| //! 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. |
| |
| use dep_graph::DepGraph; |
| use hir::{self, ParamName}; |
| use hir::HirVec; |
| use hir::map::{DefKey, DefPathData, Definitions}; |
| use hir::def_id::{DefId, DefIndex, DefIndexAddressSpace, CRATE_DEF_INDEX}; |
| use hir::def::{Def, PathResolution, PerNS}; |
| use hir::GenericArg; |
| use lint::builtin::{self, PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES, |
| ELIDED_LIFETIMES_IN_PATHS}; |
| use middle::cstore::CrateStore; |
| use rustc_data_structures::fx::FxHashSet; |
| use rustc_data_structures::indexed_vec::IndexVec; |
| use rustc_data_structures::thin_vec::ThinVec; |
| use session::Session; |
| use session::config::nightly_options; |
| use util::common::FN_OUTPUT_NAME; |
| use util::nodemap::{DefIdMap, NodeMap}; |
| |
| use std::collections::{BTreeSet, BTreeMap}; |
| use std::fmt::Debug; |
| use std::mem; |
| use smallvec::SmallVec; |
| use syntax::attr; |
| use syntax::ast; |
| use syntax::ast::*; |
| use syntax::errors; |
| use syntax::ext::hygiene::{Mark, SyntaxContext}; |
| use syntax::print::pprust; |
| use syntax::ptr::P; |
| use syntax::source_map::{self, respan, CompilerDesugaringKind, Spanned}; |
| use syntax::std_inject; |
| use syntax::symbol::{keywords, Symbol}; |
| use syntax::tokenstream::{TokenStream, TokenTree}; |
| use syntax::parse::token::Token; |
| use syntax::visit::{self, Visitor}; |
| use syntax_pos::{Span, MultiSpan}; |
| |
| const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF; |
| |
| pub struct LoweringContext<'a> { |
| crate_root: Option<&'static str>, |
| |
| // Used to assign ids to HIR nodes that do not directly correspond to an AST node. |
| sess: &'a Session, |
| |
| cstore: &'a dyn CrateStore, |
| |
| resolver: &'a mut dyn Resolver, |
| |
| /// The items being lowered are collected here. |
| items: BTreeMap<NodeId, hir::Item>, |
| |
| trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem>, |
| impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem>, |
| bodies: BTreeMap<hir::BodyId, hir::Body>, |
| exported_macros: Vec<hir::MacroDef>, |
| |
| trait_impls: BTreeMap<DefId, Vec<NodeId>>, |
| trait_auto_impl: BTreeMap<DefId, NodeId>, |
| |
| modules: BTreeMap<NodeId, hir::ModuleItems>, |
| |
| is_generator: bool, |
| |
| catch_scopes: Vec<NodeId>, |
| loop_scopes: Vec<NodeId>, |
| is_in_loop_condition: bool, |
| is_in_trait_impl: 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)>, |
| |
| // Whether or not 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. |
| in_scope_lifetimes: Vec<Ident>, |
| |
| current_module: NodeId, |
| |
| 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>, |
| } |
| |
| pub trait Resolver { |
| /// Resolve a path generated by the lowerer when expanding `for`, `if let`, etc. |
| fn resolve_hir_path( |
| &mut self, |
| path: &ast::Path, |
| is_value: bool, |
| ) -> hir::Path; |
| |
| /// Obtain the resolution for a node-id. |
| fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution>; |
| |
| /// Obtain the possible resolutions for the given `use` statement. |
| fn get_import(&mut self, id: NodeId) -> PerNS<Option<PathResolution>>; |
| |
| /// 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 a HIR 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<&str>, |
| components: &[&str], |
| is_value: bool, |
| ) -> hir::Path; |
| } |
| |
| #[derive(Debug)] |
| enum ImplTraitContext<'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(&'a mut Vec<hir::GenericParam>), |
| |
| /// Treat `impl Trait` as shorthand for a new existential parameter. |
| /// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually |
| /// equivalent to a fresh existential parameter like `existential type T; 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. |
| Existential(Option<DefId>), |
| |
| /// `impl Trait` is not accepted in this position. |
| Disallowed(ImplTraitPosition), |
| } |
| |
| /// Position in which `impl Trait` is disallowed. Used for error reporting. |
| #[derive(Debug, Copy, Clone, PartialEq, Eq)] |
| enum ImplTraitPosition { |
| Binding, |
| Other, |
| } |
| |
| impl<'a> ImplTraitContext<'a> { |
| #[inline] |
| fn disallowed() -> Self { |
| ImplTraitContext::Disallowed(ImplTraitPosition::Other) |
| } |
| |
| fn reborrow(&'b mut self) -> ImplTraitContext<'b> { |
| use self::ImplTraitContext::*; |
| match self { |
| Universal(params) => Universal(params), |
| Existential(did) => Existential(*did), |
| Disallowed(pos) => Disallowed(*pos), |
| } |
| } |
| } |
| |
| pub fn lower_crate( |
| sess: &Session, |
| cstore: &dyn CrateStore, |
| dep_graph: &DepGraph, |
| krate: &Crate, |
| resolver: &mut dyn Resolver, |
| ) -> hir::Crate { |
| // 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(); |
| |
| LoweringContext { |
| crate_root: std_inject::injected_crate_name(), |
| sess, |
| cstore, |
| resolver, |
| items: BTreeMap::new(), |
| trait_items: BTreeMap::new(), |
| impl_items: BTreeMap::new(), |
| bodies: BTreeMap::new(), |
| trait_impls: BTreeMap::new(), |
| trait_auto_impl: BTreeMap::new(), |
| modules: BTreeMap::new(), |
| exported_macros: Vec::new(), |
| catch_scopes: Vec::new(), |
| loop_scopes: Vec::new(), |
| is_in_loop_condition: false, |
| anonymous_lifetime_mode: AnonymousLifetimeMode::PassThrough, |
| type_def_lifetime_params: Default::default(), |
| current_module: CRATE_NODE_ID, |
| current_hir_id_owner: vec![(CRATE_DEF_INDEX, 0)], |
| item_local_id_counters: Default::default(), |
| node_id_to_hir_id: IndexVec::new(), |
| is_generator: false, |
| is_in_trait_impl: false, |
| lifetimes_to_define: Vec::new(), |
| is_collecting_in_band_lifetimes: false, |
| in_scope_lifetimes: Vec::new(), |
| }.lower_crate(krate) |
| } |
| |
| #[derive(Copy, Clone, PartialEq)] |
| enum ParamMode { |
| /// Any path in a type context. |
| Explicit, |
| /// The `module::Type` in `module::Type::method` in an expression. |
| Optional, |
| } |
| |
| #[derive(Debug)] |
| struct LoweredNodeId { |
| node_id: NodeId, |
| hir_id: hir::HirId, |
| } |
| |
| enum ParenthesizedGenericArgs { |
| Ok, |
| Warn, |
| 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)] |
| 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<[hir::ItemId; 1]> } |
| |
| impl<'a, 'b> Visitor<'a> for ImplTraitTypeIdVisitor<'b> { |
| fn visit_ty(&mut self, ty: &'a Ty) { |
| match ty.node { |
| | TyKind::Typeof(_) |
| | TyKind::BareFn(_) |
| => return, |
| |
| TyKind::ImplTrait(id, _) => self.ids.push(hir::ItemId { id }), |
| _ => {}, |
| } |
| visit::walk_ty(self, ty); |
| } |
| |
| fn visit_path_segment( |
| &mut self, |
| path_span: Span, |
| path_segment: &'v 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> LoweringContext<'a> { |
| fn lower_crate(mut self, c: &Crate) -> hir::Crate { |
| /// 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<'lcx, 'interner: 'lcx> { |
| lctx: &'lcx mut LoweringContext<'interner>, |
| } |
| |
| impl<'lcx, 'interner> Visitor<'lcx> for MiscCollector<'lcx, 'interner> { |
| fn visit_item(&mut self, item: &'lcx Item) { |
| self.lctx.allocate_hir_id_counter(item.id, item); |
| |
| match item.node { |
| ItemKind::Struct(_, ref generics) |
| | ItemKind::Union(_, ref generics) |
| | ItemKind::Enum(_, ref generics) |
| | ItemKind::Ty(_, ref generics) |
| | ItemKind::Existential(_, 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); |
| } |
| _ => {} |
| } |
| visit::walk_item(self, item); |
| } |
| |
| fn visit_trait_item(&mut self, item: &'lcx TraitItem) { |
| self.lctx.allocate_hir_id_counter(item.id, item); |
| visit::walk_trait_item(self, item); |
| } |
| |
| fn visit_impl_item(&mut self, item: &'lcx ImplItem) { |
| self.lctx.allocate_hir_id_counter(item.id, item); |
| visit::walk_impl_item(self, item); |
| } |
| } |
| |
| struct ItemLowerer<'lcx, 'interner: 'lcx> { |
| lctx: &'lcx mut LoweringContext<'interner>, |
| } |
| |
| impl<'lcx, 'interner> ItemLowerer<'lcx, 'interner> { |
| fn with_trait_impl_ref<F>(&mut self, trait_impl_ref: &Option<TraitRef>, f: F) |
| where |
| F: FnOnce(&mut Self), |
| { |
| let old = self.lctx.is_in_trait_impl; |
| self.lctx.is_in_trait_impl = if let &None = trait_impl_ref { |
| false |
| } else { |
| true |
| }; |
| f(self); |
| self.lctx.is_in_trait_impl = old; |
| } |
| } |
| |
| impl<'lcx, 'interner> Visitor<'lcx> for ItemLowerer<'lcx, 'interner> { |
| fn visit_mod(&mut self, m: &'lcx Mod, _s: Span, _attrs: &[Attribute], n: NodeId) { |
| self.lctx.modules.insert(n, hir::ModuleItems { |
| items: BTreeSet::new(), |
| trait_items: BTreeSet::new(), |
| impl_items: BTreeSet::new(), |
| }); |
| |
| let old = self.lctx.current_module; |
| self.lctx.current_module = n; |
| visit::walk_mod(self, m); |
| self.lctx.current_module = old; |
| } |
| |
| fn visit_item(&mut self, item: &'lcx Item) { |
| let mut item_lowered = true; |
| self.lctx.with_hir_id_owner(item.id, |lctx| { |
| if let Some(hir_item) = lctx.lower_item(item) { |
| lctx.insert_item(item.id, hir_item); |
| } else { |
| item_lowered = false; |
| } |
| }); |
| |
| if item_lowered { |
| let item_generics = match self.lctx.items.get(&item.id).unwrap().node { |
| hir::ItemKind::Impl(_, _, _, ref generics, ..) |
| | hir::ItemKind::Trait(_, _, ref generics, ..) => { |
| generics.params.clone() |
| } |
| _ => HirVec::new(), |
| }; |
| |
| self.lctx.with_parent_impl_lifetime_defs(&item_generics, |this| { |
| let this = &mut ItemLowerer { lctx: this }; |
| if let ItemKind::Impl(.., ref opt_trait_ref, _, _) = item.node { |
| this.with_trait_impl_ref(opt_trait_ref, |this| { |
| visit::walk_item(this, item) |
| }); |
| } else { |
| visit::walk_item(this, item); |
| } |
| }); |
| } |
| } |
| |
| fn visit_trait_item(&mut self, item: &'lcx TraitItem) { |
| self.lctx.with_hir_id_owner(item.id, |lctx| { |
| let id = hir::TraitItemId { node_id: item.id }; |
| let hir_item = lctx.lower_trait_item(item); |
| lctx.trait_items.insert(id, hir_item); |
| lctx.modules.get_mut(&lctx.current_module).unwrap().trait_items.insert(id); |
| }); |
| |
| visit::walk_trait_item(self, item); |
| } |
| |
| fn visit_impl_item(&mut self, item: &'lcx ImplItem) { |
| self.lctx.with_hir_id_owner(item.id, |lctx| { |
| let id = hir::ImplItemId { node_id: item.id }; |
| let hir_item = lctx.lower_impl_item(item); |
| lctx.impl_items.insert(id, hir_item); |
| lctx.modules.get_mut(&lctx.current_module).unwrap().impl_items.insert(id); |
| }); |
| visit::walk_impl_item(self, item); |
| } |
| } |
| |
| 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 }, c); |
| visit::walk_crate(&mut 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: hir::HirVec::from(self.exported_macros), |
| items: self.items, |
| trait_items: self.trait_items, |
| impl_items: self.impl_items, |
| bodies: self.bodies, |
| body_ids, |
| trait_impls: self.trait_impls, |
| trait_auto_impl: self.trait_auto_impl, |
| modules: self.modules, |
| } |
| } |
| |
| fn insert_item(&mut self, id: NodeId, item: hir::Item) { |
| self.items.insert(id, item); |
| self.modules.get_mut(&self.current_module).unwrap().items.insert(id); |
| } |
| |
| fn allocate_hir_id_counter<T: Debug>(&mut self, owner: NodeId, debug: &T) -> LoweredNodeId { |
| if self.item_local_id_counters.insert(owner, 0).is_some() { |
| bug!( |
| "Tried to allocate item_local_id_counter for {:?} twice", |
| debug |
| ); |
| } |
| // Always allocate the first `HirId` for the owner itself. |
| self.lower_node_id_with_owner(owner, owner) |
| } |
| |
| fn lower_node_id_generic<F>(&mut self, ast_node_id: NodeId, alloc_hir_id: F) -> LoweredNodeId |
| where |
| F: FnOnce(&mut Self) -> hir::HirId, |
| { |
| if ast_node_id == DUMMY_NODE_ID { |
| return LoweredNodeId { |
| node_id: DUMMY_NODE_ID, |
| hir_id: 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; |
| LoweredNodeId { |
| node_id: ast_node_id, |
| hir_id, |
| } |
| } else { |
| LoweredNodeId { |
| node_id: ast_node_id, |
| hir_id: 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) -> LoweredNodeId { |
| 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) -> LoweredNodeId { |
| 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 record_body(&mut self, value: hir::Expr, decl: Option<&FnDecl>) -> hir::BodyId { |
| let body = hir::Body { |
| arguments: decl.map_or(hir_vec![], |decl| { |
| decl.inputs.iter().map(|x| self.lower_arg(x)).collect() |
| }), |
| is_generator: self.is_generator, |
| value, |
| }; |
| let id = body.id(); |
| self.bodies.insert(id, body); |
| id |
| } |
| |
| fn next_id(&mut self) -> LoweredNodeId { |
| self.lower_node_id(self.sess.next_node_id()) |
| } |
| |
| fn expect_full_def(&mut self, id: NodeId) -> Def { |
| self.resolver.get_resolution(id).map_or(Def::Err, |pr| { |
| if pr.unresolved_segments() != 0 { |
| bug!("path not fully resolved: {:?}", pr); |
| } |
| pr.base_def() |
| }) |
| } |
| |
| fn expect_full_def_from_use(&mut self, id: NodeId) -> impl Iterator<Item = Def> { |
| self.resolver.get_import(id).present_items().map(|pr| { |
| if pr.unresolved_segments() != 0 { |
| bug!("path not fully resolved: {:?}", pr); |
| } |
| pr.base_def() |
| }) |
| } |
| |
| fn diagnostic(&self) -> &errors::Handler { |
| self.sess.diagnostic() |
| } |
| |
| fn str_to_ident(&self, s: &'static str) -> Ident { |
| Ident::with_empty_ctxt(Symbol::gensym(s)) |
| } |
| |
| fn allow_internal_unstable(&self, reason: CompilerDesugaringKind, span: Span) -> Span { |
| let mark = Mark::fresh(Mark::root()); |
| mark.set_expn_info(source_map::ExpnInfo { |
| call_site: span, |
| def_site: Some(span), |
| format: source_map::CompilerDesugaring(reason), |
| allow_internal_unstable: true, |
| allow_internal_unsafe: false, |
| local_inner_macros: false, |
| edition: source_map::hygiene::default_edition(), |
| }); |
| span.with_ctxt(SyntaxContext::empty().apply_mark(mark)) |
| } |
| |
| fn with_anonymous_lifetime_mode<R>( |
| &mut self, |
| anonymous_lifetime_mode: AnonymousLifetimeMode, |
| op: impl FnOnce(&mut Self) -> R, |
| ) -> R { |
| 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; |
| 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 |
| /// argument 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>, T) |
| where |
| F: FnOnce(&mut LoweringContext<'_>) -> (Vec<hir::GenericParam>, 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)| { |
| let def_node_id = self.next_id().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.as_interned_str(), |
| hir::LifetimeParamKind::InBand, |
| ), |
| ParamName::Fresh(_) => ( |
| keywords::UnderscoreLifetime.name().as_interned_str(), |
| hir::LifetimeParamKind::Elided, |
| ), |
| ParamName::Error => ( |
| keywords::UnderscoreLifetime.name().as_interned_str(), |
| hir::LifetimeParamKind::Error, |
| ), |
| }; |
| |
| // Add a definition for the in-band lifetime def. |
| self.resolver.definitions().create_def_with_parent( |
| parent_id.index, |
| def_node_id, |
| DefPathData::LifetimeParam(str_name), |
| DefIndexAddressSpace::High, |
| Mark::root(), |
| span, |
| ); |
| |
| hir::GenericParam { |
| id: def_node_id, |
| name: hir_name, |
| attrs: hir_vec![], |
| bounds: hir_vec![], |
| span, |
| pure_wrt_drop: false, |
| kind: hir::GenericParamKind::Lifetime { kind } |
| } |
| }) |
| .chain(in_band_ty_params.into_iter()) |
| .collect(); |
| |
| (params, res) |
| } |
| |
| /// 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(&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(); |
| 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 LoweringContext<'_>) -> T, |
| { |
| let old_len = self.in_scope_lifetimes.len(); |
| let lt_def_names = params.iter().filter_map(|param| match param.kind { |
