2501 lines
102 KiB
Rust
2501 lines
102 KiB
Rust
//! Lowers the AST to the HIR.
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//!
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//! Since the AST and HIR are fairly similar, this is mostly a simple procedure,
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//! much like a fold. Where lowering involves a bit more work things get more
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//! interesting and there are some invariants you should know about. These mostly
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//! concern spans and IDs.
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//!
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//! Spans are assigned to AST nodes during parsing and then are modified during
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//! expansion to indicate the origin of a node and the process it went through
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//! being expanded. IDs are assigned to AST nodes just before lowering.
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//!
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//! For the simpler lowering steps, IDs and spans should be preserved. Unlike
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//! expansion we do not preserve the process of lowering in the spans, so spans
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//! should not be modified here. When creating a new node (as opposed to
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//! "folding" an existing one), create a new ID using `next_id()`.
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//!
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//! You must ensure that IDs are unique. That means that you should only use the
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//! ID from an AST node in a single HIR node (you can assume that AST node-IDs
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//! are unique). Every new node must have a unique ID. Avoid cloning HIR nodes.
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//! If you do, you must then set the new node's ID to a fresh one.
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//!
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//! Spans are used for error messages and for tools to map semantics back to
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//! source code. It is therefore not as important with spans as IDs to be strict
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//! about use (you can't break the compiler by screwing up a span). Obviously, a
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//! HIR node can only have a single span. But multiple nodes can have the same
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//! span and spans don't need to be kept in order, etc. Where code is preserved
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//! by lowering, it should have the same span as in the AST. Where HIR nodes are
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//! new it is probably best to give a span for the whole AST node being lowered.
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//! All nodes should have real spans; don't use dummy spans. Tools are likely to
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//! get confused if the spans from leaf AST nodes occur in multiple places
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//! in the HIR, especially for multiple identifiers.
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#![feature(box_patterns)]
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#![feature(let_else)]
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#![feature(never_type)]
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#![recursion_limit = "256"]
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#![allow(rustc::potential_query_instability)]
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#[macro_use]
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extern crate tracing;
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use rustc_ast::ptr::P;
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use rustc_ast::visit;
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use rustc_ast::{self as ast, *};
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use rustc_ast_pretty::pprust;
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use rustc_data_structures::captures::Captures;
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use rustc_data_structures::fingerprint::Fingerprint;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_data_structures::sorted_map::SortedMap;
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use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
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use rustc_data_structures::sync::Lrc;
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use rustc_errors::{struct_span_err, Applicability, Handler, StashKey};
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use rustc_hir as hir;
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use rustc_hir::def::{DefKind, LifetimeRes, Namespace, PartialRes, PerNS, Res};
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use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
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use rustc_hir::definitions::DefPathData;
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use rustc_hir::{ConstArg, GenericArg, ItemLocalId, ParamName, TraitCandidate};
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use rustc_index::vec::{Idx, IndexVec};
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use rustc_middle::span_bug;
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use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
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use rustc_session::parse::feature_err;
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use rustc_span::hygiene::MacroKind;
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use rustc_span::source_map::DesugaringKind;
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use rustc_span::symbol::{kw, sym, Ident, Symbol};
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use rustc_span::{Span, DUMMY_SP};
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use smallvec::SmallVec;
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use std::collections::hash_map::Entry;
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macro_rules! arena_vec {
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($this:expr; $($x:expr),*) => (
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$this.arena.alloc_from_iter([$($x),*])
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);
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}
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mod asm;
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mod block;
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mod expr;
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mod index;
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mod item;
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mod lifetime_collector;
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mod pat;
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mod path;
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struct LoweringContext<'a, 'hir> {
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tcx: TyCtxt<'hir>,
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resolver: &'a mut ResolverAstLowering,
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/// Used to allocate HIR nodes.
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arena: &'hir hir::Arena<'hir>,
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/// Bodies inside the owner being lowered.
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bodies: Vec<(hir::ItemLocalId, &'hir hir::Body<'hir>)>,
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/// Attributes inside the owner being lowered.
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attrs: SortedMap<hir::ItemLocalId, &'hir [Attribute]>,
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/// Collect items that were created by lowering the current owner.
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children: FxHashMap<LocalDefId, hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>>>,
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generator_kind: Option<hir::GeneratorKind>,
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/// When inside an `async` context, this is the `HirId` of the
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/// `task_context` local bound to the resume argument of the generator.
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task_context: Option<hir::HirId>,
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/// Used to get the current `fn`'s def span to point to when using `await`
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/// outside of an `async fn`.
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current_item: Option<Span>,
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catch_scope: Option<NodeId>,
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loop_scope: Option<NodeId>,
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is_in_loop_condition: bool,
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is_in_trait_impl: bool,
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is_in_dyn_type: bool,
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current_hir_id_owner: LocalDefId,
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item_local_id_counter: hir::ItemLocalId,
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local_id_to_def_id: SortedMap<ItemLocalId, LocalDefId>,
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trait_map: FxHashMap<ItemLocalId, Box<[TraitCandidate]>>,
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impl_trait_defs: Vec<hir::GenericParam<'hir>>,
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impl_trait_bounds: Vec<hir::WherePredicate<'hir>>,
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/// NodeIds that are lowered inside the current HIR owner.
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node_id_to_local_id: FxHashMap<NodeId, hir::ItemLocalId>,
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allow_try_trait: Option<Lrc<[Symbol]>>,
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allow_gen_future: Option<Lrc<[Symbol]>>,
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allow_into_future: Option<Lrc<[Symbol]>>,
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}
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trait ResolverAstLoweringExt {
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fn legacy_const_generic_args(&self, expr: &Expr) -> Option<Vec<usize>>;
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fn get_partial_res(&self, id: NodeId) -> Option<PartialRes>;
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fn get_import_res(&self, id: NodeId) -> PerNS<Option<Res<NodeId>>>;
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fn get_label_res(&self, id: NodeId) -> Option<NodeId>;
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fn get_lifetime_res(&self, id: NodeId) -> Option<LifetimeRes>;
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fn take_extra_lifetime_params(&mut self, id: NodeId) -> Vec<(Ident, NodeId, LifetimeRes)>;
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fn decl_macro_kind(&self, def_id: LocalDefId) -> MacroKind;
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/// Record the map from `from` local def id to `to` local def id, on `generics_def_id_map`
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/// field.
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fn record_def_id_remap(&mut self, from: LocalDefId, to: LocalDefId);
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/// Get the previously recorded `to` local def id given the `from` local def id, obtained using
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/// `generics_def_id_map` field.
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fn get_remapped_def_id(&self, local_def_id: LocalDefId) -> LocalDefId;
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}
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impl ResolverAstLoweringExt for ResolverAstLowering {
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fn legacy_const_generic_args(&self, expr: &Expr) -> Option<Vec<usize>> {
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if let ExprKind::Path(None, path) = &expr.kind {
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// Don't perform legacy const generics rewriting if the path already
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// has generic arguments.
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if path.segments.last().unwrap().args.is_some() {
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return None;
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}
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let partial_res = self.partial_res_map.get(&expr.id)?;
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if partial_res.unresolved_segments() != 0 {
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return None;
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}
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if let Res::Def(DefKind::Fn, def_id) = partial_res.base_res() {
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// We only support cross-crate argument rewriting. Uses
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// within the same crate should be updated to use the new
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// const generics style.
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if def_id.is_local() {
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return None;
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}
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if let Some(v) = self.legacy_const_generic_args.get(&def_id) {
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return v.clone();
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}
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}
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}
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None
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}
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/// Obtains resolution for a `NodeId` with a single resolution.
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fn get_partial_res(&self, id: NodeId) -> Option<PartialRes> {
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self.partial_res_map.get(&id).copied()
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}
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/// Obtains per-namespace resolutions for `use` statement with the given `NodeId`.
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fn get_import_res(&self, id: NodeId) -> PerNS<Option<Res<NodeId>>> {
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self.import_res_map.get(&id).copied().unwrap_or_default()
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}
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/// Obtains resolution for a label with the given `NodeId`.
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fn get_label_res(&self, id: NodeId) -> Option<NodeId> {
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self.label_res_map.get(&id).copied()
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}
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/// Obtains resolution for a lifetime with the given `NodeId`.
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fn get_lifetime_res(&self, id: NodeId) -> Option<LifetimeRes> {
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self.lifetimes_res_map.get(&id).copied()
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}
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/// Obtain the list of lifetimes parameters to add to an item.
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///
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/// Extra lifetime parameters should only be added in places that can appear
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/// as a `binder` in `LifetimeRes`.
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///
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/// The extra lifetimes that appear from the parenthesized `Fn`-trait desugaring
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/// should appear at the enclosing `PolyTraitRef`.
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fn take_extra_lifetime_params(&mut self, id: NodeId) -> Vec<(Ident, NodeId, LifetimeRes)> {
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self.extra_lifetime_params_map.remove(&id).unwrap_or_default()
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}
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fn decl_macro_kind(&self, def_id: LocalDefId) -> MacroKind {
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self.builtin_macro_kinds.get(&def_id).copied().unwrap_or(MacroKind::Bang)
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}
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/// Push a remapping into the top-most map.
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/// Panics if no map has been pushed.
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/// Remapping is used when creating lowering `-> impl Trait` return
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/// types to create the resulting opaque type.
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#[tracing::instrument(level = "debug", skip(self))]
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fn record_def_id_remap(&mut self, from: LocalDefId, to: LocalDefId) {
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self.generics_def_id_map.last_mut().expect("no map pushed").insert(from, to);
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}
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fn get_remapped_def_id(&self, mut local_def_id: LocalDefId) -> LocalDefId {
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// `generics_def_id_map` is a stack of mappings. As we go deeper in impl traits nesting we
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// push new mappings so we need to try first the latest mappings, hence `iter().rev()`.
