| // ignore-tidy-filelength |
| |
| //! Lowers the AST to the HIR. |
| //! |
| //! Since the AST and HIR are fairly similar, this is mostly a simple procedure, |
| //! much like a fold. Where lowering involves a bit more work things get more |
| //! interesting and there are some invariants you should know about. These mostly |
| //! concern spans and IDs. |
| //! |
| //! Spans are assigned to AST nodes during parsing and then are modified during |
| //! expansion to indicate the origin of a node and the process it went through |
| //! being expanded. IDs are assigned to AST nodes just before lowering. |
| //! |
| //! For the simpler lowering steps, IDs and spans should be preserved. Unlike |
| //! expansion we do not preserve the process of lowering in the spans, so spans |
| //! should not be modified here. When creating a new node (as opposed to |
| //! 'folding' an existing one), then you create a new ID using `next_id()`. |
| //! |
| //! You must ensure that IDs are unique. That means that you should only use the |
| //! ID from an AST node in a single HIR node (you can assume that AST node-IDs |
| //! are unique). Every new node must have a unique ID. Avoid cloning HIR nodes. |
| //! If you do, you must then set the new node's ID to a fresh one. |
| //! |
| //! Spans are used for error messages and for tools to map semantics back to |
| //! source code. It is therefore not as important with spans as IDs to be strict |
| //! about use (you can't break the compiler by screwing up a span). Obviously, a |
| //! HIR node can only have a single span. But multiple nodes can have the same |
| //! span and spans don't need to be kept in order, etc. Where code is preserved |
| //! by lowering, it should have the same span as in the AST. Where HIR nodes are |
| //! new it is probably best to give a span for the whole AST node being lowered. |
| //! All nodes should have real spans, don't use dummy spans. Tools are likely to |
| //! get confused if the spans from leaf AST nodes occur in multiple places |
| //! in the HIR, especially for multiple identifiers. |
| |
| #![feature(array_value_iter)] |
| |
| use rustc::arena::Arena; |
| use rustc::dep_graph::DepGraph; |
| use rustc::hir::def::{DefKind, Namespace, PartialRes, PerNS, Res}; |
| use rustc::hir::def_id::{DefId, DefIdMap, DefIndex, CRATE_DEF_INDEX}; |
| use rustc::hir::map::{DefKey, DefPathData, Definitions}; |
| use rustc::hir::{self, ConstArg, GenericArg, ParamName}; |
| use rustc::lint; |
| use rustc::lint::builtin::{self, ELIDED_LIFETIMES_IN_PATHS}; |
| use rustc::middle::cstore::CrateStore; |
| use rustc::session::config::nightly_options; |
| use rustc::session::Session; |
| use rustc::util::captures::Captures; |
| use rustc::util::common::FN_OUTPUT_NAME; |
| use rustc::{bug, span_bug}; |
| use rustc_data_structures::fx::FxHashSet; |
| use rustc_data_structures::sync::Lrc; |
| use rustc_error_codes::*; |
| use rustc_errors::Applicability; |
| use rustc_index::vec::IndexVec; |
| use rustc_session::node_id::NodeMap; |
| use rustc_span::hygiene::ExpnId; |
| use rustc_span::source_map::{respan, DesugaringKind, ExpnData, ExpnKind, Spanned}; |
| use rustc_span::symbol::{kw, sym, Symbol}; |
| use rustc_span::Span; |
| use syntax::ast; |
| use syntax::ast::*; |
| use syntax::attr; |
| use syntax::print::pprust; |
| use syntax::ptr::P as AstP; |
| use syntax::sess::ParseSess; |
| use syntax::token::{self, Nonterminal, Token}; |
| use syntax::tokenstream::{TokenStream, TokenTree}; |
| use syntax::visit::{self, Visitor}; |
| use syntax::{help, struct_span_err, walk_list}; |
| |
| use log::{debug, trace}; |
| use smallvec::{smallvec, SmallVec}; |
| use std::collections::BTreeMap; |
| use std::mem; |
| |
| macro_rules! arena_vec { |
| ($this:expr; $($x:expr),*) => ({ |
| let a = [$($x),*]; |
| $this.arena.alloc_from_iter(std::array::IntoIter::new(a)) |
| }); |
| } |
| |
| mod expr; |
| mod item; |
| |
| const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF; |
| |
| struct LoweringContext<'a, 'hir: 'a> { |
| crate_root: Option<Symbol>, |
| |
| /// Used to assign IDs to HIR nodes that do not directly correspond to AST nodes. |
| sess: &'a Session, |
| |
| resolver: &'a mut dyn Resolver, |
| |
| /// HACK(Centril): there is a cyclic dependency between the parser and lowering |
| /// if we don't have this function pointer. To avoid that dependency so that |
| /// librustc is independent of the parser, we use dynamic dispatch here. |
| nt_to_tokenstream: NtToTokenstream, |
| |
| /// Used to allocate HIR nodes |
| arena: &'hir Arena<'hir>, |
| |
| /// The items being lowered are collected here. |
| items: BTreeMap<hir::HirId, hir::Item<'hir>>, |
| |
| trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem<'hir>>, |
| impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem<'hir>>, |
| bodies: BTreeMap<hir::BodyId, hir::Body<'hir>>, |
| exported_macros: Vec<hir::MacroDef<'hir>>, |
| non_exported_macro_attrs: Vec<ast::Attribute>, |
| |
| trait_impls: BTreeMap<DefId, Vec<hir::HirId>>, |
| |
| modules: BTreeMap<hir::HirId, hir::ModuleItems>, |
| |
| generator_kind: Option<hir::GeneratorKind>, |
| |
| /// Used to get the current `fn`'s def span to point to when using `await` |
| /// outside of an `async fn`. |
| current_item: Option<Span>, |
| |
| catch_scopes: Vec<NodeId>, |
| loop_scopes: Vec<NodeId>, |
| is_in_loop_condition: bool, |
| is_in_trait_impl: bool, |
| is_in_dyn_type: bool, |
| |
| /// What to do when we encounter either an "anonymous lifetime |
| /// reference". The term "anonymous" is meant to encompass both |
| /// `'_` lifetimes as well as fully elided cases where nothing is |
| /// written at all (e.g., `&T` or `std::cell::Ref<T>`). |
| anonymous_lifetime_mode: AnonymousLifetimeMode, |
| |
| /// Used to create lifetime definitions from in-band lifetime usages. |
| /// e.g., `fn foo(x: &'x u8) -> &'x u8` to `fn foo<'x>(x: &'x u8) -> &'x u8` |
| /// When a named lifetime is encountered in a function or impl header and |
| /// has not been defined |
| /// (i.e., it doesn't appear in the in_scope_lifetimes list), it is added |
| /// to this list. The results of this list are then added to the list of |
| /// lifetime definitions in the corresponding impl or function generics. |
| lifetimes_to_define: Vec<(Span, ParamName)>, |
| |
| /// `true` if in-band lifetimes are being collected. This is used to |
| /// indicate whether or not we're in a place where new lifetimes will result |
| /// in in-band lifetime definitions, such a function or an impl header, |
| /// including implicit lifetimes from `impl_header_lifetime_elision`. |
| is_collecting_in_band_lifetimes: bool, |
| |
| /// Currently in-scope lifetimes defined in impl headers, fn headers, or HRTB. |
| /// When `is_collectin_in_band_lifetimes` is true, each lifetime is checked |
| /// against this list to see if it is already in-scope, or if a definition |
| /// needs to be created for it. |
| /// |
| /// We always store a `modern()` version of the param-name in this |
| /// vector. |
| in_scope_lifetimes: Vec<ParamName>, |
| |
| current_module: hir::HirId, |
| |
| type_def_lifetime_params: DefIdMap<usize>, |
| |
| current_hir_id_owner: Vec<(DefIndex, u32)>, |
| item_local_id_counters: NodeMap<u32>, |
| node_id_to_hir_id: IndexVec<NodeId, hir::HirId>, |
| |
| allow_try_trait: Option<Lrc<[Symbol]>>, |
| allow_gen_future: Option<Lrc<[Symbol]>>, |
| } |
| |
| pub trait Resolver { |
| fn cstore(&self) -> &dyn CrateStore; |
| |
| /// Obtains resolution for a `NodeId` with a single resolution. |
| fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes>; |
| |
| /// Obtains per-namespace resolutions for `use` statement with the given `NodeId`. |
| fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res<NodeId>>>; |
| |
| /// Obtains resolution for a label with the given `NodeId`. |
| fn get_label_res(&mut self, id: NodeId) -> Option<NodeId>; |
| |
| /// We must keep the set of definitions up to date as we add nodes that weren't in the AST. |
| /// This should only return `None` during testing. |
| fn definitions(&mut self) -> &mut Definitions; |
| |
| /// Given suffix `["b", "c", "d"]`, creates an AST path for `[::crate_root]::b::c::d` and |
| /// resolves it based on `is_value`. |
| fn resolve_str_path( |
| &mut self, |
| span: Span, |
| crate_root: Option<Symbol>, |
| components: &[Symbol], |
| ns: Namespace, |
| ) -> (ast::Path, Res<NodeId>); |
| |
| fn lint_buffer(&mut self) -> &mut lint::LintBuffer; |
| |
| fn next_node_id(&mut self) -> NodeId; |
| } |
| |
| type NtToTokenstream = fn(&Nonterminal, &ParseSess, Span) -> TokenStream; |
| |
| /// Context of `impl Trait` in code, which determines whether it is allowed in an HIR subtree, |
| /// and if so, what meaning it has. |
| #[derive(Debug)] |
| enum ImplTraitContext<'b, 'a> { |
| /// Treat `impl Trait` as shorthand for a new universal generic parameter. |
| /// Example: `fn foo(x: impl Debug)`, where `impl Debug` is conceptually |
| /// equivalent to a fresh universal parameter like `fn foo<T: Debug>(x: T)`. |
| /// |
| /// Newly generated parameters should be inserted into the given `Vec`. |
| Universal(&'b mut Vec<hir::GenericParam<'a>>), |
| |
| /// Treat `impl Trait` as shorthand for a new opaque type. |
| /// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually |
| /// equivalent to a new opaque type like `type T = impl Debug; fn foo() -> T`. |
| /// |
| /// We optionally store a `DefId` for the parent item here so we can look up necessary |
| /// information later. It is `None` when no information about the context should be stored |
| /// (e.g., for consts and statics). |
| OpaqueTy(Option<DefId> /* fn def-ID */), |
| |
| /// `impl Trait` is not accepted in this position. |
| Disallowed(ImplTraitPosition), |
| } |
| |
| /// Position in which `impl Trait` is disallowed. |
| #[derive(Debug, Copy, Clone, PartialEq, Eq)] |
| enum ImplTraitPosition { |
| /// Disallowed in `let` / `const` / `static` bindings. |
| Binding, |
| |
| /// All other posiitons. |
| Other, |
| } |
| |
| impl<'a> ImplTraitContext<'_, 'a> { |
| #[inline] |
| fn disallowed() -> Self { |
| ImplTraitContext::Disallowed(ImplTraitPosition::Other) |
| } |
| |
| fn reborrow<'this>(&'this mut self) -> ImplTraitContext<'this, 'a> { |
| use self::ImplTraitContext::*; |
| match self { |
| Universal(params) => Universal(params), |
| OpaqueTy(fn_def_id) => OpaqueTy(*fn_def_id), |
| Disallowed(pos) => Disallowed(*pos), |
| } |
| } |
| } |
| |
| pub fn lower_crate<'a, 'hir>( |
| sess: &'a Session, |
| dep_graph: &'a DepGraph, |
| krate: &'a Crate, |
| resolver: &'a mut dyn Resolver, |
| nt_to_tokenstream: NtToTokenstream, |
| arena: &'hir Arena<'hir>, |
| ) -> hir::Crate<'hir> { |
| // We're constructing the HIR here; we don't care what we will |
| // read, since we haven't even constructed the *input* to |
| // incr. comp. yet. |
| dep_graph.assert_ignored(); |
| |
| let _prof_timer = sess.prof.generic_activity("hir_lowering"); |
| |
| LoweringContext { |
| crate_root: sess.parse_sess.injected_crate_name.try_get().copied(), |
| sess, |
| resolver, |
| nt_to_tokenstream, |
| arena, |
| items: BTreeMap::new(), |
| trait_items: BTreeMap::new(), |
| impl_items: BTreeMap::new(), |
| bodies: BTreeMap::new(), |
| trait_impls: BTreeMap::new(), |
| modules: BTreeMap::new(), |
| exported_macros: Vec::new(), |
| non_exported_macro_attrs: Vec::new(), |
| catch_scopes: Vec::new(), |
| loop_scopes: Vec::new(), |
| is_in_loop_condition: false, |
| is_in_trait_impl: false, |
| is_in_dyn_type: false, |
| anonymous_lifetime_mode: AnonymousLifetimeMode::PassThrough, |
| type_def_lifetime_params: Default::default(), |
| current_module: hir::CRATE_HIR_ID, |
| current_hir_id_owner: vec![(CRATE_DEF_INDEX, 0)], |
| item_local_id_counters: Default::default(), |
| node_id_to_hir_id: IndexVec::new(), |
| generator_kind: None, |
| current_item: None, |
| lifetimes_to_define: Vec::new(), |
| is_collecting_in_band_lifetimes: false, |
| in_scope_lifetimes: Vec::new(), |
| allow_try_trait: Some([sym::try_trait][..].into()), |
| allow_gen_future: Some([sym::gen_future][..].into()), |
| } |
| .lower_crate(krate) |
| } |
| |
| #[derive(Copy, Clone, PartialEq)] |
| enum ParamMode { |
| /// Any path in a type context. |
| Explicit, |
| /// Path in a type definition, where the anonymous lifetime `'_` is not allowed. |
| ExplicitNamed, |
| /// The `module::Type` in `module::Type::method` in an expression. |
| Optional, |
| } |
| |
| enum ParenthesizedGenericArgs { |
| Ok, |
| Err, |
| } |
| |
| /// What to do when we encounter an **anonymous** lifetime |
| /// reference. Anonymous lifetime references come in two flavors. You |
| /// have implicit, or fully elided, references to lifetimes, like the |
| /// one in `&T` or `Ref<T>`, and you have `'_` lifetimes, like `&'_ T` |
| /// or `Ref<'_, T>`. These often behave the same, but not always: |
| /// |
| /// - certain usages of implicit references are deprecated, like |
| /// `Ref<T>`, and we sometimes just give hard errors in those cases |
| /// as well. |
| /// - for object bounds there is a difference: `Box<dyn Foo>` is not |
| /// the same as `Box<dyn Foo + '_>`. |
| /// |
| /// We describe the effects of the various modes in terms of three cases: |
| /// |
| /// - **Modern** -- includes all uses of `'_`, but also the lifetime arg |
| /// of a `&` (e.g., the missing lifetime in something like `&T`) |
| /// - **Dyn Bound** -- if you have something like `Box<dyn Foo>`, |
| /// there is an elided lifetime bound (`Box<dyn Foo + 'X>`). These |
| /// elided bounds follow special rules. Note that this only covers |
| /// cases where *nothing* is written; the `'_` in `Box<dyn Foo + |
| /// '_>` is a case of "modern" elision. |
| /// - **Deprecated** -- this coverse cases like `Ref<T>`, where the lifetime |
| /// parameter to ref is completely elided. `Ref<'_, T>` would be the modern, |
| /// non-deprecated equivalent. |
| /// |
| /// Currently, the handling of lifetime elision is somewhat spread out |
| /// between HIR lowering and -- as described below -- the |
| /// `resolve_lifetime` module. Often we "fallthrough" to that code by generating |
| /// an "elided" or "underscore" lifetime name. In the future, we probably want to move |
| /// everything into HIR lowering. |
| #[derive(Copy, Clone, Debug)] |