| GenericParamKind::Lifetime { .. } => Some(param.ident.modern()), |
| _ => None, |
| }); |
| self.in_scope_lifetimes.extend(lt_def_names); |
| |
| let res = f(self); |
| |
| self.in_scope_lifetimes.truncate(old_len); |
| res |
| } |
| |
| // Same as the method above, but accepts `hir::GenericParam`s |
| // instead of `ast::GenericParam`s. |
| // This should only be used with generics that have already had their |
| // in-band lifetimes added. In practice, this means that this function is |
| // only used when lowering a child item of a trait or impl. |
| fn with_parent_impl_lifetime_defs<T, F>(&mut self, |
| params: &HirVec<hir::GenericParam>, |
| f: F |
| ) -> T where |
| F: FnOnce(&mut LoweringContext<'_>) -> T, |
| { |
| let old_len = self.in_scope_lifetimes.len(); |
| let lt_def_names = params.iter().filter_map(|param| match param.kind { |
| hir::GenericParamKind::Lifetime { .. } => Some(param.name.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 |
| /// argument 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, T) |
| where |
| F: FnOnce(&mut LoweringContext<'_>, &mut Vec<hir::GenericParam>) -> 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(); |
| let generics = this.lower_generics( |
| generics, |
| ImplTraitContext::Universal(&mut params), |
| ); |
| let res = f(this, &mut params); |
| (params, (generics, res)) |
| }) |
| }, |
| ); |
| |
| lowered_generics.params = lowered_generics |
| .params |
| .iter() |
| .cloned() |
| .chain(in_band_defs) |
| .collect(); |
| |
| (lowered_generics, res) |
| } |
| |
| fn with_catch_scope<T, F>(&mut self, catch_id: NodeId, f: F) -> T |
| where |
| F: FnOnce(&mut LoweringContext<'_>) -> T, |
| { |
| let len = self.catch_scopes.len(); |
| self.catch_scopes.push(catch_id); |
| |
| let result = f(self); |
| assert_eq!( |
| len + 1, |
| self.catch_scopes.len(), |
| "catch scopes should be added and removed in stack order" |
| ); |
| |
| self.catch_scopes.pop().unwrap(); |
| |
| result |
| } |
| |
| fn make_async_expr( |
| &mut self, |
| capture_clause: CaptureBy, |
| closure_node_id: NodeId, |
| ret_ty: Option<&Ty>, |
| body: impl FnOnce(&mut LoweringContext<'_>) -> hir::Expr, |
| ) -> hir::ExprKind { |
| let prev_is_generator = mem::replace(&mut self.is_generator, true); |
| let body_expr = body(self); |
| let span = body_expr.span; |
| let output = match ret_ty { |
| Some(ty) => FunctionRetTy::Ty(P(ty.clone())), |
| None => FunctionRetTy::Default(span), |
| }; |
| let decl = FnDecl { |
| inputs: vec![], |
| output, |
| variadic: false |
| }; |
| let body_id = self.record_body(body_expr, Some(&decl)); |
| self.is_generator = prev_is_generator; |
| |
| let capture_clause = self.lower_capture_clause(capture_clause); |
| let closure_hir_id = self.lower_node_id(closure_node_id).hir_id; |
| let decl = self.lower_fn_decl(&decl, None, /* impl trait allowed */ false, None); |
| let generator = hir::Expr { |
| id: closure_node_id, |
| hir_id: closure_hir_id, |
| node: hir::ExprKind::Closure(capture_clause, decl, body_id, span, |
| Some(hir::GeneratorMovability::Static)), |
| span, |
| attrs: ThinVec::new(), |
| }; |
| |
| let unstable_span = self.allow_internal_unstable(CompilerDesugaringKind::Async, span); |
| let gen_future = self.expr_std_path( |
| unstable_span, &["future", "from_generator"], None, ThinVec::new()); |
| hir::ExprKind::Call(P(gen_future), hir_vec![generator]) |
| } |
| |
| fn lower_body<F>(&mut self, decl: Option<&FnDecl>, f: F) -> hir::BodyId |
| where |
| F: FnOnce(&mut LoweringContext<'_>) -> hir::Expr, |
| { |
| let prev = mem::replace(&mut self.is_generator, false); |
| let result = f(self); |
| let r = self.record_body(result, decl); |
| self.is_generator = prev; |
| return r; |
| } |
| |
| fn with_loop_scope<T, F>(&mut self, loop_id: NodeId, f: F) -> T |
| where |
| F: FnOnce(&mut LoweringContext<'_>) -> T, |
| { |
| // We're no longer in the base loop's condition; we're in another loop. |
| let was_in_loop_condition = self.is_in_loop_condition; |
| self.is_in_loop_condition = false; |
| |
| let len = self.loop_scopes.len(); |
| self.loop_scopes.push(loop_id); |
| |
| let result = f(self); |
| assert_eq!( |
| len + 1, |
| self.loop_scopes.len(), |
| "Loop scopes should be added and removed in stack order" |
| ); |
| |
| self.loop_scopes.pop().unwrap(); |
| |
| self.is_in_loop_condition = was_in_loop_condition; |
| |
| result |
| } |
| |
| fn with_loop_condition_scope<T, F>(&mut self, f: F) -> T |
| where |
| F: FnOnce(&mut LoweringContext<'_>) -> T, |
| { |
| let was_in_loop_condition = self.is_in_loop_condition; |
| self.is_in_loop_condition = true; |
| |
| let result = f(self); |
| |
| self.is_in_loop_condition = was_in_loop_condition; |
| |
| result |
| } |
| |
| fn with_new_scopes<T, F>(&mut self, f: F) -> T |
| where |
| F: FnOnce(&mut LoweringContext<'_>) -> T, |
| { |
| let was_in_loop_condition = self.is_in_loop_condition; |
| self.is_in_loop_condition = false; |
| |
| let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new()); |
| let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new()); |
| 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.cstore.def_key(id) |
| } |
| } |
| |
| fn lower_label(&mut self, label: Option<Label>) -> Option<hir::Label> { |
| label.map(|label| hir::Label { |
| ident: label.ident, |
| }) |
| } |
| |
| fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination { |
| let target_id = match destination { |
| Some((id, _)) => { |
| if let Def::Label(loop_id) = self.expect_full_def(id) { |
| Ok(self.lower_node_id(loop_id).node_id) |
| } else { |
| Err(hir::LoopIdError::UnresolvedLabel) |
| } |
| } |
| None => { |
| self.loop_scopes |
| .last() |
| .cloned() |
| .map(|id| Ok(self.lower_node_id(id).node_id)) |
| .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope)) |
| .into() |
| } |
| }; |
| hir::Destination { |
| label: self.lower_label(destination.map(|(_, label)| label)), |
| target_id, |
| } |
| } |
| |
| fn lower_attrs(&mut self, attrs: &[Attribute]) -> hir::HirVec<Attribute> { |
| attrs |
| .iter() |
| .map(|a| self.lower_attr(a)) |
| .collect() |
| } |
| |
| 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. |
| Attribute { |
| id: attr.id, |
| style: attr.style, |
| path: attr.path.clone(), |
| tokens: self.lower_token_stream(attr.tokens.clone()), |
| is_sugared_doc: attr.is_sugared_doc, |
| span: attr.span, |
| } |
| } |
| |
| 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(span, token) => self.lower_token(token, span), |
| TokenTree::Delimited(span, delim, tts) => TokenTree::Delimited( |
| span, |
| delim, |
| self.lower_token_stream(tts.into()).into(), |
| ).into(), |
| } |
| } |
| |
| fn lower_token(&mut self, token: Token, span: Span) -> TokenStream { |
| match token { |
| Token::Interpolated(_) => {} |
| other => return TokenTree::Token(span, other).into(), |
| } |
| |
| let tts = token.interpolated_to_tokenstream(&self.sess.parse_sess, span); |
| self.lower_token_stream(tts) |
| } |
| |
| fn lower_arm(&mut self, arm: &Arm) -> hir::Arm { |
| hir::Arm { |
| attrs: self.lower_attrs(&arm.attrs), |
| pats: arm.pats.iter().map(|x| self.lower_pat(x)).collect(), |
| guard: match arm.guard { |
| Some(Guard::If(ref x)) => Some(hir::Guard::If(P(self.lower_expr(x)))), |
| _ => None, |
| }, |
| body: P(self.lower_expr(&arm.body)), |
| } |
| } |
| |
| fn lower_ty_binding(&mut self, b: &TypeBinding, |
| itctx: ImplTraitContext<'_>) -> hir::TypeBinding { |
| hir::TypeBinding { |
| id: self.lower_node_id(b.id).node_id, |
| ident: b.ident, |
| ty: self.lower_ty(&b.ty, itctx), |
| span: b.span, |
| } |
| } |
| |
| fn lower_generic_arg(&mut self, |
| arg: &ast::GenericArg, |
| itctx: ImplTraitContext<'_>) |
| -> hir::GenericArg { |
| match arg { |
| ast::GenericArg::Lifetime(lt) => GenericArg::Lifetime(self.lower_lifetime(<)), |
| ast::GenericArg::Type(ty) => GenericArg::Type(self.lower_ty_direct(&ty, itctx)), |
| } |
| } |
| |
| fn lower_ty(&mut self, t: &Ty, itctx: ImplTraitContext<'_>) -> P<hir::Ty> { |
| P(self.lower_ty_direct(t, itctx)) |
| } |
| |
| fn lower_ty_direct(&mut self, t: &Ty, mut itctx: ImplTraitContext<'_>) -> hir::Ty { |
| let kind = match t.node { |
| 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(P(hir::BareFnTy { |
| generic_params: this.lower_generic_params( |
| &f.generic_params, |
| &NodeMap::default(), |
| ImplTraitContext::disallowed(), |
| ), |
| unsafety: this.lower_unsafety(f.unsafety), |
| abi: f.abi, |
| decl: this.lower_fn_decl(&f.decl, None, false, None), |
| arg_names: this.lower_fn_args_to_names(&f.decl), |
| })) |
| }, |
| ) |
| }, |
| ), |
| TyKind::Never => hir::TyKind::Never, |
| TyKind::Tup(ref tys) => { |
| hir::TyKind::Tup(tys.iter().map(|ty| { |
| self.lower_ty_direct(ty, itctx.reborrow()) |
| }).collect()) |
| } |
| TyKind::Paren(ref ty) => { |
| return self.lower_ty_direct(ty, itctx); |
| } |
| TyKind::Path(ref qself, ref path) => { |
| let id = self.lower_node_id(t.id); |
| let qpath = self.lower_qpath(t.id, qself, path, ParamMode::Explicit, itctx); |
| let ty = self.ty_path(id, t.span, qpath); |
| if let hir::TyKind::TraitObject(..) = ty.node { |
| self.maybe_lint_bare_trait(t.span, t.id, qself.is_none() && path.is_global()); |
| } |
| return ty; |
| } |
| TyKind::ImplicitSelf => hir::TyKind::Path(hir::QPath::Resolved( |
| None, |
| P(hir::Path { |
| def: self.expect_full_def(t.id), |
| segments: hir_vec![hir::PathSegment::from_ident(keywords::SelfUpper.ident())], |
| 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 = bounds |
| .iter() |
| .filter_map(|bound| match *bound { |
| GenericBound::Trait(ref ty, TraitBoundModifier::None) => { |
| Some(self.lower_poly_trait_ref(ty, itctx.reborrow())) |
| } |
| GenericBound::Trait(_, TraitBoundModifier::Maybe) => None, |
| GenericBound::Outlives(ref lifetime) => { |
| if lifetime_bound.is_none() { |
| lifetime_bound = Some(self.lower_lifetime(lifetime)); |
| } |
| None |
| } |
| }) |
| .collect(); |
| let lifetime_bound = |
| lifetime_bound.unwrap_or_else(|| self.elided_dyn_bound(t.span)); |
| 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::Existential(fn_def_id) => { |
| self.lower_existential_impl_trait( |
| span, fn_def_id, def_node_id, |
| |this| this.lower_param_bounds(bounds, itctx), |
| ) |
| } |
| ImplTraitContext::Universal(in_band_ty_params) => { |
| self.lower_node_id(def_node_id); |
| // 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(&pprust::ty_to_string(t)).with_span_pos(span); |
| in_band_ty_params.push(hir::GenericParam { |
| id: def_node_id, |
| name: ParamName::Plain(ident), |
| pure_wrt_drop: false, |
| attrs: hir_vec![], |
| bounds: hir_bounds, |
| span, |
| kind: hir::GenericParamKind::Type { |
| default: None, |
| synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), |
| } |
| }); |
| |
| hir::TyKind::Path(hir::QPath::Resolved( |
| None, |
| P(hir::Path { |
| span, |
| def: Def::TyParam(DefId::local(def_index)), |
| segments: hir_vec![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(_) => panic!("TyMac should have been expanded by now."), |
| }; |
| |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(t.id); |
| hir::Ty { |
| id: node_id, |
| node: kind, |
| span: t.span, |
| hir_id, |
| } |
| } |
| |
| fn lower_existential_impl_trait( |
| &mut self, |
| span: Span, |
| fn_def_id: Option<DefId>, |
| exist_ty_node_id: NodeId, |
| lower_bounds: impl FnOnce(&mut LoweringContext<'_>) -> hir::GenericBounds, |
| ) -> hir::TyKind { |
| // 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 exist_ty_span = self.allow_internal_unstable( |
| CompilerDesugaringKind::ExistentialReturnType, |
| span, |
| ); |
| |
| let exist_ty_def_index = self |
| .resolver |
| .definitions() |
| .opt_def_index(exist_ty_node_id) |
| .unwrap(); |
| |
| self.allocate_hir_id_counter(exist_ty_node_id, &"existential impl trait"); |
| |
| let hir_bounds = self.with_hir_id_owner(exist_ty_node_id, lower_bounds); |
| |
| let (lifetimes, lifetime_defs) = self.lifetimes_from_impl_trait_bounds( |
| exist_ty_node_id, |
| exist_ty_def_index, |
| &hir_bounds, |
| ); |
| |
| self.with_hir_id_owner(exist_ty_node_id, |lctx| { |
| let exist_ty_item_kind = hir::ItemKind::Existential(hir::ExistTy { |
| generics: hir::Generics { |
| params: lifetime_defs, |
| where_clause: hir::WhereClause { |
| id: lctx.next_id().node_id, |
| predicates: Vec::new().into(), |
| }, |
| span, |
| }, |
| bounds: hir_bounds, |
| impl_trait_fn: fn_def_id, |
| }); |
| let exist_ty_id = lctx.lower_node_id(exist_ty_node_id); |
| // Generate an `existential type Foo: Trait;` declaration. |
| trace!("creating existential type with id {:#?}", exist_ty_id); |
| |
| trace!("exist ty def index: {:#?}", exist_ty_def_index); |
| let exist_ty_item = hir::Item { |
| id: exist_ty_id.node_id, |
| hir_id: exist_ty_id.hir_id, |
| ident: keywords::Invalid.ident(), |
| attrs: Default::default(), |
| node: exist_ty_item_kind, |
| vis: respan(span.shrink_to_lo(), hir::VisibilityKind::Inherited), |
| span: exist_ty_span, |
| }; |
| |
| // Insert the item into the global list. This usually happens |
| // automatically for all AST items. But this existential type item |
| // does not actually exist in the AST. |
| lctx.insert_item(exist_ty_id.node_id, exist_ty_item); |
| |
| // `impl Trait` now just becomes `Foo<'a, 'b, ..>`. |
| hir::TyKind::Def(hir::ItemId { id: exist_ty_id.node_id }, lifetimes) |
| }) |
| } |
| |
| fn lifetimes_from_impl_trait_bounds( |
| &mut self, |
| exist_ty_id: NodeId, |
| parent_index: DefIndex, |
| bounds: &hir::GenericBounds, |
| ) -> (HirVec<hir::GenericArg>, HirVec<hir::GenericParam>) { |
| // This visitor walks over impl trait bounds and creates defs for all lifetimes which |
| // 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: 'r> { |
| context: &'r mut LoweringContext<'a>, |
| parent: DefIndex, |
| exist_ty_id: NodeId, |
| collect_elided_lifetimes: bool, |
| currently_bound_lifetimes: Vec<hir::LifetimeName>, |
| already_defined_lifetimes: FxHashSet<hir::LifetimeName>, |
| output_lifetimes: Vec<hir::GenericArg>, |
| output_lifetime_params: Vec<hir::GenericParam>, |
| } |
| |
| impl<'r, 'a: 'r, 'v> hir::intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r, 'a> { |
| 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) { |
| // 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) { |
| // Don't collect elided lifetimes used inside of `fn()` syntax. |
| if let hir::TyKind::BareFn(_) = t.node { |
| 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, |
| 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) { |
| // 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 |
| // `abstract type Foo<'_>: SomeTrait<'_>;`. |
| hir::LifetimeName::Underscore |
| } else { |
| return; |
| } |
| } |
| hir::LifetimeName::Param(_) => lifetime.name, |
| 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 { |
| id: self.context.next_id().node_id, |
| span: lifetime.span, |
| name, |
| })); |
| |
| // We need to manually create the ids here, because the |
| // definitions will go into the explicit `existential type` |
| // declaration and thus need to have their owner set to that item |
| let def_node_id = self.context.sess.next_node_id(); |
| let _ = self.context.lower_node_id_with_owner(def_node_id, self.exist_ty_id); |
| self.context.resolver.definitions().create_def_with_parent( |
| self.parent, |
| def_node_id, |
| DefPathData::LifetimeParam(name.ident().as_interned_str()), |
| DefIndexAddressSpace::High, |
| Mark::root(), |
| lifetime.span, |
| ); |
| |
| let (name, kind) = match name { |
