Invalid.name()),
1835 fn_def_id: Option<DefId>,
1836 impl_trait_return_allow: bool,
1837 ) -> P<hir::FnDecl> {
1838 // NOTE: The two last parameters here have to do with impl Trait. If fn_def_id is Some,
1839 // then impl Trait arguments are lowered into generic parameters on the given
1840 // fn_def_id, otherwise impl Trait is disallowed. (for now)
1842 // Furthermore, if impl_trait_return_allow is true, then impl Trait may be used in
1843 // return positions as well. This guards against trait declarations and their impls
1844 // where impl Trait is disallowed. (again for now)
1849 if let Some(def_id) = fn_def_id {
1850 self.lower_ty(&arg.ty, ImplTraitContext::Universal(def_id))
1852 self.lower_ty(&arg.ty, ImplTraitContext::Disallowed)
1856 output: match decl.output {
1857 FunctionRetTy::Ty(ref ty) => match fn_def_id {
1858 Some(def_id) if impl_trait_return_allow => {
1859 hir::Return(self.lower_ty(ty, ImplTraitContext::Existential(def_id)))
1861 _ => hir::Return(self.lower_ty(ty, ImplTraitContext::Disallowed)),
1863 FunctionRetTy::Default(span) => hir::DefaultReturn(span),
1865 variadic: decl.variadic,
1866 has_implicit_self: decl.inputs.get(0).map_or(false, |arg| match arg.ty.node {
1867 TyKind::ImplicitSelf => true,
1868 TyKind::Rptr(_, ref mt) => mt.ty.node == TyKind::ImplicitSelf,
1874 fn lower_ty_param_bound(
1877 itctx: ImplTraitContext,
1878 ) -> hir::TyParamBound {
1880 TraitTyParamBound(ref ty, modifier) => hir::TraitTyParamBound(
1881 self.lower_poly_trait_ref(ty, itctx),
1882 self.lower_trait_bound_modifier(modifier),
1884 RegionTyParamBound(ref lifetime) => {
1885 hir::RegionTyParamBound(self.lower_lifetime(lifetime))
1893 add_bounds: &[TyParamBound],
1894 itctx: ImplTraitContext,
1896 let mut name = self.lower_ident(tp.ident);
1898 // Don't expose `Self` (recovered "keyword used as ident" parse error).
1899 // `rustc::ty` expects `Self` to be only used for a trait's `Self`.
1900 // Instead, use gensym("Self") to create a distinct name that looks the same.
1901 if name == keywords::SelfType.name() {
1902 name = Symbol::gensym("Self");
1905 let mut bounds = self.lower_bounds(&tp.bounds, itctx);
1906 if !add_bounds.is_empty() {
1909 .chain(self.lower_bounds(add_bounds, itctx).into_iter())
1914 id: self.lower_node_id(tp.id).node_id,
1919 .map(|x| self.lower_ty(x, ImplTraitContext::Disallowed)),
1920 span: tp.ident.span,
1921 pure_wrt_drop: attr::contains_name(&tp.attrs, "may_dangle"),
1924 .filter(|attr| attr.check_name("rustc_synthetic"))
1925 .map(|_| hir::SyntheticTyParamKind::ImplTrait)
1927 attrs: self.lower_attrs(&tp.attrs),
1931 fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime {
1932 let span = l.ident.span;
1933 match self.lower_ident(l.ident) {
1934 x if x == "'static" => self.new_named_lifetime(l.id, span, hir::LifetimeName::Static),
1935 x if x == "'_" => match self.anonymous_lifetime_mode {
1936 AnonymousLifetimeMode::CreateParameter => {
1937 let fresh_name = self.collect_fresh_in_band_lifetime(span);
1938 self.new_named_lifetime(l.id, span, fresh_name)
1941 AnonymousLifetimeMode::PassThrough => {
1942 self.new_named_lifetime(l.id, span, hir::LifetimeName::Underscore)
1946 self.maybe_collect_in_band_lifetime(span, name);
1947 self.new_named_lifetime(l.id, span, hir::LifetimeName::Name(name))
1952 fn new_named_lifetime(
1956 name: hir::LifetimeName,
1957 ) -> hir::Lifetime {
1959 id: self.lower_node_id(id).node_id,
1965 fn lower_lifetime_def(&mut self, l: &LifetimeDef) -> hir::LifetimeDef {
1966 let was_collecting_in_band = self.is_collecting_in_band_lifetimes;
1967 self.is_collecting_in_band_lifetimes = false;
1969 let def = hir::LifetimeDef {
1970 lifetime: self.lower_lifetime(&l.lifetime),
1971 bounds: l.bounds.iter().map(|l| self.lower_lifetime(l)).collect(),
1972 pure_wrt_drop: attr::contains_name(&l.attrs, "may_dangle"),
1976 self.is_collecting_in_band_lifetimes = was_collecting_in_band;
1981 fn lower_generic_params(
1983 params: &Vec<GenericParam>,
1984 add_bounds: &NodeMap<Vec<TyParamBound>>,
1985 itctx: ImplTraitContext,
1986 ) -> hir::HirVec<hir::GenericParam> {
1989 .map(|param| match *param {
1990 GenericParam::Lifetime(ref lifetime_def) => {
1991 hir::GenericParam::Lifetime(self.lower_lifetime_def(lifetime_def))
1993 GenericParam::Type(ref ty_param) => hir::GenericParam::Type(self.lower_ty_param(
1995 add_bounds.get(&ty_param.id).map_or(&[][..], |x| &x),
2002 fn lower_generics(&mut self, g: &Generics, itctx: ImplTraitContext) -> hir::Generics {
2003 // Collect `?Trait` bounds in where clause and move them to parameter definitions.
2004 // FIXME: This could probably be done with less rightward drift. Also looks like two control
2005 // paths where report_error is called are also the only paths that advance to after
2006 // the match statement, so the error reporting could probably just be moved there.
2007 let mut add_bounds = NodeMap();
2008 for pred in &g.where_clause.predicates {
2009 if let WherePredicate::BoundPredicate(ref bound_pred) = *pred {
2010 'next_bound: for bound in &bound_pred.bounds {
2011 if let TraitTyParamBound(_, TraitBoundModifier::Maybe) = *bound {
2012 let report_error = |this: &mut Self| {
2013 this.diagnostic().span_err(
2014 bound_pred.bounded_ty.span,
2015 "`?Trait` bounds are only permitted at the \
2016 point where a type parameter is declared",
2019 // Check if the where clause type is a plain type parameter.
2020 match bound_pred.bounded_ty.node {
2021 TyKind::Path(None, ref path)
2022 if path.segments.len() == 1
2023 && bound_pred.bound_generic_params.is_empty() =>
2025 if let Some(Def::TyParam(def_id)) = self.resolver
2026 .get_resolution(bound_pred.bounded_ty.id)
2027 .map(|d| d.base_def())
2029 if let Some(node_id) =
2030 self.resolver.definitions().as_local_node_id(def_id)
2032 for param in &g.params {
2033 if let GenericParam::Type(ref ty_param) = *param {
2034 if node_id == ty_param.id {
2037 .or_insert(Vec::new())
2038 .push(bound.clone());
2039 continue 'next_bound;
2047 _ => report_error(self),
2055 params: self.lower_generic_params(&g.params, &add_bounds, itctx),
2056 where_clause: self.lower_where_clause(&g.where_clause),
2061 fn lower_where_clause(&mut self, wc: &WhereClause) -> hir::WhereClause {
2063 id: self.lower_node_id(wc.id).node_id,
2064 predicates: wc.predicates
2066 .map(|predicate| self.lower_where_predicate(predicate))
2071 fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate {
2073 WherePredicate::BoundPredicate(WhereBoundPredicate {
2074 ref bound_generic_params,
2079 self.with_in_scope_lifetime_defs(
2080 bound_generic_params.iter().filter_map(|p| match p {
2081 GenericParam::Lifetime(ld) => Some(ld),
2085 hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
2086 bound_generic_params: this.lower_generic_params(
2087 bound_generic_params,
2089 ImplTraitContext::Disallowed,
2091 bounded_ty: this.lower_ty(bounded_ty, ImplTraitContext::Disallowed),
2094 .filter_map(|bound| match *bound {
2095 // Ignore `?Trait` bounds.
2096 // Tthey were copied into type parameters already.