| enum AnonymousLifetimeMode { |
| /// For **Modern** cases, create a new anonymous region parameter |
| /// and reference that. |
| /// |
| /// For **Dyn Bound** cases, pass responsibility to |
| /// `resolve_lifetime` code. |
| /// |
| /// For **Deprecated** cases, report an error. |
| CreateParameter, |
| |
| /// Give a hard error when either `&` or `'_` is written. Used to |
| /// rule out things like `where T: Foo<'_>`. Does not imply an |
| /// error on default object bounds (e.g., `Box<dyn Foo>`). |
| ReportError, |
| |
| /// Pass responsibility to `resolve_lifetime` code for all cases. |
| PassThrough, |
| } |
| |
| struct ImplTraitTypeIdVisitor<'a> { |
| ids: &'a mut SmallVec<[NodeId; 1]>, |
| } |
| |
| impl Visitor<'_> for ImplTraitTypeIdVisitor<'_> { |
| fn visit_ty(&mut self, ty: &Ty) { |
| match ty.kind { |
| TyKind::Typeof(_) | TyKind::BareFn(_) => return, |
| |
| TyKind::ImplTrait(id, _) => self.ids.push(id), |
| _ => {} |
| } |
| visit::walk_ty(self, ty); |
| } |
| |
| fn visit_path_segment(&mut self, path_span: Span, path_segment: &PathSegment) { |
| if let Some(ref p) = path_segment.args { |
| if let GenericArgs::Parenthesized(_) = **p { |
| return; |
| } |
| } |
| visit::walk_path_segment(self, path_span, path_segment) |
| } |
| } |
| |
| impl<'a, 'hir> LoweringContext<'a, 'hir> { |
| fn lower_crate(mut self, c: &Crate) -> hir::Crate<'hir> { |
| /// Full-crate AST visitor that inserts into a fresh |
| /// `LoweringContext` any information that may be |
| /// needed from arbitrary locations in the crate, |
| /// e.g., the number of lifetime generic parameters |
| /// declared for every type and trait definition. |
| struct MiscCollector<'tcx, 'lowering, 'hir> { |
| lctx: &'tcx mut LoweringContext<'lowering, 'hir>, |
| hir_id_owner: Option<NodeId>, |
| } |
| |
| impl MiscCollector<'_, '_, '_> { |
| fn allocate_use_tree_hir_id_counters(&mut self, tree: &UseTree, owner: DefIndex) { |
| match tree.kind { |
| UseTreeKind::Simple(_, id1, id2) => { |
| for &id in &[id1, id2] { |
| self.lctx.resolver.definitions().create_def_with_parent( |
| owner, |
| id, |
| DefPathData::Misc, |
| ExpnId::root(), |
| tree.prefix.span, |
| ); |
| self.lctx.allocate_hir_id_counter(id); |
| } |
| } |
| UseTreeKind::Glob => (), |
| UseTreeKind::Nested(ref trees) => { |
| for &(ref use_tree, id) in trees { |
| let hir_id = self.lctx.allocate_hir_id_counter(id); |
| self.allocate_use_tree_hir_id_counters(use_tree, hir_id.owner); |
| } |
| } |
| } |
| } |
| |
| fn with_hir_id_owner<F, T>(&mut self, owner: Option<NodeId>, f: F) -> T |
| where |
| F: FnOnce(&mut Self) -> T, |
| { |
| let old = mem::replace(&mut self.hir_id_owner, owner); |
| let r = f(self); |
| self.hir_id_owner = old; |
| r |
| } |
| } |
| |
| impl<'tcx, 'lowering, 'hir> Visitor<'tcx> for MiscCollector<'tcx, 'lowering, 'hir> { |
| fn visit_pat(&mut self, p: &'tcx Pat) { |
| if let PatKind::Paren(..) | PatKind::Rest = p.kind { |
| // Doesn't generate a HIR node |
| } else if let Some(owner) = self.hir_id_owner { |
| self.lctx.lower_node_id_with_owner(p.id, owner); |
| } |
| |
| visit::walk_pat(self, p) |
| } |
| |
| fn visit_item(&mut self, item: &'tcx Item) { |
| let hir_id = self.lctx.allocate_hir_id_counter(item.id); |
| |
| match item.kind { |
| ItemKind::Struct(_, ref generics) |
| | ItemKind::Union(_, ref generics) |
| | ItemKind::Enum(_, ref generics) |
| | ItemKind::TyAlias(_, ref generics) |
| | ItemKind::Trait(_, _, ref generics, ..) => { |
| let def_id = self.lctx.resolver.definitions().local_def_id(item.id); |
| let count = generics |
| .params |
| .iter() |
| .filter(|param| match param.kind { |
| ast::GenericParamKind::Lifetime { .. } => true, |
| _ => false, |
| }) |
| .count(); |
| self.lctx.type_def_lifetime_params.insert(def_id, count); |
| } |
| ItemKind::Use(ref use_tree) => { |
| self.allocate_use_tree_hir_id_counters(use_tree, hir_id.owner); |
| } |
| _ => {} |
| } |
| |
| self.with_hir_id_owner(Some(item.id), |this| { |
| visit::walk_item(this, item); |
| }); |
| } |
| |
| fn visit_trait_item(&mut self, item: &'tcx AssocItem) { |
| self.lctx.allocate_hir_id_counter(item.id); |
| |
| match item.kind { |
| AssocItemKind::Fn(_, None) => { |
| // Ignore patterns in trait methods without bodies |
| self.with_hir_id_owner(None, |this| visit::walk_trait_item(this, item)); |
| } |
| _ => self.with_hir_id_owner(Some(item.id), |this| { |
| visit::walk_trait_item(this, item); |
| }), |
| } |
| } |
| |
| fn visit_impl_item(&mut self, item: &'tcx AssocItem) { |
| self.lctx.allocate_hir_id_counter(item.id); |
| self.with_hir_id_owner(Some(item.id), |this| { |
| visit::walk_impl_item(this, item); |
| }); |
| } |
| |
| fn visit_foreign_item(&mut self, i: &'tcx ForeignItem) { |
| // Ignore patterns in foreign items |
| self.with_hir_id_owner(None, |this| visit::walk_foreign_item(this, i)); |
| } |
| |
| fn visit_ty(&mut self, t: &'tcx Ty) { |
| match t.kind { |
| // Mirrors the case in visit::walk_ty |
| TyKind::BareFn(ref f) => { |
| walk_list!(self, visit_generic_param, &f.generic_params); |
| // Mirrors visit::walk_fn_decl |
| for parameter in &f.decl.inputs { |
| // We don't lower the ids of argument patterns |
| self.with_hir_id_owner(None, |this| { |
| this.visit_pat(¶meter.pat); |
| }); |
| self.visit_ty(¶meter.ty) |
| } |
| self.visit_fn_ret_ty(&f.decl.output) |
| } |
| _ => visit::walk_ty(self, t), |
| } |
| } |
| } |
| |
| self.lower_node_id(CRATE_NODE_ID); |
| debug_assert!(self.node_id_to_hir_id[CRATE_NODE_ID] == hir::CRATE_HIR_ID); |
| |
| visit::walk_crate(&mut MiscCollector { lctx: &mut self, hir_id_owner: None }, c); |
| visit::walk_crate(&mut item::ItemLowerer { lctx: &mut self }, c); |
| |
| let module = self.lower_mod(&c.module); |
| let attrs = self.lower_attrs(&c.attrs); |
| let body_ids = body_ids(&self.bodies); |
| |
| self.resolver.definitions().init_node_id_to_hir_id_mapping(self.node_id_to_hir_id); |
| |
| hir::Crate { |
| module, |
| attrs, |
| span: c.span, |
| exported_macros: self.arena.alloc_from_iter(self.exported_macros), |
| non_exported_macro_attrs: self.arena.alloc_from_iter(self.non_exported_macro_attrs), |
| items: self.items, |
| trait_items: self.trait_items, |
| impl_items: self.impl_items, |
| bodies: self.bodies, |
| body_ids, |
| trait_impls: self.trait_impls, |
| modules: self.modules, |
| } |
| } |
| |
| fn insert_item(&mut self, item: hir::Item<'hir>) { |
| let id = item.hir_id; |
| // FIXME: Use `debug_asset-rt`. |
| assert_eq!(id.local_id, hir::ItemLocalId::from_u32(0)); |
| self.items.insert(id, item); |
| self.modules.get_mut(&self.current_module).unwrap().items.insert(id); |
| } |
| |
| fn allocate_hir_id_counter(&mut self, owner: NodeId) -> hir::HirId { |
| // Set up the counter if needed. |
| self.item_local_id_counters.entry(owner).or_insert(0); |
| // Always allocate the first `HirId` for the owner itself. |
| let lowered = self.lower_node_id_with_owner(owner, owner); |
| debug_assert_eq!(lowered.local_id.as_u32(), 0); |
| lowered |
| } |
| |
| fn lower_node_id_generic<F>(&mut self, ast_node_id: NodeId, alloc_hir_id: F) -> hir::HirId |
| where |
| F: FnOnce(&mut Self) -> hir::HirId, |
| { |
| if ast_node_id == DUMMY_NODE_ID { |
| return hir::DUMMY_HIR_ID; |
| } |
| |
| let min_size = ast_node_id.as_usize() + 1; |
| |
| if min_size > self.node_id_to_hir_id.len() { |
| self.node_id_to_hir_id.resize(min_size, hir::DUMMY_HIR_ID); |
| } |
| |
| let existing_hir_id = self.node_id_to_hir_id[ast_node_id]; |
| |
| if existing_hir_id == hir::DUMMY_HIR_ID { |
| // Generate a new `HirId`. |
| let hir_id = alloc_hir_id(self); |
| self.node_id_to_hir_id[ast_node_id] = hir_id; |
| |
| hir_id |
| } else { |
| existing_hir_id |
| } |
| } |
| |
| fn with_hir_id_owner<F, T>(&mut self, owner: NodeId, f: F) -> T |
| where |
| F: FnOnce(&mut Self) -> T, |
| { |
| let counter = self |
| .item_local_id_counters |
| .insert(owner, HIR_ID_COUNTER_LOCKED) |
| .unwrap_or_else(|| panic!("no `item_local_id_counters` entry for {:?}", owner)); |
| let def_index = self.resolver.definitions().opt_def_index(owner).unwrap(); |
| self.current_hir_id_owner.push((def_index, counter)); |
| let ret = f(self); |
| let (new_def_index, new_counter) = self.current_hir_id_owner.pop().unwrap(); |
| |
| debug_assert!(def_index == new_def_index); |
| debug_assert!(new_counter >= counter); |
| |
| let prev = self.item_local_id_counters.insert(owner, new_counter).unwrap(); |
| debug_assert!(prev == HIR_ID_COUNTER_LOCKED); |
| ret |
| } |
| |
| /// This method allocates a new `HirId` for the given `NodeId` and stores it in |
| /// the `LoweringContext`'s `NodeId => HirId` map. |
| /// Take care not to call this method if the resulting `HirId` is then not |
| /// actually used in the HIR, as that would trigger an assertion in the |
| /// `HirIdValidator` later on, which makes sure that all `NodeId`s got mapped |
| /// properly. Calling the method twice with the same `NodeId` is fine though. |
| fn lower_node_id(&mut self, ast_node_id: NodeId) -> hir::HirId { |
| self.lower_node_id_generic(ast_node_id, |this| { |
| let &mut (def_index, ref mut local_id_counter) = |
| this.current_hir_id_owner.last_mut().unwrap(); |
| let local_id = *local_id_counter; |
| *local_id_counter += 1; |
| hir::HirId { owner: def_index, local_id: hir::ItemLocalId::from_u32(local_id) } |
| }) |
| } |
| |
| fn lower_node_id_with_owner(&mut self, ast_node_id: NodeId, owner: NodeId) -> hir::HirId { |
| self.lower_node_id_generic(ast_node_id, |this| { |
| let local_id_counter = this |
| .item_local_id_counters |
| .get_mut(&owner) |
| .expect("called `lower_node_id_with_owner` before `allocate_hir_id_counter`"); |
| let local_id = *local_id_counter; |
| |
| // We want to be sure not to modify the counter in the map while it |
| // is also on the stack. Otherwise we'll get lost updates when writing |
| // back from the stack to the map. |
| debug_assert!(local_id != HIR_ID_COUNTER_LOCKED); |
| |
| *local_id_counter += 1; |
| let def_index = this.resolver.definitions().opt_def_index(owner).expect( |
| "you forgot to call `create_def_with_parent` or are lowering node-IDs \ |
| that do not belong to the current owner", |
| ); |
| |
| hir::HirId { owner: def_index, local_id: hir::ItemLocalId::from_u32(local_id) } |
| }) |
| } |
| |
| fn next_id(&mut self) -> hir::HirId { |
| let node_id = self.resolver.next_node_id(); |
| self.lower_node_id(node_id) |
| } |
| |
| fn lower_res(&mut self, res: Res<NodeId>) -> Res { |
| res.map_id(|id| { |
| self.lower_node_id_generic(id, |_| { |
| panic!("expected `NodeId` to be lowered already for res {:#?}", res); |
| }) |
| }) |
| } |
| |
| fn expect_full_res(&mut self, id: NodeId) -> Res<NodeId> { |
| self.resolver.get_partial_res(id).map_or(Res::Err, |pr| { |
| if pr.unresolved_segments() != 0 { |
| bug!("path not fully resolved: {:?}", pr); |
| } |
| pr.base_res() |
| }) |
| } |
| |
| fn expect_full_res_from_use(&mut self, id: NodeId) -> impl Iterator<Item = Res<NodeId>> { |
| self.resolver.get_import_res(id).present_items() |
| } |
| |
| fn diagnostic(&self) -> &rustc_errors::Handler { |
| self.sess.diagnostic() |
| } |
| |
| /// Reuses the span but adds information like the kind of the desugaring and features that are |
| /// allowed inside this span. |
| fn mark_span_with_reason( |
| &self, |
| reason: DesugaringKind, |
| span: Span, |
| allow_internal_unstable: Option<Lrc<[Symbol]>>, |
| ) -> Span { |
| span.fresh_expansion(ExpnData { |
| allow_internal_unstable, |
| ..ExpnData::default(ExpnKind::Desugaring(reason), span, self.sess.edition()) |
| }) |
| } |
| |
| fn with_anonymous_lifetime_mode<R>( |
| &mut self, |
| anonymous_lifetime_mode: AnonymousLifetimeMode, |
| op: impl FnOnce(&mut Self) -> R, |
| ) -> R { |
| debug!( |
| "with_anonymous_lifetime_mode(anonymous_lifetime_mode={:?})", |
| anonymous_lifetime_mode, |
| ); |
| let old_anonymous_lifetime_mode = self.anonymous_lifetime_mode; |
| self.anonymous_lifetime_mode = anonymous_lifetime_mode; |
| let result = op(self); |
| self.anonymous_lifetime_mode = old_anonymous_lifetime_mode; |
| debug!( |
| "with_anonymous_lifetime_mode: restoring anonymous_lifetime_mode={:?}", |
| old_anonymous_lifetime_mode |
| ); |
| result |
| } |
| |
| /// Creates a new `hir::GenericParam` for every new lifetime and |
| /// type parameter encountered while evaluating `f`. Definitions |
| /// are created with the parent provided. If no `parent_id` is |
| /// provided, no definitions will be returned. |
| /// |
| /// Presuming that in-band lifetimes are enabled, then |
| /// `self.anonymous_lifetime_mode` will be updated to match the |
| /// parameter while `f` is running (and restored afterwards). |
| fn collect_in_band_defs<T, F>( |
| &mut self, |
| parent_id: DefId, |
| anonymous_lifetime_mode: AnonymousLifetimeMode, |
| f: F, |
| ) -> (Vec<hir::GenericParam<'hir>>, T) |
| where |
| F: FnOnce(&mut Self) -> (Vec<hir::GenericParam<'hir>>, T), |
| { |
| assert!(!self.is_collecting_in_band_lifetimes); |
| assert!(self.lifetimes_to_define.is_empty()); |
| let old_anonymous_lifetime_mode = self.anonymous_lifetime_mode; |
| |
| self.anonymous_lifetime_mode = anonymous_lifetime_mode; |
| self.is_collecting_in_band_lifetimes = true; |
| |
| let (in_band_ty_params, res) = f(self); |
| |
| self.is_collecting_in_band_lifetimes = false; |
| self.anonymous_lifetime_mode = old_anonymous_lifetime_mode; |
| |
| let lifetimes_to_define = self.lifetimes_to_define.split_off(0); |
| |
| let params = lifetimes_to_define |
| .into_iter() |
| .map(|(span, hir_name)| self.lifetime_to_generic_param(span, hir_name, parent_id.index)) |
| .chain(in_band_ty_params.into_iter()) |
| .collect(); |
| |
| (params, res) |
| } |
| |
| /// Converts a lifetime into a new generic parameter. |
| fn lifetime_to_generic_param( |
| &mut self, |
| span: Span, |
| hir_name: ParamName, |
| parent_index: DefIndex, |
| ) -> hir::GenericParam<'hir> { |
| let node_id = self.resolver.next_node_id(); |
| |
| // Get the name we'll use to make the def-path. Note |
| // that collisions are ok here and this shouldn't |
| // really show up for end-user. |
| let (str_name, kind) = match hir_name { |
| ParamName::Plain(ident) => (ident.name, hir::LifetimeParamKind::InBand), |
| ParamName::Fresh(_) => (kw::UnderscoreLifetime, hir::LifetimeParamKind::Elided), |
| ParamName::Error => (kw::UnderscoreLifetime, hir::LifetimeParamKind::Error), |