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//
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// Consider:
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//
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// `fn test<'a, 'b>() -> impl Trait<&'a u8, Ty = impl Sized + 'b> {}`
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//
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// We would end with a generics_def_id_map like:
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//
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// `[[fn#'b -> impl_trait#'b], [fn#'b -> impl_sized#'b]]`
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//
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// for the opaque type generated on `impl Sized + 'b`, We want the result to be:
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// impl_sized#'b, so iterating forward is the wrong thing to do.
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for map in self.generics_def_id_map.iter().rev() {
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if let Some(r) = map.get(&local_def_id) {
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debug!("def_id_remapper: remapping from `{local_def_id:?}` to `{r:?}`");
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local_def_id = *r;
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} else {
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debug!("def_id_remapper: no remapping for `{local_def_id:?}` found in map");
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}
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}
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local_def_id
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}
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}
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/// Context of `impl Trait` in code, which determines whether it is allowed in an HIR subtree,
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/// and if so, what meaning it has.
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#[derive(Debug, Copy, Clone, PartialEq, Eq)]
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enum ImplTraitContext {
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/// Treat `impl Trait` as shorthand for a new universal generic parameter.
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/// Example: `fn foo(x: impl Debug)`, where `impl Debug` is conceptually
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/// equivalent to a fresh universal parameter like `fn foo<T: Debug>(x: T)`.
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///
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/// Newly generated parameters should be inserted into the given `Vec`.
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Universal,
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/// Treat `impl Trait` as shorthand for a new opaque type.
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/// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually
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/// equivalent to a new opaque type like `type T = impl Debug; fn foo() -> T`.
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///
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ReturnPositionOpaqueTy {
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/// Origin: Either OpaqueTyOrigin::FnReturn or OpaqueTyOrigin::AsyncFn,
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origin: hir::OpaqueTyOrigin,
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},
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/// Impl trait in type aliases.
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TypeAliasesOpaqueTy,
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/// `impl Trait` is not accepted in this position.
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Disallowed(ImplTraitPosition),
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}
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/// Position in which `impl Trait` is disallowed.
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#[derive(Debug, Copy, Clone, PartialEq, Eq)]
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enum ImplTraitPosition {
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Path,
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Variable,
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Type,
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Trait,
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AsyncBlock,
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Bound,
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Generic,
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ExternFnParam,
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ClosureParam,
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PointerParam,
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FnTraitParam,
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TraitParam,
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ImplParam,
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ExternFnReturn,
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ClosureReturn,
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PointerReturn,
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FnTraitReturn,
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TraitReturn,
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ImplReturn,
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}
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impl std::fmt::Display for ImplTraitPosition {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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let name = match self {
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ImplTraitPosition::Path => "path",
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ImplTraitPosition::Variable => "variable binding",
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ImplTraitPosition::Type => "type",
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ImplTraitPosition::Trait => "trait",
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ImplTraitPosition::AsyncBlock => "async block",
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ImplTraitPosition::Bound => "bound",
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ImplTraitPosition::Generic => "generic",
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ImplTraitPosition::ExternFnParam => "`extern fn` param",
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ImplTraitPosition::ClosureParam => "closure param",
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ImplTraitPosition::PointerParam => "`fn` pointer param",
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ImplTraitPosition::FnTraitParam => "`Fn` trait param",
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ImplTraitPosition::TraitParam => "trait method param",
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ImplTraitPosition::ImplParam => "`impl` method param",
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ImplTraitPosition::ExternFnReturn => "`extern fn` return",
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ImplTraitPosition::ClosureReturn => "closure return",
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ImplTraitPosition::PointerReturn => "`fn` pointer return",
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ImplTraitPosition::FnTraitReturn => "`Fn` trait return",
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ImplTraitPosition::TraitReturn => "trait method return",
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ImplTraitPosition::ImplReturn => "`impl` method return",
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};
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write!(f, "{}", name)
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}
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}
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#[derive(Debug)]
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enum FnDeclKind {
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Fn,
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Inherent,
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ExternFn,
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Closure,
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Pointer,
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Trait,
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Impl,
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}
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impl FnDeclKind {
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fn impl_trait_return_allowed(&self) -> bool {
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match self {
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FnDeclKind::Fn | FnDeclKind::Inherent => true,
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_ => false,
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}
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}
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}
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#[derive(Copy, Clone)]
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enum AstOwner<'a> {
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NonOwner,
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Crate(&'a ast::Crate),
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Item(&'a ast::Item),
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AssocItem(&'a ast::AssocItem, visit::AssocCtxt),
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ForeignItem(&'a ast::ForeignItem),
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}
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fn index_crate<'a>(
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node_id_to_def_id: &FxHashMap<NodeId, LocalDefId>,
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krate: &'a Crate,
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) -> IndexVec<LocalDefId, AstOwner<'a>> {
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let mut indexer = Indexer { node_id_to_def_id, index: IndexVec::new() };
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indexer.index.ensure_contains_elem(CRATE_DEF_ID, || AstOwner::NonOwner);
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indexer.index[CRATE_DEF_ID] = AstOwner::Crate(krate);
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visit::walk_crate(&mut indexer, krate);
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return indexer.index;
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struct Indexer<'s, 'a> {
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node_id_to_def_id: &'s FxHashMap<NodeId, LocalDefId>,
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index: IndexVec<LocalDefId, AstOwner<'a>>,
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}
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impl<'a> visit::Visitor<'a> for Indexer<'_, 'a> {
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fn visit_attribute(&mut self, _: &'a Attribute) {
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// We do not want to lower expressions that appear in attributes,
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// as they are not accessible to the rest of the HIR.
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}
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fn visit_item(&mut self, item: &'a ast::Item) {
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let def_id = self.node_id_to_def_id[&item.id];
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self.index.ensure_contains_elem(def_id, || AstOwner::NonOwner);
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self.index[def_id] = AstOwner::Item(item);
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visit::walk_item(self, item)
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}
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fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: visit::AssocCtxt) {
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let def_id = self.node_id_to_def_id[&item.id];
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self.index.ensure_contains_elem(def_id, || AstOwner::NonOwner);
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self.index[def_id] = AstOwner::AssocItem(item, ctxt);
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visit::walk_assoc_item(self, item, ctxt);
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}
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fn visit_foreign_item(&mut self, item: &'a ast::ForeignItem) {
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let def_id = self.node_id_to_def_id[&item.id];
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self.index.ensure_contains_elem(def_id, || AstOwner::NonOwner);
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self.index[def_id] = AstOwner::ForeignItem(item);
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visit::walk_foreign_item(self, item);
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}
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}
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}
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/// Compute the hash for the HIR of the full crate.
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|
/// This hash will then be part of the crate_hash which is stored in the metadata.
|
|
fn compute_hir_hash(
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tcx: TyCtxt<'_>,
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owners: &IndexVec<LocalDefId, hir::MaybeOwner<&hir::OwnerInfo<'_>>>,
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|
) -> Fingerprint {
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let mut hir_body_nodes: Vec<_> = owners
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|
.iter_enumerated()
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|
.filter_map(|(def_id, info)| {
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let info = info.as_owner()?;
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let def_path_hash = tcx.hir().def_path_hash(def_id);
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Some((def_path_hash, info))
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})
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.collect();
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hir_body_nodes.sort_unstable_by_key(|bn| bn.0);
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tcx.with_stable_hashing_context(|mut hcx| {
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let mut stable_hasher = StableHasher::new();
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hir_body_nodes.hash_stable(&mut hcx, &mut stable_hasher);
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stable_hasher.finish()
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})
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}
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|
|
pub fn lower_to_hir<'hir>(tcx: TyCtxt<'hir>, (): ()) -> hir::Crate<'hir> {
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|
let sess = tcx.sess;
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|
let krate = tcx.untracked_crate.steal();
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|
let mut resolver = tcx.resolver_for_lowering(()).steal();
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|
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|
let ast_index = index_crate(&resolver.node_id_to_def_id, &krate);
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|
let mut owners = IndexVec::from_fn_n(
|
|
|_| hir::MaybeOwner::Phantom,
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|
tcx.definitions_untracked().def_index_count(),
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|
);
|
|
|
|
for def_id in ast_index.indices() {
|
|
item::ItemLowerer {
|
|
tcx,
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|
resolver: &mut resolver,
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|
ast_index: &ast_index,
|
|
owners: &mut owners,
|
|
}
|
|
.lower_node(def_id);
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|
}
|
|
|
|
// Drop AST to free memory
|
|
std::mem::drop(ast_index);
|
|
sess.time("drop_ast", || std::mem::drop(krate));
|
|
|
|
// Discard hygiene data, which isn't required after lowering to HIR.
|
|
if !sess.opts.unstable_opts.keep_hygiene_data {
|
|
rustc_span::hygiene::clear_syntax_context_map();
|
|
}
|
|
|
|
let hir_hash = compute_hir_hash(tcx, &owners);
|
|
hir::Crate { owners, hir_hash }
|
|
}
|
|
|
|
#[derive(Copy, Clone, PartialEq, Debug)]
|
|
enum ParamMode {
|
|
/// Any path in a type context.
|
|
Explicit,
|
|
/// Path in a type definition, where the anonymous lifetime `'_` is not allowed.
|
|
ExplicitNamed,
|
|
/// The `module::Type` in `module::Type::method` in an expression.