| hir::LifetimeName::Underscore => ( |
| hir::ParamName::Plain(keywords::UnderscoreLifetime.ident()), |
| 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 { |
| id: def_node_id, |
| name, |
| span: lifetime.span, |
| pure_wrt_drop: false, |
| attrs: hir_vec![], |
| bounds: hir_vec![], |
| kind: hir::GenericParamKind::Lifetime { kind } |
| }); |
| } |
| } |
| } |
| |
| let mut lifetime_collector = ImplTraitLifetimeCollector { |
| context: self, |
| parent: parent_index, |
| exist_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); |
| } |
| |
| ( |
| lifetime_collector.output_lifetimes.into(), |
| lifetime_collector.output_lifetime_params.into(), |
| ) |
| } |
| |
| fn lower_foreign_mod(&mut self, fm: &ForeignMod) -> hir::ForeignMod { |
| hir::ForeignMod { |
| abi: fm.abi, |
| items: fm.items |
| .iter() |
| .map(|x| self.lower_foreign_item(x)) |
| .collect(), |
| } |
| } |
| |
| fn lower_global_asm(&mut self, ga: &GlobalAsm) -> P<hir::GlobalAsm> { |
| P(hir::GlobalAsm { |
| asm: ga.asm, |
| ctxt: ga.ctxt, |
| }) |
| } |
| |
| fn lower_variant(&mut self, v: &Variant) -> hir::Variant { |
| Spanned { |
| node: hir::VariantKind { |
| ident: v.node.ident, |
| attrs: self.lower_attrs(&v.node.attrs), |
| data: self.lower_variant_data(&v.node.data), |
| disr_expr: v.node.disr_expr.as_ref().map(|e| self.lower_anon_const(e)), |
| }, |
| span: v.span, |
| } |
| } |
| |
| fn lower_qpath( |
| &mut self, |
| id: NodeId, |
| qself: &Option<QSelf>, |
| p: &Path, |
| param_mode: ParamMode, |
| mut itctx: ImplTraitContext<'_>, |
| ) -> hir::QPath { |
| 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 resolution = self.resolver |
| .get_resolution(id) |
| .unwrap_or_else(|| PathResolution::new(Def::Err)); |
| |
| let proj_start = p.segments.len() - resolution.unresolved_segments(); |
| let path = P(hir::Path { |
| def: resolution.base_def(), |
| segments: 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 resolution.base_def() { |
| Def::AssociatedTy(def_id) if i + 2 == proj_start => { |
| Some(parent_def_id(self, def_id)) |
| } |
| Def::Variant(def_id) if i + 1 == proj_start => { |
| Some(parent_def_id(self, def_id)) |
| } |
| Def::Struct(def_id) |
| | Def::Union(def_id) |
| | Def::Enum(def_id) |
| | Def::TyAlias(def_id) |
| | Def::Trait(def_id) if i + 1 == proj_start => |
| { |
| Some(def_id) |
| } |
| _ => None, |
| }; |
| let parenthesized_generic_args = match resolution.base_def() { |
| // `a::b::Trait(Args)` |
| Def::Trait(..) if i + 1 == proj_start => ParenthesizedGenericArgs::Ok, |
| // `a::b::Trait(Args)::TraitItem` |
| Def::Method(..) | Def::AssociatedConst(..) | Def::AssociatedTy(..) |
| if i + 2 == proj_start => |
| { |
| ParenthesizedGenericArgs::Ok |
| } |
| // Avoid duplicated errors. |
| Def::Err => ParenthesizedGenericArgs::Ok, |
| // An error |
| Def::Struct(..) |
| | Def::Enum(..) |
| | Def::Union(..) |
| | Def::TyAlias(..) |
| | Def::Variant(..) if i + 1 == proj_start => |
| { |
| ParenthesizedGenericArgs::Err |
| } |
| // A warning for now, for compatibility reasons |
| _ => ParenthesizedGenericArgs::Warn, |
| }; |
| |
| 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.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, |
| ) |
| }) |
| .collect(), |
| span: p.span, |
| }); |
| |
| // Simple case, either no projections, or only fully-qualified. |
| // E.g., `std::mem::size_of` or `<I as Iterator>::Item`. |
| if resolution.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(); |
| P(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 = P(self.lower_path_segment( |
| p.span, |
| segment, |
| param_mode, |
| 0, |
| ParenthesizedGenericArgs::Warn, |
| 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 = P(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, |
| def: Def, |
| p: &Path, |
| param_mode: ParamMode, |
| explicit_owner: Option<NodeId>, |
| ) -> hir::Path { |
| hir::Path { |
| def, |
| segments: p.segments |
| .iter() |
| .map(|segment| { |
| self.lower_path_segment( |
| p.span, |
| segment, |
| param_mode, |
| 0, |
| ParenthesizedGenericArgs::Err, |
| ImplTraitContext::disallowed(), |
| explicit_owner, |
| ) |
| }) |
| .collect(), |
| span: p.span, |
| } |
| } |
| |
| fn lower_path(&mut self, id: NodeId, p: &Path, param_mode: ParamMode) -> hir::Path { |
| let def = self.expect_full_def(id); |
| self.lower_path_extra(def, 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<'_>, |
| explicit_owner: Option<NodeId>, |
| ) -> hir::PathSegment { |
| let (mut generic_args, infer_types) = if let Some(ref generic_args) = segment.args { |
| let msg = "parenthesized parameters may only be used with a 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::Warn => { |
| self.sess.buffer_lint( |
| PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES, |
| CRATE_NODE_ID, |
| data.span, |
| msg.into(), |
| ); |
| (hir::GenericArgs::none(), true) |
| } |
| ParenthesizedGenericArgs::Err => { |
| struct_span_err!(self.sess, data.span, E0214, "{}", msg) |
| .span_label(data.span, "only traits may use parentheses") |
| .emit(); |
| (hir::GenericArgs::none(), true) |
| } |
| }, |
| } |
| } 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) |
| .into_iter() |
| .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_ty_args = generic_args.args.len() == expected_lifetimes; |
| let no_bindings = generic_args.bindings.is_empty(); |
| let (incl_angl_brckt, insertion_span, suggestion) = if no_ty_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 type args or bindings exist"); |
| (false, first_generic_span.shrink_to_lo(), format!("{}, ", anon_lt_suggestion)) |
| }; |
| self.sess.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_span, suggestion |
| ) |
| ); |
| } |
| } |
| |
| let def = self.expect_full_def(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::new( |
| segment.ident, |
| Some(id.node_id), |
| Some(def), |
| generic_args, |
| infer_types, |
| ) |
| } |
| |
| fn lower_angle_bracketed_parameter_data( |
| &mut self, |
| data: &AngleBracketedArgs, |
| param_mode: ParamMode, |
| mut itctx: ImplTraitContext<'_>, |
| ) -> (hir::GenericArgs, bool) { |
| let &AngleBracketedArgs { ref args, ref bindings, .. } = data; |
| let has_types = args.iter().any(|arg| match arg { |
| ast::GenericArg::Type(_) => true, |
| _ => false, |
| }); |
| (hir::GenericArgs { |
| args: args.iter().map(|a| self.lower_generic_arg(a, itctx.reborrow())).collect(), |
| bindings: bindings.iter().map(|b| self.lower_ty_binding(b, itctx.reborrow())).collect(), |
| parenthesized: false, |
| }, |
| !has_types && param_mode == ParamMode::Optional) |
| } |
| |
| fn lower_parenthesized_parameter_data( |
| &mut self, |
| data: &ParenthesisedArgs, |
| ) -> (hir::GenericArgs, 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 &ParenthesisedArgs { ref inputs, ref output, span } = data; |
| let inputs = inputs |
| .iter() |
| .map(|ty| this.lower_ty_direct(ty, ImplTraitContext::disallowed())) |
| .collect(); |
| let mk_tup = |this: &mut Self, tys, span| { |
| let LoweredNodeId { node_id, hir_id } = this.next_id(); |
| hir::Ty { node: hir::TyKind::Tup(tys), id: node_id, hir_id, span } |
| }; |
| |
| ( |
| hir::GenericArgs { |
| args: hir_vec![GenericArg::Type(mk_tup(this, inputs, span))], |
| bindings: hir_vec![ |
| hir::TypeBinding { |
| id: this.next_id().node_id, |
| ident: Ident::from_str(FN_OUTPUT_NAME), |
| ty: output |
| .as_ref() |
| .map(|ty| this.lower_ty(&ty, ImplTraitContext::disallowed())) |
| .unwrap_or_else(|| P(mk_tup(this, hir::HirVec::new(), span))), |
| span: output.as_ref().map_or(span, |ty| ty.span), |
| } |
| ], |
| parenthesized: true, |
| }, |
| false, |
| ) |
| } |
| ) |
| } |
| |
| fn lower_local(&mut self, l: &Local) -> (P<hir::Local>, SmallVec<[hir::ItemId; 1]>) { |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(l.id); |
| let mut ids = SmallVec::<[hir::ItemId; 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); |
| (P(hir::Local { |
| id: node_id, |
| hir_id, |
| ty: l.ty |
| .as_ref() |
| .map(|t| self.lower_ty(t, |
| if self.sess.features_untracked().impl_trait_in_bindings { |
| ImplTraitContext::Existential(Some(parent_def_id)) |
| } else { |
| ImplTraitContext::Disallowed(ImplTraitPosition::Binding) |
| } |
| )), |
| pat: self.lower_pat(&l.pat), |
| init: l.init.as_ref().map(|e| P(self.lower_expr(e))), |
| span: l.span, |
| attrs: l.attrs.clone(), |
| source: hir::LocalSource::Normal, |
| }), ids) |
| } |
| |
| fn lower_mutability(&mut self, m: Mutability) -> hir::Mutability { |
| match m { |
| Mutability::Mutable => hir::MutMutable, |
| Mutability::Immutable => hir::MutImmutable, |
| } |
| } |
| |
| fn lower_arg(&mut self, arg: &Arg) -> hir::Arg { |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(arg.id); |
| hir::Arg { |
| id: node_id, |
| hir_id, |
| pat: self.lower_pat(&arg.pat), |
| } |
| } |
| |
| fn lower_fn_args_to_names(&mut self, decl: &FnDecl) -> hir::HirVec<Ident> { |
| decl.inputs |
| .iter() |
| .map(|arg| match arg.pat.node { |
| PatKind::Ident(_, ident, _) => ident, |
| _ => Ident::new(keywords::Invalid.name(), arg.pat.span), |
| }) |
| .collect() |
| } |
| |
| // 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>)>, |
| impl_trait_return_allow: bool, |
| make_ret_async: Option<NodeId>, |
| ) -> P<hir::FnDecl> { |
| let inputs = decl.inputs |
| .iter() |
| .map(|arg| { |
| if let Some((_, ref mut ibty)) = in_band_ty_params { |
| self.lower_ty_direct(&arg.ty, ImplTraitContext::Universal(ibty)) |
| } else { |
| self.lower_ty_direct(&arg.ty, ImplTraitContext::disallowed()) |
| } |
| }) |
| .collect::<HirVec<_>>(); |
| |
| let output = if let Some(ret_id) = make_ret_async { |
| self.lower_async_fn_ret_ty( |
| &inputs, |
| &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::Existential(Some(def_id)))) |
| } |
| _ => { |
| hir::Return(self.lower_ty(ty, ImplTraitContext::disallowed())) |
| } |
| }, |
| FunctionRetTy::Default(span) => hir::DefaultReturn(span), |
| } |
| }; |
| |
| P(hir::FnDecl { |
| inputs, |
| output, |
| variadic: decl.variadic, |
| implicit_self: decl.inputs.get(0).map_or( |
| hir::ImplicitSelfKind::None, |
| |arg| { |
| let is_mutable_pat = match arg.pat.node { |
| PatKind::Ident(BindingMode::ByValue(mt), _, _) | |
| PatKind::Ident(BindingMode::ByRef(mt), _, _) => |
| mt == Mutability::Mutable, |
| _ => false, |
| }; |
| |
| match arg.ty.node { |
| 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.node.is_implicit_self() && |
| mt.mutbl == ast::Mutability::Mutable => |
| hir::ImplicitSelfKind::MutRef, |
| TyKind::Rptr(_, ref mt) if mt.ty.node.is_implicit_self() => |
| hir::ImplicitSelfKind::ImmRef, |
| _ => hir::ImplicitSelfKind::None, |
| } |
| }, |
| ), |
| }) |
| } |
| |
| // Transform `-> T` into `-> impl Future<Output = T>` for `async fn` |
| // |
| // fn_span: the span of the async function declaration. Used for error reporting. |
| // inputs: lowered types of arguments 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. |
| fn lower_async_fn_ret_ty( |
| &mut self, |
| inputs: &[hir::Ty], |
| output: &FunctionRetTy, |
| fn_def_id: DefId, |
| return_impl_trait_id: NodeId, |
| ) -> hir::FunctionRetTy { |
| // Get lifetimes used in the input arguments to the function. Our output type must also |
| // have the same lifetime. |
| // FIXME(cramertj): multiple different lifetimes are not allowed because |
| // `impl Trait + 'a + 'b` doesn't allow for capture `'a` and `'b` where neither is a subset |
| // of the other. We really want some new lifetime that is a subset of all input lifetimes, |
| // but that doesn't exist at the moment. |
| |
| struct AsyncFnLifetimeCollector<'r, 'a: 'r> { |
| context: &'r mut LoweringContext<'a>, |
| // Lifetimes bound by HRTB. |
| currently_bound_lifetimes: Vec<hir::LifetimeName>, |
| // Whether to count elided lifetimes. |
| // Disabled inside of `Fn` or `fn` syntax. |
| collect_elided_lifetimes: bool, |
| // The lifetime found. |
| // Multiple different or elided lifetimes cannot appear in async fn for now. |
| output_lifetime: Option<(hir::LifetimeName, Span)>, |
| } |
| |
| impl<'r, 'a: 'r, 'v> hir::intravisit::Visitor<'v> for AsyncFnLifetimeCollector<'r, 'a> { |
| 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) { |
| // 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) { |
| // Don't collect elided lifetimes used inside of `fn()` syntax. |
| if let &hir::TyKind::BareFn(_) = &t.node { |
| 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, |
| 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) { |
| // 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 |
| // `abstract type Foo<'_>: SomeTrait<'_>;` |
| hir::LifetimeName::Underscore |
| } else { |
| return; |
| } |
| } |
| hir::LifetimeName::Param(_) => lifetime.name, |
| hir::LifetimeName::Error | hir::LifetimeName::Static => return, |
| }; |
| |
| if !self.currently_bound_lifetimes.contains(&name) { |
| if let Some((current_lt_name, current_lt_span)) = self.output_lifetime { |
| // We don't currently have a reliable way to desugar `async fn` with |
| // multiple potentially unrelated input lifetimes into |
| // `-> impl Trait + 'lt`, so we report an error in this case. |
| if current_lt_name != name { |
| struct_span_err!( |
| self.context.sess, |
| MultiSpan::from_spans(vec![current_lt_span, lifetime.span]), |
| E0709, |
| "multiple different lifetimes used in arguments of `async fn`", |
| ) |
| .span_label(current_lt_span, "first lifetime here") |
| .span_label(lifetime.span, "different lifetime here") |
| .help("`async fn` can only accept borrowed values \ |
| with identical lifetimes") |
| .emit() |
| } else if current_lt_name.is_elided() && name.is_elided() { |
| struct_span_err!( |
| self.context.sess, |
| MultiSpan::from_spans(vec![current_lt_span, lifetime.span]), |
| E0707, |
| "multiple elided lifetimes used in arguments of `async fn`", |
| ) |
| .span_label(current_lt_span, "first lifetime here") |
| .span_label(lifetime.span, "different lifetime here") |
| .help("consider giving these arguments named lifetimes") |
| .emit() |
| } |
| } else { |
| self.output_lifetime = Some((name, lifetime.span)); |
| } |
| } |
| } |
| } |
| |
| let bound_lifetime = { |
| let mut lifetime_collector = AsyncFnLifetimeCollector { |
| context: self, |
| currently_bound_lifetimes: Vec::new(), |
| collect_elided_lifetimes: true, |
| output_lifetime: None, |
| }; |
| |
| for arg in inputs { |
| hir::intravisit::walk_ty(&mut lifetime_collector, arg); |
| } |
| lifetime_collector.output_lifetime |
| }; |
| |
| let span = match output { |
| FunctionRetTy::Ty(ty) => ty.span, |
| FunctionRetTy::Default(span) => *span, |
| }; |
| |
| let impl_trait_ty = self.lower_existential_impl_trait( |
| span, Some(fn_def_id), return_impl_trait_id, |this| { |
| let output_ty = match output { |
| FunctionRetTy::Ty(ty) => { |
| this.lower_ty(ty, ImplTraitContext::Existential(Some(fn_def_id))) |
| } |
| FunctionRetTy::Default(span) => { |
| let LoweredNodeId { node_id, hir_id } = this.next_id(); |
| P(hir::Ty { |
| id: node_id, |
| hir_id: hir_id, |
| node: hir::TyKind::Tup(hir_vec![]), |
| span: *span, |
| }) |
| } |
| }; |
| |
| // "<Output = T>" |
| let future_params = P(hir::GenericArgs { |
| args: hir_vec![], |
| bindings: hir_vec![hir::TypeBinding { |
| ident: Ident::from_str(FN_OUTPUT_NAME), |
| ty: output_ty, |
| id: this.next_id().node_id, |
| span, |
| }], |
| parenthesized: false, |
| }); |
| |
| let future_path = |
| this.std_path(span, &["future", "Future"], Some(future_params), false); |
| |
| let LoweredNodeId { node_id, hir_id } = this.next_id(); |