2097 TraitTyParamBound(_, TraitBoundModifier::Maybe) => None,
2098 _ => Some(this.lower_ty_param_bound(
2100 ImplTraitContext::Disallowed,
2109 WherePredicate::RegionPredicate(WhereRegionPredicate {
2113 }) => hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
2115 lifetime: self.lower_lifetime(lifetime),
2118 .map(|bound| self.lower_lifetime(bound))
2121 WherePredicate::EqPredicate(WhereEqPredicate {
2126 }) => hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
2127 id: self.lower_node_id(id).node_id,
2128 lhs_ty: self.lower_ty(lhs_ty, ImplTraitContext::Disallowed),
2129 rhs_ty: self.lower_ty(rhs_ty, ImplTraitContext::Disallowed),
2135 fn lower_variant_data(&mut self, vdata: &VariantData) -> hir::VariantData {
2137 VariantData::Struct(ref fields, id) => hir::VariantData::Struct(
2141 .map(|f| self.lower_struct_field(f))
2143 self.lower_node_id(id).node_id,
2145 VariantData::Tuple(ref fields, id) => hir::VariantData::Tuple(
2149 .map(|f| self.lower_struct_field(f))
2151 self.lower_node_id(id).node_id,
2153 VariantData::Unit(id) => hir::VariantData::Unit(self.lower_node_id(id).node_id),
2157 fn lower_trait_ref(&mut self, p: &TraitRef, itctx: ImplTraitContext) -> hir::TraitRef {
2158 let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit, itctx) {
2159 hir::QPath::Resolved(None, path) => path.and_then(|path| path),
2160 qpath => bug!("lower_trait_ref: unexpected QPath `{:?}`", qpath),
2164 ref_id: self.lower_node_id(p.ref_id).node_id,
2168 fn lower_poly_trait_ref(
2171 itctx: ImplTraitContext,
2172 ) -> hir::PolyTraitRef {
2173 let bound_generic_params =
2174 self.lower_generic_params(&p.bound_generic_params, &NodeMap(), itctx);
2175 let trait_ref = self.with_parent_impl_lifetime_defs(
2176 &bound_generic_params
2178 .filter_map(|p| match *p {
2179 hir::GenericParam::Lifetime(ref ld) => Some(ld.clone()),
2182 .collect::<Vec<_>>(),
2183 |this| this.lower_trait_ref(&p.trait_ref, itctx),
2187 bound_generic_params,
2193 fn lower_struct_field(&mut self, (index, f): (usize, &StructField)) -> hir::StructField {
2196 id: self.lower_node_id(f.id).node_id,
2197 ident: match f.ident {
2198 Some(ident) => ident,
2199 // FIXME(jseyfried) positional field hygiene
2200 None => Ident::new(Symbol::intern(&index.to_string()), f.span),
2202 vis: self.lower_visibility(&f.vis, None),
2203 ty: self.lower_ty(&f.ty, ImplTraitContext::Disallowed),
2204 attrs: self.lower_attrs(&f.attrs),
2208 fn lower_field(&mut self, f: &Field) -> hir::Field {
2210 id: self.next_id().node_id,
2212 expr: P(self.lower_expr(&f.expr)),
2214 is_shorthand: f.is_shorthand,
2218 fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext) -> hir::MutTy {
2220 ty: self.lower_ty(&mt.ty, itctx),
2221 mutbl: self.lower_mutability(mt.mutbl),
2227 bounds: &[TyParamBound],
2228 itctx: ImplTraitContext,
2229 ) -> hir::TyParamBounds {
2232 .map(|bound| self.lower_ty_param_bound(bound, itctx))
2236 fn lower_block(&mut self, b: &Block, targeted_by_break: bool) -> P<hir::Block> {
2237 let mut expr = None;
2239 let mut stmts = vec![];
2241 for (index, stmt) in b.stmts.iter().enumerate() {
2242 if index == b.stmts.len() - 1 {
2243 if let StmtKind::Expr(ref e) = stmt.node {
2244 expr = Some(P(self.lower_expr(e)));
2246 stmts.extend(self.lower_stmt(stmt));
2249 stmts.extend(self.lower_stmt(stmt));
2253 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(b.id);
2258 stmts: stmts.into(),
2260 rules: self.lower_block_check_mode(&b.rules),
2263 recovered: b.recovered,
2271 attrs: &hir::HirVec<Attribute>,
2272 vis: &mut hir::Visibility,
2276 ItemKind::ExternCrate(orig_name) => hir::ItemExternCrate(orig_name),
2277 ItemKind::Use(ref use_tree) => {
2278 // Start with an empty prefix
2281 span: use_tree.span,
2284 self.lower_use_tree(use_tree, &prefix, id, vis, name, attrs)
2286 ItemKind::Static(ref t, m, ref e) => {
2287 let value = self.lower_body(None, |this| this.lower_expr(e));
2289 self.lower_ty(t, ImplTraitContext::Disallowed),
2290 self.lower_mutability(m),
2294 ItemKind::Const(ref t, ref e) => {
2295 let value = self.lower_body(None, |this| this.lower_expr(e));
2296 hir::ItemConst(self.lower_ty(t, ImplTraitContext::Disallowed), value)
2298 ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
2299 let fn_def_id = self.resolver.definitions().local_def_id(id);
2300 self.with_new_scopes(|this| {
2301 let body_id = this.lower_body(Some(decl), |this| {
2302 let body = this.lower_block(body, false);
2303 this.expr_block(body, ThinVec::new())
2305 let (generics, fn_decl) = this.add_in_band_defs(
2308 AnonymousLifetimeMode::PassThrough,
2309 |this| this.lower_fn_decl(decl, Some(fn_def_id), true),
2314 this.lower_unsafety(unsafety),
2315 this.lower_constness(constness),
2322 ItemKind::Mod(ref m) => hir::ItemMod(self.lower_mod(m)),
2323 ItemKind::ForeignMod(ref nm) => hir::ItemForeignMod(self.lower_foreign_mod(nm)),
2324 ItemKind::GlobalAsm(ref ga) => hir::ItemGlobalAsm(self.lower_global_asm(ga)),
2325 ItemKind::Ty(ref t, ref generics) => hir::ItemTy(
2326 self.lower_ty(t, ImplTraitContext::Disallowed),
2327 self.lower_generics(generics, ImplTraitContext::Disallowed),
2329 ItemKind::Enum(ref enum_definition, ref generics) => hir::ItemEnum(
2331 variants: enum_definition
2334 .map(|x| self.lower_variant(x))
2337 self.lower_generics(generics, ImplTraitContext::Disallowed),
2339 ItemKind::Struct(ref struct_def, ref generics) => {
2340 let struct_def = self.lower_variant_data(struct_def);
2343 self.lower_generics(generics, ImplTraitContext::Disallowed),
2346 ItemKind::Union(ref vdata, ref generics) => {
2347 let vdata = self.lower_variant_data(vdata);
2350 self.lower_generics(generics, ImplTraitContext::Disallowed),
2362 let def_id = self.resolver.definitions().local_def_id(id);
2364 // Lower the "impl header" first. This ordering is important
2365 // for in-band lifetimes! Consider `'a` here:
2367 // impl Foo<'a> for u32 {
2368 // fn method(&'a self) { .. }
2371 // Because we start by lowering the `Foo<'a> for u32`
2372 // part, we will add `'a` to the list of generics on
2373 // the impl. When we then encounter it later in the
2374 // method, it will not be considered an in-band
2375 // lifetime to be added, but rather a reference to a
2377 let (generics, (trait_ref, lowered_ty)) = self.add_in_band_defs(
2380 AnonymousLifetimeMode::CreateParameter,
2382 let trait_ref = trait_ref.as_ref().map(|trait_ref| {
2383 this.lower_trait_ref(trait_ref, ImplTraitContext::Disallowed)
2386 if let Some(ref trait_ref) = trait_ref {
2387 if let Def::Trait(def_id) = trait_ref.path.def {
2388 this.trait_impls.entry(def_id).or_insert(vec![]).push(id);
2392 let lowered_ty = this.lower_ty(ty, ImplTraitContext::Disallowed);
2394 (trait_ref, lowered_ty)
2398 let new_impl_items = self.with_in_scope_lifetime_defs(
2399 ast_generics.params.iter().filter_map(|p| match p {
2400 GenericParam::Lifetime(ld) => Some(ld),
2406 .map(|item| this.lower_impl_item_ref(item))
2412 self.lower_unsafety(unsafety),
2413 self.lower_impl_polarity(polarity),
2414 self.lower_defaultness(defaultness, true /* [1] */),
2421 ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref items) => {
2422 let bounds = self.lower_bounds(bounds, ImplTraitContext::Disallowed);
2425 .map(|item| self.lower_trait_item_ref(item))
2428 self.lower_is_auto(is_auto),
2429 self.lower_unsafety(unsafety),
2430 self.lower_generics(generics, ImplTraitContext::Disallowed),
2435 ItemKind::TraitAlias(ref generics, ref bounds) => hir::ItemTraitAlias(
2436 self.lower_generics(generics, ImplTraitContext::Disallowed),
2437 self.lower_bounds(bounds, ImplTraitContext::Disallowed),
2439 ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"),
2442 // [1] `defaultness.has_value()` is never called for an `impl`, always `true` in order to
2443 // not cause an assertion failure inside the `lower_defaultness` function
2451 vis: &mut hir::Visibility,
2453 attrs: &hir::HirVec<Attribute>,
2455 let path = &tree.prefix;
2458 UseTreeKind::Simple(rename, id1, id2) => {
2459 *name = tree.ident().name;
2461 // First apply the prefix to the path
2462 let mut path = Path {
2466 .chain(path.segments.iter())
2472 // Correctly resolve `self` imports
2473 if path.segments.len() > 1