|
|
Optional,
|
|
}
|
|
|
|
enum ParenthesizedGenericArgs {
|
|
Ok,
|
|
Err,
|
|
}
|
|
|
|
impl<'a, 'hir> LoweringContext<'a, 'hir> {
|
|
fn create_def(
|
|
&mut self,
|
|
parent: LocalDefId,
|
|
node_id: ast::NodeId,
|
|
data: DefPathData,
|
|
) -> LocalDefId {
|
|
debug_assert_ne!(node_id, ast::DUMMY_NODE_ID);
|
|
assert!(
|
|
self.opt_local_def_id(node_id).is_none(),
|
|
"adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
|
|
node_id,
|
|
data,
|
|
self.tcx.hir().def_key(self.local_def_id(node_id)),
|
|
);
|
|
|
|
let def_id = self.tcx.create_def(parent, data);
|
|
|
|
debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
|
|
self.resolver.node_id_to_def_id.insert(node_id, def_id);
|
|
|
|
def_id
|
|
}
|
|
|
|
fn next_node_id(&mut self) -> NodeId {
|
|
let start = self.resolver.next_node_id;
|
|
let next = start.as_u32().checked_add(1).expect("input too large; ran out of NodeIds");
|
|
self.resolver.next_node_id = ast::NodeId::from_u32(next);
|
|
start
|
|
}
|
|
|
|
/// Given the id of some node in the AST, finds the `LocalDefId` associated with it by the name
|
|
/// resolver (if any), after applying any remapping from `get_remapped_def_id`.
|
|
///
|
|
/// For example, in a function like `fn foo<'a>(x: &'a u32)`,
|
|
/// invoking with the id from the `ast::Lifetime` node found inside
|
|
/// the `&'a u32` type would return the `LocalDefId` of the
|
|
/// `'a` parameter declared on `foo`.
|
|
///
|
|
/// This function also applies remapping from `get_remapped_def_id`.
|
|
/// These are used when synthesizing opaque types from `-> impl Trait` return types and so forth.
|
|
/// For example, in a function like `fn foo<'a>() -> impl Debug + 'a`,
|
|
/// we would create an opaque type `type FooReturn<'a1> = impl Debug + 'a1`.
|
|
/// When lowering the `Debug + 'a` bounds, we add a remapping to map `'a` to `'a1`.
|
|
fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
|
|
self.resolver
|
|
.node_id_to_def_id
|
|
.get(&node)
|
|
.map(|local_def_id| self.resolver.get_remapped_def_id(*local_def_id))
|
|
}
|
|
|
|
fn local_def_id(&self, node: NodeId) -> LocalDefId {
|
|
self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{:?}`", node))
|
|
}
|
|
|
|
/// Freshen the `LoweringContext` and ready it to lower a nested item.
|
|
/// The lowered item is registered into `self.children`.
|
|
///
|
|
/// This function sets up `HirId` lowering infrastructure,
|
|
/// and stashes the shared mutable state to avoid pollution by the closure.
|
|
#[instrument(level = "debug", skip(self, f))]
|
|
fn with_hir_id_owner(
|
|
&mut self,
|
|
owner: NodeId,
|
|
f: impl FnOnce(&mut Self) -> hir::OwnerNode<'hir>,
|
|
) {
|
|
let def_id = self.local_def_id(owner);
|
|
|
|
let current_attrs = std::mem::take(&mut self.attrs);
|
|
let current_bodies = std::mem::take(&mut self.bodies);
|
|
let current_node_ids = std::mem::take(&mut self.node_id_to_local_id);
|
|
let current_id_to_def_id = std::mem::take(&mut self.local_id_to_def_id);
|
|
let current_trait_map = std::mem::take(&mut self.trait_map);
|
|
let current_owner = std::mem::replace(&mut self.current_hir_id_owner, def_id);
|
|
let current_local_counter =
|
|
std::mem::replace(&mut self.item_local_id_counter, hir::ItemLocalId::new(1));
|
|
let current_impl_trait_defs = std::mem::take(&mut self.impl_trait_defs);
|
|
let current_impl_trait_bounds = std::mem::take(&mut self.impl_trait_bounds);
|
|
|
|
// Do not reset `next_node_id` and `node_id_to_def_id`:
|
|
// we want `f` to be able to refer to the `LocalDefId`s that the caller created.
|
|
// and the caller to refer to some of the subdefinitions' nodes' `LocalDefId`s.
|
|
|
|
// Always allocate the first `HirId` for the owner itself.
|
|
let _old = self.node_id_to_local_id.insert(owner, hir::ItemLocalId::new(0));
|
|
debug_assert_eq!(_old, None);
|
|
|
|
let item = f(self);
|
|
debug_assert_eq!(def_id, item.def_id());
|
|
// `f` should have consumed all the elements in these vectors when constructing `item`.
|
|
debug_assert!(self.impl_trait_defs.is_empty());
|
|
debug_assert!(self.impl_trait_bounds.is_empty());
|
|
let info = self.make_owner_info(item);
|
|
|
|
self.attrs = current_attrs;
|
|
self.bodies = current_bodies;
|
|
self.node_id_to_local_id = current_node_ids;
|
|
self.local_id_to_def_id = current_id_to_def_id;
|
|
self.trait_map = current_trait_map;
|
|
self.current_hir_id_owner = current_owner;
|
|
self.item_local_id_counter = current_local_counter;
|
|
self.impl_trait_defs = current_impl_trait_defs;
|
|
self.impl_trait_bounds = current_impl_trait_bounds;
|
|
|
|
let _old = self.children.insert(def_id, hir::MaybeOwner::Owner(info));
|
|
debug_assert!(_old.is_none())
|
|
}
|
|
|
|
/// Installs the remapping `remap` in scope while `f` is being executed.
|
|
/// This causes references to the `LocalDefId` keys to be changed to
|
|
/// refer to the values instead.
|
|
///
|
|
/// The remapping is used when one piece of AST expands to multiple
|
|
/// pieces of HIR. For example, the function `fn foo<'a>(...) -> impl Debug + 'a`,
|
|
/// expands to both a function definition (`foo`) and a TAIT for the return value,
|
|
/// both of which have a lifetime parameter `'a`. The remapping allows us to
|
|
/// rewrite the `'a` in the return value to refer to the
|
|
/// `'a` declared on the TAIT, instead of the function.
|
|
fn with_remapping<R>(
|
|
&mut self,
|
|
remap: FxHashMap<LocalDefId, LocalDefId>,
|
|
f: impl FnOnce(&mut Self) -> R,
|
|
) -> R {
|
|
self.resolver.generics_def_id_map.push(remap);
|
|
let res = f(self);
|
|
self.resolver.generics_def_id_map.pop();
|
|
res
|
|
}
|
|
|
|
fn make_owner_info(&mut self, node: hir::OwnerNode<'hir>) -> &'hir hir::OwnerInfo<'hir> {
|
|
let attrs = std::mem::take(&mut self.attrs);
|
|
let mut bodies = std::mem::take(&mut self.bodies);
|
|
let local_id_to_def_id = std::mem::take(&mut self.local_id_to_def_id);
|
|
let trait_map = std::mem::take(&mut self.trait_map);
|
|
|
|
#[cfg(debug_assertions)]
|
|
for (id, attrs) in attrs.iter() {
|
|
// Verify that we do not store empty slices in the map.
|
|
if attrs.is_empty() {
|
|
panic!("Stored empty attributes for {:?}", id);
|
|
}
|
|
}
|
|
|
|
bodies.sort_by_key(|(k, _)| *k);
|
|
let bodies = SortedMap::from_presorted_elements(bodies);
|
|
let (hash_including_bodies, hash_without_bodies) = self.hash_owner(node, &bodies);
|
|
let (nodes, parenting) =
|
|
index::index_hir(self.tcx.sess, &*self.tcx.definitions_untracked(), node, &bodies);
|
|
let nodes = hir::OwnerNodes {
|
|
hash_including_bodies,
|
|
hash_without_bodies,
|
|
nodes,
|
|
bodies,
|
|
local_id_to_def_id,
|
|
};
|
|
let attrs = {
|
|
let hash = self.tcx.with_stable_hashing_context(|mut hcx| {
|
|
let mut stable_hasher = StableHasher::new();
|
|
attrs.hash_stable(&mut hcx, &mut stable_hasher);
|
|
stable_hasher.finish()
|
|
});
|
|
hir::AttributeMap { map: attrs, hash }
|
|
};
|
|
|
|
self.arena.alloc(hir::OwnerInfo { nodes, parenting, attrs, trait_map })
|
|
}
|
|
|
|
/// Hash the HIR node twice, one deep and one shallow hash. This allows to differentiate
|
|
/// queries which depend on the full HIR tree and those which only depend on the item signature.
|
|
fn hash_owner(
|
|
&mut self,
|
|
node: hir::OwnerNode<'hir>,
|
|
bodies: &SortedMap<hir::ItemLocalId, &'hir hir::Body<'hir>>,
|
|
) -> (Fingerprint, Fingerprint) {
|
|
self.tcx.with_stable_hashing_context(|mut hcx| {
|
|
let mut stable_hasher = StableHasher::new();
|
|
hcx.with_hir_bodies(node.def_id(), bodies, |hcx| {
|
|
node.hash_stable(hcx, &mut stable_hasher)
|
|
});
|
|
let hash_including_bodies = stable_hasher.finish();
|
|
let mut stable_hasher = StableHasher::new();
|
|
hcx.without_hir_bodies(|hcx| node.hash_stable(hcx, &mut stable_hasher));
|
|
let hash_without_bodies = stable_hasher.finish();
|
|
(hash_including_bodies, hash_without_bodies)
|
|
})
|
|
}
|
|
|
|
/// This method allocates a new `HirId` for the given `NodeId` and stores it in
|
|
/// the `LoweringContext`'s `NodeId => HirId` map.
|
|
/// Take care not to call this method if the resulting `HirId` is then not
|
|
/// actually used in the HIR, as that would trigger an assertion in the
|
|
/// `HirIdValidator` later on, which makes sure that all `NodeId`s got mapped
|
|
/// properly. Calling the method twice with the same `NodeId` is fine though.