| }; |
| |
| // Add a definition for the in-band lifetime def. |
| self.resolver.definitions().create_def_with_parent( |
| parent_index, |
| node_id, |
| DefPathData::LifetimeNs(str_name), |
| ExpnId::root(), |
| span, |
| ); |
| |
| hir::GenericParam { |
| hir_id: self.lower_node_id(node_id), |
| name: hir_name, |
| attrs: &[], |
| bounds: &[], |
| span, |
| pure_wrt_drop: false, |
| kind: hir::GenericParamKind::Lifetime { kind }, |
| } |
| } |
| |
| /// When there is a reference to some lifetime `'a`, and in-band |
| /// lifetimes are enabled, then we want to push that lifetime into |
| /// the vector of names to define later. In that case, it will get |
| /// added to the appropriate generics. |
| fn maybe_collect_in_band_lifetime(&mut self, ident: Ident) { |
| if !self.is_collecting_in_band_lifetimes { |
| return; |
| } |
| |
| if !self.sess.features_untracked().in_band_lifetimes { |
| return; |
| } |
| |
| if self.in_scope_lifetimes.contains(&ParamName::Plain(ident.modern())) { |
| return; |
| } |
| |
| let hir_name = ParamName::Plain(ident); |
| |
| if self.lifetimes_to_define.iter().any(|(_, lt_name)| lt_name.modern() == hir_name.modern()) |
| { |
| return; |
| } |
| |
| self.lifetimes_to_define.push((ident.span, hir_name)); |
| } |
| |
| /// When we have either an elided or `'_` lifetime in an impl |
| /// header, we convert it to an in-band lifetime. |
| fn collect_fresh_in_band_lifetime(&mut self, span: Span) -> ParamName { |
| assert!(self.is_collecting_in_band_lifetimes); |
| let index = self.lifetimes_to_define.len() + self.in_scope_lifetimes.len(); |
| let hir_name = ParamName::Fresh(index); |
| self.lifetimes_to_define.push((span, hir_name)); |
| hir_name |
| } |
| |
| // Evaluates `f` with the lifetimes in `params` in-scope. |
| // This is used to track which lifetimes have already been defined, and |
| // which are new in-band lifetimes that need to have a definition created |
| // for them. |
| fn with_in_scope_lifetime_defs<T, F>(&mut self, params: &[GenericParam], f: F) -> T |
| where |
| F: FnOnce(&mut Self) -> T, |
| { |
| let old_len = self.in_scope_lifetimes.len(); |
| let lt_def_names = params.iter().filter_map(|param| match param.kind { |
| GenericParamKind::Lifetime { .. } => Some(ParamName::Plain(param.ident.modern())), |
| _ => None, |
| }); |
| self.in_scope_lifetimes.extend(lt_def_names); |
| |
| let res = f(self); |
| |
| self.in_scope_lifetimes.truncate(old_len); |
| res |
| } |
| |
| /// Appends in-band lifetime defs and argument-position `impl |
| /// Trait` defs to the existing set of generics. |
| /// |
| /// Presuming that in-band lifetimes are enabled, then |
| /// `self.anonymous_lifetime_mode` will be updated to match the |
| /// parameter while `f` is running (and restored afterwards). |
| fn add_in_band_defs<F, T>( |
| &mut self, |
| generics: &Generics, |
| parent_id: DefId, |
| anonymous_lifetime_mode: AnonymousLifetimeMode, |
| f: F, |
| ) -> (hir::Generics<'hir>, T) |
| where |
| F: FnOnce(&mut Self, &mut Vec<hir::GenericParam<'hir>>) -> T, |
| { |
| let (in_band_defs, (mut lowered_generics, res)) = |
| self.with_in_scope_lifetime_defs(&generics.params, |this| { |
| this.collect_in_band_defs(parent_id, anonymous_lifetime_mode, |this| { |
| let mut params = Vec::new(); |
| // Note: it is necessary to lower generics *before* calling `f`. |
| // When lowering `async fn`, there's a final step when lowering |
| // the return type that assumes that all in-scope lifetimes have |
| // already been added to either `in_scope_lifetimes` or |
| // `lifetimes_to_define`. If we swapped the order of these two, |
| // in-band-lifetimes introduced by generics or where-clauses |
| // wouldn't have been added yet. |
| let generics = |
| this.lower_generics_mut(generics, ImplTraitContext::Universal(&mut params)); |
| let res = f(this, &mut params); |
| (params, (generics, res)) |
| }) |
| }); |
| |
| let mut lowered_params: Vec<_> = |
| lowered_generics.params.into_iter().chain(in_band_defs).collect(); |
| |
| // FIXME(const_generics): the compiler doesn't always cope with |
| // unsorted generic parameters at the moment, so we make sure |
| // that they're ordered correctly here for now. (When we chain |
| // the `in_band_defs`, we might make the order unsorted.) |
| lowered_params.sort_by_key(|param| match param.kind { |
| hir::GenericParamKind::Lifetime { .. } => ParamKindOrd::Lifetime, |
| hir::GenericParamKind::Type { .. } => ParamKindOrd::Type, |
| hir::GenericParamKind::Const { .. } => ParamKindOrd::Const, |
| }); |
| |
| lowered_generics.params = lowered_params.into(); |
| |
| let lowered_generics = lowered_generics.into_generics(self.arena); |
| (lowered_generics, res) |
| } |
| |
| fn with_dyn_type_scope<T, F>(&mut self, in_scope: bool, f: F) -> T |
| where |
| F: FnOnce(&mut Self) -> T, |
| { |
| let was_in_dyn_type = self.is_in_dyn_type; |
| self.is_in_dyn_type = in_scope; |
| |
| let result = f(self); |
| |
| self.is_in_dyn_type = was_in_dyn_type; |
| |
| result |
| } |
| |
| fn with_new_scopes<T, F>(&mut self, f: F) -> T |
| where |
| F: FnOnce(&mut Self) -> T, |
| { |
| let was_in_loop_condition = self.is_in_loop_condition; |
| self.is_in_loop_condition = false; |
| |
| let catch_scopes = mem::take(&mut self.catch_scopes); |
| let loop_scopes = mem::take(&mut self.loop_scopes); |
| let ret = f(self); |
| self.catch_scopes = catch_scopes; |
| self.loop_scopes = loop_scopes; |
| |
| self.is_in_loop_condition = was_in_loop_condition; |
| |
| ret |
| } |
| |
| fn def_key(&mut self, id: DefId) -> DefKey { |
| if id.is_local() { |
| self.resolver.definitions().def_key(id.index) |
| } else { |
| self.resolver.cstore().def_key(id) |
| } |
| } |
| |
| fn lower_attrs(&mut self, attrs: &[Attribute]) -> &'hir [Attribute] { |
| self.arena.alloc_from_iter(attrs.iter().map(|a| self.lower_attr(a))) |
| } |
| |
| fn lower_attr(&mut self, attr: &Attribute) -> Attribute { |
| // Note that we explicitly do not walk the path. Since we don't really |
| // lower attributes (we use the AST version) there is nowhere to keep |
| // the `HirId`s. We don't actually need HIR version of attributes anyway. |
| let kind = match attr.kind { |
| AttrKind::Normal(ref item) => AttrKind::Normal(AttrItem { |
| path: item.path.clone(), |
| args: self.lower_mac_args(&item.args), |
| }), |
| AttrKind::DocComment(comment) => AttrKind::DocComment(comment), |
| }; |
| |
| Attribute { kind, id: attr.id, style: attr.style, span: attr.span } |
| } |
| |
| fn lower_mac_args(&mut self, args: &MacArgs) -> MacArgs { |
| match *args { |
| MacArgs::Empty => MacArgs::Empty, |
| MacArgs::Delimited(dspan, delim, ref tokens) => { |
| MacArgs::Delimited(dspan, delim, self.lower_token_stream(tokens.clone())) |
| } |
| MacArgs::Eq(eq_span, ref tokens) => { |
| MacArgs::Eq(eq_span, self.lower_token_stream(tokens.clone())) |
| } |
| } |
| } |
| |
| fn lower_token_stream(&mut self, tokens: TokenStream) -> TokenStream { |
| tokens.into_trees().flat_map(|tree| self.lower_token_tree(tree).into_trees()).collect() |
| } |
| |
| fn lower_token_tree(&mut self, tree: TokenTree) -> TokenStream { |
| match tree { |
| TokenTree::Token(token) => self.lower_token(token), |
| TokenTree::Delimited(span, delim, tts) => { |
| TokenTree::Delimited(span, delim, self.lower_token_stream(tts)).into() |
| } |
| } |
| } |
| |
| fn lower_token(&mut self, token: Token) -> TokenStream { |
| match token.kind { |
| token::Interpolated(nt) => { |
| let tts = (self.nt_to_tokenstream)(&nt, &self.sess.parse_sess, token.span); |
| self.lower_token_stream(tts) |
| } |
| _ => TokenTree::Token(token).into(), |
| } |
| } |
| |
| /// Given an associated type constraint like one of these: |
| /// |
| /// ``` |
| /// T: Iterator<Item: Debug> |
| /// ^^^^^^^^^^^ |
| /// T: Iterator<Item = Debug> |
| /// ^^^^^^^^^^^^ |
| /// ``` |
| /// |
| /// returns a `hir::TypeBinding` representing `Item`. |
| fn lower_assoc_ty_constraint( |
| &mut self, |
| constraint: &AssocTyConstraint, |
| itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::TypeBinding<'hir> { |
| debug!("lower_assoc_ty_constraint(constraint={:?}, itctx={:?})", constraint, itctx); |
| |
| let kind = match constraint.kind { |
| AssocTyConstraintKind::Equality { ref ty } => { |
| hir::TypeBindingKind::Equality { ty: self.lower_ty(ty, itctx) } |
| } |
| AssocTyConstraintKind::Bound { ref bounds } => { |
| // Piggy-back on the `impl Trait` context to figure out the correct behavior. |
| let (desugar_to_impl_trait, itctx) = match itctx { |
| // We are in the return position: |
| // |
| // fn foo() -> impl Iterator<Item: Debug> |
| // |
| // so desugar to |
| // |
| // fn foo() -> impl Iterator<Item = impl Debug> |
| ImplTraitContext::OpaqueTy(_) => (true, itctx), |
| |
| // We are in the argument position, but within a dyn type: |
| // |
| // fn foo(x: dyn Iterator<Item: Debug>) |
| // |
| // so desugar to |
| // |
| // fn foo(x: dyn Iterator<Item = impl Debug>) |
| ImplTraitContext::Universal(_) if self.is_in_dyn_type => (true, itctx), |
| |
| // In `type Foo = dyn Iterator<Item: Debug>` we desugar to |
| // `type Foo = dyn Iterator<Item = impl Debug>` but we have to override the |
| // "impl trait context" to permit `impl Debug` in this position (it desugars |
| // then to an opaque type). |
| // |
| // FIXME: this is only needed until `impl Trait` is allowed in type aliases. |
| ImplTraitContext::Disallowed(_) if self.is_in_dyn_type => { |
| (true, ImplTraitContext::OpaqueTy(None)) |
| } |
| |
| // We are in the parameter position, but not within a dyn type: |
| // |
| // fn foo(x: impl Iterator<Item: Debug>) |
| // |
| // so we leave it as is and this gets expanded in astconv to a bound like |
| // `<T as Iterator>::Item: Debug` where `T` is the type parameter for the |
| // `impl Iterator`. |
| _ => (false, itctx), |
| }; |
| |
| if desugar_to_impl_trait { |
| // Desugar `AssocTy: Bounds` into `AssocTy = impl Bounds`. We do this by |
| // constructing the HIR for `impl bounds...` and then lowering that. |
| |
| let impl_trait_node_id = self.resolver.next_node_id(); |
| let parent_def_index = self.current_hir_id_owner.last().unwrap().0; |
| self.resolver.definitions().create_def_with_parent( |
| parent_def_index, |
| impl_trait_node_id, |
| DefPathData::ImplTrait, |
| ExpnId::root(), |
| constraint.span, |
| ); |
| |
| self.with_dyn_type_scope(false, |this| { |
| let node_id = this.resolver.next_node_id(); |
| let ty = this.lower_ty( |
| &Ty { |
| id: node_id, |
| kind: TyKind::ImplTrait(impl_trait_node_id, bounds.clone()), |
| span: constraint.span, |
| }, |
| itctx, |
| ); |
| |
| hir::TypeBindingKind::Equality { ty } |
| }) |
| } else { |
| // Desugar `AssocTy: Bounds` into a type binding where the |
| // later desugars into a trait predicate. |
| let bounds = self.lower_param_bounds(bounds, itctx); |
| |
| hir::TypeBindingKind::Constraint { bounds } |
| } |
| } |
| }; |
| |
| hir::TypeBinding { |
| hir_id: self.lower_node_id(constraint.id), |
| ident: constraint.ident, |
| kind, |
| span: constraint.span, |
| } |
| } |
| |
| fn lower_generic_arg( |
| &mut self, |
| arg: &ast::GenericArg, |
| itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::GenericArg<'hir> { |
| match arg { |
| ast::GenericArg::Lifetime(lt) => GenericArg::Lifetime(self.lower_lifetime(<)), |
| ast::GenericArg::Type(ty) => { |
| // We parse const arguments as path types as we cannot distiguish them durring |
| // parsing. We try to resolve that ambiguity by attempting resolution in both the |
| // type and value namespaces. If we resolved the path in the value namespace, we |
| // transform it into a generic const argument. |
| if let TyKind::Path(ref qself, ref path) = ty.kind { |
| if let Some(partial_res) = self.resolver.get_partial_res(ty.id) { |
| let res = partial_res.base_res(); |
| if !res.matches_ns(Namespace::TypeNS) { |
| debug!( |
| "lower_generic_arg: Lowering type argument as const argument: {:?}", |
| ty, |
| ); |
| |
| // Construct a AnonConst where the expr is the "ty"'s path. |
| |
| let parent_def_index = self.current_hir_id_owner.last().unwrap().0; |
| let node_id = self.resolver.next_node_id(); |
| |
| // Add a definition for the in-band const def. |
| self.resolver.definitions().create_def_with_parent( |
| parent_def_index, |
| node_id, |
| DefPathData::AnonConst, |
| ExpnId::root(), |
| ty.span, |
| ); |
| |
| let path_expr = Expr { |
| id: ty.id, |
| kind: ExprKind::Path(qself.clone(), path.clone()), |
| span: ty.span, |
| attrs: AttrVec::new(), |
| }; |
| |
| let ct = self.with_new_scopes(|this| hir::AnonConst { |
| hir_id: this.lower_node_id(node_id), |
| body: this.lower_const_body(path_expr.span, Some(&path_expr)), |
| }); |
| return GenericArg::Const(ConstArg { value: ct, span: ty.span }); |
| } |
| } |
| } |
| GenericArg::Type(self.lower_ty_direct(&ty, itctx)) |
| } |
| ast::GenericArg::Const(ct) => GenericArg::Const(ConstArg { |
| value: self.lower_anon_const(&ct), |
| span: ct.value.span, |
| }), |
| } |
| } |
| |
| fn lower_ty(&mut self, t: &Ty, itctx: ImplTraitContext<'_, 'hir>) -> &'hir hir::Ty<'hir> { |
| self.arena.alloc(self.lower_ty_direct(t, itctx)) |
| } |
| |
| fn lower_path_ty( |
| &mut self, |
| t: &Ty, |
| qself: &Option<QSelf>, |
| path: &Path, |
| param_mode: ParamMode, |
| itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::Ty<'hir> { |
| let id = self.lower_node_id(t.id); |
| let qpath = self.lower_qpath(t.id, qself, path, param_mode, itctx); |
| let ty = self.ty_path(id, t.span, qpath); |
| if let hir::TyKind::TraitObject(..) = ty.kind { |
| self.maybe_lint_bare_trait(t.span, t.id, qself.is_none() && path.is_global()); |
| } |
| ty |
| } |
| |
| fn ty(&mut self, span: Span, kind: hir::TyKind<'hir>) -> hir::Ty<'hir> { |
| hir::Ty { hir_id: self.next_id(), kind, span } |
| } |
| |
| fn ty_tup(&mut self, span: Span, tys: &'hir [hir::Ty<'hir>]) -> hir::Ty<'hir> { |
| self.ty(span, hir::TyKind::Tup(tys)) |
| } |
| |
| fn lower_ty_direct(&mut self, t: &Ty, mut itctx: ImplTraitContext<'_, 'hir>) -> hir::Ty<'hir> { |
| let kind = match t.kind { |
| TyKind::Infer => hir::TyKind::Infer, |
| TyKind::Err => hir::TyKind::Err, |
| TyKind::Slice(ref ty) => hir::TyKind::Slice(self.lower_ty(ty, itctx)), |
| TyKind::Ptr(ref mt) => hir::TyKind::Ptr(self.lower_mt(mt, itctx)), |