2474 && path.segments.last().unwrap().ident.name == keywords::SelfValue.name()
2476 let _ = path.segments.pop();
2477 if rename.is_none() {
2478 *name = path.segments.last().unwrap().ident.name;
2482 let parent_def_index = self.current_hir_id_owner.last().unwrap().0;
2483 let mut defs = self.expect_full_def_from_use(id);
2484 // we want to return *something* from this function, so hang onto the first item
2486 let mut ret_def = defs.next().unwrap_or(Def::Err);
2488 for (def, &new_node_id) in defs.zip([id1, id2].iter()) {
2489 let vis = vis.clone();
2490 let name = name.clone();
2491 let span = path.span;
2492 self.resolver.definitions().create_def_with_parent(
2496 DefIndexAddressSpace::High,
2499 self.allocate_hir_id_counter(new_node_id, &path);
2501 self.with_hir_id_owner(new_node_id, |this| {
2502 let new_id = this.lower_node_id(new_node_id);
2503 let path = this.lower_path_extra(def, &path, None, ParamMode::Explicit);
2504 let item = hir::ItemUse(P(path), hir::UseKind::Single);
2505 let vis = match vis {
2506 hir::Visibility::Public => hir::Visibility::Public,
2507 hir::Visibility::Crate(sugar) => hir::Visibility::Crate(sugar),
2508 hir::Visibility::Inherited => hir::Visibility::Inherited,
2509 hir::Visibility::Restricted { ref path, id: _ } => {
2510 hir::Visibility::Restricted {
2512 // We are allocating a new NodeId here
2513 id: this.next_id().node_id,
2522 hir_id: new_id.hir_id,
2524 attrs: attrs.clone(),
2533 let path = P(self.lower_path_extra(ret_def, &path, None, ParamMode::Explicit));
2534 hir::ItemUse(path, hir::UseKind::Single)
2536 UseTreeKind::Glob => {
2537 let path = P(self.lower_path(
2543 .chain(path.segments.iter())
2548 ParamMode::Explicit,
2550 hir::ItemUse(path, hir::UseKind::Glob)
2552 UseTreeKind::Nested(ref trees) => {
2557 .chain(path.segments.iter())
2560 span: prefix.span.to(path.span),
2563 // Add all the nested PathListItems in the HIR
2564 for &(ref use_tree, id) in trees {
2565 self.allocate_hir_id_counter(id, &use_tree);
2569 } = self.lower_node_id(id);
2571 let mut vis = vis.clone();
2572 let mut name = name.clone();
2574 self.lower_use_tree(use_tree, &prefix, new_id, &mut vis, &mut name, &attrs);
2576 self.with_hir_id_owner(new_id, |this| {
2577 let vis = match vis {
2578 hir::Visibility::Public => hir::Visibility::Public,
2579 hir::Visibility::Crate(sugar) => hir::Visibility::Crate(sugar),
2580 hir::Visibility::Inherited => hir::Visibility::Inherited,
2581 hir::Visibility::Restricted { ref path, id: _ } => {
2582 hir::Visibility::Restricted {
2584 // We are allocating a new NodeId here
2585 id: this.next_id().node_id,
2596 attrs: attrs.clone(),
2599 span: use_tree.span,
2605 // Privatize the degenerate import base, used only to check
2606 // the stability of `use a::{};`, to avoid it showing up as
2607 // a re-export by accident when `pub`, e.g. in documentation.
2608 let path = P(self.lower_path(id, &prefix, ParamMode::Explicit));
2609 *vis = hir::Inherited;
2610 hir::ItemUse(path, hir::UseKind::ListStem)
2615 fn lower_trait_item(&mut self, i: &TraitItem) -> hir::TraitItem {
2616 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id);
2617 let trait_item_def_id = self.resolver.definitions().local_def_id(node_id);
2619 let (generics, node) = match i.node {
2620 TraitItemKind::Const(ref ty, ref default) => (
2621 self.lower_generics(&i.generics, ImplTraitContext::Disallowed),
2622 hir::TraitItemKind::Const(
2623 self.lower_ty(ty, ImplTraitContext::Disallowed),
2626 .map(|x| self.lower_body(None, |this| this.lower_expr(x))),
2629 TraitItemKind::Method(ref sig, None) => {
2630 let names = self.lower_fn_args_to_names(&sig.decl);
2631 self.add_in_band_defs(
2634 AnonymousLifetimeMode::PassThrough,
2636 hir::TraitItemKind::Method(
2637 this.lower_method_sig(sig, trait_item_def_id, false),
2638 hir::TraitMethod::Required(names),
2643 TraitItemKind::Method(ref sig, Some(ref body)) => {
2644 let body_id = self.lower_body(Some(&sig.decl), |this| {
2645 let body = this.lower_block(body, false);
2646 this.expr_block(body, ThinVec::new())
2649 self.add_in_band_defs(
2652 AnonymousLifetimeMode::PassThrough,
2654 hir::TraitItemKind::Method(
2655 this.lower_method_sig(sig, trait_item_def_id, false),
2656 hir::TraitMethod::Provided(body_id),
2661 TraitItemKind::Type(ref bounds, ref default) => (
2662 self.lower_generics(&i.generics, ImplTraitContext::Disallowed),
2663 hir::TraitItemKind::Type(
2664 self.lower_bounds(bounds, ImplTraitContext::Disallowed),
2667 .map(|x| self.lower_ty(x, ImplTraitContext::Disallowed)),
2670 TraitItemKind::Macro(..) => panic!("Shouldn't exist any more"),
2676 name: self.lower_ident(i.ident),
2677 attrs: self.lower_attrs(&i.attrs),
2684 fn lower_trait_item_ref(&mut self, i: &TraitItem) -> hir::TraitItemRef {
2685 let (kind, has_default) = match i.node {
2686 TraitItemKind::Const(_, ref default) => {
2687 (hir::AssociatedItemKind::Const, default.is_some())
2689 TraitItemKind::Type(_, ref default) => {
2690 (hir::AssociatedItemKind::Type, default.is_some())
2692 TraitItemKind::Method(ref sig, ref default) => (
2693 hir::AssociatedItemKind::Method {
2694 has_self: sig.decl.has_self(),
2698 TraitItemKind::Macro(..) => unimplemented!(),
2701 id: hir::TraitItemId { node_id: i.id },
2702 name: self.lower_ident(i.ident),
2704 defaultness: self.lower_defaultness(Defaultness::Default, has_default),
2709 fn lower_impl_item(&mut self, i: &ImplItem) -> hir::ImplItem {
2710 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id);
2711 let impl_item_def_id = self.resolver.definitions().local_def_id(node_id);
2713 let (generics, node) = match i.node {
2714 ImplItemKind::Const(ref ty, ref expr) => {
2715 let body_id = self.lower_body(None, |this| this.lower_expr(expr));
2717 self.lower_generics(&i.generics, ImplTraitContext::Disallowed),
2718 hir::ImplItemKind::Const(
2719 self.lower_ty(ty, ImplTraitContext::Disallowed),
2724 ImplItemKind::Method(ref sig, ref body) => {
2725 let body_id = self.lower_body(Some(&sig.decl), |this| {
2726 let body = this.lower_block(body, false);
2727 this.expr_block(body, ThinVec::new())
2729 let impl_trait_return_allow = !self.is_in_trait_impl;
2731 self.add_in_band_defs(
2734 AnonymousLifetimeMode::PassThrough,
2736 hir::ImplItemKind::Method(
2737 this.lower_method_sig(
2740 impl_trait_return_allow,
2747 ImplItemKind::Type(ref ty) => (
2748 self.lower_generics(&i.generics, ImplTraitContext::Disallowed),
2749 hir::ImplItemKind::Type(self.lower_ty(ty, ImplTraitContext::Disallowed)),
2751 ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"),
2757 name: self.lower_ident(i.ident),
2758 attrs: self.lower_attrs(&i.attrs),
2760 vis: self.lower_visibility(&i.vis, None),
2761 defaultness: self.lower_defaultness(i.defaultness, true /* [1] */),
2766 // [1] since `default impl` is not yet implemented, this is always true in impls
2769 fn lower_impl_item_ref(&mut self, i: &ImplItem) -> hir::ImplItemRef {
2771 id: hir::ImplItemId { node_id: i.id },
2772 name: self.lower_ident(i.ident),
2774 vis: self.lower_visibility(&i.vis, Some(i.id)),
2775 defaultness: self.lower_defaultness(i.defaultness, true /* [1] */),
2776 kind: match i.node {
2777 ImplItemKind::Const(..) => hir::AssociatedItemKind::Const,
2778 ImplItemKind::Type(..) => hir::AssociatedItemKind::Type,
2779 ImplItemKind::Method(ref sig, _) => hir::AssociatedItemKind::Method {
2780 has_self: sig.decl.has_self(),
2782 ImplItemKind::Macro(..) => unimplemented!(),
2786 // [1] since `default impl` is not yet implemented, this is always true in impls
2789 fn lower_mod(&mut self, m: &Mod) -> hir::Mod {
2792 item_ids: m.items.iter().flat_map(|x| self.lower_item_id(x)).collect(),
2796 fn lower_item_id(&mut self, i: &Item) -> SmallVector<hir::ItemId> {
2798 ItemKind::Use(ref use_tree) => {
2799 let mut vec = SmallVector::one(hir::ItemId { id: i.id });
2800 self.lower_item_id_use_tree(use_tree, i.id, &mut vec);
2803 ItemKind::MacroDef(..) => return SmallVector::new(),
2806 SmallVector::one(hir::ItemId { id: i.id })
2809 fn lower_item_id_use_tree(&mut self,
2812 vec: &mut SmallVector<hir::ItemId>)
2815 UseTreeKind::Nested(ref nested_vec) => for &(ref nested, id) in nested_vec {
2816 vec.push(hir::ItemId { id });
2817 self.lower_item_id_use_tree(nested, id, vec);