|
|
fn lower_node_id(&mut self, ast_node_id: NodeId) -> hir::HirId {
|
|
assert_ne!(ast_node_id, DUMMY_NODE_ID);
|
|
|
|
match self.node_id_to_local_id.entry(ast_node_id) {
|
|
Entry::Occupied(o) => {
|
|
hir::HirId { owner: self.current_hir_id_owner, local_id: *o.get() }
|
|
}
|
|
Entry::Vacant(v) => {
|
|
// Generate a new `HirId`.
|
|
let owner = self.current_hir_id_owner;
|
|
let local_id = self.item_local_id_counter;
|
|
let hir_id = hir::HirId { owner, local_id };
|
|
|
|
v.insert(local_id);
|
|
self.item_local_id_counter.increment_by(1);
|
|
|
|
assert_ne!(local_id, hir::ItemLocalId::new(0));
|
|
if let Some(def_id) = self.opt_local_def_id(ast_node_id) {
|
|
// Do not override a `MaybeOwner::Owner` that may already here.
|
|
self.children.entry(def_id).or_insert(hir::MaybeOwner::NonOwner(hir_id));
|
|
self.local_id_to_def_id.insert(local_id, def_id);
|
|
}
|
|
|
|
if let Some(traits) = self.resolver.trait_map.remove(&ast_node_id) {
|
|
self.trait_map.insert(hir_id.local_id, traits.into_boxed_slice());
|
|
}
|
|
|
|
hir_id
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Generate a new `HirId` without a backing `NodeId`.
|
|
fn next_id(&mut self) -> hir::HirId {
|
|
let owner = self.current_hir_id_owner;
|
|
let local_id = self.item_local_id_counter;
|
|
assert_ne!(local_id, hir::ItemLocalId::new(0));
|
|
self.item_local_id_counter.increment_by(1);
|
|
hir::HirId { owner, local_id }
|
|
}
|
|
|
|
#[instrument(level = "trace", skip(self))]
|
|
fn lower_res(&mut self, res: Res<NodeId>) -> Res {
|
|
let res: Result<Res, ()> = res.apply_id(|id| {
|
|
let owner = self.current_hir_id_owner;
|
|
let local_id = self.node_id_to_local_id.get(&id).copied().ok_or(())?;
|
|
Ok(hir::HirId { owner, local_id })
|
|
});
|
|
trace!(?res);
|
|
|
|
// We may fail to find a HirId when the Res points to a Local from an enclosing HIR owner.
|
|
// This can happen when trying to lower the return type `x` in erroneous code like
|
|
// async fn foo(x: u8) -> x {}
|
|
// In that case, `x` is lowered as a function parameter, and the return type is lowered as
|
|
// an opaque type as a synthesized HIR owner.
|
|
res.unwrap_or(Res::Err)
|
|
}
|
|
|
|
fn expect_full_res(&mut self, id: NodeId) -> Res<NodeId> {
|
|
self.resolver.get_partial_res(id).map_or(Res::Err, |pr| {
|
|
if pr.unresolved_segments() != 0 {
|
|
panic!("path not fully resolved: {:?}", pr);
|
|
}
|
|
pr.base_res()
|
|
})
|
|
}
|
|
|
|
fn expect_full_res_from_use(&mut self, id: NodeId) -> impl Iterator<Item = Res<NodeId>> {
|
|
self.resolver.get_import_res(id).present_items()
|
|
}
|
|
|
|
fn diagnostic(&self) -> &Handler {
|
|
self.tcx.sess.diagnostic()
|
|
}
|
|
|
|
/// Reuses the span but adds information like the kind of the desugaring and features that are
|
|
/// allowed inside this span.
|
|
fn mark_span_with_reason(
|
|
&self,
|
|
reason: DesugaringKind,
|
|
span: Span,
|
|
allow_internal_unstable: Option<Lrc<[Symbol]>>,
|
|
) -> Span {
|
|
self.tcx.with_stable_hashing_context(|hcx| {
|
|
span.mark_with_reason(allow_internal_unstable, reason, self.tcx.sess.edition(), hcx)
|
|
})
|
|
}
|
|
|
|
/// Intercept all spans entering HIR.
|
|
/// Mark a span as relative to the current owning item.
|
|
fn lower_span(&self, span: Span) -> Span {
|
|
if self.tcx.sess.opts.unstable_opts.incremental_relative_spans {
|
|
span.with_parent(Some(self.current_hir_id_owner))
|
|
} else {
|
|
// Do not make spans relative when not using incremental compilation.
|
|
span
|
|
}
|
|
}
|
|
|
|
fn lower_ident(&self, ident: Ident) -> Ident {
|
|
Ident::new(ident.name, self.lower_span(ident.span))
|
|
}
|
|
|
|
/// Converts a lifetime into a new generic parameter.
|
|
#[tracing::instrument(level = "debug", skip(self))]
|
|
fn lifetime_res_to_generic_param(
|
|
&mut self,
|
|
ident: Ident,
|
|
node_id: NodeId,
|
|
res: LifetimeRes,
|
|
) -> Option<hir::GenericParam<'hir>> {
|
|
let (name, kind) = match res {
|
|
LifetimeRes::Param { .. } => {
|
|
(hir::ParamName::Plain(ident), hir::LifetimeParamKind::Explicit)
|
|
}
|
|
LifetimeRes::Fresh { param, .. } => {
|
|
// Late resolution delegates to us the creation of the `LocalDefId`.
|
|
let _def_id = self.create_def(
|
|
self.current_hir_id_owner,
|
|
param,
|
|
DefPathData::LifetimeNs(kw::UnderscoreLifetime),
|
|
);
|
|
debug!(?_def_id);
|
|
|
|
(hir::ParamName::Fresh, hir::LifetimeParamKind::Elided)
|
|
}
|
|
LifetimeRes::Static | LifetimeRes::Error => return None,
|
|
res => panic!(
|
|
"Unexpected lifetime resolution {:?} for {:?} at {:?}",
|
|
res, ident, ident.span
|
|
),
|
|
};
|
|
let hir_id = self.lower_node_id(node_id);
|
|
Some(hir::GenericParam {
|
|
hir_id,
|
|
name,
|
|
span: self.lower_span(ident.span),
|
|
pure_wrt_drop: false,
|
|
kind: hir::GenericParamKind::Lifetime { kind },
|
|
colon_span: None,
|
|
})
|
|
}
|
|
|
|
/// Lowers a lifetime binder that defines `generic_params`, returning the corresponding HIR
|
|
/// nodes. The returned list includes any "extra" lifetime parameters that were added by the
|
|
/// name resolver owing to lifetime elision; this also populates the resolver's node-id->def-id
|
|
/// map, so that later calls to `opt_node_id_to_def_id` that refer to these extra lifetime
|
|
/// parameters will be successful.
|
|
#[tracing::instrument(level = "debug", skip(self))]
|
|
#[inline]
|
|
fn lower_lifetime_binder(
|
|
&mut self,
|
|
binder: NodeId,
|
|
generic_params: &[GenericParam],
|
|
) -> &'hir [hir::GenericParam<'hir>] {
|
|
let mut generic_params: Vec<_> = self.lower_generic_params_mut(generic_params).collect();
|
|
let extra_lifetimes = self.resolver.take_extra_lifetime_params(binder);
|
|
debug!(?extra_lifetimes);
|
|
generic_params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| {
|
|
self.lifetime_res_to_generic_param(ident, node_id, res)
|
|
}));
|
|
let generic_params = self.arena.alloc_from_iter(generic_params);
|
|
debug!(?generic_params);
|
|
|
|
generic_params
|
|
}
|
|
|
|
fn with_dyn_type_scope<T>(&mut self, in_scope: bool, f: impl FnOnce(&mut Self) -> T) -> T {
|
|
let was_in_dyn_type = self.is_in_dyn_type;
|
|
self.is_in_dyn_type = in_scope;
|
|
|
|
let result = f(self);
|
|
|
|
self.is_in_dyn_type = was_in_dyn_type;
|
|
|
|
result
|
|
}
|
|
|
|
fn with_new_scopes<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T {
|
|
let was_in_loop_condition = self.is_in_loop_condition;
|
|
self.is_in_loop_condition = false;
|
|
|
|
let catch_scope = self.catch_scope.take();
|
|
let loop_scope = self.loop_scope.take();
|
|
let ret = f(self);
|
|
self.catch_scope = catch_scope;
|
|
self.loop_scope = loop_scope;
|
|
|
|
self.is_in_loop_condition = was_in_loop_condition;
|
|
|
|
ret
|
|
}
|
|
|
|
fn lower_attrs(&mut self, id: hir::HirId, attrs: &[Attribute]) -> Option<&'hir [Attribute]> {
|
|
if attrs.is_empty() {
|
|
None
|
|
} else {
|
|
debug_assert_eq!(id.owner, self.current_hir_id_owner);
|
|
let ret = self.arena.alloc_from_iter(attrs.iter().map(|a| self.lower_attr(a)));
|
|
debug_assert!(!ret.is_empty());
|
|
self.attrs.insert(id.local_id, ret);
|
|
Some(ret)
|
|
}
|
|
}
|
|
|
|
fn lower_attr(&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.
|
|
// Tokens are also not needed after macro expansion and parsing.