| TyKind::Rptr(ref region, ref mt) => { |
| let span = self.sess.source_map().next_point(t.span.shrink_to_lo()); |
| let lifetime = match *region { |
| Some(ref lt) => self.lower_lifetime(lt), |
| None => self.elided_ref_lifetime(span), |
| }; |
| hir::TyKind::Rptr(lifetime, self.lower_mt(mt, itctx)) |
| } |
| TyKind::BareFn(ref f) => self.with_in_scope_lifetime_defs(&f.generic_params, |this| { |
| this.with_anonymous_lifetime_mode(AnonymousLifetimeMode::PassThrough, |this| { |
| hir::TyKind::BareFn(this.arena.alloc(hir::BareFnTy { |
| generic_params: this.lower_generic_params( |
| &f.generic_params, |
| &NodeMap::default(), |
| ImplTraitContext::disallowed(), |
| ), |
| unsafety: f.unsafety, |
| abi: this.lower_extern(f.ext), |
| decl: this.lower_fn_decl(&f.decl, None, false, None), |
| param_names: this.lower_fn_params_to_names(&f.decl), |
| })) |
| }) |
| }), |
| TyKind::Never => hir::TyKind::Never, |
| TyKind::Tup(ref tys) => { |
| hir::TyKind::Tup(self.arena.alloc_from_iter( |
| tys.iter().map(|ty| self.lower_ty_direct(ty, itctx.reborrow())), |
| )) |
| } |
| TyKind::Paren(ref ty) => { |
| return self.lower_ty_direct(ty, itctx); |
| } |
| TyKind::Path(ref qself, ref path) => { |
| return self.lower_path_ty(t, qself, path, ParamMode::Explicit, itctx); |
| } |
| TyKind::ImplicitSelf => { |
| let res = self.expect_full_res(t.id); |
| let res = self.lower_res(res); |
| hir::TyKind::Path(hir::QPath::Resolved( |
| None, |
| self.arena.alloc(hir::Path { |
| res, |
| segments: arena_vec![self; hir::PathSegment::from_ident( |
| Ident::with_dummy_span(kw::SelfUpper) |
| )], |
| span: t.span, |
| }), |
| )) |
| } |
| TyKind::Array(ref ty, ref length) => { |
| hir::TyKind::Array(self.lower_ty(ty, itctx), self.lower_anon_const(length)) |
| } |
| TyKind::Typeof(ref expr) => hir::TyKind::Typeof(self.lower_anon_const(expr)), |
| TyKind::TraitObject(ref bounds, kind) => { |
| let mut lifetime_bound = None; |
| let (bounds, lifetime_bound) = self.with_dyn_type_scope(true, |this| { |
| let bounds = |
| this.arena.alloc_from_iter(bounds.iter().filter_map( |
| |bound| match *bound { |
| GenericBound::Trait(ref ty, TraitBoundModifier::None) => { |
| Some(this.lower_poly_trait_ref(ty, itctx.reborrow())) |
| } |
| GenericBound::Trait(_, TraitBoundModifier::Maybe) => None, |
| GenericBound::Outlives(ref lifetime) => { |
| if lifetime_bound.is_none() { |
| lifetime_bound = Some(this.lower_lifetime(lifetime)); |
| } |
| None |
| } |
| }, |
| )); |
| let lifetime_bound = |
| lifetime_bound.unwrap_or_else(|| this.elided_dyn_bound(t.span)); |
| (bounds, lifetime_bound) |
| }); |
| if kind != TraitObjectSyntax::Dyn { |
| self.maybe_lint_bare_trait(t.span, t.id, false); |
| } |
| hir::TyKind::TraitObject(bounds, lifetime_bound) |
| } |
| TyKind::ImplTrait(def_node_id, ref bounds) => { |
| let span = t.span; |
| match itctx { |
| ImplTraitContext::OpaqueTy(fn_def_id) => { |
| self.lower_opaque_impl_trait(span, fn_def_id, def_node_id, |this| { |
| this.lower_param_bounds(bounds, itctx) |
| }) |
| } |
| ImplTraitContext::Universal(in_band_ty_params) => { |
| // Add a definition for the in-band `Param`. |
| let def_index = |
| self.resolver.definitions().opt_def_index(def_node_id).unwrap(); |
| |
| let hir_bounds = self.lower_param_bounds( |
| bounds, |
| ImplTraitContext::Universal(in_band_ty_params), |
| ); |
| // Set the name to `impl Bound1 + Bound2`. |
| let ident = Ident::from_str_and_span(&pprust::ty_to_string(t), span); |
| in_band_ty_params.push(hir::GenericParam { |
| hir_id: self.lower_node_id(def_node_id), |
| name: ParamName::Plain(ident), |
| pure_wrt_drop: false, |
| attrs: &[], |
| bounds: hir_bounds, |
| span, |
| kind: hir::GenericParamKind::Type { |
| default: None, |
| synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), |
| }, |
| }); |
| |
| hir::TyKind::Path(hir::QPath::Resolved( |
| None, |
| self.arena.alloc(hir::Path { |
| span, |
| res: Res::Def(DefKind::TyParam, DefId::local(def_index)), |
| segments: arena_vec![self; hir::PathSegment::from_ident(ident)], |
| }), |
| )) |
| } |
| ImplTraitContext::Disallowed(pos) => { |
| let allowed_in = if self.sess.features_untracked().impl_trait_in_bindings { |
| "bindings or function and inherent method return types" |
| } else { |
| "function and inherent method return types" |
| }; |
| let mut err = struct_span_err!( |
| self.sess, |
| t.span, |
| E0562, |
| "`impl Trait` not allowed outside of {}", |
| allowed_in, |
| ); |
| if pos == ImplTraitPosition::Binding && nightly_options::is_nightly_build() |
| { |
| help!( |
| err, |
| "add `#![feature(impl_trait_in_bindings)]` to the crate \ |
| attributes to enable" |
| ); |
| } |
| err.emit(); |
| hir::TyKind::Err |
| } |
| } |
| } |
| TyKind::Mac(_) => bug!("`TyKind::Mac` should have been expanded by now"), |
| TyKind::CVarArgs => { |
| self.sess.delay_span_bug( |
| t.span, |
| "`TyKind::CVarArgs` should have been handled elsewhere", |
| ); |
| hir::TyKind::Err |
| } |
| }; |
| |
| hir::Ty { kind, span: t.span, hir_id: self.lower_node_id(t.id) } |
| } |
| |
| fn lower_opaque_impl_trait( |
| &mut self, |
| span: Span, |
| fn_def_id: Option<DefId>, |
| opaque_ty_node_id: NodeId, |
| lower_bounds: impl FnOnce(&mut Self) -> hir::GenericBounds<'hir>, |
| ) -> hir::TyKind<'hir> { |
| debug!( |
| "lower_opaque_impl_trait(fn_def_id={:?}, opaque_ty_node_id={:?}, span={:?})", |
| fn_def_id, opaque_ty_node_id, span, |
| ); |
| |
| // Make sure we know that some funky desugaring has been going on here. |
| // This is a first: there is code in other places like for loop |
| // desugaring that explicitly states that we don't want to track that. |
| // Not tracking it makes lints in rustc and clippy very fragile, as |
| // frequently opened issues show. |
| let opaque_ty_span = self.mark_span_with_reason(DesugaringKind::OpaqueTy, span, None); |
| |
| let opaque_ty_def_index = |
| self.resolver.definitions().opt_def_index(opaque_ty_node_id).unwrap(); |
| |
| self.allocate_hir_id_counter(opaque_ty_node_id); |
| |
| let hir_bounds = self.with_hir_id_owner(opaque_ty_node_id, lower_bounds); |
| |
| let (lifetimes, lifetime_defs) = self.lifetimes_from_impl_trait_bounds( |
| opaque_ty_node_id, |
| opaque_ty_def_index, |
| &hir_bounds, |
| ); |
| |
| debug!("lower_opaque_impl_trait: lifetimes={:#?}", lifetimes,); |
| |
| debug!("lower_opaque_impl_trait: lifetime_defs={:#?}", lifetime_defs,); |
| |
| self.with_hir_id_owner(opaque_ty_node_id, move |lctx| { |
| let opaque_ty_item = hir::OpaqueTy { |
| generics: hir::Generics { |
| params: lifetime_defs, |
| where_clause: hir::WhereClause { predicates: &[], span }, |
| span, |
| }, |
| bounds: hir_bounds, |
| impl_trait_fn: fn_def_id, |
| origin: hir::OpaqueTyOrigin::FnReturn, |
| }; |
| |
| trace!("lower_opaque_impl_trait: {:#?}", opaque_ty_def_index); |
| let opaque_ty_id = |
| lctx.generate_opaque_type(opaque_ty_node_id, opaque_ty_item, span, opaque_ty_span); |
| |
| // `impl Trait` now just becomes `Foo<'a, 'b, ..>`. |
| hir::TyKind::Def(hir::ItemId { id: opaque_ty_id }, lifetimes) |
| }) |
| } |
| |
| /// Registers a new opaque type with the proper `NodeId`s and |
| /// returns the lowered node-ID for the opaque type. |
| fn generate_opaque_type( |
| &mut self, |
| opaque_ty_node_id: NodeId, |
| opaque_ty_item: hir::OpaqueTy<'hir>, |
| span: Span, |
| opaque_ty_span: Span, |
| ) -> hir::HirId { |
| let opaque_ty_item_kind = hir::ItemKind::OpaqueTy(opaque_ty_item); |
| let opaque_ty_id = self.lower_node_id(opaque_ty_node_id); |
| // Generate an `type Foo = impl Trait;` declaration. |
| trace!("registering opaque type with id {:#?}", opaque_ty_id); |
| let opaque_ty_item = hir::Item { |
| hir_id: opaque_ty_id, |
| ident: Ident::invalid(), |
| attrs: Default::default(), |
| kind: opaque_ty_item_kind, |
| vis: respan(span.shrink_to_lo(), hir::VisibilityKind::Inherited), |
| span: opaque_ty_span, |
| }; |
| |
| // Insert the item into the global item list. This usually happens |
| // automatically for all AST items. But this opaque type item |
| // does not actually exist in the AST. |
| self.insert_item(opaque_ty_item); |
| opaque_ty_id |
| } |
| |
| fn lifetimes_from_impl_trait_bounds( |
| &mut self, |
| opaque_ty_id: NodeId, |
| parent_index: DefIndex, |
| bounds: hir::GenericBounds<'hir>, |
| ) -> (&'hir [hir::GenericArg<'hir>], &'hir [hir::GenericParam<'hir>]) { |
| debug!( |
| "lifetimes_from_impl_trait_bounds(opaque_ty_id={:?}, \ |
| parent_index={:?}, \ |
| bounds={:#?})", |
| opaque_ty_id, parent_index, bounds, |
| ); |
| |
| // This visitor walks over `impl Trait` bounds and creates defs for all lifetimes that |
| // appear in the bounds, excluding lifetimes that are created within the bounds. |
| // E.g., `'a`, `'b`, but not `'c` in `impl for<'c> SomeTrait<'a, 'b, 'c>`. |
| struct ImplTraitLifetimeCollector<'r, 'a, 'hir> { |
| context: &'r mut LoweringContext<'a, 'hir>, |
| parent: DefIndex, |
| opaque_ty_id: NodeId, |
| collect_elided_lifetimes: bool, |
| currently_bound_lifetimes: Vec<hir::LifetimeName>, |
| already_defined_lifetimes: FxHashSet<hir::LifetimeName>, |
| output_lifetimes: Vec<hir::GenericArg<'hir>>, |
| output_lifetime_params: Vec<hir::GenericParam<'hir>>, |
| } |
| |
| impl<'r, 'a, 'v, 'hir> hir::intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r, 'a, 'hir> { |
| fn nested_visit_map<'this>( |
| &'this mut self, |
| ) -> hir::intravisit::NestedVisitorMap<'this, 'v> { |
| hir::intravisit::NestedVisitorMap::None |
| } |
| |
| fn visit_generic_args(&mut self, span: Span, parameters: &'v hir::GenericArgs<'v>) { |
| // Don't collect elided lifetimes used inside of `Fn()` syntax. |
| if parameters.parenthesized { |
| let old_collect_elided_lifetimes = self.collect_elided_lifetimes; |
| self.collect_elided_lifetimes = false; |
| hir::intravisit::walk_generic_args(self, span, parameters); |
| self.collect_elided_lifetimes = old_collect_elided_lifetimes; |
| } else { |
| hir::intravisit::walk_generic_args(self, span, parameters); |
| } |
| } |
| |
| fn visit_ty(&mut self, t: &'v hir::Ty<'v>) { |
| // Don't collect elided lifetimes used inside of `fn()` syntax. |
| if let hir::TyKind::BareFn(_) = t.kind { |
| let old_collect_elided_lifetimes = self.collect_elided_lifetimes; |
| self.collect_elided_lifetimes = false; |
| |
| // Record the "stack height" of `for<'a>` lifetime bindings |
| // to be able to later fully undo their introduction. |
| let old_len = self.currently_bound_lifetimes.len(); |
| hir::intravisit::walk_ty(self, t); |
| self.currently_bound_lifetimes.truncate(old_len); |
| |
| self.collect_elided_lifetimes = old_collect_elided_lifetimes; |
| } else { |
| hir::intravisit::walk_ty(self, t) |
| } |
| } |
| |
| fn visit_poly_trait_ref( |
| &mut self, |
| trait_ref: &'v hir::PolyTraitRef<'v>, |
| modifier: hir::TraitBoundModifier, |
| ) { |
| // Record the "stack height" of `for<'a>` lifetime bindings |
| // to be able to later fully undo their introduction. |
| let old_len = self.currently_bound_lifetimes.len(); |
| hir::intravisit::walk_poly_trait_ref(self, trait_ref, modifier); |
| self.currently_bound_lifetimes.truncate(old_len); |
| } |
| |
| fn visit_generic_param(&mut self, param: &'v hir::GenericParam<'v>) { |
| // Record the introduction of 'a in `for<'a> ...`. |
| if let hir::GenericParamKind::Lifetime { .. } = param.kind { |
| // Introduce lifetimes one at a time so that we can handle |
| // cases like `fn foo<'d>() -> impl for<'a, 'b: 'a, 'c: 'b + 'd>`. |
| let lt_name = hir::LifetimeName::Param(param.name); |
| self.currently_bound_lifetimes.push(lt_name); |
| } |
| |
| hir::intravisit::walk_generic_param(self, param); |
| } |
| |
| fn visit_lifetime(&mut self, lifetime: &'v hir::Lifetime) { |
| let name = match lifetime.name { |
| hir::LifetimeName::Implicit | hir::LifetimeName::Underscore => { |
| if self.collect_elided_lifetimes { |
| // Use `'_` for both implicit and underscore lifetimes in |
| // `type Foo<'_> = impl SomeTrait<'_>;`. |
| hir::LifetimeName::Underscore |
| } else { |
| return; |
| } |
| } |
| hir::LifetimeName::Param(_) => lifetime.name, |
| |
| // Refers to some other lifetime that is "in |
| // scope" within the type. |
| hir::LifetimeName::ImplicitObjectLifetimeDefault => return, |
| |
| hir::LifetimeName::Error | hir::LifetimeName::Static => return, |
| }; |
| |
| if !self.currently_bound_lifetimes.contains(&name) |
| && !self.already_defined_lifetimes.contains(&name) |
| { |
| self.already_defined_lifetimes.insert(name); |
| |
| self.output_lifetimes.push(hir::GenericArg::Lifetime(hir::Lifetime { |
| hir_id: self.context.next_id(), |
| span: lifetime.span, |
| name, |
| })); |
| |
| let def_node_id = self.context.resolver.next_node_id(); |
| let hir_id = |
| self.context.lower_node_id_with_owner(def_node_id, self.opaque_ty_id); |
| self.context.resolver.definitions().create_def_with_parent( |
| self.parent, |
| def_node_id, |
| DefPathData::LifetimeNs(name.ident().name), |
| ExpnId::root(), |
| lifetime.span, |
| ); |
| |
| let (name, kind) = match name { |
| hir::LifetimeName::Underscore => ( |
| hir::ParamName::Plain(Ident::with_dummy_span(kw::UnderscoreLifetime)), |
| hir::LifetimeParamKind::Elided, |
| ), |
| hir::LifetimeName::Param(param_name) => { |
| (param_name, hir::LifetimeParamKind::Explicit) |
| } |
| _ => bug!("expected `LifetimeName::Param` or `ParamName::Plain`"), |
| }; |
| |
| self.output_lifetime_params.push(hir::GenericParam { |
| hir_id, |
| name, |
| span: lifetime.span, |
| pure_wrt_drop: false, |
| attrs: &[], |
| bounds: &[], |
| kind: hir::GenericParamKind::Lifetime { kind }, |
| }); |
| } |
| } |
| } |
| |
| let mut lifetime_collector = ImplTraitLifetimeCollector { |
| context: self, |
| parent: parent_index, |
| opaque_ty_id, |
| collect_elided_lifetimes: true, |
| currently_bound_lifetimes: Vec::new(), |
| already_defined_lifetimes: FxHashSet::default(), |
| output_lifetimes: Vec::new(), |
| output_lifetime_params: Vec::new(), |
| }; |
| |
| for bound in bounds { |
| hir::intravisit::walk_param_bound(&mut lifetime_collector, &bound); |
| } |
| |
| let ImplTraitLifetimeCollector { output_lifetimes, output_lifetime_params, .. } = |
| lifetime_collector; |
| |
| ( |
| self.arena.alloc_from_iter(output_lifetimes), |
| self.arena.alloc_from_iter(output_lifetime_params), |
| ) |
| } |
| |
| fn lower_qpath( |
| &mut self, |
| id: NodeId, |