2819 UseTreeKind::Glob => {}
2820 UseTreeKind::Simple(_, id1, id2) => {
2821 for (_, &id) in self.expect_full_def_from_use(base_id)
2823 .zip([id1, id2].iter())
2825 vec.push(hir::ItemId { id });
2831 pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> {
2832 let mut name = i.ident.name;
2833 let mut vis = self.lower_visibility(&i.vis, None);
2834 let attrs = self.lower_attrs(&i.attrs);
2835 if let ItemKind::MacroDef(ref def) = i.node {
2836 if !def.legacy || attr::contains_name(&i.attrs, "macro_export") {
2837 let body = self.lower_token_stream(def.stream());
2838 self.exported_macros.push(hir::MacroDef {
2851 let node = self.lower_item_kind(i.id, &mut name, &attrs, &mut vis, &i.node);
2853 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id);
2866 fn lower_foreign_item(&mut self, i: &ForeignItem) -> hir::ForeignItem {
2867 let node_id = self.lower_node_id(i.id).node_id;
2868 let def_id = self.resolver.definitions().local_def_id(node_id);
2872 attrs: self.lower_attrs(&i.attrs),
2873 node: match i.node {
2874 ForeignItemKind::Fn(ref fdec, ref generics) => {
2875 let (generics, (fn_dec, fn_args)) = self.add_in_band_defs(
2878 AnonymousLifetimeMode::PassThrough,
2881 // Disallow impl Trait in foreign items
2882 this.lower_fn_decl(fdec, None, false),
2883 this.lower_fn_args_to_names(fdec),
2888 hir::ForeignItemFn(fn_dec, fn_args, generics)
2890 ForeignItemKind::Static(ref t, m) => {
2891 hir::ForeignItemStatic(self.lower_ty(t, ImplTraitContext::Disallowed), m)
2893 ForeignItemKind::Ty => hir::ForeignItemType,
2894 ForeignItemKind::Macro(_) => panic!("shouldn't exist here"),
2896 vis: self.lower_visibility(&i.vis, None),
2901 fn lower_method_sig(
2905 impl_trait_return_allow: bool,
2906 ) -> hir::MethodSig {
2909 unsafety: self.lower_unsafety(sig.unsafety),
2910 constness: self.lower_constness(sig.constness),
2911 decl: self.lower_fn_decl(&sig.decl, Some(fn_def_id), impl_trait_return_allow),
2915 fn lower_is_auto(&mut self, a: IsAuto) -> hir::IsAuto {
2917 IsAuto::Yes => hir::IsAuto::Yes,
2918 IsAuto::No => hir::IsAuto::No,
2922 fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety {
2924 Unsafety::Unsafe => hir::Unsafety::Unsafe,
2925 Unsafety::Normal => hir::Unsafety::Normal,
2929 fn lower_constness(&mut self, c: Spanned<Constness>) -> hir::Constness {
2931 Constness::Const => hir::Constness::Const,
2932 Constness::NotConst => hir::Constness::NotConst,
2936 fn lower_unop(&mut self, u: UnOp) -> hir::UnOp {
2938 UnOp::Deref => hir::UnDeref,
2939 UnOp::Not => hir::UnNot,
2940 UnOp::Neg => hir::UnNeg,
2944 fn lower_binop(&mut self, b: BinOp) -> hir::BinOp {
2946 node: match b.node {
2947 BinOpKind::Add => hir::BiAdd,
2948 BinOpKind::Sub => hir::BiSub,
2949 BinOpKind::Mul => hir::BiMul,
2950 BinOpKind::Div => hir::BiDiv,
2951 BinOpKind::Rem => hir::BiRem,
2952 BinOpKind::And => hir::BiAnd,
2953 BinOpKind::Or => hir::BiOr,
2954 BinOpKind::BitXor => hir::BiBitXor,
2955 BinOpKind::BitAnd => hir::BiBitAnd,
2956 BinOpKind::BitOr => hir::BiBitOr,
2957 BinOpKind::Shl => hir::BiShl,
2958 BinOpKind::Shr => hir::BiShr,
2959 BinOpKind::Eq => hir::BiEq,
2960 BinOpKind::Lt => hir::BiLt,
2961 BinOpKind::Le => hir::BiLe,
2962 BinOpKind::Ne => hir::BiNe,
2963 BinOpKind::Ge => hir::BiGe,
2964 BinOpKind::Gt => hir::BiGt,
2970 fn lower_pat(&mut self, p: &Pat) -> P<hir::Pat> {
2971 let node = match p.node {
2972 PatKind::Wild => hir::PatKind::Wild,
2973 PatKind::Ident(ref binding_mode, ident, ref sub) => {
2974 match self.resolver.get_resolution(p.id).map(|d| d.base_def()) {
2975 // `None` can occur in body-less function signatures
2976 def @ None | def @ Some(Def::Local(_)) => {
2977 let canonical_id = match def {
2978 Some(Def::Local(id)) => id,
2981 hir::PatKind::Binding(
2982 self.lower_binding_mode(binding_mode),
2984 respan(ident.span, ident.name),
2985 sub.as_ref().map(|x| self.lower_pat(x)),
2988 Some(def) => hir::PatKind::Path(hir::QPath::Resolved(
2993 segments: hir_vec![hir::PathSegment::from_name(ident.name)],
2998 PatKind::Lit(ref e) => hir::PatKind::Lit(P(self.lower_expr(e))),
2999 PatKind::TupleStruct(ref path, ref pats, ddpos) => {
3000 let qpath = self.lower_qpath(
3004 ParamMode::Optional,
3005 ImplTraitContext::Disallowed,
3007 hir::PatKind::TupleStruct(
3009 pats.iter().map(|x| self.lower_pat(x)).collect(),
3013 PatKind::Path(ref qself, ref path) => hir::PatKind::Path(self.lower_qpath(
3017 ParamMode::Optional,
3018 ImplTraitContext::Disallowed,
3020 PatKind::Struct(ref path, ref fields, etc) => {
3021 let qpath = self.lower_qpath(
3025 ParamMode::Optional,
3026 ImplTraitContext::Disallowed,
3033 node: hir::FieldPat {
3034 id: self.next_id().node_id,
3035 ident: f.node.ident,
3036 pat: self.lower_pat(&f.node.pat),
3037 is_shorthand: f.node.is_shorthand,
3041 hir::PatKind::Struct(qpath, fs, etc)
3043 PatKind::Tuple(ref elts, ddpos) => {
3044 hir::PatKind::Tuple(elts.iter().map(|x| self.lower_pat(x)).collect(), ddpos)
3046 PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)),
3047 PatKind::Ref(ref inner, mutbl) => {
3048 hir::PatKind::Ref(self.lower_pat(inner), self.lower_mutability(mutbl))
3050 PatKind::Range(ref e1, ref e2, ref end) => hir::PatKind::Range(
3051 P(self.lower_expr(e1)),
3052 P(self.lower_expr(e2)),
3053 self.lower_range_end(end),
3055 PatKind::Slice(ref before, ref slice, ref after) => hir::PatKind::Slice(
3056 before.iter().map(|x| self.lower_pat(x)).collect(),
3057 slice.as_ref().map(|x| self.lower_pat(x)),
3058 after.iter().map(|x| self.lower_pat(x)).collect(),
3060 PatKind::Paren(ref inner) => return self.lower_pat(inner),
3061 PatKind::Mac(_) => panic!("Shouldn't exist here"),
3064 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(p.id);
3073 fn lower_range_end(&mut self, e: &RangeEnd) -> hir::RangeEnd {
3075 RangeEnd::Included(_) => hir::RangeEnd::Included,
3076 RangeEnd::Excluded => hir::RangeEnd::Excluded,
3080 fn lower_anon_const(&mut self, c: &AnonConst) -> hir::AnonConst {
3081 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(c.id);
3086 body: self.lower_body(None, |this| this.lower_expr(&c.value)),
3090 fn lower_expr(&mut self, e: &Expr) -> hir::Expr {
3091 let kind = match e.node {
3092 ExprKind::Box(ref inner) => hir::ExprBox(P(self.lower_expr(inner))),
3093 ExprKind::ObsoleteInPlace(..) => {
3094 self.sess.abort_if_errors();
3095 span_bug!(e.span, "encountered ObsoleteInPlace expr during lowering");
3097 ExprKind::Array(ref exprs) => {
3098 hir::ExprArray(exprs.iter().map(|x| self.lower_expr(x)).collect())
3100 ExprKind::Repeat(ref expr, ref count) => {
3101 let expr = P(self.lower_expr(expr));
3102 let count = self.lower_anon_const(count);
3103 hir::ExprRepeat(expr, count)
3105 ExprKind::Tup(ref elts) => {
3106 hir::ExprTup(elts.iter().map(|x| self.lower_expr(x)).collect())
3108 ExprKind::Call(ref f, ref args) => {
3109 let f = P(self.lower_expr(f));
3110 hir::ExprCall(f, args.iter().map(|x| self.lower_expr(x)).collect())
3112 ExprKind::MethodCall(ref seg, ref args) => {
3113 let hir_seg = self.lower_path_segment(
3116 ParamMode::Optional,
3118 ParenthesizedGenericArgs::Err,
3119 ImplTraitContext::Disallowed,
3121 let args = args.iter().map(|x| self.lower_expr(x)).collect();
3122 hir::ExprMethodCall(hir_seg, seg.ident.span, args)
3124 ExprKind::Binary(binop, ref lhs, ref rhs) => {
3125 let binop = self.lower_binop(binop);
3126 let lhs = P(self.lower_expr(lhs));
3127 let rhs = P(self.lower_expr(rhs));
3128 hir::ExprBinary(binop, lhs, rhs)
3130 ExprKind::Unary(op, ref ohs) => {
3131 let op = self.lower_unop(op);
3132 let ohs = P(self.lower_expr(ohs));
3133 hir::ExprUnary(op, ohs)
3135 ExprKind::Lit(ref l) => hir::ExprLit(P((**l).clone())),
3136 ExprKind::Cast(ref expr, ref ty) => {
3137 let expr = P(self.lower_expr(expr));
3138 hir::ExprCast(expr, self.lower_ty(ty, ImplTraitContext::Disallowed))
3140 ExprKind::Type(ref expr, ref ty) => {
3141 let expr = P(self.lower_expr(expr));
3142 hir::ExprType(expr, self.lower_ty(ty, ImplTraitContext::Disallowed))
3144 ExprKind::AddrOf(m, ref ohs) => {
3145 let m = self.lower_mutability(m);
3146 let ohs = P(self.lower_expr(ohs));
3147 hir::ExprAddrOf(m, ohs)
3149 // More complicated than you might expect because the else branch
3150 // might be `if let`.