|
|
let kind = match attr.kind {
|
|
AttrKind::Normal(ref normal) => AttrKind::Normal(P(NormalAttr {
|
|
item: AttrItem {
|
|
path: normal.item.path.clone(),
|
|
args: self.lower_mac_args(&normal.item.args),
|
|
tokens: None,
|
|
},
|
|
tokens: None,
|
|
})),
|
|
AttrKind::DocComment(comment_kind, data) => AttrKind::DocComment(comment_kind, data),
|
|
};
|
|
|
|
Attribute { kind, id: attr.id, style: attr.style, span: self.lower_span(attr.span) }
|
|
}
|
|
|
|
fn alias_attrs(&mut self, id: hir::HirId, target_id: hir::HirId) {
|
|
debug_assert_eq!(id.owner, self.current_hir_id_owner);
|
|
debug_assert_eq!(target_id.owner, self.current_hir_id_owner);
|
|
if let Some(&a) = self.attrs.get(&target_id.local_id) {
|
|
debug_assert!(!a.is_empty());
|
|
self.attrs.insert(id.local_id, a);
|
|
}
|
|
}
|
|
|
|
fn lower_mac_args(&self, args: &MacArgs) -> MacArgs {
|
|
match *args {
|
|
MacArgs::Empty => MacArgs::Empty,
|
|
MacArgs::Delimited(dspan, delim, ref tokens) => {
|
|
// This is either a non-key-value attribute, or a `macro_rules!` body.
|
|
// We either not have any nonterminals present (in the case of an attribute),
|
|
// or have tokens available for all nonterminals in the case of a nested
|
|
// `macro_rules`: e.g:
|
|
//
|
|
// ```rust
|
|
// macro_rules! outer {
|
|
// ($e:expr) => {
|
|
// macro_rules! inner {
|
|
// () => { $e }
|
|
// }
|
|
// }
|
|
// }
|
|
// ```
|
|
//
|
|
// In both cases, we don't want to synthesize any tokens
|
|
MacArgs::Delimited(dspan, delim, tokens.flattened())
|
|
}
|
|
// This is an inert key-value attribute - it will never be visible to macros
|
|
// after it gets lowered to HIR. Therefore, we can extract literals to handle
|
|
// nonterminals in `#[doc]` (e.g. `#[doc = $e]`).
|
|
MacArgs::Eq(eq_span, MacArgsEq::Ast(ref expr)) => {
|
|
// In valid code the value always ends up as a single literal. Otherwise, a dummy
|
|
// literal suffices because the error is handled elsewhere.
|
|
let lit = if let ExprKind::Lit(lit) = &expr.kind {
|
|
lit.clone()
|
|
} else {
|
|
Lit {
|
|
token_lit: token::Lit::new(token::LitKind::Err, kw::Empty, None),
|
|
kind: LitKind::Err,
|
|
span: DUMMY_SP,
|
|
}
|
|
};
|
|
MacArgs::Eq(eq_span, MacArgsEq::Hir(lit))
|
|
}
|
|
MacArgs::Eq(_, MacArgsEq::Hir(ref lit)) => {
|
|
unreachable!("in literal form when lowering mac args eq: {:?}", lit)
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Given an associated type constraint like one of these:
|
|
///
|
|
/// ```ignore (illustrative)
|
|
/// T: Iterator<Item: Debug>
|
|
/// ^^^^^^^^^^^
|
|
/// T: Iterator<Item = Debug>
|
|
/// ^^^^^^^^^^^^
|
|
/// ```
|
|
///
|
|
/// returns a `hir::TypeBinding` representing `Item`.
|
|
#[instrument(level = "debug", skip(self))]
|
|
fn lower_assoc_ty_constraint(
|
|
&mut self,
|
|
constraint: &AssocConstraint,
|
|
itctx: ImplTraitContext,
|
|
) -> hir::TypeBinding<'hir> {
|
|
debug!("lower_assoc_ty_constraint(constraint={:?}, itctx={:?})", constraint, itctx);
|
|
// lower generic arguments of identifier in constraint
|
|
let gen_args = if let Some(ref gen_args) = constraint.gen_args {
|
|
let gen_args_ctor = match gen_args {
|
|
GenericArgs::AngleBracketed(ref data) => {
|
|
self.lower_angle_bracketed_parameter_data(data, ParamMode::Explicit, itctx).0
|
|
}
|
|
GenericArgs::Parenthesized(ref data) => {
|
|
self.emit_bad_parenthesized_trait_in_assoc_ty(data);
|
|
self.lower_angle_bracketed_parameter_data(
|
|
&data.as_angle_bracketed_args(),
|
|
ParamMode::Explicit,
|
|
itctx,
|
|
)
|
|
.0
|
|
}
|
|
};
|
|
gen_args_ctor.into_generic_args(self)
|
|
} else {
|
|
self.arena.alloc(hir::GenericArgs::none())
|
|
};
|
|
|
|
let kind = match constraint.kind {
|
|
AssocConstraintKind::Equality { ref term } => {
|
|
let term = match term {
|
|
Term::Ty(ref ty) => self.lower_ty(ty, itctx).into(),
|
|
Term::Const(ref c) => self.lower_anon_const(c).into(),
|
|
};
|
|
hir::TypeBindingKind::Equality { term }
|
|
}
|
|
AssocConstraintKind::Bound { ref bounds } => {
|
|
// Piggy-back on the `impl Trait` context to figure out the correct behavior.
|
|
let (desugar_to_impl_trait, itctx) = match itctx {
|
|
// We are in the return position:
|
|
//
|
|
// fn foo() -> impl Iterator<Item: Debug>
|
|
//
|
|
// so desugar to
|
|
//
|
|
// fn foo() -> impl Iterator<Item = impl Debug>
|
|
ImplTraitContext::ReturnPositionOpaqueTy { .. }
|
|
| ImplTraitContext::TypeAliasesOpaqueTy { .. } => (true, itctx),
|
|
|
|
// We are in the argument position, but within a dyn type:
|
|
//
|
|
// fn foo(x: dyn Iterator<Item: Debug>)
|
|
//
|
|
// so desugar to
|
|
//
|
|
// fn foo(x: dyn Iterator<Item = impl Debug>)
|
|
ImplTraitContext::Universal if self.is_in_dyn_type => (true, itctx),
|
|
|
|
// In `type Foo = dyn Iterator<Item: Debug>` we desugar to
|
|
// `type Foo = dyn Iterator<Item = impl Debug>` but we have to override the
|
|
// "impl trait context" to permit `impl Debug` in this position (it desugars
|
|
// then to an opaque type).
|
|
//
|
|
// FIXME: this is only needed until `impl Trait` is allowed in type aliases.
|
|
ImplTraitContext::Disallowed(_) if self.is_in_dyn_type => {
|
|
(true, ImplTraitContext::TypeAliasesOpaqueTy)
|
|
}
|
|
|
|
// We are in the parameter position, but not within a dyn type:
|
|
//
|
|
// fn foo(x: impl Iterator<Item: Debug>)
|
|
//
|
|
// so we leave it as is and this gets expanded in astconv to a bound like
|
|
// `<T as Iterator>::Item: Debug` where `T` is the type parameter for the
|
|
// `impl Iterator`.
|
|
_ => (false, itctx),
|
|
};
|
|
|
|
if desugar_to_impl_trait {
|
|
// Desugar `AssocTy: Bounds` into `AssocTy = impl Bounds`. We do this by
|
|
// constructing the HIR for `impl bounds...` and then lowering that.
|
|
|
|
let parent_def_id = self.current_hir_id_owner;
|
|
let impl_trait_node_id = self.next_node_id();
|
|
self.create_def(parent_def_id, impl_trait_node_id, DefPathData::ImplTrait);
|
|
|
|
self.with_dyn_type_scope(false, |this| {
|
|
let node_id = this.next_node_id();
|
|
let ty = this.lower_ty(
|
|
&Ty {
|
|
id: node_id,
|
|
kind: TyKind::ImplTrait(impl_trait_node_id, bounds.clone()),
|
|
span: this.lower_span(constraint.span),
|
|
tokens: None,
|
|
},
|
|
itctx,
|
|
);
|
|
|
|
hir::TypeBindingKind::Equality { term: ty.into() }
|
|
})
|
|
} else {
|
|
// Desugar `AssocTy: Bounds` into a type binding where the
|
|
// later desugars into a trait predicate.
|
|
let bounds = self.lower_param_bounds(bounds, itctx);
|
|
|
|
hir::TypeBindingKind::Constraint { bounds }
|
|
}
|
|
}
|
|
};
|
|
|
|
hir::TypeBinding {
|
|
hir_id: self.lower_node_id(constraint.id),
|
|
ident: self.lower_ident(constraint.ident),
|
|
gen_args,
|
|
kind,
|
|
span: self.lower_span(constraint.span),
|
|
}
|
|
}
|
|
|
|
fn emit_bad_parenthesized_trait_in_assoc_ty(&self, data: &ParenthesizedArgs) {
|
|
let mut err = self.tcx.sess.struct_span_err(
|
|
data.span,
|
|
"parenthesized generic arguments cannot be used in associated type constraints",
|
|
);
|
|
// Suggest removing empty parentheses: "Trait()" -> "Trait"
|
|
if data.inputs.is_empty() {
|
|
let parentheses_span =
|
|
data.inputs_span.shrink_to_lo().to(data.inputs_span.shrink_to_hi());
|
|
err.multipart_suggestion(
|
|
"remove these parentheses",
|
|
vec![(parentheses_span, String::new())],
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
// Suggest replacing parentheses with angle brackets `Trait(params...)` to `Trait<params...>`
|
|
else {
|
|
// Start of parameters to the 1st argument
|
|
let open_param = data.inputs_span.shrink_to_lo().to(data
|
|
.inputs
|
|
.first()
|
|
.unwrap()
|
|
.span
|
|
.shrink_to_lo());
|
|
// End of last argument to end of parameters
|
|
let close_param =
|
|
data.inputs.last().unwrap().span.shrink_to_hi().to(data.inputs_span.shrink_to_hi());
|
|
err.multipart_suggestion(
|
|
&format!("use angle brackets instead",),
|
|
vec![(open_param, String::from("<")), (close_param, String::from(">"))],
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
err.emit();
|
|
}
|
|
|
|
#[instrument(level = "debug", skip(self))]
|
|
fn lower_generic_arg(
|
|
&mut self,
|
|
arg: &ast::GenericArg,
|
|
itctx: ImplTraitContext,
|
|
) -> hir::GenericArg<'hir> {
|
|
match arg {
|
|
ast::GenericArg::Lifetime(lt) => GenericArg::Lifetime(self.lower_lifetime(<)),
|
|
ast::GenericArg::Type(ty) => {
|
|
match ty.kind {
|
|
TyKind::Infer if self.tcx.features().generic_arg_infer => {
|
|
return GenericArg::Infer(hir::InferArg {
|
|
hir_id: self.lower_node_id(ty.id),
|
|
span: self.lower_span(ty.span),
|
|
});
|
|
}
|
|
// We parse const arguments as path types as we cannot distinguish them during
|
|
// parsing. We try to resolve that ambiguity by attempting resolution in both the
|
|
// type and value namespaces. If we resolved the path in the value namespace, we
|
|
// transform it into a generic const argument.