| qself: &Option<QSelf>, |
| p: &Path, |
| param_mode: ParamMode, |
| mut itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::QPath<'hir> { |
| let qself_position = qself.as_ref().map(|q| q.position); |
| let qself = qself.as_ref().map(|q| self.lower_ty(&q.ty, itctx.reborrow())); |
| |
| let partial_res = |
| self.resolver.get_partial_res(id).unwrap_or_else(|| PartialRes::new(Res::Err)); |
| |
| let proj_start = p.segments.len() - partial_res.unresolved_segments(); |
| let path = self.arena.alloc(hir::Path { |
| res: self.lower_res(partial_res.base_res()), |
| segments: self.arena.alloc_from_iter(p.segments[..proj_start].iter().enumerate().map( |
| |(i, segment)| { |
| let param_mode = match (qself_position, param_mode) { |
| (Some(j), ParamMode::Optional) if i < j => { |
| // This segment is part of the trait path in a |
| // qualified path - one of `a`, `b` or `Trait` |
| // in `<X as a::b::Trait>::T::U::method`. |
| ParamMode::Explicit |
| } |
| _ => param_mode, |
| }; |
| |
| // Figure out if this is a type/trait segment, |
| // which may need lifetime elision performed. |
| let parent_def_id = |this: &mut Self, def_id: DefId| DefId { |
| krate: def_id.krate, |
| index: this.def_key(def_id).parent.expect("missing parent"), |
| }; |
| let type_def_id = match partial_res.base_res() { |
| Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => { |
| Some(parent_def_id(self, def_id)) |
| } |
| Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => { |
| Some(parent_def_id(self, def_id)) |
| } |
| Res::Def(DefKind::Struct, def_id) |
| | Res::Def(DefKind::Union, def_id) |
| | Res::Def(DefKind::Enum, def_id) |
| | Res::Def(DefKind::TyAlias, def_id) |
| | Res::Def(DefKind::Trait, def_id) |
| if i + 1 == proj_start => |
| { |
| Some(def_id) |
| } |
| _ => None, |
| }; |
| let parenthesized_generic_args = match partial_res.base_res() { |
| // `a::b::Trait(Args)` |
| Res::Def(DefKind::Trait, _) if i + 1 == proj_start => { |
| ParenthesizedGenericArgs::Ok |
| } |
| // `a::b::Trait(Args)::TraitItem` |
| Res::Def(DefKind::Method, _) |
| | Res::Def(DefKind::AssocConst, _) |
| | Res::Def(DefKind::AssocTy, _) |
| if i + 2 == proj_start => |
| { |
| ParenthesizedGenericArgs::Ok |
| } |
| // Avoid duplicated errors. |
| Res::Err => ParenthesizedGenericArgs::Ok, |
| // An error |
| _ => ParenthesizedGenericArgs::Err, |
| }; |
| |
| let num_lifetimes = type_def_id.map_or(0, |def_id| { |
| if let Some(&n) = self.type_def_lifetime_params.get(&def_id) { |
| return n; |
| } |
| assert!(!def_id.is_local()); |
| let item_generics = self |
| .resolver |
| .cstore() |
| .item_generics_cloned_untracked(def_id, self.sess); |
| let n = item_generics.own_counts().lifetimes; |
| self.type_def_lifetime_params.insert(def_id, n); |
| n |
| }); |
| self.lower_path_segment( |
| p.span, |
| segment, |
| param_mode, |
| num_lifetimes, |
| parenthesized_generic_args, |
| itctx.reborrow(), |
| None, |
| ) |
| }, |
| )), |
| span: p.span, |
| }); |
| |
| // Simple case, either no projections, or only fully-qualified. |
| // E.g., `std::mem::size_of` or `<I as Iterator>::Item`. |
| if partial_res.unresolved_segments() == 0 { |
| return hir::QPath::Resolved(qself, path); |
| } |
| |
| // Create the innermost type that we're projecting from. |
| let mut ty = if path.segments.is_empty() { |
| // If the base path is empty that means there exists a |
| // syntactical `Self`, e.g., `&i32` in `<&i32>::clone`. |
| qself.expect("missing QSelf for <T>::...") |
| } else { |
| // Otherwise, the base path is an implicit `Self` type path, |
| // e.g., `Vec` in `Vec::new` or `<I as Iterator>::Item` in |
| // `<I as Iterator>::Item::default`. |
| let new_id = self.next_id(); |
| self.arena.alloc(self.ty_path(new_id, p.span, hir::QPath::Resolved(qself, path))) |
| }; |
| |
| // Anything after the base path are associated "extensions", |
| // out of which all but the last one are associated types, |
| // e.g., for `std::vec::Vec::<T>::IntoIter::Item::clone`: |
| // * base path is `std::vec::Vec<T>` |
| // * "extensions" are `IntoIter`, `Item` and `clone` |
| // * type nodes are: |
| // 1. `std::vec::Vec<T>` (created above) |
| // 2. `<std::vec::Vec<T>>::IntoIter` |
| // 3. `<<std::vec::Vec<T>>::IntoIter>::Item` |
| // * final path is `<<<std::vec::Vec<T>>::IntoIter>::Item>::clone` |
| for (i, segment) in p.segments.iter().enumerate().skip(proj_start) { |
| let segment = self.arena.alloc(self.lower_path_segment( |
| p.span, |
| segment, |
| param_mode, |
| 0, |
| ParenthesizedGenericArgs::Err, |
| itctx.reborrow(), |
| None, |
| )); |
| let qpath = hir::QPath::TypeRelative(ty, segment); |
| |
| // It's finished, return the extension of the right node type. |
| if i == p.segments.len() - 1 { |
| return qpath; |
| } |
| |
| // Wrap the associated extension in another type node. |
| let new_id = self.next_id(); |
| ty = self.arena.alloc(self.ty_path(new_id, p.span, qpath)); |
| } |
| |
| // We should've returned in the for loop above. |
| span_bug!( |
| p.span, |
| "lower_qpath: no final extension segment in {}..{}", |
| proj_start, |
| p.segments.len() |
| ) |
| } |
| |
| fn lower_path_extra( |
| &mut self, |
| res: Res, |
| p: &Path, |
| param_mode: ParamMode, |
| explicit_owner: Option<NodeId>, |
| ) -> &'hir hir::Path<'hir> { |
| self.arena.alloc(hir::Path { |
| res, |
| segments: self.arena.alloc_from_iter(p.segments.iter().map(|segment| { |
| self.lower_path_segment( |
| p.span, |
| segment, |
| param_mode, |
| 0, |
| ParenthesizedGenericArgs::Err, |
| ImplTraitContext::disallowed(), |
| explicit_owner, |
| ) |
| })), |
| span: p.span, |
| }) |
| } |
| |
| fn lower_path(&mut self, id: NodeId, p: &Path, param_mode: ParamMode) -> &'hir hir::Path<'hir> { |
| let res = self.expect_full_res(id); |
| let res = self.lower_res(res); |
| self.lower_path_extra(res, p, param_mode, None) |
| } |
| |
| fn lower_path_segment( |
| &mut self, |
| path_span: Span, |
| segment: &PathSegment, |
| param_mode: ParamMode, |
| expected_lifetimes: usize, |
| parenthesized_generic_args: ParenthesizedGenericArgs, |
| itctx: ImplTraitContext<'_, 'hir>, |
| explicit_owner: Option<NodeId>, |
| ) -> hir::PathSegment<'hir> { |
| let (mut generic_args, infer_args) = if let Some(ref generic_args) = segment.args { |
| let msg = "parenthesized type parameters may only be used with a `Fn` trait"; |
| match **generic_args { |
| GenericArgs::AngleBracketed(ref data) => { |
| self.lower_angle_bracketed_parameter_data(data, param_mode, itctx) |
| } |
| GenericArgs::Parenthesized(ref data) => match parenthesized_generic_args { |
| ParenthesizedGenericArgs::Ok => self.lower_parenthesized_parameter_data(data), |
| ParenthesizedGenericArgs::Err => { |
| let mut err = struct_span_err!(self.sess, data.span, E0214, "{}", msg); |
| err.span_label(data.span, "only `Fn` traits may use parentheses"); |
| if let Ok(snippet) = self.sess.source_map().span_to_snippet(data.span) { |
| // Do not suggest going from `Trait()` to `Trait<>` |
| if data.inputs.len() > 0 { |
| if let Some(split) = snippet.find('(') { |
| let trait_name = &snippet[0..split]; |
| let args = &snippet[split + 1..snippet.len() - 1]; |
| err.span_suggestion( |
| data.span, |
| "use angle brackets instead", |
| format!("{}<{}>", trait_name, args), |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| }; |
| err.emit(); |
| ( |
| self.lower_angle_bracketed_parameter_data( |
| &data.as_angle_bracketed_args(), |
| param_mode, |
| itctx, |
| ) |
| .0, |
| false, |
| ) |
| } |
| }, |
| } |
| } else { |
| self.lower_angle_bracketed_parameter_data(&Default::default(), param_mode, itctx) |
| }; |
| |
| let has_lifetimes = generic_args.args.iter().any(|arg| match arg { |
| GenericArg::Lifetime(_) => true, |
| _ => false, |
| }); |
| let first_generic_span = generic_args |
| .args |
| .iter() |
| .map(|a| a.span()) |
| .chain(generic_args.bindings.iter().map(|b| b.span)) |
| .next(); |
| if !generic_args.parenthesized && !has_lifetimes { |
| generic_args.args = self |
| .elided_path_lifetimes(path_span, expected_lifetimes) |
| .map(|lt| GenericArg::Lifetime(lt)) |
| .chain(generic_args.args.into_iter()) |
| .collect(); |
| if expected_lifetimes > 0 && param_mode == ParamMode::Explicit { |
| let anon_lt_suggestion = vec!["'_"; expected_lifetimes].join(", "); |
| let no_non_lt_args = generic_args.args.len() == expected_lifetimes; |
| let no_bindings = generic_args.bindings.is_empty(); |
| let (incl_angl_brckt, insertion_sp, suggestion) = if no_non_lt_args && no_bindings { |
| // If there are no (non-implicit) generic args or associated type |
| // bindings, our suggestion includes the angle brackets. |
| (true, path_span.shrink_to_hi(), format!("<{}>", anon_lt_suggestion)) |
| } else { |
| // Otherwise (sorry, this is kind of gross) we need to infer the |
| // place to splice in the `'_, ` from the generics that do exist. |
| let first_generic_span = first_generic_span |
| .expect("already checked that non-lifetime args or bindings exist"); |
| (false, first_generic_span.shrink_to_lo(), format!("{}, ", anon_lt_suggestion)) |
| }; |
| match self.anonymous_lifetime_mode { |
| // In create-parameter mode we error here because we don't want to support |
| // deprecated impl elision in new features like impl elision and `async fn`, |
| // both of which work using the `CreateParameter` mode: |
| // |
| // impl Foo for std::cell::Ref<u32> // note lack of '_ |
| // async fn foo(_: std::cell::Ref<u32>) { ... } |
| AnonymousLifetimeMode::CreateParameter => { |
| let mut err = struct_span_err!( |
| self.sess, |
| path_span, |
| E0726, |
| "implicit elided lifetime not allowed here" |
| ); |
| crate::lint::builtin::add_elided_lifetime_in_path_suggestion( |
| &self.sess, |
| &mut err, |
| expected_lifetimes, |
| path_span, |
| incl_angl_brckt, |
| insertion_sp, |
| suggestion, |
| ); |
| err.emit(); |
| } |
| AnonymousLifetimeMode::PassThrough | AnonymousLifetimeMode::ReportError => { |
| self.resolver.lint_buffer().buffer_lint_with_diagnostic( |
| ELIDED_LIFETIMES_IN_PATHS, |
| CRATE_NODE_ID, |
| path_span, |
| "hidden lifetime parameters in types are deprecated", |
| builtin::BuiltinLintDiagnostics::ElidedLifetimesInPaths( |
| expected_lifetimes, |
| path_span, |
| incl_angl_brckt, |
| insertion_sp, |
| suggestion, |
| ), |
| ); |
| } |
| } |
| } |
| } |
| |
| let res = self.expect_full_res(segment.id); |
| let id = if let Some(owner) = explicit_owner { |
| self.lower_node_id_with_owner(segment.id, owner) |
| } else { |
| self.lower_node_id(segment.id) |
| }; |
| debug!( |
| "lower_path_segment: ident={:?} original-id={:?} new-id={:?}", |
| segment.ident, segment.id, id, |
| ); |
| |
| hir::PathSegment { |
| ident: segment.ident, |
| hir_id: Some(id), |
| res: Some(self.lower_res(res)), |
| infer_args, |
| args: if generic_args.is_empty() { |
| None |
| } else { |
| Some(self.arena.alloc(generic_args.into_generic_args(self.arena))) |
| }, |
| } |
| } |
| |
| fn lower_angle_bracketed_parameter_data( |
| &mut self, |
| data: &AngleBracketedArgs, |
| param_mode: ParamMode, |
| mut itctx: ImplTraitContext<'_, 'hir>, |
| ) -> (GenericArgsCtor<'hir>, bool) { |
| let &AngleBracketedArgs { ref args, ref constraints, .. } = data; |
| let has_non_lt_args = args.iter().any(|arg| match arg { |
| ast::GenericArg::Lifetime(_) => false, |
| ast::GenericArg::Type(_) => true, |
| ast::GenericArg::Const(_) => true, |
| }); |
| ( |
| GenericArgsCtor { |
| args: args.iter().map(|a| self.lower_generic_arg(a, itctx.reborrow())).collect(), |
| bindings: self.arena.alloc_from_iter( |
| constraints.iter().map(|b| self.lower_assoc_ty_constraint(b, itctx.reborrow())), |
| ), |
| parenthesized: false, |
| }, |
| !has_non_lt_args && param_mode == ParamMode::Optional, |
| ) |
| } |
| |
| fn lower_parenthesized_parameter_data( |
| &mut self, |
| data: &ParenthesizedArgs, |
| ) -> (GenericArgsCtor<'hir>, bool) { |
| // Switch to `PassThrough` mode for anonymous lifetimes; this |
| // means that we permit things like `&Ref<T>`, where `Ref` has |
| // a hidden lifetime parameter. This is needed for backwards |
| // compatibility, even in contexts like an impl header where |
| // we generally don't permit such things (see #51008). |
| self.with_anonymous_lifetime_mode(AnonymousLifetimeMode::PassThrough, |this| { |
| let &ParenthesizedArgs { ref inputs, ref output, span } = data; |
| let inputs = this.arena.alloc_from_iter( |
| inputs.iter().map(|ty| this.lower_ty_direct(ty, ImplTraitContext::disallowed())), |
| ); |
| let output_ty = match output { |
| FunctionRetTy::Ty(ty) => this.lower_ty(&ty, ImplTraitContext::disallowed()), |
| FunctionRetTy::Default(_) => this.arena.alloc(this.ty_tup(span, &[])), |
| }; |
| let args = smallvec![GenericArg::Type(this.ty_tup(span, inputs))]; |
| let binding = hir::TypeBinding { |
| hir_id: this.next_id(), |
| ident: Ident::with_dummy_span(FN_OUTPUT_NAME), |
| span: output_ty.span, |
| kind: hir::TypeBindingKind::Equality { ty: output_ty }, |
| }; |
| ( |
| GenericArgsCtor { args, bindings: arena_vec![this; binding], parenthesized: true }, |
| false, |
| ) |
| }) |
| } |
| |
| fn lower_local(&mut self, l: &Local) -> (hir::Local<'hir>, SmallVec<[NodeId; 1]>) { |
| let mut ids = SmallVec::<[NodeId; 1]>::new(); |
| if self.sess.features_untracked().impl_trait_in_bindings { |
| if let Some(ref ty) = l.ty { |
| let mut visitor = ImplTraitTypeIdVisitor { ids: &mut ids }; |
| visitor.visit_ty(ty); |
| } |
| } |
| let parent_def_id = DefId::local(self.current_hir_id_owner.last().unwrap().0); |
| let ty = l.ty.as_ref().map(|t| { |
| self.lower_ty( |
| t, |
| if self.sess.features_untracked().impl_trait_in_bindings { |
| ImplTraitContext::OpaqueTy(Some(parent_def_id)) |
| } else { |
| ImplTraitContext::Disallowed(ImplTraitPosition::Binding) |
| }, |
| ) |
| }); |
| let init = l.init.as_ref().map(|e| self.lower_expr(e)); |
| ( |
| hir::Local { |
| hir_id: self.lower_node_id(l.id), |
| ty, |
| pat: self.lower_pat(&l.pat), |
| init, |
| span: l.span, |
| attrs: l.attrs.clone(), |
| source: hir::LocalSource::Normal, |
| }, |
| ids, |
| ) |
| } |
| |
| fn lower_fn_params_to_names(&mut self, decl: &FnDecl) -> &'hir [Ident] { |
| // Skip the `...` (`CVarArgs`) trailing arguments from the AST, |
| // as they are not explicit in HIR/Ty function signatures. |
| // (instead, the `c_variadic` flag is set to `true`) |