| let mut bounds = vec![ |
| hir::GenericBound::Trait( |
| hir::PolyTraitRef { |
| trait_ref: hir::TraitRef { |
| path: future_path, |
| ref_id: node_id, |
| hir_ref_id: hir_id, |
| }, |
| bound_generic_params: hir_vec![], |
| span, |
| }, |
| hir::TraitBoundModifier::None |
| ), |
| ]; |
| |
| if let Some((name, span)) = bound_lifetime { |
| bounds.push(hir::GenericBound::Outlives( |
| hir::Lifetime { id: this.next_id().node_id, name, span })); |
| } |
| |
| hir::HirVec::from(bounds) |
| }); |
| |
| let LoweredNodeId { node_id, hir_id } = self.next_id(); |
| let impl_trait_ty = P(hir::Ty { |
| id: node_id, |
| node: impl_trait_ty, |
| span, |
| hir_id, |
| }); |
| |
| hir::FunctionRetTy::Return(impl_trait_ty) |
| } |
| |
| fn lower_param_bound( |
| &mut self, |
| tpb: &GenericBound, |
| itctx: ImplTraitContext<'_>, |
| ) -> hir::GenericBound { |
| 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 == keywords::StaticLifetime.name() => |
| self.new_named_lifetime(l.id, span, hir::LifetimeName::Static), |
| ident if ident.name == keywords::UnderscoreLifetime.name() => |
| 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 { |
| id: self.lower_node_id(id).node_id, |
| span, |
| name: name, |
| } |
| } |
| |
| fn lower_generic_params( |
| &mut self, |
| params: &[GenericParam], |
| add_bounds: &NodeMap<Vec<GenericBound>>, |
| mut itctx: ImplTraitContext<'_>, |
| ) -> hir::HirVec<hir::GenericParam> { |
| params.iter().map(|param| { |
| self.lower_generic_param(param, add_bounds, itctx.reborrow()) |
| }).collect() |
| } |
| |
| fn lower_generic_param(&mut self, |
| param: &GenericParam, |
| add_bounds: &NodeMap<Vec<GenericBound>>, |
| mut itctx: ImplTraitContext<'_>) |
| -> hir::GenericParam { |
| let mut bounds = self.with_anonymous_lifetime_mode( |
| AnonymousLifetimeMode::ReportError, |
| |this| this.lower_param_bounds(¶m.bounds, itctx.reborrow()), |
| ); |
| |
| 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::Error => ParamName::Error, |
| }; |
| let param = hir::GenericParam { |
| id: lt.id, |
| name: param_name, |
| span: lt.span, |
| pure_wrt_drop: attr::contains_name(¶m.attrs, "may_dangle"), |
| attrs: self.lower_attrs(¶m.attrs), |
| bounds, |
| kind: hir::GenericParamKind::Lifetime { |
| kind: hir::LifetimeParamKind::Explicit, |
| } |
| }; |
| |
| self.is_collecting_in_band_lifetimes = was_collecting_in_band; |
| |
| param |
| } |
| GenericParamKind::Type { ref default, .. } => { |
| // Don't expose `Self` (recovered "keyword used as ident" parse error). |
| // `rustc::ty` expects `Self` to be only used for a trait's `Self`. |
| // Instead, use `gensym("Self")` to create a distinct name that looks the same. |
| let ident = if param.ident.name == keywords::SelfUpper.name() { |
| param.ident.gensym() |
| } else { |
| param.ident |
| }; |
| |
| let add_bounds = add_bounds.get(¶m.id).map_or(&[][..], |x| &x); |
| if !add_bounds.is_empty() { |
| let params = self.lower_param_bounds(add_bounds, itctx.reborrow()).into_iter(); |
| bounds = bounds.into_iter() |
| .chain(params) |
| .collect(); |
| } |
| |
| hir::GenericParam { |
| id: self.lower_node_id(param.id).node_id, |
| name: hir::ParamName::Plain(ident), |
| pure_wrt_drop: attr::contains_name(¶m.attrs, "may_dangle"), |
| attrs: self.lower_attrs(¶m.attrs), |
| bounds, |
| span: ident.span, |
| kind: hir::GenericParamKind::Type { |
| default: default.as_ref().map(|x| { |
| self.lower_ty(x, ImplTraitContext::disallowed()) |
| }), |
| synthetic: param.attrs.iter() |
| .filter(|attr| attr.check_name("rustc_synthetic")) |
| .map(|_| hir::SyntheticTyParamKind::ImplTrait) |
| .next(), |
| } |
| } |
| } |
| } |
| } |
| |
| fn lower_generics( |
| &mut self, |
| generics: &Generics, |
| itctx: ImplTraitContext<'_>) |
| -> hir::Generics |
| { |
| // Collect `?Trait` bounds in where clause and move them to parameter definitions. |
| // FIXME: this could probably be done with less rightward drift. Also looks like two control |
| // paths where report_error is called are also the only paths that advance to after |
| // the match statement, so the error reporting could probably just be moved there. |
| let mut add_bounds: NodeMap<Vec<_>> = Default::default(); |
| for pred in &generics.where_clause.predicates { |
| if let WherePredicate::BoundPredicate(ref bound_pred) = *pred { |
| 'next_bound: for bound in &bound_pred.bounds { |
| if let GenericBound::Trait(_, TraitBoundModifier::Maybe) = *bound { |
| let report_error = |this: &mut Self| { |
| this.diagnostic().span_err( |
| bound_pred.bounded_ty.span, |
| "`?Trait` bounds are only permitted at the \ |
| point where a type parameter is declared", |
| ); |
| }; |
| // Check if the where clause type is a plain type parameter. |
| match bound_pred.bounded_ty.node { |
| TyKind::Path(None, ref path) |
| if path.segments.len() == 1 |
| && bound_pred.bound_generic_params.is_empty() => |
| { |
| if let Some(Def::TyParam(def_id)) = self.resolver |
| .get_resolution(bound_pred.bounded_ty.id) |
| .map(|d| d.base_def()) |
| { |
| if let Some(node_id) = |
| self.resolver.definitions().as_local_node_id(def_id) |
| { |
| for param in &generics.params { |
| match param.kind { |
| GenericParamKind::Type { .. } => { |
| if node_id == param.id { |
| add_bounds.entry(param.id) |
| .or_default() |
| .push(bound.clone()); |
| continue 'next_bound; |
| } |
| } |
| _ => {} |
| } |
| } |
| } |
| } |
| report_error(self) |
| } |
| _ => report_error(self), |
| } |
| } |
| } |
| } |
| } |
| |
| hir::Generics { |
| params: self.lower_generic_params(&generics.params, &add_bounds, itctx), |
| where_clause: self.lower_where_clause(&generics.where_clause), |
| span: generics.span, |
| } |
| } |
| |
| fn lower_where_clause(&mut self, wc: &WhereClause) -> hir::WhereClause { |
| self.with_anonymous_lifetime_mode( |
| AnonymousLifetimeMode::ReportError, |
| |this| { |
| hir::WhereClause { |
| id: this.lower_node_id(wc.id).node_id, |
| predicates: wc.predicates |
| .iter() |
| .map(|predicate| this.lower_where_predicate(predicate)) |
| .collect(), |
| } |
| }, |
| ) |
| } |
| |
| fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate { |
| match *pred { |
| WherePredicate::BoundPredicate(WhereBoundPredicate { |
| ref bound_generic_params, |
| ref bounded_ty, |
| ref bounds, |
| span, |
| }) => { |
| self.with_in_scope_lifetime_defs( |
| &bound_generic_params, |
| |this| { |
| hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate { |
| bound_generic_params: this.lower_generic_params( |
| bound_generic_params, |
| &NodeMap::default(), |
| ImplTraitContext::disallowed(), |
| ), |
| bounded_ty: this.lower_ty(bounded_ty, ImplTraitContext::disallowed()), |
| bounds: bounds |
| .iter() |
| .filter_map(|bound| match *bound { |
| // Ignore `?Trait` bounds. |
| // They were copied into type parameters already. |
| GenericBound::Trait(_, TraitBoundModifier::Maybe) => None, |
| _ => Some(this.lower_param_bound( |
| bound, |
| ImplTraitContext::disallowed(), |
| )), |
| }) |
| .collect(), |
| span, |
| }) |
| }, |
| ) |
| } |
| WherePredicate::RegionPredicate(WhereRegionPredicate { |
| ref lifetime, |
| ref bounds, |
| span, |
| }) => hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate { |
| span, |
| lifetime: self.lower_lifetime(lifetime), |
| bounds: self.lower_param_bounds(bounds, ImplTraitContext::disallowed()), |
| }), |
| WherePredicate::EqPredicate(WhereEqPredicate { |
| id, |
| ref lhs_ty, |
| ref rhs_ty, |
| span, |
| }) => hir::WherePredicate::EqPredicate(hir::WhereEqPredicate { |
| id: self.lower_node_id(id).node_id, |
| lhs_ty: self.lower_ty(lhs_ty, ImplTraitContext::disallowed()), |
| rhs_ty: self.lower_ty(rhs_ty, ImplTraitContext::disallowed()), |
| span, |
| }), |
| } |
| } |
| |
| fn lower_variant_data(&mut self, vdata: &VariantData) -> hir::VariantData { |
| match *vdata { |
| VariantData::Struct(ref fields, id) => hir::VariantData::Struct( |
| fields |
| .iter() |
| .enumerate() |
| .map(|f| self.lower_struct_field(f)) |
| .collect(), |
| self.lower_node_id(id).node_id, |
| ), |
| VariantData::Tuple(ref fields, id) => hir::VariantData::Tuple( |
| fields |
| .iter() |
| .enumerate() |
| .map(|f| self.lower_struct_field(f)) |
| .collect(), |
| self.lower_node_id(id).node_id, |
| ), |
| VariantData::Unit(id) => hir::VariantData::Unit(self.lower_node_id(id).node_id), |
| } |
| } |
| |
| fn lower_trait_ref(&mut self, p: &TraitRef, itctx: ImplTraitContext<'_>) -> hir::TraitRef { |
| let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit, itctx) { |
| hir::QPath::Resolved(None, path) => path.and_then(|path| path), |
| qpath => bug!("lower_trait_ref: unexpected QPath `{:?}`", qpath), |
| }; |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(p.ref_id); |
| hir::TraitRef { |
| path, |
| ref_id: node_id, |
| hir_ref_id: hir_id, |
| } |
| } |
| |
| fn lower_poly_trait_ref( |
| &mut self, |
| p: &PolyTraitRef, |
| mut itctx: ImplTraitContext<'_>, |
| ) -> hir::PolyTraitRef { |
| let bound_generic_params = self.lower_generic_params( |
| &p.bound_generic_params, |
| &NodeMap::default(), |
| itctx.reborrow(), |
| ); |
| let trait_ref = self.with_parent_impl_lifetime_defs( |
| &bound_generic_params, |
| |this| this.lower_trait_ref(&p.trait_ref, itctx), |
| ); |
| |
| hir::PolyTraitRef { |
| bound_generic_params, |
| trait_ref, |
| span: p.span, |
| } |
| } |
| |
| fn lower_struct_field(&mut self, (index, f): (usize, &StructField)) -> hir::StructField { |
| hir::StructField { |
| span: f.span, |
| id: self.lower_node_id(f.id).node_id, |
| ident: match f.ident { |
| Some(ident) => ident, |
| // FIXME(jseyfried): positional field hygiene |
| None => Ident::new(Symbol::intern(&index.to_string()), f.span), |
| }, |
| vis: self.lower_visibility(&f.vis, None), |
| ty: self.lower_ty(&f.ty, ImplTraitContext::disallowed()), |
| attrs: self.lower_attrs(&f.attrs), |
| } |
| } |
| |
| fn lower_field(&mut self, f: &Field) -> hir::Field { |
| hir::Field { |
| id: self.next_id().node_id, |
| ident: f.ident, |
| expr: P(self.lower_expr(&f.expr)), |
| span: f.span, |
| is_shorthand: f.is_shorthand, |
| } |
| } |
| |
| fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext<'_>) -> hir::MutTy { |
| hir::MutTy { |
| ty: self.lower_ty(&mt.ty, itctx), |
| mutbl: self.lower_mutability(mt.mutbl), |
| } |
| } |
| |
| fn lower_param_bounds(&mut self, bounds: &[GenericBound], mut itctx: ImplTraitContext<'_>) |
| -> hir::GenericBounds { |
| bounds.iter().map(|bound| self.lower_param_bound(bound, itctx.reborrow())).collect() |
| } |
| |
| fn lower_block(&mut self, b: &Block, targeted_by_break: bool) -> P<hir::Block> { |
| let mut expr = None; |
| |
| let mut stmts = vec![]; |
| |
| for (index, stmt) in b.stmts.iter().enumerate() { |
| if index == b.stmts.len() - 1 { |
| if let StmtKind::Expr(ref e) = stmt.node { |
| expr = Some(P(self.lower_expr(e))); |
| } else { |
| stmts.extend(self.lower_stmt(stmt)); |
| } |
| } else { |
| stmts.extend(self.lower_stmt(stmt)); |
| } |
| } |
| |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(b.id); |
| |
| P(hir::Block { |
| id: node_id, |
| hir_id, |
| stmts: stmts.into(), |
| expr, |
| rules: self.lower_block_check_mode(&b.rules), |
| span: b.span, |
| targeted_by_break, |
| }) |
| } |
| |
| fn lower_async_body( |
| &mut self, |
| decl: &FnDecl, |
| asyncness: IsAsync, |
| body: &Block, |
| ) -> hir::BodyId { |
| self.lower_body(Some(decl), |this| { |
| if let IsAsync::Async { closure_id, .. } = asyncness { |
| let async_expr = this.make_async_expr( |
| CaptureBy::Value, closure_id, None, |
| |this| { |
| let body = this.lower_block(body, false); |
| this.expr_block(body, ThinVec::new()) |
| }); |
| this.expr(body.span, async_expr, ThinVec::new()) |
| } else { |
| let body = this.lower_block(body, false); |
| this.expr_block(body, ThinVec::new()) |
| } |
| }) |
| } |
| |
| fn lower_item_kind( |
| &mut self, |
| id: NodeId, |
| ident: &mut Ident, |
| attrs: &hir::HirVec<Attribute>, |
| vis: &mut hir::Visibility, |
| i: &ItemKind, |
| ) -> hir::ItemKind { |
| match *i { |
| ItemKind::ExternCrate(orig_name) => hir::ItemKind::ExternCrate(orig_name), |
| ItemKind::Use(ref use_tree) => { |
| // Start with an empty prefix |
| let prefix = Path { |
| segments: vec![], |
| span: use_tree.span, |
| }; |
| |
| self.lower_use_tree(use_tree, &prefix, id, vis, ident, attrs) |
| } |
| ItemKind::Static(ref t, m, ref e) => { |
| let value = self.lower_body(None, |this| this.lower_expr(e)); |
| hir::ItemKind::Static( |
| self.lower_ty( |
| t, |
| if self.sess.features_untracked().impl_trait_in_bindings { |
| ImplTraitContext::Existential(None) |
| } else { |
| ImplTraitContext::Disallowed(ImplTraitPosition::Binding) |
| } |
| ), |
| self.lower_mutability(m), |
| value, |
| ) |
| } |
| ItemKind::Const(ref t, ref e) => { |
| let value = self.lower_body(None, |this| this.lower_expr(e)); |
| hir::ItemKind::Const( |
| self.lower_ty( |
| t, |
| if self.sess.features_untracked().impl_trait_in_bindings { |
| ImplTraitContext::Existential(None) |
| } else { |
| ImplTraitContext::Disallowed(ImplTraitPosition::Binding) |
| } |
| ), |
| value |
| ) |
| } |
| ItemKind::Fn(ref decl, header, ref generics, ref body) => { |
| let fn_def_id = self.resolver.definitions().local_def_id(id); |
| self.with_new_scopes(|this| { |
| // Note: we don't need to change the return type from `T` to |
| // `impl Future<Output = T>` here because lower_body |
| // only cares about the input argument patterns in the function |
| // declaration (decl), not the return types. |
| let body_id = this.lower_async_body(decl, header.asyncness, body); |
| |
| let (generics, fn_decl) = this.add_in_band_defs( |
| generics, |
| fn_def_id, |
| AnonymousLifetimeMode::PassThrough, |
| |this, idty| this.lower_fn_decl( |
| decl, |
| Some((fn_def_id, idty)), |
| true, |
| header.asyncness.opt_return_id() |
| ), |
| ); |
| |
| hir::ItemKind::Fn( |
| fn_decl, |
| this.lower_fn_header(header), |
| generics, |
| body_id, |
| ) |
| }) |
| } |
| ItemKind::Mod(ref m) => hir::ItemKind::Mod(self.lower_mod(m)), |
| ItemKind::ForeignMod(ref nm) => hir::ItemKind::ForeignMod(self.lower_foreign_mod(nm)), |
| ItemKind::GlobalAsm(ref ga) => hir::ItemKind::GlobalAsm(self.lower_global_asm(ga)), |
| ItemKind::Ty(ref t, ref generics) => hir::ItemKind::Ty( |
| self.lower_ty(t, ImplTraitContext::disallowed()), |
| self.lower_generics(generics, ImplTraitContext::disallowed()), |
| ), |
| ItemKind::Existential(ref b, ref generics) => hir::ItemKind::Existential(hir::ExistTy { |
| generics: self.lower_generics(generics, ImplTraitContext::disallowed()), |
| bounds: self.lower_param_bounds(b, ImplTraitContext::disallowed()), |
| impl_trait_fn: None, |
| }), |
| ItemKind::Enum(ref enum_definition, ref generics) => hir::ItemKind::Enum( |
| hir::EnumDef { |
| variants: enum_definition |
| .variants |
| .iter() |
| .map(|x| self.lower_variant(x)) |
| .collect(), |
| }, |
| self.lower_generics(generics, ImplTraitContext::disallowed()), |
| ), |
| ItemKind::Struct(ref struct_def, ref generics) => { |
| let struct_def = self.lower_variant_data(struct_def); |
| hir::ItemKind::Struct( |
| struct_def, |
| self.lower_generics(generics, ImplTraitContext::disallowed()), |
| ) |
| } |
| ItemKind::Union(ref vdata, ref generics) => { |
| let vdata = self.lower_variant_data(vdata); |
| hir::ItemKind::Union( |
| vdata, |
| self.lower_generics(generics, ImplTraitContext::disallowed()), |
| ) |
| } |
| ItemKind::Impl( |
| unsafety, |
| polarity, |
| defaultness, |
| ref ast_generics, |
| ref trait_ref, |
| ref ty, |
| ref impl_items, |
| ) => { |