|
|
TyKind::Path(ref qself, ref path) => {
|
|
if let Some(partial_res) = self.resolver.get_partial_res(ty.id) {
|
|
let res = partial_res.base_res();
|
|
if !res.matches_ns(Namespace::TypeNS) {
|
|
debug!(
|
|
"lower_generic_arg: Lowering type argument as const argument: {:?}",
|
|
ty,
|
|
);
|
|
|
|
// Construct an AnonConst where the expr is the "ty"'s path.
|
|
|
|
let parent_def_id = self.current_hir_id_owner;
|
|
let node_id = self.next_node_id();
|
|
|
|
// Add a definition for the in-band const def.
|
|
self.create_def(parent_def_id, node_id, DefPathData::AnonConst);
|
|
|
|
let span = self.lower_span(ty.span);
|
|
let path_expr = Expr {
|
|
id: ty.id,
|
|
kind: ExprKind::Path(qself.clone(), path.clone()),
|
|
span,
|
|
attrs: AttrVec::new(),
|
|
tokens: None,
|
|
};
|
|
|
|
let ct = self.with_new_scopes(|this| hir::AnonConst {
|
|
hir_id: this.lower_node_id(node_id),
|
|
body: this.lower_const_body(path_expr.span, Some(&path_expr)),
|
|
});
|
|
return GenericArg::Const(ConstArg { value: ct, span });
|
|
}
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
GenericArg::Type(self.lower_ty_direct(&ty, itctx))
|
|
}
|
|
ast::GenericArg::Const(ct) => GenericArg::Const(ConstArg {
|
|
value: self.lower_anon_const(&ct),
|
|
span: self.lower_span(ct.value.span),
|
|
}),
|
|
}
|
|
}
|
|
|
|
#[instrument(level = "debug", skip(self))]
|
|
fn lower_ty(&mut self, t: &Ty, itctx: ImplTraitContext) -> &'hir hir::Ty<'hir> {
|
|
self.arena.alloc(self.lower_ty_direct(t, itctx))
|
|
}
|
|
|
|
fn lower_path_ty(
|
|
&mut self,
|
|
t: &Ty,
|
|
qself: &Option<QSelf>,
|
|
path: &Path,
|
|
param_mode: ParamMode,
|
|
itctx: ImplTraitContext,
|
|
) -> hir::Ty<'hir> {
|
|
// Check whether we should interpret this as a bare trait object.
|
|
// This check mirrors the one in late resolution. We only introduce this special case in
|
|
// the rare occurence we need to lower `Fresh` anonymous lifetimes.
|
|
// The other cases when a qpath should be opportunistically made a trait object are handled
|
|
// by `ty_path`.
|
|
if qself.is_none()
|
|
&& let Some(partial_res) = self.resolver.get_partial_res(t.id)
|
|
&& partial_res.unresolved_segments() == 0
|
|
&& let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = partial_res.base_res()
|
|
{
|
|
let (bounds, lifetime_bound) = self.with_dyn_type_scope(true, |this| {
|
|
let bound = this.lower_poly_trait_ref(
|
|
&PolyTraitRef {
|
|
bound_generic_params: vec![],
|
|
trait_ref: TraitRef { path: path.clone(), ref_id: t.id },
|
|
span: t.span
|
|
},
|
|
itctx,
|
|
);
|
|
let bounds = this.arena.alloc_from_iter([bound]);
|
|
let lifetime_bound = this.elided_dyn_bound(t.span);
|
|
(bounds, lifetime_bound)
|
|
});
|
|
let kind = hir::TyKind::TraitObject(bounds, lifetime_bound, TraitObjectSyntax::None);
|
|
return hir::Ty { kind, span: self.lower_span(t.span), hir_id: self.next_id() };
|
|
}
|
|
|
|
let id = self.lower_node_id(t.id);
|
|
let qpath = self.lower_qpath(t.id, qself, path, param_mode, itctx);
|
|
self.ty_path(id, t.span, qpath)
|
|
}
|
|
|
|
fn ty(&mut self, span: Span, kind: hir::TyKind<'hir>) -> hir::Ty<'hir> {
|
|
hir::Ty { hir_id: self.next_id(), kind, span: self.lower_span(span) }
|
|
}
|
|
|
|
fn ty_tup(&mut self, span: Span, tys: &'hir [hir::Ty<'hir>]) -> hir::Ty<'hir> {
|
|
self.ty(span, hir::TyKind::Tup(tys))
|
|
}
|
|
|
|
fn lower_ty_direct(&mut self, t: &Ty, itctx: ImplTraitContext) -> hir::Ty<'hir> {
|
|
let kind = match t.kind {
|
|
TyKind::Infer => hir::TyKind::Infer,
|
|
TyKind::Err => hir::TyKind::Err,
|
|
TyKind::Slice(ref ty) => hir::TyKind::Slice(self.lower_ty(ty, itctx)),
|
|
TyKind::Ptr(ref mt) => hir::TyKind::Ptr(self.lower_mt(mt, itctx)),
|
|
TyKind::Rptr(ref region, ref mt) => {
|
|
let region = region.unwrap_or_else(|| {
|
|
let id = if let Some(LifetimeRes::ElidedAnchor { start, end }) =
|
|
self.resolver.get_lifetime_res(t.id)
|
|
{
|
|
debug_assert_eq!(start.plus(1), end);
|
|
start
|
|
} else {
|
|
self.next_node_id()
|
|
};
|
|
let span = self.tcx.sess.source_map().start_point(t.span);
|
|
Lifetime { ident: Ident::new(kw::UnderscoreLifetime, span), id }
|
|
});
|
|
let lifetime = self.lower_lifetime(®ion);
|
|
hir::TyKind::Rptr(lifetime, self.lower_mt(mt, itctx))
|
|
}
|
|
TyKind::BareFn(ref f) => {
|
|
let generic_params = self.lower_lifetime_binder(t.id, &f.generic_params);
|
|
hir::TyKind::BareFn(self.arena.alloc(hir::BareFnTy {
|
|
generic_params,
|
|
unsafety: self.lower_unsafety(f.unsafety),
|
|
abi: self.lower_extern(f.ext),
|
|
decl: self.lower_fn_decl(&f.decl, None, FnDeclKind::Pointer, None),
|
|
param_names: self.lower_fn_params_to_names(&f.decl),
|
|
}))
|
|
}
|
|
TyKind::Never => hir::TyKind::Never,
|
|
TyKind::Tup(ref tys) => hir::TyKind::Tup(
|
|
self.arena.alloc_from_iter(tys.iter().map(|ty| self.lower_ty_direct(ty, itctx))),
|
|
),
|
|
TyKind::Paren(ref ty) => {
|
|
return self.lower_ty_direct(ty, itctx);
|
|
}
|
|
TyKind::Path(ref qself, ref path) => {
|
|
return self.lower_path_ty(t, qself, path, ParamMode::Explicit, itctx);
|
|
}
|
|
TyKind::ImplicitSelf => {
|
|
let res = self.expect_full_res(t.id);
|
|
let res = self.lower_res(res);
|
|
hir::TyKind::Path(hir::QPath::Resolved(
|
|
None,
|
|
self.arena.alloc(hir::Path {
|
|
res,
|
|
segments: arena_vec![self; hir::PathSegment::from_ident(
|
|
Ident::with_dummy_span(kw::SelfUpper)
|
|
)],
|
|
span: self.lower_span(t.span),
|
|
}),
|
|
))
|
|
}
|
|
TyKind::Array(ref ty, ref length) => {
|
|
hir::TyKind::Array(self.lower_ty(ty, itctx), self.lower_array_length(length))
|
|
}
|
|
TyKind::Typeof(ref expr) => hir::TyKind::Typeof(self.lower_anon_const(expr)),
|
|
TyKind::TraitObject(ref bounds, kind) => {
|
|
let mut lifetime_bound = None;
|
|
let (bounds, lifetime_bound) = self.with_dyn_type_scope(true, |this| {
|
|
let bounds =
|
|
this.arena.alloc_from_iter(bounds.iter().filter_map(
|
|
|bound| match *bound {
|
|
GenericBound::Trait(
|
|
ref ty,
|
|
TraitBoundModifier::None | TraitBoundModifier::MaybeConst,
|
|
) => Some(this.lower_poly_trait_ref(ty, itctx)),
|
|
// `~const ?Bound` will cause an error during AST validation
|
|
// anyways, so treat it like `?Bound` as compilation proceeds.