| let mut inputs = &decl.inputs[..]; |
| if decl.c_variadic() { |
| inputs = &inputs[..inputs.len() - 1]; |
| } |
| self.arena.alloc_from_iter(inputs.iter().map(|param| match param.pat.kind { |
| PatKind::Ident(_, ident, _) => ident, |
| _ => Ident::new(kw::Invalid, param.pat.span), |
| })) |
| } |
| |
| // Lowers a function declaration. |
| // |
| // `decl`: the unlowered (AST) function declaration. |
| // `fn_def_id`: if `Some`, impl Trait arguments are lowered into generic parameters on the |
| // given DefId, otherwise impl Trait is disallowed. Must be `Some` if |
| // `make_ret_async` is also `Some`. |
| // `impl_trait_return_allow`: determines whether `impl Trait` can be used in return position. |
| // This guards against trait declarations and implementations where `impl Trait` is |
| // disallowed. |
| // `make_ret_async`: if `Some`, converts `-> T` into `-> impl Future<Output = T>` in the |
| // return type. This is used for `async fn` declarations. The `NodeId` is the ID of the |
| // return type `impl Trait` item. |
| fn lower_fn_decl( |
| &mut self, |
| decl: &FnDecl, |
| mut in_band_ty_params: Option<(DefId, &mut Vec<hir::GenericParam<'hir>>)>, |
| impl_trait_return_allow: bool, |
| make_ret_async: Option<NodeId>, |
| ) -> &'hir hir::FnDecl<'hir> { |
| debug!( |
| "lower_fn_decl(\ |
| fn_decl: {:?}, \ |
| in_band_ty_params: {:?}, \ |
| impl_trait_return_allow: {}, \ |
| make_ret_async: {:?})", |
| decl, in_band_ty_params, impl_trait_return_allow, make_ret_async, |
| ); |
| let lt_mode = if make_ret_async.is_some() { |
| // In `async fn`, argument-position elided lifetimes |
| // must be transformed into fresh generic parameters so that |
| // they can be applied to the opaque `impl Trait` return type. |
| AnonymousLifetimeMode::CreateParameter |
| } else { |
| self.anonymous_lifetime_mode |
| }; |
| |
| let c_variadic = decl.c_variadic(); |
| |
| // Remember how many lifetimes were already around so that we can |
| // only look at the lifetime parameters introduced by the arguments. |
| let inputs = self.with_anonymous_lifetime_mode(lt_mode, |this| { |
| // Skip the `...` (`CVarArgs`) trailing arguments from the AST, |
| // as they are not explicit in HIR/Ty function signatures. |
| // (instead, the `c_variadic` flag is set to `true`) |
| let mut inputs = &decl.inputs[..]; |
| if c_variadic { |
| inputs = &inputs[..inputs.len() - 1]; |
| } |
| this.arena.alloc_from_iter(inputs.iter().map(|param| { |
| if let Some((_, ibty)) = &mut in_band_ty_params { |
| this.lower_ty_direct(¶m.ty, ImplTraitContext::Universal(ibty)) |
| } else { |
| this.lower_ty_direct(¶m.ty, ImplTraitContext::disallowed()) |
| } |
| })) |
| }); |
| |
| let output = if let Some(ret_id) = make_ret_async { |
| self.lower_async_fn_ret_ty( |
| &decl.output, |
| in_band_ty_params.expect("`make_ret_async` but no `fn_def_id`").0, |
| ret_id, |
| ) |
| } else { |
| match decl.output { |
| FunctionRetTy::Ty(ref ty) => match in_band_ty_params { |
| Some((def_id, _)) if impl_trait_return_allow => { |
| hir::Return(self.lower_ty(ty, ImplTraitContext::OpaqueTy(Some(def_id)))) |
| } |
| _ => hir::Return(self.lower_ty(ty, ImplTraitContext::disallowed())), |
| }, |
| FunctionRetTy::Default(span) => hir::DefaultReturn(span), |
| } |
| }; |
| |
| self.arena.alloc(hir::FnDecl { |
| inputs, |
| output, |
| c_variadic, |
| implicit_self: decl.inputs.get(0).map_or(hir::ImplicitSelfKind::None, |arg| { |
| let is_mutable_pat = match arg.pat.kind { |
| PatKind::Ident(BindingMode::ByValue(mt), _, _) |
| | PatKind::Ident(BindingMode::ByRef(mt), _, _) => mt == Mutability::Mut, |
| _ => false, |
| }; |
| |
| match arg.ty.kind { |
| TyKind::ImplicitSelf if is_mutable_pat => hir::ImplicitSelfKind::Mut, |
| TyKind::ImplicitSelf => hir::ImplicitSelfKind::Imm, |
| // Given we are only considering `ImplicitSelf` types, we needn't consider |
| // the case where we have a mutable pattern to a reference as that would |
| // no longer be an `ImplicitSelf`. |
| TyKind::Rptr(_, ref mt) |
| if mt.ty.kind.is_implicit_self() && mt.mutbl == ast::Mutability::Mut => |
| { |
| hir::ImplicitSelfKind::MutRef |
| } |
| TyKind::Rptr(_, ref mt) if mt.ty.kind.is_implicit_self() => { |
| hir::ImplicitSelfKind::ImmRef |
| } |
| _ => hir::ImplicitSelfKind::None, |
| } |
| }), |
| }) |
| } |
| |
| // Transforms `-> T` for `async fn` into `-> OpaqueTy { .. }` |
| // combined with the following definition of `OpaqueTy`: |
| // |
| // type OpaqueTy<generics_from_parent_fn> = impl Future<Output = T>; |
| // |
| // `inputs`: lowered types of parameters to the function (used to collect lifetimes) |
| // `output`: unlowered output type (`T` in `-> T`) |
| // `fn_def_id`: `DefId` of the parent function (used to create child impl trait definition) |
| // `opaque_ty_node_id`: `NodeId` of the opaque `impl Trait` type that should be created |
| // `elided_lt_replacement`: replacement for elided lifetimes in the return type |
| fn lower_async_fn_ret_ty( |
| &mut self, |
| output: &FunctionRetTy, |
| fn_def_id: DefId, |
| opaque_ty_node_id: NodeId, |
| ) -> hir::FunctionRetTy<'hir> { |
| debug!( |
| "lower_async_fn_ret_ty(\ |
| output={:?}, \ |
| fn_def_id={:?}, \ |
| opaque_ty_node_id={:?})", |
| output, fn_def_id, opaque_ty_node_id, |
| ); |
| |
| let span = output.span(); |
| |
| let opaque_ty_span = self.mark_span_with_reason(DesugaringKind::Async, span, None); |
| |
| let opaque_ty_def_index = |
| self.resolver.definitions().opt_def_index(opaque_ty_node_id).unwrap(); |
| |
| self.allocate_hir_id_counter(opaque_ty_node_id); |
| |
| // When we create the opaque type for this async fn, it is going to have |
| // to capture all the lifetimes involved in the signature (including in the |
| // return type). This is done by introducing lifetime parameters for: |
| // |
| // - all the explicitly declared lifetimes from the impl and function itself; |
| // - all the elided lifetimes in the fn arguments; |
| // - all the elided lifetimes in the return type. |
| // |
| // So for example in this snippet: |
| // |
| // ```rust |
| // impl<'a> Foo<'a> { |
| // async fn bar<'b>(&self, x: &'b Vec<f64>, y: &str) -> &u32 { |
| // // ^ '0 ^ '1 ^ '2 |
| // // elided lifetimes used below |
| // } |
| // } |
| // ``` |
| // |
| // we would create an opaque type like: |
| // |
| // ``` |
| // type Bar<'a, 'b, '0, '1, '2> = impl Future<Output = &'2 u32>; |
| // ``` |
| // |
| // and we would then desugar `bar` to the equivalent of: |
| // |
| // ```rust |
| // impl<'a> Foo<'a> { |
| // fn bar<'b, '0, '1>(&'0 self, x: &'b Vec<f64>, y: &'1 str) -> Bar<'a, 'b, '0, '1, '_> |
| // } |
| // ``` |
| // |
| // Note that the final parameter to `Bar` is `'_`, not `'2` -- |
| // this is because the elided lifetimes from the return type |
| // should be figured out using the ordinary elision rules, and |
| // this desugaring achieves that. |
| // |
| // The variable `input_lifetimes_count` tracks the number of |
| // lifetime parameters to the opaque type *not counting* those |
| // lifetimes elided in the return type. This includes those |
| // that are explicitly declared (`in_scope_lifetimes`) and |
| // those elided lifetimes we found in the arguments (current |
| // content of `lifetimes_to_define`). Next, we will process |
| // the return type, which will cause `lifetimes_to_define` to |
| // grow. |
| let input_lifetimes_count = self.in_scope_lifetimes.len() + self.lifetimes_to_define.len(); |
| |
| let (opaque_ty_id, lifetime_params) = self.with_hir_id_owner(opaque_ty_node_id, |this| { |
| // We have to be careful to get elision right here. The |
| // idea is that we create a lifetime parameter for each |
| // lifetime in the return type. So, given a return type |
| // like `async fn foo(..) -> &[&u32]`, we lower to `impl |
| // Future<Output = &'1 [ &'2 u32 ]>`. |
| // |
| // Then, we will create `fn foo(..) -> Foo<'_, '_>`, and |
| // hence the elision takes place at the fn site. |
| let future_bound = this |
| .with_anonymous_lifetime_mode(AnonymousLifetimeMode::CreateParameter, |this| { |
| this.lower_async_fn_output_type_to_future_bound(output, fn_def_id, span) |
| }); |
| |
| debug!("lower_async_fn_ret_ty: future_bound={:#?}", future_bound); |
| |
| // Calculate all the lifetimes that should be captured |
| // by the opaque type. This should include all in-scope |
| // lifetime parameters, including those defined in-band. |
| // |
| // Note: this must be done after lowering the output type, |
| // as the output type may introduce new in-band lifetimes. |
| let lifetime_params: Vec<(Span, ParamName)> = this |
| .in_scope_lifetimes |
| .iter() |
| .cloned() |
| .map(|name| (name.ident().span, name)) |
| .chain(this.lifetimes_to_define.iter().cloned()) |
| .collect(); |
| |
| debug!("lower_async_fn_ret_ty: in_scope_lifetimes={:#?}", this.in_scope_lifetimes); |
| debug!("lower_async_fn_ret_ty: lifetimes_to_define={:#?}", this.lifetimes_to_define); |
| debug!("lower_async_fn_ret_ty: lifetime_params={:#?}", lifetime_params); |
| |
| let generic_params = |
| this.arena.alloc_from_iter(lifetime_params.iter().map(|(span, hir_name)| { |
| this.lifetime_to_generic_param(*span, *hir_name, opaque_ty_def_index) |
| })); |
| |
| let opaque_ty_item = hir::OpaqueTy { |
| generics: hir::Generics { |
| params: generic_params, |
| where_clause: hir::WhereClause { predicates: &[], span }, |
| span, |
| }, |
| bounds: arena_vec![this; future_bound], |
| impl_trait_fn: Some(fn_def_id), |
| origin: hir::OpaqueTyOrigin::AsyncFn, |
| }; |
| |
| trace!("exist ty from async fn def index: {:#?}", opaque_ty_def_index); |
| let opaque_ty_id = |
| this.generate_opaque_type(opaque_ty_node_id, opaque_ty_item, span, opaque_ty_span); |
| |
| (opaque_ty_id, lifetime_params) |
| }); |
| |
| // As documented above on the variable |
| // `input_lifetimes_count`, we need to create the lifetime |
| // arguments to our opaque type. Continuing with our example, |
| // we're creating the type arguments for the return type: |
| // |
| // ``` |
| // Bar<'a, 'b, '0, '1, '_> |
| // ``` |
| // |
| // For the "input" lifetime parameters, we wish to create |
| // references to the parameters themselves, including the |
| // "implicit" ones created from parameter types (`'a`, `'b`, |
| // '`0`, `'1`). |
| // |
| // For the "output" lifetime parameters, we just want to |
| // generate `'_`. |
| let mut generic_args: Vec<_> = lifetime_params[..input_lifetimes_count] |
| .iter() |
| .map(|&(span, hir_name)| { |
| // Input lifetime like `'a` or `'1`: |
| GenericArg::Lifetime(hir::Lifetime { |
| hir_id: self.next_id(), |
| span, |
| name: hir::LifetimeName::Param(hir_name), |
| }) |
| }) |
| .collect(); |
| generic_args.extend(lifetime_params[input_lifetimes_count..].iter().map(|&(span, _)| |
| // Output lifetime like `'_`. |
| GenericArg::Lifetime(hir::Lifetime { |
| hir_id: self.next_id(), |
| span, |
| name: hir::LifetimeName::Implicit, |
| }))); |
| let generic_args = self.arena.alloc_from_iter(generic_args); |
| |
| // Create the `Foo<...>` reference itself. Note that the `type |
| // Foo = impl Trait` is, internally, created as a child of the |
| // async fn, so the *type parameters* are inherited. It's |
| // only the lifetime parameters that we must supply. |
| let opaque_ty_ref = hir::TyKind::Def(hir::ItemId { id: opaque_ty_id }, generic_args); |
| let opaque_ty = self.ty(opaque_ty_span, opaque_ty_ref); |
| hir::FunctionRetTy::Return(self.arena.alloc(opaque_ty)) |
| } |
| |
| /// Transforms `-> T` into `Future<Output = T>` |
| fn lower_async_fn_output_type_to_future_bound( |
| &mut self, |
| output: &FunctionRetTy, |
| fn_def_id: DefId, |
| span: Span, |
| ) -> hir::GenericBound<'hir> { |
| // Compute the `T` in `Future<Output = T>` from the return type. |
| let output_ty = match output { |
| FunctionRetTy::Ty(ty) => self.lower_ty(ty, ImplTraitContext::OpaqueTy(Some(fn_def_id))), |
| FunctionRetTy::Default(ret_ty_span) => self.arena.alloc(self.ty_tup(*ret_ty_span, &[])), |
| }; |
| |
| // "<Output = T>" |
| let future_params = self.arena.alloc(hir::GenericArgs { |
| args: &[], |
| bindings: arena_vec![self; hir::TypeBinding { |
| ident: Ident::with_dummy_span(FN_OUTPUT_NAME), |
| kind: hir::TypeBindingKind::Equality { ty: output_ty }, |
| hir_id: self.next_id(), |
| span, |
| }], |
| parenthesized: false, |
| }); |
| |
| // ::std::future::Future<future_params> |
| let future_path = |
| self.std_path(span, &[sym::future, sym::Future], Some(future_params), false); |
| |
| hir::GenericBound::Trait( |
| hir::PolyTraitRef { |
| trait_ref: hir::TraitRef { path: future_path, hir_ref_id: self.next_id() }, |
| bound_generic_params: &[], |
| span, |
| }, |
| hir::TraitBoundModifier::None, |
| ) |
| } |
| |
| fn lower_param_bound( |
| &mut self, |
| tpb: &GenericBound, |
| itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::GenericBound<'hir> { |
| match *tpb { |
| GenericBound::Trait(ref ty, modifier) => hir::GenericBound::Trait( |
| self.lower_poly_trait_ref(ty, itctx), |
| self.lower_trait_bound_modifier(modifier), |
| ), |
| GenericBound::Outlives(ref lifetime) => { |
| hir::GenericBound::Outlives(self.lower_lifetime(lifetime)) |
| } |
| } |
| } |
| |
| fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime { |
| let span = l.ident.span; |
| match l.ident { |
| ident if ident.name == kw::StaticLifetime => { |
| self.new_named_lifetime(l.id, span, hir::LifetimeName::Static) |
| } |
| ident if ident.name == kw::UnderscoreLifetime => match self.anonymous_lifetime_mode { |
| AnonymousLifetimeMode::CreateParameter => { |
| let fresh_name = self.collect_fresh_in_band_lifetime(span); |
| self.new_named_lifetime(l.id, span, hir::LifetimeName::Param(fresh_name)) |
| } |
| |
| AnonymousLifetimeMode::PassThrough => { |
| self.new_named_lifetime(l.id, span, hir::LifetimeName::Underscore) |
| } |
| |
| AnonymousLifetimeMode::ReportError => self.new_error_lifetime(Some(l.id), span), |
| }, |
| ident => { |
| self.maybe_collect_in_band_lifetime(ident); |
| let param_name = ParamName::Plain(ident); |
| self.new_named_lifetime(l.id, span, hir::LifetimeName::Param(param_name)) |
| } |
| } |
| } |
| |
| fn new_named_lifetime( |
| &mut self, |
| id: NodeId, |
| span: Span, |
| name: hir::LifetimeName, |
| ) -> hir::Lifetime { |
| hir::Lifetime { hir_id: self.lower_node_id(id), span, name } |
| } |
| |
| fn lower_generic_params_mut<'s>( |