3151 ExprKind::If(ref cond, ref blk, ref else_opt) => {
3152 let else_opt = else_opt.as_ref().map(|els| {
3154 ExprKind::IfLet(..) => {
3155 // wrap the if-let expr in a block
3156 let span = els.span;
3157 let els = P(self.lower_expr(els));
3158 let LoweredNodeId { node_id, hir_id } = self.next_id();
3159 let blk = P(hir::Block {
3164 rules: hir::DefaultBlock,
3166 targeted_by_break: false,
3167 recovered: blk.recovered,
3169 P(self.expr_block(blk, ThinVec::new()))
3171 _ => P(self.lower_expr(els)),
3175 let then_blk = self.lower_block(blk, false);
3176 let then_expr = self.expr_block(then_blk, ThinVec::new());
3178 hir::ExprIf(P(self.lower_expr(cond)), P(then_expr), else_opt)
3180 ExprKind::While(ref cond, ref body, opt_label) => self.with_loop_scope(e.id, |this| {
3182 this.with_loop_condition_scope(|this| P(this.lower_expr(cond))),
3183 this.lower_block(body, false),
3184 this.lower_label(opt_label),
3187 ExprKind::Loop(ref body, opt_label) => self.with_loop_scope(e.id, |this| {
3189 this.lower_block(body, false),
3190 this.lower_label(opt_label),
3191 hir::LoopSource::Loop,
3194 ExprKind::Catch(ref body) => {
3195 self.with_catch_scope(body.id, |this| {
3197 this.allow_internal_unstable(CompilerDesugaringKind::Catch, body.span);
3198 let mut block = this.lower_block(body, true).into_inner();
3199 let tail = block.expr.take().map_or_else(
3201 let LoweredNodeId { node_id, hir_id } = this.next_id();
3202 let span = this.sess.codemap().end_point(unstable_span);
3206 node: hir::ExprTup(hir_vec![]),
3207 attrs: ThinVec::new(),
3211 |x: P<hir::Expr>| x.into_inner(),
3213 block.expr = Some(this.wrap_in_try_constructor(
3214 "from_ok", tail, unstable_span));
3215 hir::ExprBlock(P(block), None)
3218 ExprKind::Match(ref expr, ref arms) => hir::ExprMatch(
3219 P(self.lower_expr(expr)),
3220 arms.iter().map(|x| self.lower_arm(x)).collect(),
3221 hir::MatchSource::Normal,
3223 ExprKind::Closure(capture_clause, movability, ref decl, ref body, fn_decl_span) => {
3224 self.with_new_scopes(|this| {
3225 let mut is_generator = false;
3226 let body_id = this.lower_body(Some(decl), |this| {
3227 let e = this.lower_expr(body);
3228 is_generator = this.is_generator;
3231 let generator_option = if is_generator {
3232 if !decl.inputs.is_empty() {
3237 "generators cannot have explicit arguments"
3239 this.sess.abort_if_errors();
3241 Some(match movability {
3242 Movability::Movable => hir::GeneratorMovability::Movable,
3243 Movability::Static => hir::GeneratorMovability::Static,
3246 if movability == Movability::Static {
3251 "closures cannot be static"
3257 this.lower_capture_clause(capture_clause),
3258 this.lower_fn_decl(decl, None, false),
3265 ExprKind::Block(ref blk, opt_label) => {
3266 hir::ExprBlock(self.lower_block(blk,
3267 opt_label.is_some()),
3268 self.lower_label(opt_label))
3270 ExprKind::Assign(ref el, ref er) => {
3271 hir::ExprAssign(P(self.lower_expr(el)), P(self.lower_expr(er)))
3273 ExprKind::AssignOp(op, ref el, ref er) => hir::ExprAssignOp(
3274 self.lower_binop(op),
3275 P(self.lower_expr(el)),
3276 P(self.lower_expr(er)),
3278 ExprKind::Field(ref el, ident) => hir::ExprField(P(self.lower_expr(el)), ident),
3279 ExprKind::Index(ref el, ref er) => {
3280 hir::ExprIndex(P(self.lower_expr(el)), P(self.lower_expr(er)))
3282 // Desugar `<start>..=<end>` to `std::ops::RangeInclusive::new(<start>, <end>)`
3283 ExprKind::Range(Some(ref e1), Some(ref e2), RangeLimits::Closed) => {
3284 // FIXME: Use e.span directly after RangeInclusive::new() is stabilized in stage0.
3285 let span = self.allow_internal_unstable(CompilerDesugaringKind::DotFill, e.span);
3286 let id = self.next_id();
3287 let e1 = self.lower_expr(e1);
3288 let e2 = self.lower_expr(e2);
3289 let ty_path = P(self.std_path(span, &["ops", "RangeInclusive"], false));
3290 let ty = self.ty_path(id, span, hir::QPath::Resolved(None, ty_path));
3291 let new_seg = P(hir::PathSegment::from_name(Symbol::intern("new")));
3292 let new_path = hir::QPath::TypeRelative(ty, new_seg);
3293 let new = P(self.expr(span, hir::ExprPath(new_path), ThinVec::new()));
3294 hir::ExprCall(new, hir_vec![e1, e2])
3296 ExprKind::Range(ref e1, ref e2, lims) => {
3297 use syntax::ast::RangeLimits::*;
3299 let path = match (e1, e2, lims) {
3300 (&None, &None, HalfOpen) => "RangeFull",
3301 (&Some(..), &None, HalfOpen) => "RangeFrom",
3302 (&None, &Some(..), HalfOpen) => "RangeTo",
3303 (&Some(..), &Some(..), HalfOpen) => "Range",
3304 (&None, &Some(..), Closed) => "RangeToInclusive",
3305 (&Some(..), &Some(..), Closed) => unreachable!(),
3306 (_, &None, Closed) => self.diagnostic()
3307 .span_fatal(e.span, "inclusive range with no end")
3311 let fields = e1.iter()
3312 .map(|e| ("start", e))
3313 .chain(e2.iter().map(|e| ("end", e)))
3315 let expr = P(self.lower_expr(&e));
3317 self.allow_internal_unstable(CompilerDesugaringKind::DotFill, e.span);
3318 let ident = Ident::new(Symbol::intern(s), unstable_span);
3319 self.field(ident, expr, unstable_span)
3321 .collect::<P<[hir::Field]>>();
3323 let is_unit = fields.is_empty();
3325 self.allow_internal_unstable(CompilerDesugaringKind::DotFill, e.span);
3326 let struct_path = iter::once("ops")
3327 .chain(iter::once(path))
3328 .collect::<Vec<_>>();
3329 let struct_path = self.std_path(unstable_span, &struct_path, is_unit);
3330 let struct_path = hir::QPath::Resolved(None, P(struct_path));
3332 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
3338 hir::ExprPath(struct_path)
3340 hir::ExprStruct(struct_path, fields, None)
3342 span: unstable_span,
3343 attrs: e.attrs.clone(),
3346 ExprKind::Path(ref qself, ref path) => hir::ExprPath(self.lower_qpath(
3350 ParamMode::Optional,
3351 ImplTraitContext::Disallowed,
3353 ExprKind::Break(opt_label, ref opt_expr) => {
3354 let destination = if self.is_in_loop_condition && opt_label.is_none() {
3357 target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into(),
3360 self.lower_loop_destination(opt_label.map(|label| (e.id, label)))
3364 opt_expr.as_ref().map(|x| P(self.lower_expr(x))),
3367 ExprKind::Continue(opt_label) => {
3368 hir::ExprAgain(if self.is_in_loop_condition && opt_label.is_none() {
3371 target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into(),
3374 self.lower_loop_destination(opt_label.map(|label| (e.id, label)))
3377 ExprKind::Ret(ref e) => hir::ExprRet(e.as_ref().map(|x| P(self.lower_expr(x)))),
3378 ExprKind::InlineAsm(ref asm) => {
3379 let hir_asm = hir::InlineAsm {
3380 inputs: asm.inputs.iter().map(|&(ref c, _)| c.clone()).collect(),
3381 outputs: asm.outputs
3383 .map(|out| hir::InlineAsmOutput {
3384 constraint: out.constraint.clone(),
3386 is_indirect: out.is_indirect,
3389 asm: asm.asm.clone(),
3390 asm_str_style: asm.asm_str_style,
3391 clobbers: asm.clobbers.clone().into(),
3392 volatile: asm.volatile,
3393 alignstack: asm.alignstack,
3394 dialect: asm.dialect,
3397 let outputs = asm.outputs
3399 .map(|out| self.lower_expr(&out.expr))
3401 let inputs = asm.inputs
3403 .map(|&(_, ref input)| self.lower_expr(input))
3405 hir::ExprInlineAsm(P(hir_asm), outputs, inputs)
3407 ExprKind::Struct(ref path, ref fields, ref maybe_expr) => hir::ExprStruct(
3412 ParamMode::Optional,
3413 ImplTraitContext::Disallowed,
3415 fields.iter().map(|x| self.lower_field(x)).collect(),
3416 maybe_expr.as_ref().map(|x| P(self.lower_expr(x))),
3418 ExprKind::Paren(ref ex) => {
3419 let mut ex = self.lower_expr(ex);
3420 // include parens in span, but only if it is a super-span.