| let def_id = self.resolver.definitions().local_def_id(id); |
| |
| // Lower the "impl header" first. This ordering is important |
| // for in-band lifetimes! Consider `'a` here: |
| // |
| // impl Foo<'a> for u32 { |
| // fn method(&'a self) { .. } |
| // } |
| // |
| // Because we start by lowering the `Foo<'a> for u32` |
| // part, we will add `'a` to the list of generics on |
| // the impl. When we then encounter it later in the |
| // method, it will not be considered an in-band |
| // lifetime to be added, but rather a reference to a |
| // parent lifetime. |
| let (generics, (trait_ref, lowered_ty)) = self.add_in_band_defs( |
| ast_generics, |
| def_id, |
| AnonymousLifetimeMode::CreateParameter, |
| |this, _| { |
| let trait_ref = trait_ref.as_ref().map(|trait_ref| { |
| this.lower_trait_ref(trait_ref, ImplTraitContext::disallowed()) |
| }); |
| |
| if let Some(ref trait_ref) = trait_ref { |
| if let Def::Trait(def_id) = trait_ref.path.def { |
| this.trait_impls.entry(def_id).or_default().push(id); |
| } |
| } |
| |
| let lowered_ty = this.lower_ty(ty, ImplTraitContext::disallowed()); |
| |
| (trait_ref, lowered_ty) |
| }, |
| ); |
| |
| let new_impl_items = self.with_in_scope_lifetime_defs( |
| &ast_generics.params, |
| |this| { |
| impl_items |
| .iter() |
| .map(|item| this.lower_impl_item_ref(item)) |
| .collect() |
| }, |
| ); |
| |
| hir::ItemKind::Impl( |
| self.lower_unsafety(unsafety), |
| self.lower_impl_polarity(polarity), |
| self.lower_defaultness(defaultness, true /* [1] */), |
| generics, |
| trait_ref, |
| lowered_ty, |
| new_impl_items, |
| ) |
| } |
| ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref items) => { |
| let bounds = self.lower_param_bounds(bounds, ImplTraitContext::disallowed()); |
| let items = items |
| .iter() |
| .map(|item| self.lower_trait_item_ref(item)) |
| .collect(); |
| hir::ItemKind::Trait( |
| self.lower_is_auto(is_auto), |
| self.lower_unsafety(unsafety), |
| self.lower_generics(generics, ImplTraitContext::disallowed()), |
| bounds, |
| items, |
| ) |
| } |
| ItemKind::TraitAlias(ref generics, ref bounds) => hir::ItemKind::TraitAlias( |
| self.lower_generics(generics, ImplTraitContext::disallowed()), |
| self.lower_param_bounds(bounds, ImplTraitContext::disallowed()), |
| ), |
| ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"), |
| } |
| |
| // [1] `defaultness.has_value()` is never called for an `impl`, always `true` in order to |
| // not cause an assertion failure inside the `lower_defaultness` function. |
| } |
| |
| fn lower_use_tree( |
| &mut self, |
| tree: &UseTree, |
| prefix: &Path, |
| id: NodeId, |
| vis: &mut hir::Visibility, |
| ident: &mut Ident, |
| attrs: &hir::HirVec<Attribute>, |
| ) -> hir::ItemKind { |
| debug!("lower_use_tree(tree={:?})", tree); |
| debug!("lower_use_tree: vis = {:?}", vis); |
| |
| let path = &tree.prefix; |
| let segments = prefix |
| .segments |
| .iter() |
| .chain(path.segments.iter()) |
| .cloned() |
| .collect(); |
| |
| match tree.kind { |
| UseTreeKind::Simple(rename, id1, id2) => { |
| *ident = tree.ident(); |
| |
| // First, apply the prefix to the path. |
| let mut path = Path { |
| segments, |
| span: path.span, |
| }; |
| |
| // Correctly resolve `self` imports. |
| if path.segments.len() > 1 |
| && path.segments.last().unwrap().ident.name == keywords::SelfLower.name() |
| { |
| let _ = path.segments.pop(); |
| if rename.is_none() { |
| *ident = path.segments.last().unwrap().ident; |
| } |
| } |
| |
| let parent_def_index = self.current_hir_id_owner.last().unwrap().0; |
| let mut defs = self.expect_full_def_from_use(id); |
| // We want to return *something* from this function, so hold onto the first item |
| // for later. |
| let ret_def = defs.next().unwrap_or(Def::Err); |
| |
| // Here, we are looping over namespaces, if they exist for the definition |
| // being imported. We only handle type and value namespaces because we |
| // won't be dealing with macros in the rest of the compiler. |
| // Essentially a single `use` which imports two names is desugared into |
| // two imports. |
| for (def, &new_node_id) in defs.zip([id1, id2].iter()) { |
| let vis = vis.clone(); |
| let ident = ident.clone(); |
| let mut path = path.clone(); |
| for seg in &mut path.segments { |
| seg.id = self.sess.next_node_id(); |
| } |
| let span = path.span; |
| self.resolver.definitions().create_def_with_parent( |
| parent_def_index, |
| new_node_id, |
| DefPathData::Misc, |
| DefIndexAddressSpace::High, |
| Mark::root(), |
| span); |
| self.allocate_hir_id_counter(new_node_id, &path); |
| |
| self.with_hir_id_owner(new_node_id, |this| { |
| let new_id = this.lower_node_id(new_node_id); |
| let path = |
| this.lower_path_extra(def, &path, ParamMode::Explicit, None); |
| let item = hir::ItemKind::Use(P(path), hir::UseKind::Single); |
| let vis_kind = match vis.node { |
| hir::VisibilityKind::Public => hir::VisibilityKind::Public, |
| hir::VisibilityKind::Crate(sugar) => hir::VisibilityKind::Crate(sugar), |
| hir::VisibilityKind::Inherited => hir::VisibilityKind::Inherited, |
| hir::VisibilityKind::Restricted { ref path, id: _, hir_id: _ } => { |
| let id = this.next_id(); |
| let path = this.renumber_segment_ids(path); |
| hir::VisibilityKind::Restricted { |
| path, |
| id: id.node_id, |
| hir_id: id.hir_id, |
| } |
| } |
| }; |
| let vis = respan(vis.span, vis_kind); |
| |
| this.insert_item( |
| new_id.node_id, |
| hir::Item { |
| id: new_id.node_id, |
| hir_id: new_id.hir_id, |
| ident, |
| attrs: attrs.clone(), |
| node: item, |
| vis, |
| span, |
| }, |
| ); |
| }); |
| } |
| |
| let path = |
| P(self.lower_path_extra(ret_def, &path, ParamMode::Explicit, None)); |
| hir::ItemKind::Use(path, hir::UseKind::Single) |
| } |
| UseTreeKind::Glob => { |
| let path = P(self.lower_path( |
| id, |
| &Path { |
| segments, |
| span: path.span, |
| }, |
| ParamMode::Explicit, |
| )); |
| hir::ItemKind::Use(path, hir::UseKind::Glob) |
| } |
| UseTreeKind::Nested(ref trees) => { |
| // Nested imports are desugared into simple imports. |
| // So, if we start with |
| // |
| // ``` |
| // pub(x) use foo::{a, b}; |
| // ``` |
| // |
| // we will create three items: |
| // |
| // ``` |
| // pub(x) use foo::a; |
| // pub(x) use foo::b; |
| // pub(x) use foo::{}; // <-- this is called the `ListStem` |
| // ``` |
| // |
| // The first two are produced by recursively invoking |
| // `lower_use_tree` (and indeed there may be things |
| // like `use foo::{a::{b, c}}` and so forth). They |
| // wind up being directly added to |
| // `self.items`. However, the structure of this |
| // function also requires us to return one item, and |
| // for that we return the `{}` import (called the |
| // `ListStem`). |
| |
| let prefix = Path { |
| segments, |
| span: prefix.span.to(path.span), |
| }; |
| |
| // Add all the nested `PathListItem`s to the HIR. |
| for &(ref use_tree, id) in trees { |
| self.allocate_hir_id_counter(id, &use_tree); |
| |
| let LoweredNodeId { |
| node_id: new_id, |
| hir_id: new_hir_id, |
| } = self.lower_node_id(id); |
| |
| let mut vis = vis.clone(); |
| let mut ident = ident.clone(); |
| let mut prefix = prefix.clone(); |
| |
| // Give the segments new node-ids since they are being cloned. |
| for seg in &mut prefix.segments { |
| seg.id = self.sess.next_node_id(); |
| } |
| |
| // Each `use` import is an item and thus are owners of the |
| // names in the path. Up to this point the nested import is |
| // the current owner, since we want each desugared import to |
| // own its own names, we have to adjust the owner before |
| // lowering the rest of the import. |
| self.with_hir_id_owner(new_id, |this| { |
| let item = this.lower_use_tree(use_tree, |
| &prefix, |
| new_id, |
| &mut vis, |
| &mut ident, |
| attrs); |
| |
| let vis_kind = match vis.node { |
| hir::VisibilityKind::Public => hir::VisibilityKind::Public, |
| hir::VisibilityKind::Crate(sugar) => hir::VisibilityKind::Crate(sugar), |
| hir::VisibilityKind::Inherited => hir::VisibilityKind::Inherited, |
| hir::VisibilityKind::Restricted { ref path, id: _, hir_id: _ } => { |
| let id = this.next_id(); |
| let path = this.renumber_segment_ids(path); |
| hir::VisibilityKind::Restricted { |
| path: path, |
| id: id.node_id, |
| hir_id: id.hir_id, |
| } |
| } |
| }; |
| let vis = respan(vis.span, vis_kind); |
| |
| this.insert_item( |
| new_id, |
| hir::Item { |
| id: new_id, |
| hir_id: new_hir_id, |
| ident, |
| attrs: attrs.clone(), |
| node: item, |
| vis, |
| span: use_tree.span, |
| }, |
| ); |
| }); |
| } |
| |
| // Subtle and a bit hacky: we lower the privacy level |
| // of the list stem to "private" most of the time, but |
| // not for "restricted" paths. The key thing is that |
| // we don't want it to stay as `pub` (with no caveats) |
| // because that affects rustdoc and also the lints |
| // about `pub` items. But we can't *always* make it |
| // private -- particularly not for restricted paths -- |
| // because it contains node-ids that would then be |
| // unused, failing the check that HirIds are "densely |
| // assigned". |
| match vis.node { |
| hir::VisibilityKind::Public | |
| hir::VisibilityKind::Crate(_) | |
| hir::VisibilityKind::Inherited => { |
| *vis = respan(prefix.span.shrink_to_lo(), hir::VisibilityKind::Inherited); |
| } |
| hir::VisibilityKind::Restricted { .. } => { |
| // Do nothing here, as described in the comment on the match. |
| } |
| } |
| |
| let def = self.expect_full_def_from_use(id).next().unwrap_or(Def::Err); |
| let path = P(self.lower_path_extra(def, &prefix, ParamMode::Explicit, None)); |
| hir::ItemKind::Use(path, hir::UseKind::ListStem) |
| } |
| } |
| } |
| |
| /// Paths like the visibility path in `pub(super) use foo::{bar, baz}` are repeated |
| /// many times in the HIR tree; for each occurrence, we need to assign distinct |
| /// node-ids. (See e.g., #56128.) |
| fn renumber_segment_ids(&mut self, path: &P<hir::Path>) -> P<hir::Path> { |
| debug!("renumber_segment_ids(path = {:?})", path); |
| let mut path = path.clone(); |
| for seg in path.segments.iter_mut() { |
| if seg.id.is_some() { |
| seg.id = Some(self.next_id().node_id); |
| } |
| } |
| path |
| } |
| |
| fn lower_trait_item(&mut self, i: &TraitItem) -> hir::TraitItem { |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id); |
| let trait_item_def_id = self.resolver.definitions().local_def_id(node_id); |
| |
| let (generics, node) = match i.node { |
| TraitItemKind::Const(ref ty, ref default) => ( |
| self.lower_generics(&i.generics, ImplTraitContext::disallowed()), |
| hir::TraitItemKind::Const( |
| self.lower_ty(ty, ImplTraitContext::disallowed()), |
| default |
| .as_ref() |
| .map(|x| self.lower_body(None, |this| this.lower_expr(x))), |
| ), |
| ), |
| TraitItemKind::Method(ref sig, None) => { |
| let names = self.lower_fn_args_to_names(&sig.decl); |
| let (generics, sig) = self.lower_method_sig( |
| &i.generics, |
| sig, |
| trait_item_def_id, |
| false, |
| None, |
| ); |
| (generics, hir::TraitItemKind::Method(sig, hir::TraitMethod::Required(names))) |
| } |
| TraitItemKind::Method(ref sig, Some(ref body)) => { |
| let body_id = self.lower_body(Some(&sig.decl), |this| { |
| let body = this.lower_block(body, false); |
| this.expr_block(body, ThinVec::new()) |
| }); |
| let (generics, sig) = self.lower_method_sig( |
| &i.generics, |
| sig, |
| trait_item_def_id, |
| false, |
| None, |
| ); |
| (generics, hir::TraitItemKind::Method(sig, hir::TraitMethod::Provided(body_id))) |
| } |
| TraitItemKind::Type(ref bounds, ref default) => ( |
| self.lower_generics(&i.generics, ImplTraitContext::disallowed()), |
| hir::TraitItemKind::Type( |
| self.lower_param_bounds(bounds, ImplTraitContext::disallowed()), |
| default |
| .as_ref() |
| .map(|x| self.lower_ty(x, ImplTraitContext::disallowed())), |
| ), |
| ), |
| TraitItemKind::Macro(..) => panic!("Shouldn't exist any more"), |
| }; |
| |
| hir::TraitItem { |
| id: node_id, |
| hir_id, |
| ident: i.ident, |
| attrs: self.lower_attrs(&i.attrs), |
| generics, |
| node, |
| span: i.span, |
| } |
| } |
| |
| fn lower_trait_item_ref(&mut self, i: &TraitItem) -> hir::TraitItemRef { |
| let (kind, has_default) = match i.node { |
| TraitItemKind::Const(_, ref default) => { |
| (hir::AssociatedItemKind::Const, default.is_some()) |
| } |
| TraitItemKind::Type(_, ref default) => { |
| (hir::AssociatedItemKind::Type, default.is_some()) |
| } |
| TraitItemKind::Method(ref sig, ref default) => ( |
| hir::AssociatedItemKind::Method { |
| has_self: sig.decl.has_self(), |
| }, |
| default.is_some(), |
| ), |
| TraitItemKind::Macro(..) => unimplemented!(), |
| }; |
| hir::TraitItemRef { |
| id: hir::TraitItemId { node_id: i.id }, |
| ident: i.ident, |
| span: i.span, |
| defaultness: self.lower_defaultness(Defaultness::Default, has_default), |
| kind, |
| } |
| } |
| |
| fn lower_impl_item(&mut self, i: &ImplItem) -> hir::ImplItem { |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id); |
| let impl_item_def_id = self.resolver.definitions().local_def_id(node_id); |
| |
| let (generics, node) = match i.node { |
| ImplItemKind::Const(ref ty, ref expr) => { |
| let body_id = self.lower_body(None, |this| this.lower_expr(expr)); |
| ( |
| self.lower_generics(&i.generics, ImplTraitContext::disallowed()), |
| hir::ImplItemKind::Const( |
| self.lower_ty(ty, ImplTraitContext::disallowed()), |
| body_id, |
| ), |
| ) |
| } |
| ImplItemKind::Method(ref sig, ref body) => { |
| let body_id = self.lower_async_body(&sig.decl, sig.header.asyncness, body); |
| let impl_trait_return_allow = !self.is_in_trait_impl; |
| let (generics, sig) = self.lower_method_sig( |
| &i.generics, |
| sig, |
| impl_item_def_id, |
| impl_trait_return_allow, |
| sig.header.asyncness.opt_return_id(), |
| ); |
| (generics, hir::ImplItemKind::Method(sig, body_id)) |
| } |
| ImplItemKind::Type(ref ty) => ( |
| self.lower_generics(&i.generics, ImplTraitContext::disallowed()), |
| hir::ImplItemKind::Type(self.lower_ty(ty, ImplTraitContext::disallowed())), |
| ), |
| ImplItemKind::Existential(ref bounds) => ( |
| self.lower_generics(&i.generics, ImplTraitContext::disallowed()), |
| hir::ImplItemKind::Existential( |
| self.lower_param_bounds(bounds, ImplTraitContext::disallowed()), |
| ), |
| ), |
| ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"), |
| }; |
| |
| hir::ImplItem { |
| id: node_id, |
| hir_id, |
| ident: i.ident, |
| attrs: self.lower_attrs(&i.attrs), |
| generics, |
| vis: self.lower_visibility(&i.vis, None), |
| defaultness: self.lower_defaultness(i.defaultness, true /* [1] */), |
| node, |
| span: i.span, |
| } |
| |
| // [1] since `default impl` is not yet implemented, this is always true in impls |
| } |
| |
| fn lower_impl_item_ref(&mut self, i: &ImplItem) -> hir::ImplItemRef { |
| hir::ImplItemRef { |
| id: hir::ImplItemId { node_id: i.id }, |
| ident: i.ident, |
| span: i.span, |
| vis: self.lower_visibility(&i.vis, Some(i.id)), |
| defaultness: self.lower_defaultness(i.defaultness, true /* [1] */), |
| kind: match i.node { |
| ImplItemKind::Const(..) => hir::AssociatedItemKind::Const, |
| ImplItemKind::Type(..) => hir::AssociatedItemKind::Type, |
| ImplItemKind::Existential(..) => hir::AssociatedItemKind::Existential, |
| ImplItemKind::Method(ref sig, _) => hir::AssociatedItemKind::Method { |
| has_self: sig.decl.has_self(), |
| }, |
| ImplItemKind::Macro(..) => unimplemented!(), |
| }, |
| } |
| |
| // [1] since `default impl` is not yet implemented, this is always true in impls |
| } |
| |
| fn lower_mod(&mut self, m: &Mod) -> hir::Mod { |
| hir::Mod { |
| inner: m.inner, |