| &'s mut self, |
| params: &'s [GenericParam], |
| add_bounds: &'s NodeMap<Vec<GenericBound>>, |
| mut itctx: ImplTraitContext<'s, 'hir>, |
| ) -> impl Iterator<Item = hir::GenericParam<'hir>> + Captures<'a> + Captures<'s> { |
| params |
| .iter() |
| .map(move |param| self.lower_generic_param(param, add_bounds, itctx.reborrow())) |
| } |
| |
| fn lower_generic_params( |
| &mut self, |
| params: &[GenericParam], |
| add_bounds: &NodeMap<Vec<GenericBound>>, |
| itctx: ImplTraitContext<'_, 'hir>, |
| ) -> &'hir [hir::GenericParam<'hir>] { |
| self.arena.alloc_from_iter(self.lower_generic_params_mut(params, add_bounds, itctx)) |
| } |
| |
| fn lower_generic_param( |
| &mut self, |
| param: &GenericParam, |
| add_bounds: &NodeMap<Vec<GenericBound>>, |
| mut itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::GenericParam<'hir> { |
| let mut bounds: Vec<_> = self |
| .with_anonymous_lifetime_mode(AnonymousLifetimeMode::ReportError, |this| { |
| this.lower_param_bounds_mut(¶m.bounds, itctx.reborrow()).collect() |
| }); |
| |
| let (name, kind) = match param.kind { |
| GenericParamKind::Lifetime => { |
| let was_collecting_in_band = self.is_collecting_in_band_lifetimes; |
| self.is_collecting_in_band_lifetimes = false; |
| |
| let lt = self |
| .with_anonymous_lifetime_mode(AnonymousLifetimeMode::ReportError, |this| { |
| this.lower_lifetime(&Lifetime { id: param.id, ident: param.ident }) |
| }); |
| let param_name = match lt.name { |
| hir::LifetimeName::Param(param_name) => param_name, |
| hir::LifetimeName::Implicit |
| | hir::LifetimeName::Underscore |
| | hir::LifetimeName::Static => hir::ParamName::Plain(lt.name.ident()), |
| hir::LifetimeName::ImplicitObjectLifetimeDefault => { |
| span_bug!( |
| param.ident.span, |
| "object-lifetime-default should not occur here", |
| ); |
| } |
| hir::LifetimeName::Error => ParamName::Error, |
| }; |
| |
| let kind = |
| hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Explicit }; |
| |
| self.is_collecting_in_band_lifetimes = was_collecting_in_band; |
| |
| (param_name, kind) |
| } |
| GenericParamKind::Type { ref default, .. } => { |
| let add_bounds = add_bounds.get(¶m.id).map_or(&[][..], |x| &x); |
| if !add_bounds.is_empty() { |
| let params = self.lower_param_bounds_mut(add_bounds, itctx.reborrow()); |
| bounds.extend(params); |
| } |
| |
| let kind = hir::GenericParamKind::Type { |
| default: default |
| .as_ref() |
| .map(|x| self.lower_ty(x, ImplTraitContext::OpaqueTy(None))), |
| synthetic: param |
| .attrs |
| .iter() |
| .filter(|attr| attr.check_name(sym::rustc_synthetic)) |
| .map(|_| hir::SyntheticTyParamKind::ImplTrait) |
| .next(), |
| }; |
| |
| (hir::ParamName::Plain(param.ident), kind) |
| } |
| GenericParamKind::Const { ref ty } => ( |
| hir::ParamName::Plain(param.ident), |
| hir::GenericParamKind::Const { |
| ty: self.lower_ty(&ty, ImplTraitContext::disallowed()), |
| }, |
| ), |
| }; |
| |
| hir::GenericParam { |
| hir_id: self.lower_node_id(param.id), |
| name, |
| span: param.ident.span, |
| pure_wrt_drop: attr::contains_name(¶m.attrs, sym::may_dangle), |
| attrs: self.lower_attrs(¶m.attrs), |
| bounds: self.arena.alloc_from_iter(bounds), |
| kind, |
| } |
| } |
| |
| fn lower_trait_ref( |
| &mut self, |
| p: &TraitRef, |
| itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::TraitRef<'hir> { |
| let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit, itctx) { |
| hir::QPath::Resolved(None, path) => path, |
| qpath => bug!("lower_trait_ref: unexpected QPath `{:?}`", qpath), |
| }; |
| hir::TraitRef { path, hir_ref_id: self.lower_node_id(p.ref_id) } |
| } |
| |
| fn lower_poly_trait_ref( |
| &mut self, |
| p: &PolyTraitRef, |
| mut itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::PolyTraitRef<'hir> { |
| let bound_generic_params = self.lower_generic_params( |
| &p.bound_generic_params, |
| &NodeMap::default(), |
| itctx.reborrow(), |
| ); |
| let trait_ref = self.with_in_scope_lifetime_defs(&p.bound_generic_params, |this| { |
| this.lower_trait_ref(&p.trait_ref, itctx) |
| }); |
| |
| hir::PolyTraitRef { bound_generic_params, trait_ref, span: p.span } |
| } |
| |
| fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext<'_, 'hir>) -> hir::MutTy<'hir> { |
| hir::MutTy { ty: self.lower_ty(&mt.ty, itctx), mutbl: mt.mutbl } |
| } |
| |
| fn lower_param_bounds( |
| &mut self, |
| bounds: &[GenericBound], |
| itctx: ImplTraitContext<'_, 'hir>, |
| ) -> hir::GenericBounds<'hir> { |
| self.arena.alloc_from_iter(self.lower_param_bounds_mut(bounds, itctx)) |
| } |
| |
| fn lower_param_bounds_mut<'s>( |
| &'s mut self, |
| bounds: &'s [GenericBound], |
| mut itctx: ImplTraitContext<'s, 'hir>, |
| ) -> impl Iterator<Item = hir::GenericBound<'hir>> + Captures<'s> + Captures<'a> { |
| bounds.iter().map(move |bound| self.lower_param_bound(bound, itctx.reborrow())) |
| } |
| |
| fn lower_block(&mut self, b: &Block, targeted_by_break: bool) -> &'hir hir::Block<'hir> { |
| self.arena.alloc(self.lower_block_noalloc(b, targeted_by_break)) |
| } |
| |
| fn lower_block_noalloc(&mut self, b: &Block, targeted_by_break: bool) -> hir::Block<'hir> { |
| let mut stmts = vec![]; |
| let mut expr: Option<&'hir _> = None; |
| |
| for (index, stmt) in b.stmts.iter().enumerate() { |
| if index == b.stmts.len() - 1 { |
| if let StmtKind::Expr(ref e) = stmt.kind { |
| expr = Some(self.lower_expr(e)); |
| } else { |
| stmts.extend(self.lower_stmt(stmt)); |
| } |
| } else { |
| stmts.extend(self.lower_stmt(stmt)); |
| } |
| } |
| |
| hir::Block { |
| hir_id: self.lower_node_id(b.id), |
| stmts: self.arena.alloc_from_iter(stmts), |
| expr, |
| rules: self.lower_block_check_mode(&b.rules), |
| span: b.span, |
| targeted_by_break, |
| } |
| } |
| |
| /// Lowers a block directly to an expression, presuming that it |
| /// has no attributes and is not targeted by a `break`. |
| fn lower_block_expr(&mut self, b: &Block) -> hir::Expr<'hir> { |
| let block = self.lower_block(b, false); |
| self.expr_block(block, AttrVec::new()) |
| } |
| |
| fn lower_pat(&mut self, p: &Pat) -> &'hir hir::Pat<'hir> { |
| let node = match p.kind { |
| PatKind::Wild => hir::PatKind::Wild, |
| PatKind::Ident(ref binding_mode, ident, ref sub) => { |
| let lower_sub = |this: &mut Self| sub.as_ref().map(|s| this.lower_pat(&*s)); |
| let node = self.lower_pat_ident(p, binding_mode, ident, lower_sub); |
| node |
| } |
| PatKind::Lit(ref e) => hir::PatKind::Lit(self.lower_expr(e)), |
| PatKind::TupleStruct(ref path, ref pats) => { |
| let qpath = self.lower_qpath( |
| p.id, |
| &None, |
| path, |
| ParamMode::Optional, |
| ImplTraitContext::disallowed(), |
| ); |
| let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple struct"); |
| hir::PatKind::TupleStruct(qpath, pats, ddpos) |
| } |
| PatKind::Or(ref pats) => { |
| hir::PatKind::Or(self.arena.alloc_from_iter(pats.iter().map(|x| self.lower_pat(x)))) |
| } |
| PatKind::Path(ref qself, ref path) => { |
| let qpath = self.lower_qpath( |
| p.id, |
| qself, |
| path, |
| ParamMode::Optional, |
| ImplTraitContext::disallowed(), |
| ); |
| hir::PatKind::Path(qpath) |
| } |
| PatKind::Struct(ref path, ref fields, etc) => { |
| let qpath = self.lower_qpath( |
| p.id, |
| &None, |
| path, |
| ParamMode::Optional, |
| ImplTraitContext::disallowed(), |
| ); |
| |
| let fs = self.arena.alloc_from_iter(fields.iter().map(|f| hir::FieldPat { |
| hir_id: self.next_id(), |
| ident: f.ident, |
| pat: self.lower_pat(&f.pat), |
| is_shorthand: f.is_shorthand, |
| span: f.span, |
| })); |
| hir::PatKind::Struct(qpath, fs, etc) |
| } |
| PatKind::Tuple(ref pats) => { |
| let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple"); |
| hir::PatKind::Tuple(pats, ddpos) |
| } |
| PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)), |
| PatKind::Ref(ref inner, mutbl) => hir::PatKind::Ref(self.lower_pat(inner), mutbl), |
| PatKind::Range(ref e1, ref e2, Spanned { node: ref end, .. }) => hir::PatKind::Range( |
| self.lower_expr(e1), |
| self.lower_expr(e2), |
| self.lower_range_end(end), |
| ), |
| PatKind::Slice(ref pats) => self.lower_pat_slice(pats), |
| PatKind::Rest => { |
| // If we reach here the `..` pattern is not semantically allowed. |
| self.ban_illegal_rest_pat(p.span) |
| } |
| PatKind::Paren(ref inner) => return self.lower_pat(inner), |
| PatKind::Mac(_) => panic!("Shouldn't exist here"), |
| }; |
| |
| self.pat_with_node_id_of(p, node) |
| } |
| |
| fn lower_pat_tuple( |
| &mut self, |
| pats: &[AstP<Pat>], |
| ctx: &str, |
| ) -> (&'hir [&'hir hir::Pat<'hir>], Option<usize>) { |
| let mut elems = Vec::with_capacity(pats.len()); |
| let mut rest = None; |
| |
| let mut iter = pats.iter().enumerate(); |
| for (idx, pat) in iter.by_ref() { |
| // Interpret the first `..` pattern as a sub-tuple pattern. |
| // Note that unlike for slice patterns, |
| // where `xs @ ..` is a legal sub-slice pattern, |
| // it is not a legal sub-tuple pattern. |
| if pat.is_rest() { |
| rest = Some((idx, pat.span)); |
| break; |
| } |
| // It was not a sub-tuple pattern so lower it normally. |
| elems.push(self.lower_pat(pat)); |
| } |
| |
| for (_, pat) in iter { |
| // There was a previous sub-tuple pattern; make sure we don't allow more... |
| if pat.is_rest() { |
| // ...but there was one again, so error. |
| self.ban_extra_rest_pat(pat.span, rest.unwrap().1, ctx); |
| } else { |
| elems.push(self.lower_pat(pat)); |
| } |
| } |
| |
| (self.arena.alloc_from_iter(elems), rest.map(|(ddpos, _)| ddpos)) |
| } |
| |
| /// Lower a slice pattern of form `[pat_0, ..., pat_n]` into |
| /// `hir::PatKind::Slice(before, slice, after)`. |
| /// |
| /// When encountering `($binding_mode $ident @)? ..` (`slice`), |
| /// this is interpreted as a sub-slice pattern semantically. |
| /// Patterns that follow, which are not like `slice` -- or an error occurs, are in `after`. |
| fn lower_pat_slice(&mut self, pats: &[AstP<Pat>]) -> hir::PatKind<'hir> { |
| let mut before = Vec::new(); |
| let mut after = Vec::new(); |
| let mut slice = None; |
| let mut prev_rest_span = None; |
| |
| let mut iter = pats.iter(); |
| // Lower all the patterns until the first occurence of a sub-slice pattern. |
| for pat in iter.by_ref() { |
| match pat.kind { |
| // Found a sub-slice pattern `..`. Record, lower it to `_`, and stop here. |
| PatKind::Rest => { |
| prev_rest_span = Some(pat.span); |
| slice = Some(self.pat_wild_with_node_id_of(pat)); |
| break; |
| } |
| // Found a sub-slice pattern `$binding_mode $ident @ ..`. |
| // Record, lower it to `$binding_mode $ident @ _`, and stop here. |
| PatKind::Ident(ref bm, ident, Some(ref sub)) if sub.is_rest() => { |
| prev_rest_span = Some(sub.span); |
| let lower_sub = |this: &mut Self| Some(this.pat_wild_with_node_id_of(sub)); |
| let node = self.lower_pat_ident(pat, bm, ident, lower_sub); |
| slice = Some(self.pat_with_node_id_of(pat, node)); |
| break; |
| } |
| // It was not a subslice pattern so lower it normally. |
| _ => before.push(self.lower_pat(pat)), |
| } |
| } |
| |
| // Lower all the patterns after the first sub-slice pattern. |
| for pat in iter { |
| // There was a previous subslice pattern; make sure we don't allow more. |
| let rest_span = match pat.kind { |
| PatKind::Rest => Some(pat.span), |
| PatKind::Ident(.., Some(ref sub)) if sub.is_rest() => { |
| // The `HirValidator` is merciless; add a `_` pattern to avoid ICEs. |
| after.push(self.pat_wild_with_node_id_of(pat)); |
| Some(sub.span) |
| } |
| _ => None, |
| }; |
| if let Some(rest_span) = rest_span { |
| // We have e.g., `[a, .., b, ..]`. That's no good, error! |
| self.ban_extra_rest_pat(rest_span, prev_rest_span.unwrap(), "slice"); |
| } else { |
| // Lower the pattern normally. |
| after.push(self.lower_pat(pat)); |
| } |
| } |
| |
| hir::PatKind::Slice( |
| self.arena.alloc_from_iter(before), |
| slice, |
| self.arena.alloc_from_iter(after), |
| ) |
| } |
| |
| fn lower_pat_ident( |
| &mut self, |
| p: &Pat, |
| binding_mode: &BindingMode, |
| ident: Ident, |
| lower_sub: impl FnOnce(&mut Self) -> Option<&'hir hir::Pat<'hir>>, |
| ) -> hir::PatKind<'hir> { |
| match self.resolver.get_partial_res(p.id).map(|d| d.base_res()) { |
| // `None` can occur in body-less function signatures |
| res @ None | res @ Some(Res::Local(_)) => { |
| let canonical_id = match res { |
| Some(Res::Local(id)) => id, |
| _ => p.id, |
| }; |
| |
| hir::PatKind::Binding( |
| self.lower_binding_mode(binding_mode), |
| self.lower_node_id(canonical_id), |
| ident, |
| lower_sub(self), |
| ) |
| } |
| Some(res) => hir::PatKind::Path(hir::QPath::Resolved( |
| None, |
| self.arena.alloc(hir::Path { |
| span: ident.span, |
| res: self.lower_res(res), |
| segments: arena_vec![self; hir::PathSegment::from_ident(ident)], |
| }), |
| )), |
| } |
| } |
| |
| fn pat_wild_with_node_id_of(&mut self, p: &Pat) -> &'hir hir::Pat<'hir> { |
| self.pat_with_node_id_of(p, hir::PatKind::Wild) |
| } |
| |
| /// Construct a `Pat` with the `HirId` of `p.id` lowered. |
| fn pat_with_node_id_of(&mut self, p: &Pat, kind: hir::PatKind<'hir>) -> &'hir hir::Pat<'hir> { |
| self.arena.alloc(hir::Pat { hir_id: self.lower_node_id(p.id), kind, span: p.span }) |
| } |
| |
| /// Emit a friendly error for extra `..` patterns in a tuple/tuple struct/slice pattern. |
| fn ban_extra_rest_pat(&self, sp: Span, prev_sp: Span, ctx: &str) { |
| self.diagnostic() |
| .struct_span_err(sp, &format!("`..` can only be used once per {} pattern", ctx)) |
| .span_label(sp, &format!("can only be used once per {} pattern", ctx)) |
| .span_label(prev_sp, "previously used here") |
| .emit(); |
| } |
| |
| /// Used to ban the `..` pattern in places it shouldn't be semantically. |
| fn ban_illegal_rest_pat(&self, sp: Span) -> hir::PatKind<'hir> { |
| self.diagnostic() |
| .struct_span_err(sp, "`..` patterns are not allowed here") |
| .note("only allowed in tuple, tuple struct, and slice patterns") |
| .emit(); |
| |
| // We're not in a list context so `..` can be reasonably treated |
| // as `_` because it should always be valid and roughly matches the |
| // intent of `..` (notice that the rest of a single slot is that slot). |
| hir::PatKind::Wild |
| } |
| |
| fn lower_range_end(&mut self, e: &RangeEnd) -> hir::RangeEnd { |
| match *e { |
| RangeEnd::Included(_) => hir::RangeEnd::Included, |
| RangeEnd::Excluded => hir::RangeEnd::Excluded, |
| } |
| } |
| |