3421 if e.span.contains(ex.span) {
3424 // merge attributes into the inner expression.
3425 let mut attrs = e.attrs.clone();
3426 attrs.extend::<Vec<_>>(ex.attrs.into());
3431 ExprKind::Yield(ref opt_expr) => {
3432 self.is_generator = true;
3435 .map(|x| self.lower_expr(x))
3436 .unwrap_or_else(|| self.expr(e.span, hir::ExprTup(hir_vec![]), ThinVec::new()));
3437 hir::ExprYield(P(expr))
3440 // Desugar ExprIfLet
3441 // From: `if let <pat> = <sub_expr> <body> [<else_opt>]`
3442 ExprKind::IfLet(ref pats, ref sub_expr, ref body, ref else_opt) => {
3445 // match <sub_expr> {
3447 // _ => [<else_opt> | ()]
3450 let mut arms = vec![];
3452 // `<pat> => <body>`
3454 let body = self.lower_block(body, false);
3455 let body_expr = P(self.expr_block(body, ThinVec::new()));
3456 let pats = pats.iter().map(|pat| self.lower_pat(pat)).collect();
3457 arms.push(self.arm(pats, body_expr));
3460 // _ => [<else_opt>|()]
3462 let wildcard_arm: Option<&Expr> = else_opt.as_ref().map(|p| &**p);
3463 let wildcard_pattern = self.pat_wild(e.span);
3464 let body = if let Some(else_expr) = wildcard_arm {
3465 P(self.lower_expr(else_expr))
3467 self.expr_tuple(e.span, hir_vec![])
3469 arms.push(self.arm(hir_vec![wildcard_pattern], body));
3472 let contains_else_clause = else_opt.is_some();
3474 let sub_expr = P(self.lower_expr(sub_expr));
3479 hir::MatchSource::IfLetDesugar {
3480 contains_else_clause,
3485 // Desugar ExprWhileLet
3486 // From: `[opt_ident]: while let <pat> = <sub_expr> <body>`
3487 ExprKind::WhileLet(ref pats, ref sub_expr, ref body, opt_label) => {
3490 // [opt_ident]: loop {
3491 // match <sub_expr> {
3497 // Note that the block AND the condition are evaluated in the loop scope.
3498 // This is done to allow `break` from inside the condition of the loop.
3499 let (body, break_expr, sub_expr) = self.with_loop_scope(e.id, |this| {
3501 this.lower_block(body, false),
3502 this.expr_break(e.span, ThinVec::new()),
3503 this.with_loop_condition_scope(|this| P(this.lower_expr(sub_expr))),
3507 // `<pat> => <body>`
3509 let body_expr = P(self.expr_block(body, ThinVec::new()));
3510 let pats = pats.iter().map(|pat| self.lower_pat(pat)).collect();
3511 self.arm(pats, body_expr)
3516 let pat_under = self.pat_wild(e.span);
3517 self.arm(hir_vec![pat_under], break_expr)
3520 // `match <sub_expr> { ... }`
3521 let arms = hir_vec![pat_arm, break_arm];
3522 let match_expr = self.expr(
3524 hir::ExprMatch(sub_expr, arms, hir::MatchSource::WhileLetDesugar),
3528 // `[opt_ident]: loop { ... }`
3529 let loop_block = P(self.block_expr(P(match_expr)));
3530 let loop_expr = hir::ExprLoop(
3532 self.lower_label(opt_label),
3533 hir::LoopSource::WhileLet,
3535 // add attributes to the outer returned expr node
3539 // Desugar ExprForLoop
3540 // From: `[opt_ident]: for <pat> in <head> <body>`
3541 ExprKind::ForLoop(ref pat, ref head, ref body, opt_label) => {
3545 // let result = match ::std::iter::IntoIterator::into_iter(<head>) {
3547 // [opt_ident]: loop {
3549 // match ::std::iter::Iterator::next(&mut iter) {
3550 // ::std::option::Option::Some(val) => __next = val,
3551 // ::std::option::Option::None => break
3553 // let <pat> = __next;
3554 // StmtExpr(<body>);
3562 let head = self.lower_expr(head);
3563 let head_sp = head.span;
3565 let iter = self.str_to_ident("iter");
3567 let next_ident = self.str_to_ident("__next");
3568 let next_pat = self.pat_ident_binding_mode(
3571 hir::BindingAnnotation::Mutable,
3574 // `::std::option::Option::Some(val) => next = val`
3576 let val_ident = self.str_to_ident("val");
3577 let val_pat = self.pat_ident(pat.span, val_ident);
3578 let val_expr = P(self.expr_ident(pat.span, val_ident, val_pat.id));
3579 let next_expr = P(self.expr_ident(pat.span, next_ident, next_pat.id));
3580 let assign = P(self.expr(
3582 hir::ExprAssign(next_expr, val_expr),
3585 let some_pat = self.pat_some(pat.span, val_pat);
3586 self.arm(hir_vec![some_pat], assign)
3589 // `::std::option::Option::None => break`
3592 self.with_loop_scope(e.id, |this| this.expr_break(e.span, ThinVec::new()));
3593 let pat = self.pat_none(e.span);
3594 self.arm(hir_vec![pat], break_expr)
3599 self.pat_ident_binding_mode(head_sp, iter, hir::BindingAnnotation::Mutable);
3601 // `match ::std::iter::Iterator::next(&mut iter) { ... }`
3603 let iter = P(self.expr_ident(head_sp, iter, iter_pat.id));
3604 let ref_mut_iter = self.expr_mut_addr_of(head_sp, iter);
3605 let next_path = &["iter", "Iterator", "next"];
3606 let next_path = P(self.expr_std_path(head_sp, next_path, ThinVec::new()));
3607 let next_expr = P(self.expr_call(head_sp, next_path, hir_vec![ref_mut_iter]));
3608 let arms = hir_vec![pat_arm, break_arm];
3612 hir::ExprMatch(next_expr, arms, hir::MatchSource::ForLoopDesugar),
3616 let match_stmt = respan(head_sp, hir::StmtExpr(match_expr, self.next_id().node_id));
3618 let next_expr = P(self.expr_ident(head_sp, next_ident, next_pat.id));
3622 self.stmt_let_pat(head_sp, None, next_pat, hir::LocalSource::ForLoopDesugar);
3624 // `let <pat> = __next`
3625 let pat = self.lower_pat(pat);
3626 let pat_let = self.stmt_let_pat(
3630 hir::LocalSource::ForLoopDesugar,
3633 let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false));
3634 let body_expr = P(self.expr_block(body_block, ThinVec::new()));
3635 let body_stmt = respan(body.span, hir::StmtExpr(body_expr, self.next_id().node_id));
3637 let loop_block = P(self.block_all(
3639 hir_vec![next_let, match_stmt, pat_let, body_stmt],
3643 // `[opt_ident]: loop { ... }`
3644 let loop_expr = hir::ExprLoop(
3646 self.lower_label(opt_label),
3647 hir::LoopSource::ForLoop,
3649 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
3650 let loop_expr = P(hir::Expr {
3655 attrs: ThinVec::new(),
3658 // `mut iter => { ... }`
3659 let iter_arm = self.arm(hir_vec![iter_pat], loop_expr);
3661 // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }`
3662 let into_iter_expr = {
3663 let into_iter_path = &["iter", "IntoIterator", "into_iter"];
3664 let into_iter = P(self.expr_std_path(head_sp, into_iter_path, ThinVec::new()));
3665 P(self.expr_call(head_sp, into_iter, hir_vec![head]))
3668 let match_expr = P(self.expr_match(
3672 hir::MatchSource::ForLoopDesugar,
3675 // `{ let _result = ...; _result }`
3676 // underscore prevents an unused_variables lint if the head diverges
3677 let result_ident = self.str_to_ident("_result");