|
|
GenericBound::Trait(
|
|
_,
|
|
TraitBoundModifier::Maybe | TraitBoundModifier::MaybeConstMaybe,
|
|
) => None,
|
|
GenericBound::Outlives(ref lifetime) => {
|
|
if lifetime_bound.is_none() {
|
|
lifetime_bound = Some(this.lower_lifetime(lifetime));
|
|
}
|
|
None
|
|
}
|
|
},
|
|
));
|
|
let lifetime_bound =
|
|
lifetime_bound.unwrap_or_else(|| this.elided_dyn_bound(t.span));
|
|
(bounds, lifetime_bound)
|
|
});
|
|
hir::TyKind::TraitObject(bounds, lifetime_bound, kind)
|
|
}
|
|
TyKind::ImplTrait(def_node_id, ref bounds) => {
|
|
let span = t.span;
|
|
match itctx {
|
|
ImplTraitContext::ReturnPositionOpaqueTy { origin } => {
|
|
self.lower_opaque_impl_trait(span, origin, def_node_id, bounds, itctx)
|
|
}
|
|
ImplTraitContext::TypeAliasesOpaqueTy => {
|
|
let nested_itctx = ImplTraitContext::TypeAliasesOpaqueTy;
|
|
self.lower_opaque_impl_trait(
|
|
span,
|
|
hir::OpaqueTyOrigin::TyAlias,
|
|
def_node_id,
|
|
bounds,
|
|
nested_itctx,
|
|
)
|
|
}
|
|
ImplTraitContext::Universal => {
|
|
let span = t.span;
|
|
let ident = Ident::from_str_and_span(&pprust::ty_to_string(t), span);
|
|
let (param, bounds, path) =
|
|
self.lower_generic_and_bounds(def_node_id, span, ident, bounds);
|
|
self.impl_trait_defs.push(param);
|
|
if let Some(bounds) = bounds {
|
|
self.impl_trait_bounds.push(bounds);
|
|
}
|
|
path
|
|
}
|
|
ImplTraitContext::Disallowed(position) => {
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
t.span,
|
|
E0562,
|
|
"`impl Trait` only allowed in function and inherent method return types, not in {}",
|
|
position
|
|
);
|
|
err.emit();
|
|
hir::TyKind::Err
|
|
}
|
|
}
|
|
}
|
|
TyKind::MacCall(_) => panic!("`TyKind::MacCall` should have been expanded by now"),
|
|
TyKind::CVarArgs => {
|
|
self.tcx.sess.delay_span_bug(
|
|
t.span,
|
|
"`TyKind::CVarArgs` should have been handled elsewhere",
|
|
);
|
|
hir::TyKind::Err
|
|
}
|
|
};
|
|
|
|
hir::Ty { kind, span: self.lower_span(t.span), hir_id: self.lower_node_id(t.id) }
|
|
}
|
|
|
|
/// Lowers a `ReturnPositionOpaqueTy` (`-> impl Trait`) or a `TypeAliasesOpaqueTy` (`type F =
|
|
/// impl Trait`): this creates the associated Opaque Type (TAIT) definition and then returns a
|
|
/// HIR type that references the TAIT.
|
|
///
|
|
/// Given a function definition like:
|
|
///
|
|
/// ```rust
|
|
/// fn test<'a, T: Debug>(x: &'a T) -> impl Debug + 'a {
|
|
/// x
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// we will create a TAIT definition in the HIR like
|
|
///
|
|
/// ```
|
|
/// type TestReturn<'a, T, 'x> = impl Debug + 'x
|
|
/// ```
|
|
///
|
|
/// and return a type like `TestReturn<'static, T, 'a>`, so that the function looks like:
|
|
///
|
|
/// ```rust
|
|
/// fn test<'a, T: Debug>(x: &'a T) -> TestReturn<'static, T, 'a>
|
|
/// ```
|
|
///
|
|
/// Note the subtlety around type parameters! The new TAIT, `TestReturn`, inherits all the
|
|
/// type parameters from the function `test` (this is implemented in the query layer, they aren't
|
|
/// added explicitly in the HIR). But this includes all the lifetimes, and we only want to
|
|
/// capture the lifetimes that are referenced in the bounds. Therefore, we add *extra* lifetime parameters
|
|
/// for the lifetimes that get captured (`'x`, in our example above) and reference those.
|
|
#[tracing::instrument(level = "debug", skip(self))]
|
|
fn lower_opaque_impl_trait(
|
|
&mut self,
|
|
span: Span,
|
|
origin: hir::OpaqueTyOrigin,
|
|
opaque_ty_node_id: NodeId,
|
|
bounds: &GenericBounds,
|
|
itctx: ImplTraitContext,
|
|
) -> hir::TyKind<'hir> {
|
|
// Make sure we know that some funky desugaring has been going on here.
|
|
// This is a first: there is code in other places like for loop
|
|
// desugaring that explicitly states that we don't want to track that.
|
|
// Not tracking it makes lints in rustc and clippy very fragile, as
|
|
// frequently opened issues show.
|
|
let opaque_ty_span = self.mark_span_with_reason(DesugaringKind::OpaqueTy, span, None);
|
|
|
|
let opaque_ty_def_id = self.local_def_id(opaque_ty_node_id);
|
|
debug!(?opaque_ty_def_id);
|
|
|
|
// Contains the new lifetime definitions created for the TAIT (if any).
|
|
let mut collected_lifetimes = Vec::new();
|
|
|
|
// If this came from a TAIT (as opposed to a function that returns an RPIT), we only want
|
|
// to capture the lifetimes that appear in the bounds. So visit the bounds to find out
|
|
// exactly which ones those are.
|
|
let lifetimes_to_remap = if origin == hir::OpaqueTyOrigin::TyAlias {
|
|
// in a TAIT like `type Foo<'a> = impl Foo<'a>`, we don't keep all the lifetime parameters
|
|
Vec::new()
|
|
} else {
|
|
// in fn return position, like the `fn test<'a>() -> impl Debug + 'a` example,
|
|
// we only keep the lifetimes that appear in the `impl Debug` itself:
|
|
lifetime_collector::lifetimes_in_bounds(&self.resolver, bounds)
|
|
};
|
|
debug!(?lifetimes_to_remap);
|
|
|
|
self.with_hir_id_owner(opaque_ty_node_id, |lctx| {
|
|
let mut new_remapping = FxHashMap::default();
|
|
|
|
// If this opaque type is only capturing a subset of the lifetimes (those that appear
|
|
// in bounds), then create the new lifetime parameters required and create a mapping
|
|
// from the old `'a` (on the function) to the new `'a` (on the opaque type).
|
|
collected_lifetimes = lctx.create_lifetime_defs(
|
|
opaque_ty_def_id,
|
|
&lifetimes_to_remap,
|
|
&mut new_remapping,
|
|
);
|
|
debug!(?collected_lifetimes);
|
|
debug!(?new_remapping);
|
|
|
|
// Install the remapping from old to new (if any):
|
|
lctx.with_remapping(new_remapping, |lctx| {
|
|
// This creates HIR lifetime definitions as `hir::GenericParam`, in the given
|
|
// example `type TestReturn<'a, T, 'x> = impl Debug + 'x`, it creates a collection
|
|
// containing `&['x]`.
|
|
let lifetime_defs = lctx.arena.alloc_from_iter(collected_lifetimes.iter().map(
|
|
|&(new_node_id, lifetime)| {
|
|
let hir_id = lctx.lower_node_id(new_node_id);
|
|
debug_assert_ne!(lctx.opt_local_def_id(new_node_id), None);
|
|
|
|
let (name, kind) = if lifetime.ident.name == kw::UnderscoreLifetime {
|
|
(hir::ParamName::Fresh, hir::LifetimeParamKind::Elided)
|
|
} else {
|
|
(
|
|
hir::ParamName::Plain(lifetime.ident),
|
|
hir::LifetimeParamKind::Explicit,
|
|
)
|
|
};
|
|
|
|
hir::GenericParam {
|
|
hir_id,
|
|
name,
|
|
span: lifetime.ident.span,
|
|
pure_wrt_drop: false,
|
|
kind: hir::GenericParamKind::Lifetime { kind },
|
|
colon_span: None,
|
|
}
|
|
},
|
|
));
|
|
debug!(?lifetime_defs);
|
|
|
|
// Then when we lower the param bounds, references to 'a are remapped to 'a1, so we
|
|
// get back Debug + 'a1, which is suitable for use on the TAIT.
|
|
let hir_bounds = lctx.lower_param_bounds(bounds, itctx);
|
|
debug!(?hir_bounds);
|
|
|
|
let opaque_ty_item = hir::OpaqueTy {
|
|
generics: self.arena.alloc(hir::Generics {
|
|
params: lifetime_defs,
|
|
predicates: &[],
|
|
has_where_clause_predicates: false,
|
|
where_clause_span: lctx.lower_span(span),
|
|
span: lctx.lower_span(span),
|
|
}),
|
|
bounds: hir_bounds,
|
|
origin,
|
|
};
|
|
debug!(?opaque_ty_item);
|
|
|
|
lctx.generate_opaque_type(opaque_ty_def_id, opaque_ty_item, span, opaque_ty_span)
|
|
})
|
|
});
|
|
|
|
// This creates HIR lifetime arguments as `hir::GenericArg`, in the given example `type
|
|
// TestReturn<'a, T, 'x> = impl Debug + 'x`, it creates a collection containing `&['x]`.
|
|
let lifetimes =
|
|
self.arena.alloc_from_iter(collected_lifetimes.into_iter().map(|(_, lifetime)| {
|
|
let id = self.next_node_id();
|
|
let span = lifetime.ident.span;
|
|
|
|
let ident = if lifetime.ident.name == kw::UnderscoreLifetime {
|
|
Ident::with_dummy_span(kw::UnderscoreLifetime)
|
|
} else {
|
|
lifetime.ident
|
|
};
|
|
|
|
let l = self.new_named_lifetime(lifetime.id, id, span, ident);
|
|
hir::GenericArg::Lifetime(l)
|
|
}));
|
|
debug!(?lifetimes);
|
|
|
|
// `impl Trait` now just becomes `Foo<'a, 'b, ..>`.