| item_ids: m.items.iter().flat_map(|x| self.lower_item_id(x)).collect(), |
| } |
| } |
| |
| fn lower_item_id(&mut self, i: &Item) -> SmallVec<[hir::ItemId; 1]> { |
| match i.node { |
| ItemKind::Use(ref use_tree) => { |
| let mut vec = smallvec![hir::ItemId { id: i.id }]; |
| self.lower_item_id_use_tree(use_tree, i.id, &mut vec); |
| vec |
| } |
| ItemKind::MacroDef(..) => SmallVec::new(), |
| ItemKind::Fn(..) | |
| ItemKind::Impl(.., None, _, _) => smallvec![hir::ItemId { id: i.id }], |
| ItemKind::Static(ref ty, ..) => { |
| let mut ids = smallvec![hir::ItemId { id: i.id }]; |
| if self.sess.features_untracked().impl_trait_in_bindings { |
| let mut visitor = ImplTraitTypeIdVisitor { ids: &mut ids }; |
| visitor.visit_ty(ty); |
| } |
| ids |
| }, |
| ItemKind::Const(ref ty, ..) => { |
| let mut ids = smallvec![hir::ItemId { id: i.id }]; |
| if self.sess.features_untracked().impl_trait_in_bindings { |
| let mut visitor = ImplTraitTypeIdVisitor { ids: &mut ids }; |
| visitor.visit_ty(ty); |
| } |
| ids |
| }, |
| _ => smallvec![hir::ItemId { id: i.id }], |
| } |
| } |
| |
| fn lower_item_id_use_tree(&mut self, |
| tree: &UseTree, |
| base_id: NodeId, |
| vec: &mut SmallVec<[hir::ItemId; 1]>) |
| { |
| match tree.kind { |
| UseTreeKind::Nested(ref nested_vec) => for &(ref nested, id) in nested_vec { |
| vec.push(hir::ItemId { id }); |
| self.lower_item_id_use_tree(nested, id, vec); |
| }, |
| UseTreeKind::Glob => {} |
| UseTreeKind::Simple(_, id1, id2) => { |
| for (_, &id) in self.expect_full_def_from_use(base_id) |
| .skip(1) |
| .zip([id1, id2].iter()) |
| { |
| vec.push(hir::ItemId { id }); |
| } |
| }, |
| } |
| } |
| |
| pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> { |
| let mut ident = i.ident; |
| let mut vis = self.lower_visibility(&i.vis, None); |
| let attrs = self.lower_attrs(&i.attrs); |
| if let ItemKind::MacroDef(ref def) = i.node { |
| if !def.legacy || attr::contains_name(&i.attrs, "macro_export") || |
| attr::contains_name(&i.attrs, "rustc_doc_only_macro") { |
| let body = self.lower_token_stream(def.stream()); |
| self.exported_macros.push(hir::MacroDef { |
| name: ident.name, |
| vis, |
| attrs, |
| id: i.id, |
| span: i.span, |
| body, |
| legacy: def.legacy, |
| }); |
| } |
| return None; |
| } |
| |
| let node = self.lower_item_kind(i.id, &mut ident, &attrs, &mut vis, &i.node); |
| |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id); |
| |
| Some(hir::Item { |
| id: node_id, |
| hir_id, |
| ident, |
| attrs, |
| node, |
| vis, |
| span: i.span, |
| }) |
| } |
| |
| fn lower_foreign_item(&mut self, i: &ForeignItem) -> hir::ForeignItem { |
| let node_id = self.lower_node_id(i.id).node_id; |
| let def_id = self.resolver.definitions().local_def_id(node_id); |
| hir::ForeignItem { |
| id: node_id, |
| ident: i.ident, |
| attrs: self.lower_attrs(&i.attrs), |
| node: match i.node { |
| ForeignItemKind::Fn(ref fdec, ref generics) => { |
| let (generics, (fn_dec, fn_args)) = self.add_in_band_defs( |
| generics, |
| def_id, |
| AnonymousLifetimeMode::PassThrough, |
| |this, _| { |
| ( |
| // Disallow impl Trait in foreign items |
| this.lower_fn_decl(fdec, None, false, None), |
| this.lower_fn_args_to_names(fdec), |
| ) |
| }, |
| ); |
| |
| hir::ForeignItemKind::Fn(fn_dec, fn_args, generics) |
| } |
| ForeignItemKind::Static(ref t, m) => { |
| hir::ForeignItemKind::Static( |
| self.lower_ty(t, ImplTraitContext::disallowed()), m) |
| } |
| ForeignItemKind::Ty => hir::ForeignItemKind::Type, |
| ForeignItemKind::Macro(_) => panic!("shouldn't exist here"), |
| }, |
| vis: self.lower_visibility(&i.vis, None), |
| span: i.span, |
| } |
| } |
| |
| fn lower_method_sig( |
| &mut self, |
| generics: &Generics, |
| sig: &MethodSig, |
| fn_def_id: DefId, |
| impl_trait_return_allow: bool, |
| is_async: Option<NodeId>, |
| ) -> (hir::Generics, hir::MethodSig) { |
| let header = self.lower_fn_header(sig.header); |
| let (generics, decl) = self.add_in_band_defs( |
| generics, |
| fn_def_id, |
| AnonymousLifetimeMode::PassThrough, |
| |this, idty| this.lower_fn_decl( |
| &sig.decl, |
| Some((fn_def_id, idty)), |
| impl_trait_return_allow, |
| is_async, |
| ), |
| ); |
| (generics, hir::MethodSig { header, decl }) |
| } |
| |
| fn lower_is_auto(&mut self, a: IsAuto) -> hir::IsAuto { |
| match a { |
| IsAuto::Yes => hir::IsAuto::Yes, |
| IsAuto::No => hir::IsAuto::No, |
| } |
| } |
| |
| fn lower_fn_header(&mut self, h: FnHeader) -> hir::FnHeader { |
| hir::FnHeader { |
| unsafety: self.lower_unsafety(h.unsafety), |
| asyncness: self.lower_asyncness(h.asyncness), |
| constness: self.lower_constness(h.constness), |
| abi: h.abi, |
| } |
| } |
| |
| fn lower_unsafety(&mut self, u: Unsafety) -> hir::Unsafety { |
| match u { |
| Unsafety::Unsafe => hir::Unsafety::Unsafe, |
| Unsafety::Normal => hir::Unsafety::Normal, |
| } |
| } |
| |
| fn lower_constness(&mut self, c: Spanned<Constness>) -> hir::Constness { |
| match c.node { |
| Constness::Const => hir::Constness::Const, |
| Constness::NotConst => hir::Constness::NotConst, |
| } |
| } |
| |
| fn lower_asyncness(&mut self, a: IsAsync) -> hir::IsAsync { |
| match a { |
| IsAsync::Async { .. } => hir::IsAsync::Async, |
| IsAsync::NotAsync => hir::IsAsync::NotAsync, |
| } |
| } |
| |
| fn lower_unop(&mut self, u: UnOp) -> hir::UnOp { |
| match u { |
| UnOp::Deref => hir::UnDeref, |
| UnOp::Not => hir::UnNot, |
| UnOp::Neg => hir::UnNeg, |
| } |
| } |
| |
| fn lower_binop(&mut self, b: BinOp) -> hir::BinOp { |
| Spanned { |
| node: match b.node { |
| BinOpKind::Add => hir::BinOpKind::Add, |
| BinOpKind::Sub => hir::BinOpKind::Sub, |
| BinOpKind::Mul => hir::BinOpKind::Mul, |
| BinOpKind::Div => hir::BinOpKind::Div, |
| BinOpKind::Rem => hir::BinOpKind::Rem, |
| BinOpKind::And => hir::BinOpKind::And, |
| BinOpKind::Or => hir::BinOpKind::Or, |
| BinOpKind::BitXor => hir::BinOpKind::BitXor, |
| BinOpKind::BitAnd => hir::BinOpKind::BitAnd, |
| BinOpKind::BitOr => hir::BinOpKind::BitOr, |
| BinOpKind::Shl => hir::BinOpKind::Shl, |
| BinOpKind::Shr => hir::BinOpKind::Shr, |
| BinOpKind::Eq => hir::BinOpKind::Eq, |
| BinOpKind::Lt => hir::BinOpKind::Lt, |
| BinOpKind::Le => hir::BinOpKind::Le, |
| BinOpKind::Ne => hir::BinOpKind::Ne, |
| BinOpKind::Ge => hir::BinOpKind::Ge, |
| BinOpKind::Gt => hir::BinOpKind::Gt, |
| }, |
| span: b.span, |
| } |
| } |
| |
| fn lower_pat(&mut self, p: &Pat) -> P<hir::Pat> { |
| let node = match p.node { |
| PatKind::Wild => hir::PatKind::Wild, |
| PatKind::Ident(ref binding_mode, ident, ref sub) => { |
| match self.resolver.get_resolution(p.id).map(|d| d.base_def()) { |
| // `None` can occur in body-less function signatures |
| def @ None | def @ Some(Def::Local(_)) => { |
| let canonical_id = match def { |
| Some(Def::Local(id)) => id, |
| _ => p.id, |
| }; |
| hir::PatKind::Binding( |
| self.lower_binding_mode(binding_mode), |
| canonical_id, |
| ident, |
| sub.as_ref().map(|x| self.lower_pat(x)), |
| ) |
| } |
| Some(def) => hir::PatKind::Path(hir::QPath::Resolved( |
| None, |
| P(hir::Path { |
| span: ident.span, |
| def, |
| segments: hir_vec![hir::PathSegment::from_ident(ident)], |
| }), |
| )), |
| } |
| } |
| PatKind::Lit(ref e) => hir::PatKind::Lit(P(self.lower_expr(e))), |
| PatKind::TupleStruct(ref path, ref pats, ddpos) => { |
| let qpath = self.lower_qpath( |
| p.id, |
| &None, |
| path, |
| ParamMode::Optional, |
| ImplTraitContext::disallowed(), |
| ); |
| hir::PatKind::TupleStruct( |
| qpath, |
| pats.iter().map(|x| self.lower_pat(x)).collect(), |
| ddpos, |
| ) |
| } |
| 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 = fields |
| .iter() |
| .map(|f| Spanned { |
| span: f.span, |
| node: hir::FieldPat { |
| id: self.next_id().node_id, |
| ident: f.node.ident, |
| pat: self.lower_pat(&f.node.pat), |
| is_shorthand: f.node.is_shorthand, |
| }, |
| }) |
| .collect(); |
| hir::PatKind::Struct(qpath, fs, etc) |
| } |
| PatKind::Tuple(ref elts, ddpos) => { |
| hir::PatKind::Tuple(elts.iter().map(|x| self.lower_pat(x)).collect(), ddpos) |
| } |
| PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)), |
| PatKind::Ref(ref inner, mutbl) => { |
| hir::PatKind::Ref(self.lower_pat(inner), self.lower_mutability(mutbl)) |
| } |
| PatKind::Range(ref e1, ref e2, Spanned { node: ref end, .. }) => hir::PatKind::Range( |
| P(self.lower_expr(e1)), |
| P(self.lower_expr(e2)), |
| self.lower_range_end(end), |
| ), |
| PatKind::Slice(ref before, ref slice, ref after) => hir::PatKind::Slice( |
| before.iter().map(|x| self.lower_pat(x)).collect(), |
| slice.as_ref().map(|x| self.lower_pat(x)), |
| after.iter().map(|x| self.lower_pat(x)).collect(), |
| ), |
| PatKind::Paren(ref inner) => return self.lower_pat(inner), |
| PatKind::Mac(_) => panic!("Shouldn't exist here"), |
| }; |
| |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(p.id); |
| P(hir::Pat { |
| id: node_id, |
| hir_id, |
| node, |
| span: p.span, |
| }) |
| } |
| |
| 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| { |
| let LoweredNodeId { node_id, hir_id } = this.lower_node_id(c.id); |
| hir::AnonConst { |
| id: node_id, |
| hir_id, |
| body: this.lower_body(None, |this| this.lower_expr(&c.value)), |
| } |
| }) |
| } |
| |
| fn lower_expr(&mut self, e: &Expr) -> hir::Expr { |
| let kind = match e.node { |
| ExprKind::Box(ref inner) => hir::ExprKind::Box(P(self.lower_expr(inner))), |
| ExprKind::ObsoleteInPlace(..) => { |
| self.sess.abort_if_errors(); |
| span_bug!(e.span, "encountered ObsoleteInPlace expr during lowering"); |
| } |
| ExprKind::Array(ref exprs) => { |
| hir::ExprKind::Array(exprs.iter().map(|x| self.lower_expr(x)).collect()) |
| } |
| ExprKind::Repeat(ref expr, ref count) => { |
| let expr = P(self.lower_expr(expr)); |
| let count = self.lower_anon_const(count); |
| hir::ExprKind::Repeat(expr, count) |
| } |
| ExprKind::Tup(ref elts) => { |
| hir::ExprKind::Tup(elts.iter().map(|x| self.lower_expr(x)).collect()) |
| } |
| ExprKind::Call(ref f, ref args) => { |
| let f = P(self.lower_expr(f)); |
| hir::ExprKind::Call(f, args.iter().map(|x| self.lower_expr(x)).collect()) |
| } |
| ExprKind::MethodCall(ref seg, ref args) => { |
| let hir_seg = self.lower_path_segment( |
| e.span, |
| seg, |
| ParamMode::Optional, |
| 0, |
| ParenthesizedGenericArgs::Err, |
| ImplTraitContext::disallowed(), |
| None, |
| ); |
| let args = args.iter().map(|x| self.lower_expr(x)).collect(); |
| hir::ExprKind::MethodCall(hir_seg, seg.ident.span, args) |
| } |
| ExprKind::Binary(binop, ref lhs, ref rhs) => { |
| let binop = self.lower_binop(binop); |
| let lhs = P(self.lower_expr(lhs)); |
| let rhs = P(self.lower_expr(rhs)); |
| hir::ExprKind::Binary(binop, lhs, rhs) |
| } |
| ExprKind::Unary(op, ref ohs) => { |
| let op = self.lower_unop(op); |
| let ohs = P(self.lower_expr(ohs)); |
| hir::ExprKind::Unary(op, ohs) |
| } |
| ExprKind::Lit(ref l) => hir::ExprKind::Lit(P((*l).clone())), |
| ExprKind::Cast(ref expr, ref ty) => { |
| let expr = P(self.lower_expr(expr)); |
| hir::ExprKind::Cast(expr, self.lower_ty(ty, ImplTraitContext::disallowed())) |
| } |
| ExprKind::Type(ref expr, ref ty) => { |
| let expr = P(self.lower_expr(expr)); |
| hir::ExprKind::Type(expr, self.lower_ty(ty, ImplTraitContext::disallowed())) |
| } |
| ExprKind::AddrOf(m, ref ohs) => { |
| let m = self.lower_mutability(m); |
| let ohs = P(self.lower_expr(ohs)); |
| hir::ExprKind::AddrOf(m, ohs) |
| } |
| // More complicated than you might expect because the else branch |
| // might be `if let`. |
| ExprKind::If(ref cond, ref blk, ref else_opt) => { |
| let else_opt = else_opt.as_ref().map(|els| { |
| match els.node { |
| ExprKind::IfLet(..) => { |
| // Wrap the `if let` expr in a block. |
| let span = els.span; |
| let els = P(self.lower_expr(els)); |
| let LoweredNodeId { node_id, hir_id } = self.next_id(); |
| let blk = P(hir::Block { |
| stmts: hir_vec![], |
| expr: Some(els), |
| id: node_id, |
| hir_id, |
| rules: hir::DefaultBlock, |
| span, |
| targeted_by_break: false, |
| }); |
| P(self.expr_block(blk, ThinVec::new())) |
| } |
| _ => P(self.lower_expr(els)), |
| } |
| }); |
| |
| let then_blk = self.lower_block(blk, false); |
| let then_expr = self.expr_block(then_blk, ThinVec::new()); |
| |
| hir::ExprKind::If(P(self.lower_expr(cond)), P(then_expr), else_opt) |
| } |
| ExprKind::While(ref cond, ref body, opt_label) => self.with_loop_scope(e.id, |this| { |
| hir::ExprKind::While( |
| this.with_loop_condition_scope(|this| P(this.lower_expr(cond))), |
| this.lower_block(body, false), |
| this.lower_label(opt_label), |
| ) |
| }), |
| ExprKind::Loop(ref body, opt_label) => self.with_loop_scope(e.id, |this| { |
| hir::ExprKind::Loop( |
| this.lower_block(body, false), |
| this.lower_label(opt_label), |
| hir::LoopSource::Loop, |
| ) |
| }), |
| ExprKind::TryBlock(ref body) => { |
| self.with_catch_scope(body.id, |this| { |
| let unstable_span = |
| this.allow_internal_unstable(CompilerDesugaringKind::TryBlock, body.span); |
| let mut block = this.lower_block(body, true).into_inner(); |
| let tail = block.expr.take().map_or_else( |
| || { |
| let LoweredNodeId { node_id, hir_id } = this.next_id(); |
| let span = this.sess.source_map().end_point(unstable_span); |
| hir::Expr { |
| id: node_id, |
| span, |
| node: hir::ExprKind::Tup(hir_vec![]), |
| attrs: ThinVec::new(), |
| hir_id, |
| } |
| }, |
| |x: P<hir::Expr>| x.into_inner(), |
| ); |
| block.expr = Some(this.wrap_in_try_constructor( |
| "from_ok", tail, unstable_span)); |
| hir::ExprKind::Block(P(block), None) |
| }) |
| } |
| ExprKind::Match(ref expr, ref arms) => hir::ExprKind::Match( |
| P(self.lower_expr(expr)), |
| arms.iter().map(|x| self.lower_arm(x)).collect(), |
| hir::MatchSource::Normal, |
| ), |
| ExprKind::Async(capture_clause, closure_node_id, ref block) => { |
| self.make_async_expr(capture_clause, closure_node_id, None, |this| { |
| this.with_new_scopes(|this| { |
| let block = this.lower_block(block, false); |
| this.expr_block(block, ThinVec::new()) |
| }) |
| }) |
| } |
| ExprKind::Closure( |
| capture_clause, asyncness, movability, ref decl, ref body, fn_decl_span |
| ) => { |
| if let IsAsync::Async { closure_id, .. } = asyncness { |
| let outer_decl = FnDecl { |
| inputs: decl.inputs.clone(), |
| output: FunctionRetTy::Default(fn_decl_span), |
| variadic: false, |
| }; |
| // We need to lower the declaration outside the new scope, because we |
| // have to conserve the state of being inside a loop condition for the |
| // closure argument types. |
| let fn_decl = self.lower_fn_decl(&outer_decl, None, false, None); |
| |
| self.with_new_scopes(|this| { |
| // FIXME(cramertj): allow `async` non-`move` closures with arguments. |
| if capture_clause == CaptureBy::Ref && |
| !decl.inputs.is_empty() |
| { |
| struct_span_err!( |
| this.sess, |
| fn_decl_span, |
| E0708, |
| "`async` non-`move` closures with arguments \ |
| are not currently supported", |
| ) |
| .help("consider using `let` statements to manually capture \ |
| variables by reference before entering an \ |
| `async move` closure") |
| .emit(); |
| } |
| |
| // Transform `async |x: u8| -> X { ... }` into |
| // `|x: u8| future_from_generator(|| -> X { ... })`. |
| let body_id = this.lower_body(Some(&outer_decl), |this| { |
| let async_ret_ty = if let FunctionRetTy::Ty(ty) = &decl.output { |
| Some(&**ty) |
| } else { None }; |
| let async_body = this.make_async_expr( |
| capture_clause, closure_id, async_ret_ty, |
| |this| { |
| this.with_new_scopes(|this| this.lower_expr(body)) |
| }); |
| this.expr(fn_decl_span, async_body, ThinVec::new()) |
| }); |