3678 let (let_stmt, let_stmt_binding) =
3679 self.stmt_let(e.span, false, result_ident, match_expr);
3681 let result = P(self.expr_ident(e.span, result_ident, let_stmt_binding));
3682 let block = P(self.block_all(e.span, hir_vec![let_stmt], Some(result)));
3683 // add the attributes to the outer returned expr node
3684 return self.expr_block(block, e.attrs.clone());
3687 // Desugar ExprKind::Try
3689 ExprKind::Try(ref sub_expr) => {
3692 // match Try::into_result(<expr>) {
3693 // Ok(val) => #[allow(unreachable_code)] val,
3694 // Err(err) => #[allow(unreachable_code)]
3695 // // If there is an enclosing `catch {...}`
3696 // break 'catch_target Try::from_error(From::from(err)),
3698 // return Try::from_error(From::from(err)),
3702 self.allow_internal_unstable(CompilerDesugaringKind::QuestionMark, e.span);
3704 // Try::into_result(<expr>)
3707 let sub_expr = self.lower_expr(sub_expr);
3709 let path = &["ops", "Try", "into_result"];
3710 let path = P(self.expr_std_path(unstable_span, path, ThinVec::new()));
3711 P(self.expr_call(e.span, path, hir_vec![sub_expr]))
3714 // #[allow(unreachable_code)]
3716 // allow(unreachable_code)
3718 let allow_ident = Ident::from_str("allow").with_span_pos(e.span);
3719 let uc_ident = Ident::from_str("unreachable_code").with_span_pos(e.span);
3720 let uc_nested = attr::mk_nested_word_item(uc_ident);
3721 attr::mk_list_item(e.span, allow_ident, vec![uc_nested])
3723 attr::mk_spanned_attr_outer(e.span, attr::mk_attr_id(), allow)
3725 let attrs = vec![attr];
3727 // Ok(val) => #[allow(unreachable_code)] val,
3729 let val_ident = self.str_to_ident("val");
3730 let val_pat = self.pat_ident(e.span, val_ident);
3731 let val_expr = P(self.expr_ident_with_attrs(
3735 ThinVec::from(attrs.clone()),
3737 let ok_pat = self.pat_ok(e.span, val_pat);
3739 self.arm(hir_vec![ok_pat], val_expr)
3742 // Err(err) => #[allow(unreachable_code)]
3743 // return Try::from_error(From::from(err)),
3745 let err_ident = self.str_to_ident("err");
3746 let err_local = self.pat_ident(e.span, err_ident);
3748 let path = &["convert", "From", "from"];
3749 let from = P(self.expr_std_path(e.span, path, ThinVec::new()));
3750 let err_expr = self.expr_ident(e.span, err_ident, err_local.id);
3752 self.expr_call(e.span, from, hir_vec![err_expr])
3755 self.wrap_in_try_constructor("from_error", from_expr, unstable_span);
3756 let thin_attrs = ThinVec::from(attrs);
3757 let catch_scope = self.catch_scopes.last().map(|x| *x);
3758 let ret_expr = if let Some(catch_node) = catch_scope {
3764 target_id: Ok(catch_node),
3766 Some(from_err_expr),
3771 P(self.expr(e.span, hir::Expr_::ExprRet(Some(from_err_expr)), thin_attrs))
3774 let err_pat = self.pat_err(e.span, err_local);
3775 self.arm(hir_vec![err_pat], ret_expr)
3780 hir_vec![err_arm, ok_arm],
3781 hir::MatchSource::TryDesugar,
3785 ExprKind::Mac(_) => panic!("Shouldn't exist here"),
3788 let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id);
3795 attrs: e.attrs.clone(),
3799 fn lower_stmt(&mut self, s: &Stmt) -> SmallVector<hir::Stmt> {
3800 SmallVector::one(match s.node {
3801 StmtKind::Local(ref l) => Spanned {
3802 node: hir::StmtDecl(
3804 node: hir::DeclLocal(self.lower_local(l)),
3807 self.lower_node_id(s.id).node_id,
3811 StmtKind::Item(ref it) => {
3812 // Can only use the ID once.
3813 let mut id = Some(s.id);
3814 return self.lower_item_id(it)
3816 .map(|item_id| Spanned {
3817 node: hir::StmtDecl(
3819 node: hir::DeclItem(item_id),
3823 .map(|id| self.lower_node_id(id).node_id)
3824 .unwrap_or_else(|| self.next_id().node_id),
3830 StmtKind::Expr(ref e) => Spanned {
3831 node: hir::StmtExpr(P(self.lower_expr(e)), self.lower_node_id(s.id).node_id),
3834 StmtKind::Semi(ref e) => Spanned {
3835 node: hir::StmtSemi(P(self.lower_expr(e)), self.lower_node_id(s.id).node_id),
3838 StmtKind::Mac(..) => panic!("Shouldn't exist here"),
3842 fn lower_capture_clause(&mut self, c: CaptureBy) -> hir::CaptureClause {
3844 CaptureBy::Value => hir::CaptureByValue,
3845 CaptureBy::Ref => hir::CaptureByRef,
3849 /// If an `explicit_owner` is given, this method allocates the `HirId` in
3850 /// the address space of that item instead of the item currently being
3851 /// lowered. This can happen during `lower_impl_item_ref()` where we need to
3852 /// lower a `Visibility` value although we haven't lowered the owning
3853 /// `ImplItem` in question yet.
3854 fn lower_visibility(
3857 explicit_owner: Option<NodeId>,
3858 ) -> hir::Visibility {
3860 VisibilityKind::Public => hir::Public,
3861 VisibilityKind::Crate(sugar) => hir::Visibility::Crate(sugar),
3862 VisibilityKind::Restricted { ref path, id, .. } => hir::Visibility::Restricted {
3863 path: P(self.lower_path(id, path, ParamMode::Explicit)),
3864 id: if let Some(owner) = explicit_owner {
3865 self.lower_node_id_with_owner(id, owner).node_id
3867 self.lower_node_id(id).node_id
3870 VisibilityKind::Inherited => hir::Inherited,
3874 fn lower_defaultness(&mut self, d: Defaultness, has_value: bool) -> hir::Defaultness {
3876 Defaultness::Default => hir::Defaultness::Default {
3877 has_value: has_value,
3879 Defaultness::Final => {
3881 hir::Defaultness::Final
3886 fn lower_block_check_mode(&mut self, b: &BlockCheckMode) -> hir::BlockCheckMode {
3888 BlockCheckMode::Default => hir::DefaultBlock,
3889 BlockCheckMode::Unsafe(u) => hir::UnsafeBlock(self.lower_unsafe_source(u)),
3893 fn lower_binding_mode(&mut self, b: &BindingMode) -> hir::BindingAnnotation {
3895 BindingMode::ByValue(Mutability::Immutable) => hir::BindingAnnotation::Unannotated,
3896 BindingMode::ByRef(Mutability::Immutable) => hir::BindingAnnotation::Ref,
3897 BindingMode::ByValue(Mutability::Mutable) => hir::BindingAnnotation::Mutable,
3898 BindingMode::ByRef(Mutability::Mutable) => hir::BindingAnnotation::RefMut,
3902 fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
3904 CompilerGenerated => hir::CompilerGenerated,
3905 UserProvided => hir::UserProvided,
3909 fn lower_impl_polarity(&mut self, i: ImplPolarity) -> hir::ImplPolarity {
3911 ImplPolarity::Positive => hir::ImplPolarity::Positive,
3912 ImplPolarity::Negative => hir::ImplPolarity::Negative,
3916 fn lower_trait_bound_modifier(&mut self, f: TraitBoundModifier) -> hir::TraitBoundModifier {
3918 TraitBoundModifier::None => hir::TraitBoundModifier::None,
3919 TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe,
3923 // Helper methods for building HIR.