| fn lower_anon_const(&mut self, c: &AnonConst) -> hir::AnonConst { |
| self.with_new_scopes(|this| hir::AnonConst { |
| hir_id: this.lower_node_id(c.id), |
| body: this.lower_const_body(c.value.span, Some(&c.value)), |
| }) |
| } |
| |
| fn lower_stmt(&mut self, s: &Stmt) -> SmallVec<[hir::Stmt<'hir>; 1]> { |
| let kind = match s.kind { |
| StmtKind::Local(ref l) => { |
| let (l, item_ids) = self.lower_local(l); |
| let mut ids: SmallVec<[hir::Stmt<'hir>; 1]> = item_ids |
| .into_iter() |
| .map(|item_id| { |
| let item_id = hir::ItemId { id: self.lower_node_id(item_id) }; |
| self.stmt(s.span, hir::StmtKind::Item(item_id)) |
| }) |
| .collect(); |
| ids.push({ |
| hir::Stmt { |
| hir_id: self.lower_node_id(s.id), |
| kind: hir::StmtKind::Local(self.arena.alloc(l)), |
| span: s.span, |
| } |
| }); |
| return ids; |
| } |
| StmtKind::Item(ref it) => { |
| // Can only use the ID once. |
| let mut id = Some(s.id); |
| return self |
| .lower_item_id(it) |
| .into_iter() |
| .map(|item_id| { |
| let hir_id = id |
| .take() |
| .map(|id| self.lower_node_id(id)) |
| .unwrap_or_else(|| self.next_id()); |
| |
| hir::Stmt { hir_id, kind: hir::StmtKind::Item(item_id), span: s.span } |
| }) |
| .collect(); |
| } |
| StmtKind::Expr(ref e) => hir::StmtKind::Expr(self.lower_expr(e)), |
| StmtKind::Semi(ref e) => hir::StmtKind::Semi(self.lower_expr(e)), |
| StmtKind::Mac(..) => panic!("shouldn't exist here"), |
| }; |
| smallvec![hir::Stmt { hir_id: self.lower_node_id(s.id), kind, span: s.span }] |
| } |
| |
| fn lower_block_check_mode(&mut self, b: &BlockCheckMode) -> hir::BlockCheckMode { |
| match *b { |
| BlockCheckMode::Default => hir::DefaultBlock, |
| BlockCheckMode::Unsafe(u) => hir::UnsafeBlock(self.lower_unsafe_source(u)), |
| } |
| } |
| |
| fn lower_binding_mode(&mut self, b: &BindingMode) -> hir::BindingAnnotation { |
| match *b { |
| BindingMode::ByValue(Mutability::Not) => hir::BindingAnnotation::Unannotated, |
| BindingMode::ByRef(Mutability::Not) => hir::BindingAnnotation::Ref, |
| BindingMode::ByValue(Mutability::Mut) => hir::BindingAnnotation::Mutable, |
| BindingMode::ByRef(Mutability::Mut) => hir::BindingAnnotation::RefMut, |
| } |
| } |
| |
| fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource { |
| match u { |
| CompilerGenerated => hir::CompilerGenerated, |
| UserProvided => hir::UserProvided, |
| } |
| } |
| |
| fn lower_trait_bound_modifier(&mut self, f: TraitBoundModifier) -> hir::TraitBoundModifier { |
| match f { |
| TraitBoundModifier::None => hir::TraitBoundModifier::None, |
| TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe, |
| } |
| } |
| |
| // Helper methods for building HIR. |
| |
| fn stmt(&mut self, span: Span, kind: hir::StmtKind<'hir>) -> hir::Stmt<'hir> { |
| hir::Stmt { span, kind, hir_id: self.next_id() } |
| } |
| |
| fn stmt_expr(&mut self, span: Span, expr: hir::Expr<'hir>) -> hir::Stmt<'hir> { |
| self.stmt(span, hir::StmtKind::Expr(self.arena.alloc(expr))) |
| } |
| |
| fn stmt_let_pat( |
| &mut self, |
| attrs: AttrVec, |
| span: Span, |
| init: Option<&'hir hir::Expr<'hir>>, |
| pat: &'hir hir::Pat<'hir>, |
| source: hir::LocalSource, |
| ) -> hir::Stmt<'hir> { |
| let local = hir::Local { attrs, hir_id: self.next_id(), init, pat, source, span, ty: None }; |
| self.stmt(span, hir::StmtKind::Local(self.arena.alloc(local))) |
| } |
| |
| fn block_expr(&mut self, expr: &'hir hir::Expr<'hir>) -> &'hir hir::Block<'hir> { |
| self.block_all(expr.span, &[], Some(expr)) |
| } |
| |
| fn block_all( |
| &mut self, |
| span: Span, |
| stmts: &'hir [hir::Stmt<'hir>], |
| expr: Option<&'hir hir::Expr<'hir>>, |
| ) -> &'hir hir::Block<'hir> { |
| let blk = hir::Block { |
| stmts, |
| expr, |
| hir_id: self.next_id(), |
| rules: hir::DefaultBlock, |
| span, |
| targeted_by_break: false, |
| }; |
| self.arena.alloc(blk) |
| } |
| |
| /// Constructs a `true` or `false` literal pattern. |
| fn pat_bool(&mut self, span: Span, val: bool) -> &'hir hir::Pat<'hir> { |
| let expr = self.expr_bool(span, val); |
| self.pat(span, hir::PatKind::Lit(expr)) |
| } |
| |
| fn pat_ok(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> { |
| self.pat_std_enum(span, &[sym::result, sym::Result, sym::Ok], arena_vec![self; pat]) |
| } |
| |
| fn pat_err(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> { |
| self.pat_std_enum(span, &[sym::result, sym::Result, sym::Err], arena_vec![self; pat]) |
| } |
| |
| fn pat_some(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> { |
| self.pat_std_enum(span, &[sym::option, sym::Option, sym::Some], arena_vec![self; pat]) |
| } |
| |
| fn pat_none(&mut self, span: Span) -> &'hir hir::Pat<'hir> { |
| self.pat_std_enum(span, &[sym::option, sym::Option, sym::None], &[]) |
| } |
| |
| fn pat_std_enum( |
| &mut self, |
| span: Span, |
| components: &[Symbol], |
| subpats: &'hir [&'hir hir::Pat<'hir>], |
| ) -> &'hir hir::Pat<'hir> { |
| let path = self.std_path(span, components, None, true); |
| let qpath = hir::QPath::Resolved(None, path); |
| let pt = if subpats.is_empty() { |
| hir::PatKind::Path(qpath) |
| } else { |
| hir::PatKind::TupleStruct(qpath, subpats, None) |
| }; |
| self.pat(span, pt) |
| } |
| |
| fn pat_ident(&mut self, span: Span, ident: Ident) -> (&'hir hir::Pat<'hir>, hir::HirId) { |
| self.pat_ident_binding_mode(span, ident, hir::BindingAnnotation::Unannotated) |
| } |
| |
| fn pat_ident_binding_mode( |
| &mut self, |
| span: Span, |
| ident: Ident, |
| bm: hir::BindingAnnotation, |
| ) -> (&'hir hir::Pat<'hir>, hir::HirId) { |
| let hir_id = self.next_id(); |
| |
| ( |
| self.arena.alloc(hir::Pat { |
| hir_id, |
| kind: hir::PatKind::Binding(bm, hir_id, ident.with_span_pos(span), None), |
| span, |
| }), |
| hir_id, |
| ) |
| } |
| |
| fn pat_wild(&mut self, span: Span) -> &'hir hir::Pat<'hir> { |
| self.pat(span, hir::PatKind::Wild) |
| } |
| |
| fn pat(&mut self, span: Span, kind: hir::PatKind<'hir>) -> &'hir hir::Pat<'hir> { |
| self.arena.alloc(hir::Pat { hir_id: self.next_id(), kind, span }) |
| } |
| |
| /// Given a suffix `["b", "c", "d"]`, returns path `::std::b::c::d` when |
| /// `fld.cx.use_std`, and `::core::b::c::d` otherwise. |
| /// The path is also resolved according to `is_value`. |
| fn std_path( |
| &mut self, |
| span: Span, |
| components: &[Symbol], |
| params: Option<&'hir hir::GenericArgs<'hir>>, |
| is_value: bool, |
| ) -> &'hir hir::Path<'hir> { |
| let ns = if is_value { Namespace::ValueNS } else { Namespace::TypeNS }; |
| let (path, res) = self.resolver.resolve_str_path(span, self.crate_root, components, ns); |
| |
| let mut segments: Vec<_> = path |
| .segments |
| .iter() |
| .map(|segment| { |
| let res = self.expect_full_res(segment.id); |
| hir::PathSegment { |
| ident: segment.ident, |
| hir_id: Some(self.lower_node_id(segment.id)), |
| res: Some(self.lower_res(res)), |
| infer_args: true, |
| args: None, |
| } |
| }) |
| .collect(); |
| segments.last_mut().unwrap().args = params; |
| |
| self.arena.alloc(hir::Path { |
| span, |
| res: res.map_id(|_| panic!("unexpected `NodeId`")), |
| segments: self.arena.alloc_from_iter(segments), |
| }) |
| } |
| |
| fn ty_path( |
| &mut self, |
| mut hir_id: hir::HirId, |
| span: Span, |
| qpath: hir::QPath<'hir>, |
| ) -> hir::Ty<'hir> { |
| let kind = match qpath { |
| hir::QPath::Resolved(None, path) => { |
| // Turn trait object paths into `TyKind::TraitObject` instead. |
| match path.res { |
| Res::Def(DefKind::Trait, _) | Res::Def(DefKind::TraitAlias, _) => { |
| let principal = hir::PolyTraitRef { |
| bound_generic_params: &[], |
| trait_ref: hir::TraitRef { path, hir_ref_id: hir_id }, |
| span, |
| }; |
| |
| // The original ID is taken by the `PolyTraitRef`, |
| // so the `Ty` itself needs a different one. |
| hir_id = self.next_id(); |
| hir::TyKind::TraitObject( |
| arena_vec![self; principal], |
| self.elided_dyn_bound(span), |
| ) |
| } |
| _ => hir::TyKind::Path(hir::QPath::Resolved(None, path)), |
| } |
| } |
| _ => hir::TyKind::Path(qpath), |
| }; |
| |
| hir::Ty { hir_id, kind, span } |
| } |
| |
| /// Invoked to create the lifetime argument for a type `&T` |
| /// with no explicit lifetime. |
| fn elided_ref_lifetime(&mut self, span: Span) -> hir::Lifetime { |
| match self.anonymous_lifetime_mode { |
| // Intercept when we are in an impl header or async fn and introduce an in-band |
| // lifetime. |
| // Hence `impl Foo for &u32` becomes `impl<'f> Foo for &'f u32` for some fresh |
| // `'f`. |
| AnonymousLifetimeMode::CreateParameter => { |
| let fresh_name = self.collect_fresh_in_band_lifetime(span); |
| hir::Lifetime { |
| hir_id: self.next_id(), |
| span, |
| name: hir::LifetimeName::Param(fresh_name), |
| } |
| } |
| |
| AnonymousLifetimeMode::ReportError => self.new_error_lifetime(None, span), |
| |
| AnonymousLifetimeMode::PassThrough => self.new_implicit_lifetime(span), |
| } |
| } |
| |
| /// Report an error on illegal use of `'_` or a `&T` with no explicit lifetime; |
| /// return a "error lifetime". |
| fn new_error_lifetime(&mut self, id: Option<NodeId>, span: Span) -> hir::Lifetime { |
| let (id, msg, label) = match id { |
| Some(id) => (id, "`'_` cannot be used here", "`'_` is a reserved lifetime name"), |
| |
| None => ( |
| self.resolver.next_node_id(), |
| "`&` without an explicit lifetime name cannot be used here", |
| "explicit lifetime name needed here", |
| ), |
| }; |
| |
| let mut err = struct_span_err!(self.sess, span, E0637, "{}", msg,); |
| err.span_label(span, label); |
| err.emit(); |
| |
| self.new_named_lifetime(id, span, hir::LifetimeName::Error) |
| } |
| |
| /// Invoked to create the lifetime argument(s) for a path like |
| /// `std::cell::Ref<T>`; note that implicit lifetimes in these |
| /// sorts of cases are deprecated. This may therefore report a warning or an |
| /// error, depending on the mode. |
| fn elided_path_lifetimes<'s>( |
| &'s mut self, |
| span: Span, |
| count: usize, |
| ) -> impl Iterator<Item = hir::Lifetime> + Captures<'a> + Captures<'s> + Captures<'hir> { |
| (0..count).map(move |_| self.elided_path_lifetime(span)) |
| } |
| |
| fn elided_path_lifetime(&mut self, span: Span) -> hir::Lifetime { |
| match self.anonymous_lifetime_mode { |
| AnonymousLifetimeMode::CreateParameter => { |
| // We should have emitted E0726 when processing this path above |
| self.sess |
| .delay_span_bug(span, "expected 'implicit elided lifetime not allowed' error"); |
| let id = self.resolver.next_node_id(); |
| self.new_named_lifetime(id, span, hir::LifetimeName::Error) |
| } |
| // `PassThrough` is the normal case. |
| // `new_error_lifetime`, which would usually be used in the case of `ReportError`, |
| // is unsuitable here, as these can occur from missing lifetime parameters in a |
| // `PathSegment`, for which there is no associated `'_` or `&T` with no explicit |
| // lifetime. Instead, we simply create an implicit lifetime, which will be checked |
| // later, at which point a suitable error will be emitted. |
| AnonymousLifetimeMode::PassThrough | AnonymousLifetimeMode::ReportError => { |
| self.new_implicit_lifetime(span) |
| } |
| } |
| } |
| |
| /// Invoked to create the lifetime argument(s) for an elided trait object |
| /// bound, like the bound in `Box<dyn Debug>`. This method is not invoked |
| /// when the bound is written, even if it is written with `'_` like in |
| /// `Box<dyn Debug + '_>`. In those cases, `lower_lifetime` is invoked. |
| fn elided_dyn_bound(&mut self, span: Span) -> hir::Lifetime { |
| match self.anonymous_lifetime_mode { |
| // NB. We intentionally ignore the create-parameter mode here. |
| // and instead "pass through" to resolve-lifetimes, which will apply |
| // the object-lifetime-defaulting rules. Elided object lifetime defaults |
| // do not act like other elided lifetimes. In other words, given this: |
| // |
| // impl Foo for Box<dyn Debug> |
| // |
| // we do not introduce a fresh `'_` to serve as the bound, but instead |
| // ultimately translate to the equivalent of: |
| // |
| // impl Foo for Box<dyn Debug + 'static> |
| // |
| // `resolve_lifetime` has the code to make that happen. |
| AnonymousLifetimeMode::CreateParameter => {} |
| |
| AnonymousLifetimeMode::ReportError => { |
| // ReportError applies to explicit use of `'_`. |
| } |
| |
| // This is the normal case. |
| AnonymousLifetimeMode::PassThrough => {} |
| } |
| |
| let r = hir::Lifetime { |
| hir_id: self.next_id(), |
| span, |
| name: hir::LifetimeName::ImplicitObjectLifetimeDefault, |
| }; |
| debug!("elided_dyn_bound: r={:?}", r); |
| r |
| } |
| |
| fn new_implicit_lifetime(&mut self, span: Span) -> hir::Lifetime { |
| hir::Lifetime { hir_id: self.next_id(), span, name: hir::LifetimeName::Implicit } |
| } |
| |
| fn maybe_lint_bare_trait(&mut self, span: Span, id: NodeId, is_global: bool) { |
| // FIXME(davidtwco): This is a hack to detect macros which produce spans of the |
| // call site which do not have a macro backtrace. See #61963. |
| let is_macro_callsite = self |
| .sess |
| .source_map() |
| .span_to_snippet(span) |
| .map(|snippet| snippet.starts_with("#[")) |
| .unwrap_or(true); |
| if !is_macro_callsite { |
| self.resolver.lint_buffer().buffer_lint_with_diagnostic( |
| builtin::BARE_TRAIT_OBJECTS, |
| id, |
| span, |
| "trait objects without an explicit `dyn` are deprecated", |
| builtin::BuiltinLintDiagnostics::BareTraitObject(span, is_global), |
| ) |
| } |
| } |
| } |
| |
| fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body<'_>>) -> Vec<hir::BodyId> { |
| // Sorting by span ensures that we get things in order within a |
| // file, and also puts the files in a sensible order. |
| let mut body_ids: Vec<_> = bodies.keys().cloned().collect(); |
| body_ids.sort_by_key(|b| bodies[b].value.span); |
| body_ids |
| } |
| |
| /// Helper struct for delayed construction of GenericArgs. |
| struct GenericArgsCtor<'hir> { |
| args: SmallVec<[hir::GenericArg<'hir>; 4]>, |
| bindings: &'hir [hir::TypeBinding<'hir>], |
| parenthesized: bool, |
| } |
| |
| impl<'hir> GenericArgsCtor<'hir> { |
| fn is_empty(&self) -> bool { |
| self.args.is_empty() && self.bindings.is_empty() && !self.parenthesized |
| } |
| |
| fn into_generic_args(self, arena: &'hir Arena<'hir>) -> hir::GenericArgs<'hir> { |
| hir::GenericArgs { |
| args: arena.alloc_from_iter(self.args), |
| bindings: self.bindings, |
| parenthesized: self.parenthesized, |
| } |
| } |
| } |