| hir::ExprKind::Closure( |
| this.lower_capture_clause(capture_clause), |
| fn_decl, |
| body_id, |
| fn_decl_span, |
| None, |
| ) |
| }) |
| } else { |
| // Lower outside new scope to preserve `is_in_loop_condition`. |
| let fn_decl = self.lower_fn_decl(decl, None, false, None); |
| |
| self.with_new_scopes(|this| { |
| let mut is_generator = false; |
| let body_id = this.lower_body(Some(decl), |this| { |
| let e = this.lower_expr(body); |
| is_generator = this.is_generator; |
| e |
| }); |
| let generator_option = if is_generator { |
| if !decl.inputs.is_empty() { |
| span_err!( |
| this.sess, |
| fn_decl_span, |
| E0628, |
| "generators cannot have explicit arguments" |
| ); |
| this.sess.abort_if_errors(); |
| } |
| Some(match movability { |
| Movability::Movable => hir::GeneratorMovability::Movable, |
| Movability::Static => hir::GeneratorMovability::Static, |
| }) |
| } else { |
| if movability == Movability::Static { |
| span_err!( |
| this.sess, |
| fn_decl_span, |
| E0697, |
| "closures cannot be static" |
| ); |
| } |
| None |
| }; |
| hir::ExprKind::Closure( |
| this.lower_capture_clause(capture_clause), |
| fn_decl, |
| body_id, |
| fn_decl_span, |
| generator_option, |
| ) |
| }) |
| } |
| } |
| ExprKind::Block(ref blk, opt_label) => { |
| hir::ExprKind::Block(self.lower_block(blk, |
| opt_label.is_some()), |
| self.lower_label(opt_label)) |
| } |
| ExprKind::Assign(ref el, ref er) => { |
| hir::ExprKind::Assign(P(self.lower_expr(el)), P(self.lower_expr(er))) |
| } |
| ExprKind::AssignOp(op, ref el, ref er) => hir::ExprKind::AssignOp( |
| self.lower_binop(op), |
| P(self.lower_expr(el)), |
| P(self.lower_expr(er)), |
| ), |
| ExprKind::Field(ref el, ident) => hir::ExprKind::Field(P(self.lower_expr(el)), ident), |
| ExprKind::Index(ref el, ref er) => { |
| hir::ExprKind::Index(P(self.lower_expr(el)), P(self.lower_expr(er))) |
| } |
| // Desugar `<start>..=<end>` into `std::ops::RangeInclusive::new(<start>, <end>)`. |
| ExprKind::Range(Some(ref e1), Some(ref e2), RangeLimits::Closed) => { |
| let id = self.next_id(); |
| let e1 = self.lower_expr(e1); |
| let e2 = self.lower_expr(e2); |
| let ty_path = P(self.std_path(e.span, &["ops", "RangeInclusive"], None, false)); |
| let ty = P(self.ty_path(id, e.span, hir::QPath::Resolved(None, ty_path))); |
| let new_seg = P(hir::PathSegment::from_ident(Ident::from_str("new"))); |
| let new_path = hir::QPath::TypeRelative(ty, new_seg); |
| let new = P(self.expr(e.span, hir::ExprKind::Path(new_path), ThinVec::new())); |
| hir::ExprKind::Call(new, hir_vec![e1, e2]) |
| } |
| ExprKind::Range(ref e1, ref e2, lims) => { |
| use syntax::ast::RangeLimits::*; |
| |
| let path = match (e1, e2, lims) { |
| (&None, &None, HalfOpen) => "RangeFull", |
| (&Some(..), &None, HalfOpen) => "RangeFrom", |
| (&None, &Some(..), HalfOpen) => "RangeTo", |
| (&Some(..), &Some(..), HalfOpen) => "Range", |
| (&None, &Some(..), Closed) => "RangeToInclusive", |
| (&Some(..), &Some(..), Closed) => unreachable!(), |
| (_, &None, Closed) => self.diagnostic() |
| .span_fatal(e.span, "inclusive range with no end") |
| .raise(), |
| }; |
| |
| let fields = e1.iter() |
| .map(|e| ("start", e)) |
| .chain(e2.iter().map(|e| ("end", e))) |
| .map(|(s, e)| { |
| let expr = P(self.lower_expr(&e)); |
| let ident = Ident::new(Symbol::intern(s), e.span); |
| self.field(ident, expr, e.span) |
| }) |
| .collect::<P<[hir::Field]>>(); |
| |
| let is_unit = fields.is_empty(); |
| let struct_path = ["ops", path]; |
| let struct_path = self.std_path(e.span, &struct_path, None, is_unit); |
| let struct_path = hir::QPath::Resolved(None, P(struct_path)); |
| |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id); |
| |
| return hir::Expr { |
| id: node_id, |
| hir_id, |
| node: if is_unit { |
| hir::ExprKind::Path(struct_path) |
| } else { |
| hir::ExprKind::Struct(struct_path, fields, None) |
| }, |
| span: e.span, |
| attrs: e.attrs.clone(), |
| }; |
| } |
| ExprKind::Path(ref qself, ref path) => { |
| let qpath = self.lower_qpath( |
| e.id, |
| qself, |
| path, |
| ParamMode::Optional, |
| ImplTraitContext::disallowed(), |
| ); |
| hir::ExprKind::Path(qpath) |
| } |
| ExprKind::Break(opt_label, ref opt_expr) => { |
| let destination = if self.is_in_loop_condition && opt_label.is_none() { |
| hir::Destination { |
| label: None, |
| target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into(), |
| } |
| } else { |
| self.lower_loop_destination(opt_label.map(|label| (e.id, label))) |
| }; |
| hir::ExprKind::Break( |
| destination, |
| opt_expr.as_ref().map(|x| P(self.lower_expr(x))), |
| ) |
| } |
| ExprKind::Continue(opt_label) => { |
| hir::ExprKind::Continue(if self.is_in_loop_condition && opt_label.is_none() { |
| hir::Destination { |
| label: None, |
| target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition).into(), |
| } |
| } else { |
| self.lower_loop_destination(opt_label.map(|label| (e.id, label))) |
| }) |
| } |
| ExprKind::Ret(ref e) => hir::ExprKind::Ret(e.as_ref().map(|x| P(self.lower_expr(x)))), |
| ExprKind::InlineAsm(ref asm) => { |
| let hir_asm = hir::InlineAsm { |
| inputs: asm.inputs.iter().map(|&(ref c, _)| c.clone()).collect(), |
| outputs: asm.outputs |
| .iter() |
| .map(|out| hir::InlineAsmOutput { |
| constraint: out.constraint.clone(), |
| is_rw: out.is_rw, |
| is_indirect: out.is_indirect, |
| span: out.expr.span, |
| }) |
| .collect(), |
| asm: asm.asm.clone(), |
| asm_str_style: asm.asm_str_style, |
| clobbers: asm.clobbers.clone().into(), |
| volatile: asm.volatile, |
| alignstack: asm.alignstack, |
| dialect: asm.dialect, |
| ctxt: asm.ctxt, |
| }; |
| let outputs = asm.outputs |
| .iter() |
| .map(|out| self.lower_expr(&out.expr)) |
| .collect(); |
| let inputs = asm.inputs |
| .iter() |
| .map(|&(_, ref input)| self.lower_expr(input)) |
| .collect(); |
| hir::ExprKind::InlineAsm(P(hir_asm), outputs, inputs) |
| } |
| ExprKind::Struct(ref path, ref fields, ref maybe_expr) => hir::ExprKind::Struct( |
| self.lower_qpath( |
| e.id, |
| &None, |
| path, |
| ParamMode::Optional, |
| ImplTraitContext::disallowed(), |
| ), |
| fields.iter().map(|x| self.lower_field(x)).collect(), |
| maybe_expr.as_ref().map(|x| P(self.lower_expr(x))), |
| ), |
| ExprKind::Paren(ref ex) => { |
| let mut ex = self.lower_expr(ex); |
| // Include parens in span, but only if it is a super-span. |
| if e.span.contains(ex.span) { |
| ex.span = e.span; |
| } |
| // Merge attributes into the inner expression. |
| let mut attrs = e.attrs.clone(); |
| attrs.extend::<Vec<_>>(ex.attrs.into()); |
| ex.attrs = attrs; |
| return ex; |
| } |
| |
| ExprKind::Yield(ref opt_expr) => { |
| self.is_generator = true; |
| let expr = opt_expr |
| .as_ref() |
| .map(|x| self.lower_expr(x)) |
| .unwrap_or_else(|| |
| self.expr(e.span, hir::ExprKind::Tup(hir_vec![]), ThinVec::new()) |
| ); |
| hir::ExprKind::Yield(P(expr)) |
| } |
| |
| ExprKind::Err => hir::ExprKind::Err, |
| |
| // Desugar `ExprIfLet` |
| // from: `if let <pat> = <sub_expr> <body> [<else_opt>]` |
| ExprKind::IfLet(ref pats, ref sub_expr, ref body, ref else_opt) => { |
| // to: |
| // |
| // match <sub_expr> { |
| // <pat> => <body>, |
| // _ => [<else_opt> | ()] |
| // } |
| |
| let mut arms = vec![]; |
| |
| // `<pat> => <body>` |
| { |
| let body = self.lower_block(body, false); |
| let body_expr = P(self.expr_block(body, ThinVec::new())); |
| let pats = pats.iter().map(|pat| self.lower_pat(pat)).collect(); |
| arms.push(self.arm(pats, body_expr)); |
| } |
| |
| // _ => [<else_opt>|()] |
| { |
| let wildcard_arm: Option<&Expr> = else_opt.as_ref().map(|p| &**p); |
| let wildcard_pattern = self.pat_wild(e.span); |
| let body = if let Some(else_expr) = wildcard_arm { |
| P(self.lower_expr(else_expr)) |
| } else { |
| self.expr_tuple(e.span, hir_vec![]) |
| }; |
| arms.push(self.arm(hir_vec![wildcard_pattern], body)); |
| } |
| |
| let contains_else_clause = else_opt.is_some(); |
| |
| let sub_expr = P(self.lower_expr(sub_expr)); |
| |
| hir::ExprKind::Match( |
| sub_expr, |
| arms.into(), |
| hir::MatchSource::IfLetDesugar { |
| contains_else_clause, |
| }, |
| ) |
| } |
| |
| // Desugar `ExprWhileLet` |
| // from: `[opt_ident]: while let <pat> = <sub_expr> <body>` |
| ExprKind::WhileLet(ref pats, ref sub_expr, ref body, opt_label) => { |
| // to: |
| // |
| // [opt_ident]: loop { |
| // match <sub_expr> { |
| // <pat> => <body>, |
| // _ => break |
| // } |
| // } |
| |
| // Note that the block AND the condition are evaluated in the loop scope. |
| // This is done to allow `break` from inside the condition of the loop. |
| let (body, break_expr, sub_expr) = self.with_loop_scope(e.id, |this| { |
| ( |
| this.lower_block(body, false), |
| this.expr_break(e.span, ThinVec::new()), |
| this.with_loop_condition_scope(|this| P(this.lower_expr(sub_expr))), |
| ) |
| }); |
| |
| // `<pat> => <body>` |
| let pat_arm = { |
| let body_expr = P(self.expr_block(body, ThinVec::new())); |
| let pats = pats.iter().map(|pat| self.lower_pat(pat)).collect(); |
| self.arm(pats, body_expr) |
| }; |
| |
| // `_ => break` |
| let break_arm = { |
| let pat_under = self.pat_wild(e.span); |
| self.arm(hir_vec![pat_under], break_expr) |
| }; |
| |
| // `match <sub_expr> { ... }` |
| let arms = hir_vec![pat_arm, break_arm]; |
| let match_expr = self.expr( |
| sub_expr.span, |
| hir::ExprKind::Match(sub_expr, arms, hir::MatchSource::WhileLetDesugar), |
| ThinVec::new(), |
| ); |
| |
| // `[opt_ident]: loop { ... }` |
| let loop_block = P(self.block_expr(P(match_expr))); |
| let loop_expr = hir::ExprKind::Loop( |
| loop_block, |
| self.lower_label(opt_label), |
| hir::LoopSource::WhileLet, |
| ); |
| // Add attributes to the outer returned expr node. |
| loop_expr |
| } |
| |
| // Desugar `ExprForLoop` |
| // from: `[opt_ident]: for <pat> in <head> <body>` |
| ExprKind::ForLoop(ref pat, ref head, ref body, opt_label) => { |
| // to: |
| // |
| // { |
| // let result = match ::std::iter::IntoIterator::into_iter(<head>) { |
| // mut iter => { |
| // [opt_ident]: loop { |
| // let mut __next; |
| // match ::std::iter::Iterator::next(&mut iter) { |
| // ::std::option::Option::Some(val) => __next = val, |
| // ::std::option::Option::None => break |
| // }; |
| // let <pat> = __next; |
| // StmtKind::Expr(<body>); |
| // } |
| // } |
| // }; |
| // result |
| // } |
| |
| // expand <head> |
| let head = self.lower_expr(head); |
| let head_sp = head.span; |
| let desugared_span = self.allow_internal_unstable( |
| CompilerDesugaringKind::ForLoop, |
| head_sp, |
| ); |
| |
| let iter = self.str_to_ident("iter"); |
| |
| let next_ident = self.str_to_ident("__next"); |
| let next_pat = self.pat_ident_binding_mode( |
| desugared_span, |
| next_ident, |
| hir::BindingAnnotation::Mutable, |
| ); |
| |
| // `::std::option::Option::Some(val) => next = val` |
| let pat_arm = { |
| let val_ident = self.str_to_ident("val"); |
| let val_pat = self.pat_ident(pat.span, val_ident); |
| let val_expr = P(self.expr_ident(pat.span, val_ident, val_pat.id)); |
| let next_expr = P(self.expr_ident(pat.span, next_ident, next_pat.id)); |
| let assign = P(self.expr( |
| pat.span, |
| hir::ExprKind::Assign(next_expr, val_expr), |
| ThinVec::new(), |
| )); |
| let some_pat = self.pat_some(pat.span, val_pat); |
| self.arm(hir_vec![some_pat], assign) |
| }; |
| |
| // `::std::option::Option::None => break` |
| let break_arm = { |
| let break_expr = |
| self.with_loop_scope(e.id, |this| this.expr_break(e.span, ThinVec::new())); |
| let pat = self.pat_none(e.span); |
| self.arm(hir_vec![pat], break_expr) |
| }; |
| |
| // `mut iter` |
| let iter_pat = self.pat_ident_binding_mode( |
| desugared_span, |
| iter, |
| hir::BindingAnnotation::Mutable |
| ); |
| |
| // `match ::std::iter::Iterator::next(&mut iter) { ... }` |
| let match_expr = { |
| let iter = P(self.expr_ident(head_sp, iter, iter_pat.id)); |
| let ref_mut_iter = self.expr_mut_addr_of(head_sp, iter); |
| let next_path = &["iter", "Iterator", "next"]; |
| let next_path = P(self.expr_std_path(head_sp, next_path, None, ThinVec::new())); |
| let next_expr = P(self.expr_call(head_sp, next_path, hir_vec![ref_mut_iter])); |
| let arms = hir_vec![pat_arm, break_arm]; |
| |
| P(self.expr( |
| head_sp, |
| hir::ExprKind::Match( |
| next_expr, |
| arms, |
| hir::MatchSource::ForLoopDesugar |
| ), |
| ThinVec::new(), |
| )) |
| }; |
| let match_stmt = respan( |
| head_sp, |
| hir::StmtKind::Expr(match_expr, self.next_id().node_id) |
| ); |
| |
| let next_expr = P(self.expr_ident(head_sp, next_ident, next_pat.id)); |
| |
| // `let mut __next` |
| let next_let = self.stmt_let_pat( |
| desugared_span, |
| None, |
| next_pat, |
| hir::LocalSource::ForLoopDesugar, |
| ); |
| |
| // `let <pat> = __next` |
| let pat = self.lower_pat(pat); |
| let pat_let = self.stmt_let_pat( |
| head_sp, |
| Some(next_expr), |
| pat, |
| hir::LocalSource::ForLoopDesugar, |
| ); |
| |
| let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false)); |
| let body_expr = P(self.expr_block(body_block, ThinVec::new())); |
| let body_stmt = respan( |
| body.span, |
| hir::StmtKind::Expr(body_expr, self.next_id().node_id) |
| ); |
| |
| let loop_block = P(self.block_all( |
| e.span, |
| hir_vec![next_let, match_stmt, pat_let, body_stmt], |
| None, |
| )); |
| |
| // `[opt_ident]: loop { ... }` |
| let loop_expr = hir::ExprKind::Loop( |
| loop_block, |
| self.lower_label(opt_label), |
| hir::LoopSource::ForLoop, |
| ); |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id); |
| let loop_expr = P(hir::Expr { |
| id: node_id, |
| hir_id, |
| node: loop_expr, |
| span: e.span, |
| attrs: ThinVec::new(), |
| }); |
| |
| // `mut iter => { ... }` |
| let iter_arm = self.arm(hir_vec![iter_pat], loop_expr); |
| |
| // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }` |
| let into_iter_expr = { |
| let into_iter_path = &["iter", "IntoIterator", "into_iter"]; |
| let into_iter = P(self.expr_std_path( |
| head_sp, into_iter_path, None, ThinVec::new())); |
| P(self.expr_call(head_sp, into_iter, hir_vec![head])) |
| }; |
| |
| let match_expr = P(self.expr_match( |
| head_sp, |
| into_iter_expr, |
| hir_vec![iter_arm], |
| hir::MatchSource::ForLoopDesugar, |
| )); |
| |
| // `{ let _result = ...; _result }` |
| // Underscore prevents an `unused_variables` lint if the head diverges. |
| let result_ident = self.str_to_ident("_result"); |
| let (let_stmt, let_stmt_binding) = |
| self.stmt_let(e.span, false, result_ident, match_expr); |
| |
| let result = P(self.expr_ident(e.span, result_ident, let_stmt_binding)); |
| let block = P(self.block_all(e.span, hir_vec![let_stmt], Some(result))); |
| // Add the attributes to the outer returned expr node. |
| return self.expr_block(block, e.attrs.clone()); |
| } |
| |
| // Desugar `ExprKind::Try` |
| // from: `<expr>?` |
| ExprKind::Try(ref sub_expr) => { |
| // into: |
| // |
| // match Try::into_result(<expr>) { |
| // Ok(val) => #[allow(unreachable_code)] val, |
| // Err(err) => #[allow(unreachable_code)] |
| // // If there is an enclosing `catch {...}` |
| // break 'catch_target Try::from_error(From::from(err)), |
| // // Otherwise |
| // return Try::from_error(From::from(err)), |
| // } |
| |
| let unstable_span = |
| self.allow_internal_unstable(CompilerDesugaringKind::QuestionMark, e.span); |
| |
| // `Try::into_result(<expr>)` |
| let discr = { |
| // expand <expr> |
| let sub_expr = self.lower_expr(sub_expr); |
| |
| let path = &["ops", "Try", "into_result"]; |
| let path = P(self.expr_std_path( |
| unstable_span, path, None, ThinVec::new())); |
| P(self.expr_call(e.span, path, hir_vec![sub_expr])) |