3925 fn arm(&mut self, pats: hir::HirVec<P<hir::Pat>>, expr: P<hir::Expr>) -> hir::Arm {
3934 fn field(&mut self, ident: Ident, expr: P<hir::Expr>, span: Span) -> hir::Field {
3936 id: self.next_id().node_id,
3940 is_shorthand: false,
3944 fn expr_break(&mut self, span: Span, attrs: ThinVec<Attribute>) -> P<hir::Expr> {
3945 let expr_break = hir::ExprBreak(self.lower_loop_destination(None), None);
3946 P(self.expr(span, expr_break, attrs))
3953 args: hir::HirVec<hir::Expr>,
3955 self.expr(span, hir::ExprCall(e, args), ThinVec::new())
3958 fn expr_ident(&mut self, span: Span, id: Name, binding: NodeId) -> hir::Expr {
3959 self.expr_ident_with_attrs(span, id, binding, ThinVec::new())
3962 fn expr_ident_with_attrs(
3967 attrs: ThinVec<Attribute>,
3969 let expr_path = hir::ExprPath(hir::QPath::Resolved(
3973 def: Def::Local(binding),
3974 segments: hir_vec![hir::PathSegment::from_name(id)],
3978 self.expr(span, expr_path, attrs)
3981 fn expr_mut_addr_of(&mut self, span: Span, e: P<hir::Expr>) -> hir::Expr {
3982 self.expr(span, hir::ExprAddrOf(hir::MutMutable, e), ThinVec::new())
3988 components: &[&str],
3989 attrs: ThinVec<Attribute>,
3991 let path = self.std_path(span, components, true);
3994 hir::ExprPath(hir::QPath::Resolved(None, P(path))),
4003 arms: hir::HirVec<hir::Arm>,
4004 source: hir::MatchSource,
4006 self.expr(span, hir::ExprMatch(arg, arms, source), ThinVec::new())
4009 fn expr_block(&mut self, b: P<hir::Block>, attrs: ThinVec<Attribute>) -> hir::Expr {
4010 self.expr(b.span, hir::ExprBlock(b, None), attrs)
4013 fn expr_tuple(&mut self, sp: Span, exprs: hir::HirVec<hir::Expr>) -> P<hir::Expr> {
4014 P(self.expr(sp, hir::ExprTup(exprs), ThinVec::new()))
4017 fn expr(&mut self, span: Span, node: hir::Expr_, attrs: ThinVec<Attribute>) -> hir::Expr {
4018 let LoweredNodeId { node_id, hir_id } = self.next_id();
4031 ex: Option<P<hir::Expr>>,
4033 source: hir::LocalSource,
4035 let LoweredNodeId { node_id, hir_id } = self.next_id();
4037 let local = P(hir::Local {
4044 attrs: ThinVec::new(),
4047 let decl = respan(sp, hir::DeclLocal(local));
4048 respan(sp, hir::StmtDecl(P(decl), self.next_id().node_id))
4057 ) -> (hir::Stmt, NodeId) {
4058 let pat = if mutbl {
4059 self.pat_ident_binding_mode(sp, ident, hir::BindingAnnotation::Mutable)
4061 self.pat_ident(sp, ident)
4063 let pat_id = pat.id;
4065 self.stmt_let_pat(sp, Some(ex), pat, hir::LocalSource::Normal),
4070 fn block_expr(&mut self, expr: P<hir::Expr>) -> hir::Block {
4071 self.block_all(expr.span, hir::HirVec::new(), Some(expr))
4077 stmts: hir::HirVec<hir::Stmt>,
4078 expr: Option<P<hir::Expr>>,
4080 let LoweredNodeId { node_id, hir_id } = self.next_id();
4087 rules: hir::DefaultBlock,
4089 targeted_by_break: false,
4094 fn pat_ok(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
4095 self.pat_std_enum(span, &["result", "Result", "Ok"], hir_vec![pat])
4098 fn pat_err(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
4099 self.pat_std_enum(span, &["result", "Result", "Err"], hir_vec![pat])
4102 fn pat_some(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
4103 self.pat_std_enum(span, &["option", "Option", "Some"], hir_vec![pat])
4106 fn pat_none(&mut self, span: Span) -> P<hir::Pat> {
4107 self.pat_std_enum(span, &["option", "Option", "None"], hir_vec![])
4113 components: &[&str],
4114 subpats: hir::HirVec<P<hir::Pat>>,
4116 let path = self.std_path(span, components, true);
4117 let qpath = hir::QPath::Resolved(None, P(path));
4118 let pt = if subpats.is_empty() {
4119 hir::PatKind::Path(qpath)
4121 hir::PatKind::TupleStruct(qpath, subpats, None)
4126 fn pat_ident(&mut self, span: Span, name: Name) -> P<hir::Pat> {
4127 self.pat_ident_binding_mode(span, name, hir::BindingAnnotation::Unannotated)
4130 fn pat_ident_binding_mode(
4134 bm: hir::BindingAnnotation,
4136 let LoweredNodeId { node_id, hir_id } = self.next_id();
4141 node: hir::PatKind::Binding(bm, node_id, Spanned { span, node: name }, None),
4146 fn pat_wild(&mut self, span: Span) -> P<hir::Pat> {
4147 self.pat(span, hir::PatKind::Wild)
4150 fn pat(&mut self, span: Span, pat: hir::PatKind) -> P<hir::Pat> {
4151 let LoweredNodeId { node_id, hir_id } = self.next_id();
4160 /// Given suffix ["b","c","d"], returns path `::std::b::c::d` when
4161 /// `fld.cx.use_std`, and `::core::b::c::d` otherwise.
4162 /// The path is also resolved according to `is_value`.
4163 fn std_path(&mut self, span: Span, components: &[&str], is_value: bool) -> hir::Path {
4165 .resolve_str_path(span, self.crate_root, components, is_value)
4168 fn ty_path(&mut self, id: LoweredNodeId, span: Span, qpath: hir::QPath) -> P<hir::Ty> {
4170 let node = match qpath {
4171 hir::QPath::Resolved(None, path) => {
4172 // Turn trait object paths into `TyTraitObject` instead.
4173 if let Def::Trait(_) = path.def {
4174 let principal = hir::PolyTraitRef {
4175 bound_generic_params: hir::HirVec::new(),
4176 trait_ref: hir::TraitRef {
4177 path: path.and_then(|path| path),
4183 // The original ID is taken by the `PolyTraitRef`,
4184 // so the `Ty` itself needs a different one.
4185 id = self.next_id();
4186 hir::TyTraitObject(hir_vec![principal], self.elided_dyn_bound(span))
4188 hir::TyPath(hir::QPath::Resolved(None, path))
4191 _ => hir::TyPath(qpath),
4201 /// Invoked to create the lifetime argument for a type `&T`
4202 /// with no explicit lifetime.
4203 fn elided_ref_lifetime(&mut self, span: Span) -> hir::Lifetime {
4204 match self.anonymous_lifetime_mode {
4205 // Intercept when we are in an impl header and introduce an in-band lifetime.
4206 // Hence `impl Foo for &u32` becomes `impl<'f> Foo for &'f u32` for some fresh
4208 AnonymousLifetimeMode::CreateParameter => {
4209 let fresh_name = self.collect_fresh_in_band_lifetime(span);
4211 id: self.next_id().node_id,
4217 AnonymousLifetimeMode::PassThrough => self.new_implicit_lifetime(span),
4221 /// Invoked to create the lifetime argument(s) for a path like
4222 /// `std::cell::Ref<T>`; note that implicit lifetimes in these
4223 /// sorts of cases are deprecated. This may therefore report a warning or an
4224 /// error, depending on the mode.
4225 fn elided_path_lifetimes(&mut self, span: Span, count: usize) -> P<[hir::Lifetime]> {
4226 match self.anonymous_lifetime_mode {
4227 // NB. We intentionally ignore the create-parameter mode here
4228 // and instead "pass through" to resolve-lifetimes, which will then
4229 // report an error. This is because we don't want to support
4230 // impl elision for deprecated forms like
4232 // impl Foo for std::cell::Ref<u32> // note lack of '_
4233 AnonymousLifetimeMode::CreateParameter => {}
4235 // This is the normal case.
4236 AnonymousLifetimeMode::PassThrough => {}
4240 .map(|_| self.new_implicit_lifetime(span))
4244 /// Invoked to create the lifetime argument(s) for an elided trait object
4245 /// bound, like the bound in `Box<dyn Debug>`. This method is not invoked
4246 /// when the bound is written, even if it is written with `'_` like in
4247 /// `Box<dyn Debug + '_>`. In those cases, `lower_lifetime` is invoked.
4248 fn elided_dyn_bound(&mut self, span: Span) -> hir::Lifetime {
4249 match self.anonymous_lifetime_mode {
4250 // NB. We intentionally ignore the create-parameter mode here.
4251 // and instead "pass through" to resolve-lifetimes, which will apply
4252 // the object-lifetime-defaulting rules. Elided object lifetime defaults
4253 // do not act like other elided lifetimes. In other words, given this:
4255 // impl Foo for Box<dyn Debug>
4257 // we do not introduce a fresh `'_` to serve as the bound, but instead
4258 // ultimately translate to the equivalent of:
4260 // impl Foo for Box<dyn Debug + 'static>
4262 // `resolve_lifetime` has the code to make that happen.
4263 AnonymousLifetimeMode::CreateParameter => {}
4265 // This is the normal case.
4266 AnonymousLifetimeMode::PassThrough => {}
4269 self.new_implicit_lifetime(span)
4272 fn new_implicit_lifetime(&mut self, span: Span) -> hir::Lifetime {
4274 id: self.next_id().node_id,
4276 name: hir::LifetimeName::Implicit,
4280 fn maybe_lint_bare_trait(&self, span: Span, id: NodeId, is_global: bool) {
4281 self.sess.buffer_lint_with_diagnostic(
4282 builtin::BARE_TRAIT_OBJECTS,
4285 "trait objects without an explicit `dyn` are deprecated",
4286 builtin::BuiltinLintDiagnostics::BareTraitObject(span, is_global),
4290 fn wrap_in_try_constructor(
4292 method: &'static str,
4294 unstable_span: Span,
4296 let path = &["ops", "Try", method];
4297 let from_err = P(self.expr_std_path(unstable_span, path,
4299 P(self.expr_call(e.span, from_err, hir_vec![e]))
4303 fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
4304 // Sorting by span ensures that we get things in order within a
4305 // file, and also puts the files in a sensible order.
4306 let mut body_ids: Vec<_> = bodies.keys().cloned().collect();
4307 body_ids.sort_by_key(|b| bodies[b].value.span);