| }; |
| |
| // `#[allow(unreachable_code)]` |
| let attr = { |
| // `allow(unreachable_code)` |
| let allow = { |
| let allow_ident = Ident::from_str("allow").with_span_pos(e.span); |
| let uc_ident = Ident::from_str("unreachable_code").with_span_pos(e.span); |
| let uc_nested = attr::mk_nested_word_item(uc_ident); |
| attr::mk_list_item(e.span, allow_ident, vec![uc_nested]) |
| }; |
| attr::mk_spanned_attr_outer(e.span, attr::mk_attr_id(), allow) |
| }; |
| let attrs = vec![attr]; |
| |
| // `Ok(val) => #[allow(unreachable_code)] val,` |
| let ok_arm = { |
| let val_ident = self.str_to_ident("val"); |
| let val_pat = self.pat_ident(e.span, val_ident); |
| let val_expr = P(self.expr_ident_with_attrs( |
| e.span, |
| val_ident, |
| val_pat.id, |
| ThinVec::from(attrs.clone()), |
| )); |
| let ok_pat = self.pat_ok(e.span, val_pat); |
| |
| self.arm(hir_vec![ok_pat], val_expr) |
| }; |
| |
| // `Err(err) => #[allow(unreachable_code)] |
| // return Try::from_error(From::from(err)),` |
| let err_arm = { |
| let err_ident = self.str_to_ident("err"); |
| let err_local = self.pat_ident(e.span, err_ident); |
| let from_expr = { |
| let path = &["convert", "From", "from"]; |
| let from = P(self.expr_std_path( |
| e.span, path, None, ThinVec::new())); |
| let err_expr = self.expr_ident(e.span, err_ident, err_local.id); |
| |
| self.expr_call(e.span, from, hir_vec![err_expr]) |
| }; |
| let from_err_expr = |
| self.wrap_in_try_constructor("from_error", from_expr, unstable_span); |
| let thin_attrs = ThinVec::from(attrs); |
| let catch_scope = self.catch_scopes.last().map(|x| *x); |
| let ret_expr = if let Some(catch_node) = catch_scope { |
| P(self.expr( |
| e.span, |
| hir::ExprKind::Break( |
| hir::Destination { |
| label: None, |
| target_id: Ok(catch_node), |
| }, |
| Some(from_err_expr), |
| ), |
| thin_attrs, |
| )) |
| } else { |
| P(self.expr(e.span, hir::ExprKind::Ret(Some(from_err_expr)), thin_attrs)) |
| }; |
| |
| let err_pat = self.pat_err(e.span, err_local); |
| self.arm(hir_vec![err_pat], ret_expr) |
| }; |
| |
| hir::ExprKind::Match( |
| discr, |
| hir_vec![err_arm, ok_arm], |
| hir::MatchSource::TryDesugar, |
| ) |
| } |
| |
| ExprKind::Mac(_) => panic!("Shouldn't exist here"), |
| }; |
| |
| let LoweredNodeId { node_id, hir_id } = self.lower_node_id(e.id); |
| |
| hir::Expr { |
| id: node_id, |
| hir_id, |
| node: kind, |
| span: e.span, |
| attrs: e.attrs.clone(), |
| } |
| } |
| |
| fn lower_stmt(&mut self, s: &Stmt) -> SmallVec<[hir::Stmt; 1]> { |
| smallvec![match s.node { |
| StmtKind::Local(ref l) => { |
| let (l, item_ids) = self.lower_local(l); |
| let mut ids: SmallVec<[hir::Stmt; 1]> = item_ids |
| .into_iter() |
| .map(|item_id| Spanned { |
| node: hir::StmtKind::Decl( |
| P(Spanned { |
| node: hir::DeclKind::Item(item_id), |
| span: s.span, |
| }), |
| self.next_id().node_id, |
| ), |
| span: s.span, |
| }) |
| .collect(); |
| ids.push(Spanned { |
| node: hir::StmtKind::Decl( |
| P(Spanned { |
| node: hir::DeclKind::Local(l), |
| span: s.span, |
| }), |
| self.lower_node_id(s.id).node_id, |
| ), |
| 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| Spanned { |
| node: hir::StmtKind::Decl( |
| P(Spanned { |
| node: hir::DeclKind::Item(item_id), |
| span: s.span, |
| }), |
| id.take() |
| .map(|id| self.lower_node_id(id).node_id) |
| .unwrap_or_else(|| self.next_id().node_id), |
| ), |
| span: s.span, |
| }) |
| .collect(); |
| } |
| StmtKind::Expr(ref e) => Spanned { |
| node: hir::StmtKind::Expr(P(self.lower_expr(e)), self.lower_node_id(s.id).node_id), |
| span: s.span, |
| }, |
| StmtKind::Semi(ref e) => Spanned { |
| node: hir::StmtKind::Semi(P(self.lower_expr(e)), self.lower_node_id(s.id).node_id), |
| span: s.span, |
| }, |
| StmtKind::Mac(..) => panic!("Shouldn't exist here"), |
| }] |
| } |
| |
| fn lower_capture_clause(&mut self, c: CaptureBy) -> hir::CaptureClause { |
| match c { |
| CaptureBy::Value => hir::CaptureByValue, |
| CaptureBy::Ref => hir::CaptureByRef, |
| } |
| } |
| |
| /// If an `explicit_owner` is given, this method allocates the `HirId` in |
| /// the address space of that item instead of the item currently being |
| /// lowered. This can happen during `lower_impl_item_ref()` where we need to |
| /// lower a `Visibility` value although we haven't lowered the owning |
| /// `ImplItem` in question yet. |
| fn lower_visibility( |
| &mut self, |
| v: &Visibility, |
| explicit_owner: Option<NodeId>, |
| ) -> hir::Visibility { |
| let node = match v.node { |
| VisibilityKind::Public => hir::VisibilityKind::Public, |
| VisibilityKind::Crate(sugar) => hir::VisibilityKind::Crate(sugar), |
| VisibilityKind::Restricted { ref path, id } => { |
| debug!("lower_visibility: restricted path id = {:?}", id); |
| let lowered_id = if let Some(owner) = explicit_owner { |
| self.lower_node_id_with_owner(id, owner) |
| } else { |
| self.lower_node_id(id) |
| }; |
| let def = self.expect_full_def(id); |
| hir::VisibilityKind::Restricted { |
| path: P(self.lower_path_extra( |
| def, |
| path, |
| ParamMode::Explicit, |
| explicit_owner, |
| )), |
| id: lowered_id.node_id, |
| hir_id: lowered_id.hir_id, |
| } |
| }, |
| VisibilityKind::Inherited => hir::VisibilityKind::Inherited, |
| }; |
| respan(v.span, node) |
| } |
| |
| fn lower_defaultness(&self, d: Defaultness, has_value: bool) -> hir::Defaultness { |
| match d { |
| Defaultness::Default => hir::Defaultness::Default { |
| has_value: has_value, |
| }, |
| Defaultness::Final => { |
| assert!(has_value); |
| hir::Defaultness::Final |
| } |
| } |
| } |
| |
| 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::Immutable) => hir::BindingAnnotation::Unannotated, |
| BindingMode::ByRef(Mutability::Immutable) => hir::BindingAnnotation::Ref, |
| BindingMode::ByValue(Mutability::Mutable) => hir::BindingAnnotation::Mutable, |
| BindingMode::ByRef(Mutability::Mutable) => hir::BindingAnnotation::RefMut, |
| } |
| } |
| |
| fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource { |
| match u { |
| CompilerGenerated => hir::CompilerGenerated, |
| UserProvided => hir::UserProvided, |
| } |
| } |
| |
| fn lower_impl_polarity(&mut self, i: ImplPolarity) -> hir::ImplPolarity { |
| match i { |
| ImplPolarity::Positive => hir::ImplPolarity::Positive, |
| ImplPolarity::Negative => hir::ImplPolarity::Negative, |
| } |
| } |
| |
| 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 arm(&mut self, pats: hir::HirVec<P<hir::Pat>>, expr: P<hir::Expr>) -> hir::Arm { |
| hir::Arm { |
| attrs: hir_vec![], |
| pats, |
| guard: None, |
| body: expr, |
| } |
| } |
| |
| fn field(&mut self, ident: Ident, expr: P<hir::Expr>, span: Span) -> hir::Field { |
| hir::Field { |
| id: self.next_id().node_id, |
| ident, |
| span, |
| expr, |
| is_shorthand: false, |
| } |
| } |
| |
| fn expr_break(&mut self, span: Span, attrs: ThinVec<Attribute>) -> P<hir::Expr> { |
| let expr_break = hir::ExprKind::Break(self.lower_loop_destination(None), None); |
| P(self.expr(span, expr_break, attrs)) |
| } |
| |
| fn expr_call( |
| &mut self, |
| span: Span, |
| e: P<hir::Expr>, |
| args: hir::HirVec<hir::Expr>, |
| ) -> hir::Expr { |
| self.expr(span, hir::ExprKind::Call(e, args), ThinVec::new()) |
| } |
| |
| fn expr_ident(&mut self, span: Span, ident: Ident, binding: NodeId) -> hir::Expr { |
| self.expr_ident_with_attrs(span, ident, binding, ThinVec::new()) |
| } |
| |
| fn expr_ident_with_attrs( |
| &mut self, |
| span: Span, |
| ident: Ident, |
| binding: NodeId, |
| attrs: ThinVec<Attribute>, |
| ) -> hir::Expr { |
| let expr_path = hir::ExprKind::Path(hir::QPath::Resolved( |
| None, |
| P(hir::Path { |
| span, |
| def: Def::Local(binding), |
| segments: hir_vec![hir::PathSegment::from_ident(ident)], |
| }), |
| )); |
| |
| self.expr(span, expr_path, attrs) |
| } |
| |
| fn expr_mut_addr_of(&mut self, span: Span, e: P<hir::Expr>) -> hir::Expr { |
| self.expr(span, hir::ExprKind::AddrOf(hir::MutMutable, e), ThinVec::new()) |
| } |
| |
| fn expr_std_path( |
| &mut self, |
| span: Span, |
| components: &[&str], |
| params: Option<P<hir::GenericArgs>>, |
| attrs: ThinVec<Attribute>, |
| ) -> hir::Expr { |
| let path = self.std_path(span, components, params, true); |
| self.expr( |
| span, |
| hir::ExprKind::Path(hir::QPath::Resolved(None, P(path))), |
| attrs, |
| ) |
| } |
| |
| fn expr_match( |
| &mut self, |
| span: Span, |
| arg: P<hir::Expr>, |
| arms: hir::HirVec<hir::Arm>, |
| source: hir::MatchSource, |
| ) -> hir::Expr { |
| self.expr(span, hir::ExprKind::Match(arg, arms, source), ThinVec::new()) |
| } |
| |
| fn expr_block(&mut self, b: P<hir::Block>, attrs: ThinVec<Attribute>) -> hir::Expr { |
| self.expr(b.span, hir::ExprKind::Block(b, None), attrs) |
| } |
| |
| fn expr_tuple(&mut self, sp: Span, exprs: hir::HirVec<hir::Expr>) -> P<hir::Expr> { |
| P(self.expr(sp, hir::ExprKind::Tup(exprs), ThinVec::new())) |
| } |
| |
| fn expr(&mut self, span: Span, node: hir::ExprKind, attrs: ThinVec<Attribute>) -> hir::Expr { |
| let LoweredNodeId { node_id, hir_id } = self.next_id(); |
| hir::Expr { |
| id: node_id, |
| hir_id, |
| node, |
| span, |
| attrs, |
| } |
| } |
| |
| fn stmt_let_pat( |
| &mut self, |
| sp: Span, |
| ex: Option<P<hir::Expr>>, |
| pat: P<hir::Pat>, |
| source: hir::LocalSource, |
| ) -> hir::Stmt { |
| let LoweredNodeId { node_id, hir_id } = self.next_id(); |
| |
| let local = P(hir::Local { |
| pat, |
| ty: None, |
| init: ex, |
| id: node_id, |
| hir_id, |
| span: sp, |
| attrs: ThinVec::new(), |
| source, |
| }); |
| let decl = respan(sp, hir::DeclKind::Local(local)); |
| respan(sp, hir::StmtKind::Decl(P(decl), self.next_id().node_id)) |
| } |
| |
| fn stmt_let( |
| &mut self, |
| sp: Span, |
| mutbl: bool, |
| ident: Ident, |
| ex: P<hir::Expr>, |
| ) -> (hir::Stmt, NodeId) { |
| let pat = if mutbl { |
| self.pat_ident_binding_mode(sp, ident, hir::BindingAnnotation::Mutable) |
| } else { |
| self.pat_ident(sp, ident) |
| }; |
| let pat_id = pat.id; |
| ( |
| self.stmt_let_pat(sp, Some(ex), pat, hir::LocalSource::Normal), |
| pat_id, |
| ) |
| } |
| |
| fn block_expr(&mut self, expr: P<hir::Expr>) -> hir::Block { |
| self.block_all(expr.span, hir::HirVec::new(), Some(expr)) |
| } |
| |
| fn block_all( |
| &mut self, |
| span: Span, |
| stmts: hir::HirVec<hir::Stmt>, |
| expr: Option<P<hir::Expr>>, |
| ) -> hir::Block { |
| let LoweredNodeId { node_id, hir_id } = self.next_id(); |
| |
| hir::Block { |
| stmts, |
| expr, |
| id: node_id, |
| hir_id, |
| rules: hir::DefaultBlock, |
| span, |
| targeted_by_break: false, |
| } |
| } |
| |
| fn pat_ok(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> { |
| self.pat_std_enum(span, &["result", "Result", "Ok"], hir_vec![pat]) |
| } |
| |
| fn pat_err(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> { |
| self.pat_std_enum(span, &["result", "Result", "Err"], hir_vec![pat]) |
| } |
| |
| fn pat_some(&mut self, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> { |
| self.pat_std_enum(span, &["option", "Option", "Some"], hir_vec![pat]) |
| } |
| |
| fn pat_none(&mut self, span: Span) -> P<hir::Pat> { |
| self.pat_std_enum(span, &["option", "Option", "None"], hir_vec![]) |
| } |
| |
| fn pat_std_enum( |
| &mut self, |
| span: Span, |
| components: &[&str], |
| subpats: hir::HirVec<P<hir::Pat>>, |
| ) -> P<hir::Pat> { |
| let path = self.std_path(span, components, None, true); |
| let qpath = hir::QPath::Resolved(None, P(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) -> P<hir::Pat> { |
| self.pat_ident_binding_mode(span, ident, hir::BindingAnnotation::Unannotated) |
| } |
| |
| fn pat_ident_binding_mode( |
| &mut self, |
| span: Span, |
| ident: Ident, |
| bm: hir::BindingAnnotation, |
| ) -> P<hir::Pat> { |
| let LoweredNodeId { node_id, hir_id } = self.next_id(); |
| |
| P(hir::Pat { |
| id: node_id, |
| hir_id, |
| node: hir::PatKind::Binding(bm, node_id, ident.with_span_pos(span), None), |
| span, |
| }) |
| } |
| |
| fn pat_wild(&mut self, span: Span) -> P<hir::Pat> { |
| self.pat(span, hir::PatKind::Wild) |
| } |
| |
| fn pat(&mut self, span: Span, pat: hir::PatKind) -> P<hir::Pat> { |
| let LoweredNodeId { node_id, hir_id } = self.next_id(); |
| P(hir::Pat { |
| id: node_id, |
| hir_id, |
| node: pat, |
| span, |
| }) |
| } |
| |
| /// Given 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: &[&str], |
| params: Option<P<hir::GenericArgs>>, |
| is_value: bool |
| ) -> hir::Path { |
| let mut path = self.resolver |
| .resolve_str_path(span, self.crate_root, components, is_value); |
| path.segments.last_mut().unwrap().args = params; |
| |
| |
| for seg in path.segments.iter_mut() { |
| if let Some(id) = seg.id { |
| seg.id = Some(self.lower_node_id(id).node_id); |
| } |
| } |
| path |
| } |
| |
| fn ty_path(&mut self, id: LoweredNodeId, span: Span, qpath: hir::QPath) -> hir::Ty { |
| let mut id = id; |
| let node = match qpath { |
| hir::QPath::Resolved(None, path) => { |
| // Turn trait object paths into `TyKind::TraitObject` instead. |
| match path.def { |
| Def::Trait(_) | Def::TraitAlias(_) => { |
| let principal = hir::PolyTraitRef { |
| bound_generic_params: hir::HirVec::new(), |
| trait_ref: hir::TraitRef { |
| path: path.and_then(|path| path), |
| ref_id: id.node_id, |
| hir_ref_id: id.hir_id, |
| }, |
| span, |
| }; |
| |
| // The original ID is taken by the `PolyTraitRef`, |
| // so the `Ty` itself needs a different one. |
| id = self.next_id(); |
| hir::TyKind::TraitObject(hir_vec![principal], self.elided_dyn_bound(span)) |
| } |
| _ => hir::TyKind::Path(hir::QPath::Resolved(None, path)), |
| } |
| } |
| _ => hir::TyKind::Path(qpath), |
| }; |
| hir::Ty { |
| id: id.node_id, |
| hir_id: id.hir_id, |
| node, |
| 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 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 { |
| id: self.next_id().node_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.next_id().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(&mut self, span: Span, count: usize) -> P<[hir::Lifetime]> { |
| match self.anonymous_lifetime_mode { |
| // N.B., We intentionally ignore the create-parameter mode here |
| // and instead "pass through" to resolve-lifetimes, which will then |
| // report an error. This is because we don't want to support |
| // impl elision for deprecated forms like |
| // |
| // impl Foo for std::cell::Ref<u32> // note lack of '_ |
| AnonymousLifetimeMode::CreateParameter => {} |
| |
| AnonymousLifetimeMode::ReportError => { |
| return (0..count) |
| .map(|_| self.new_error_lifetime(None, span)) |
| .collect(); |
| } |
| |
| // This is the normal case. |
| AnonymousLifetimeMode::PassThrough => {} |
| } |
| |
| (0..count) |
| .map(|_| self.new_implicit_lifetime(span)) |
| .collect() |
| } |
| |
| /// 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 => {} |
| } |
| |
| self.new_implicit_lifetime(span) |
| } |
| |
| fn new_implicit_lifetime(&mut self, span: Span) -> hir::Lifetime { |
| hir::Lifetime { |
| id: self.next_id().node_id, |
| span, |
| name: hir::LifetimeName::Implicit, |
| } |
| } |
| |
| fn maybe_lint_bare_trait(&self, span: Span, id: NodeId, is_global: bool) { |
| self.sess.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 wrap_in_try_constructor( |
| &mut self, |
| method: &'static str, |
| e: hir::Expr, |
| unstable_span: Span, |
| ) -> P<hir::Expr> { |
| let path = &["ops", "Try", method]; |
| let from_err = P(self.expr_std_path(unstable_span, path, None, |
| ThinVec::new())); |
| P(self.expr_call(e.span, from_err, hir_vec![e])) |
| } |
| } |
| |
| 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 |
| } |