|
|
hir::TyKind::OpaqueDef(hir::ItemId { def_id: opaque_ty_def_id }, lifetimes)
|
|
}
|
|
|
|
/// Registers a new opaque type with the proper `NodeId`s and
|
|
/// returns the lowered node-ID for the opaque type.
|
|
fn generate_opaque_type(
|
|
&mut self,
|
|
opaque_ty_id: LocalDefId,
|
|
opaque_ty_item: hir::OpaqueTy<'hir>,
|
|
span: Span,
|
|
opaque_ty_span: Span,
|
|
) -> hir::OwnerNode<'hir> {
|
|
let opaque_ty_item_kind = hir::ItemKind::OpaqueTy(opaque_ty_item);
|
|
// Generate an `type Foo = impl Trait;` declaration.
|
|
trace!("registering opaque type with id {:#?}", opaque_ty_id);
|
|
let opaque_ty_item = hir::Item {
|
|
def_id: opaque_ty_id,
|
|
ident: Ident::empty(),
|
|
kind: opaque_ty_item_kind,
|
|
vis_span: self.lower_span(span.shrink_to_lo()),
|
|
span: self.lower_span(opaque_ty_span),
|
|
};
|
|
hir::OwnerNode::Item(self.arena.alloc(opaque_ty_item))
|
|
}
|
|
|
|
/// Given a `parent_def_id`, a list of `lifetimes_in_bounds and a `remapping` hash to be
|
|
/// filled, this function creates new definitions for `Param` and `Fresh` lifetimes, inserts the
|
|
/// new definition, adds it to the remapping with the definition of the given lifetime and
|
|
/// returns a list of lifetimes to be lowered afterwards.
|
|
fn create_lifetime_defs(
|
|
&mut self,
|
|
parent_def_id: LocalDefId,
|
|
lifetimes_in_bounds: &[Lifetime],
|
|
remapping: &mut FxHashMap<LocalDefId, LocalDefId>,
|
|
) -> Vec<(NodeId, Lifetime)> {
|
|
let mut result = Vec::new();
|
|
|
|
for lifetime in lifetimes_in_bounds {
|
|
let res = self.resolver.get_lifetime_res(lifetime.id).unwrap_or(LifetimeRes::Error);
|
|
debug!(?res);
|
|
|
|
match res {
|
|
LifetimeRes::Param { param: old_def_id, binder: _ } => {
|
|
if remapping.get(&old_def_id).is_none() {
|
|
let node_id = self.next_node_id();
|
|
|
|
let new_def_id = self.create_def(
|
|
parent_def_id,
|
|
node_id,
|
|
DefPathData::LifetimeNs(lifetime.ident.name),
|
|
);
|
|
remapping.insert(old_def_id, new_def_id);
|
|
|
|
result.push((node_id, *lifetime));
|
|
}
|
|
}
|
|
|
|
LifetimeRes::Fresh { param, binder: _ } => {
|
|
debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
|
|
let old_def_id = self.local_def_id(param);
|
|
if remapping.get(&old_def_id).is_none() {
|
|
let node_id = self.next_node_id();
|
|
|
|
let new_def_id = self.create_def(
|
|
parent_def_id,
|
|
node_id,
|
|
DefPathData::LifetimeNs(kw::UnderscoreLifetime),
|
|
);
|
|
remapping.insert(old_def_id, new_def_id);
|
|
|
|
result.push((node_id, *lifetime));
|
|
}
|
|
}
|
|
|
|
LifetimeRes::Static | LifetimeRes::Error => {}
|
|
|
|
res => {
|
|
let bug_msg = format!(
|
|
"Unexpected lifetime resolution {:?} for {:?} at {:?}",
|
|
res, lifetime.ident, lifetime.ident.span
|
|
);
|
|
span_bug!(lifetime.ident.span, "{}", bug_msg);
|
|
}
|
|
}
|
|
}
|
|
|
|
result
|
|
}
|
|
|
|
fn lower_fn_params_to_names(&mut self, decl: &FnDecl) -> &'hir [Ident] {
|
|
// Skip the `...` (`CVarArgs`) trailing arguments from the AST,
|
|
// as they are not explicit in HIR/Ty function signatures.
|
|
// (instead, the `c_variadic` flag is set to `true`)
|
|
let mut inputs = &decl.inputs[..];
|
|
if decl.c_variadic() {
|
|
inputs = &inputs[..inputs.len() - 1];
|
|
}
|
|
self.arena.alloc_from_iter(inputs.iter().map(|param| match param.pat.kind {
|
|
PatKind::Ident(_, ident, _) => self.lower_ident(ident),
|
|
_ => Ident::new(kw::Empty, self.lower_span(param.pat.span)),
|
|
}))
|
|
}
|
|
|
|
// Lowers a function declaration.
|
|
//
|
|
// `decl`: the unlowered (AST) function declaration.
|
|
// `fn_def_id`: if `Some`, impl Trait arguments are lowered into generic parameters on the
|
|
// given DefId, otherwise impl Trait is disallowed. Must be `Some` if
|
|
// `make_ret_async` is also `Some`.
|
|
// `impl_trait_return_allow`: determines whether `impl Trait` can be used in return position.
|
|
// This guards against trait declarations and implementations where `impl Trait` is
|
|
// disallowed.
|
|
// `make_ret_async`: if `Some`, converts `-> T` into `-> impl Future<Output = T>` in the
|
|
// return type. This is used for `async fn` declarations. The `NodeId` is the ID of the
|
|
// return type `impl Trait` item.
|
|
#[tracing::instrument(level = "debug", skip(self))]
|
|
fn lower_fn_decl(
|
|
&mut self,
|
|
decl: &FnDecl,
|
|
fn_node_id: Option<NodeId>,
|
|
kind: FnDeclKind,
|
|
make_ret_async: Option<NodeId>,
|
|
) -> &'hir hir::FnDecl<'hir> {
|
|
let c_variadic = decl.c_variadic();
|
|
|
|
// Skip the `...` (`CVarArgs`) trailing arguments from the AST,
|
|
// as they are not explicit in HIR/Ty function signatures.
|
|
// (instead, the `c_variadic` flag is set to `true`)
|
|
let mut inputs = &decl.inputs[..];
|
|
if c_variadic {
|
|
inputs = &inputs[..inputs.len() - 1];
|
|
}
|
|
let inputs = self.arena.alloc_from_iter(inputs.iter().map(|param| {
|
|
if fn_node_id.is_some() {
|
|
self.lower_ty_direct(¶m.ty, ImplTraitContext::Universal)
|
|
} else {
|
|
self.lower_ty_direct(
|
|
¶m.ty,
|
|
ImplTraitContext::Disallowed(match kind {
|
|
FnDeclKind::Fn | FnDeclKind::Inherent => {
|
|
unreachable!("fn should allow in-band lifetimes")
|
|
}
|
|
FnDeclKind::ExternFn => ImplTraitPosition::ExternFnParam,
|
|
FnDeclKind::Closure => ImplTraitPosition::ClosureParam,
|
|
FnDeclKind::Pointer => ImplTraitPosition::PointerParam,
|
|
FnDeclKind::Trait => ImplTraitPosition::TraitParam,
|
|
FnDeclKind::Impl => ImplTraitPosition::ImplParam,
|
|
}),
|
|
)
|
|
}
|
|
}));
|
|
|
|
let output = if let Some(ret_id) = make_ret_async {
|
|
self.lower_async_fn_ret_ty(
|
|
&decl.output,
|
|
fn_node_id.expect("`make_ret_async` but no `fn_def_id`"),
|
|
ret_id,
|
|
)
|
|
} else {
|
|
match decl.output {
|
|
FnRetTy::Ty(ref ty) => {
|
|
let context = match fn_node_id {
|
|
Some(fn_node_id) if kind.impl_trait_return_allowed() => {
|
|
let fn_def_id = self.local_def_id(fn_node_id);
|
|
ImplTraitContext::ReturnPositionOpaqueTy {
|
|
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
|
|
}
|
|
}
|
|
_ => ImplTraitContext::Disallowed(match kind {
|
|
FnDeclKind::Fn | FnDeclKind::Inherent => {
|
|
unreachable!("fn should allow in-band lifetimes")
|
|
}
|
|
FnDeclKind::ExternFn => ImplTraitPosition::ExternFnReturn,
|
|
FnDeclKind::Closure => ImplTraitPosition::ClosureReturn,
|
|
FnDeclKind::Pointer => ImplTraitPosition::PointerReturn,
|
|
FnDeclKind::Trait => ImplTraitPosition::TraitReturn,
|
|
FnDeclKind::Impl => ImplTraitPosition::ImplReturn,
|
|
}),
|
|
};
|
|
hir::FnRetTy::Return(self.lower_ty(ty, context))
|
|
}
|
|
FnRetTy::Default(span) => hir::FnRetTy::DefaultReturn(self.lower_span(span)),
|
|
}
|
|
};
|
|
|
|
self.arena.alloc(hir::FnDecl {
|
|
inputs,
|
|
output,
|
|
c_variadic,
|
|
implicit_self: decl.inputs.get(0).map_or(hir::ImplicitSelfKind::None, |arg| {
|
|
use BindingMode::{ByRef, ByValue};
|
|
let is_mutable_pat = matches!(
|
|
arg.pat.kind,
|
|
PatKind::Ident(ByValue(Mutability::Mut) | ByRef(Mutability::Mut), ..)
|
|
);
|
|
|
|
match arg.ty.kind {
|
|
TyKind::ImplicitSelf if is_mutable_pat => hir::ImplicitSelfKind::Mut,
|
|
TyKind::ImplicitSelf => hir::ImplicitSelfKind::Imm,
|
|
// Given we are only considering `ImplicitSelf` types, we needn't consider
|
|
// the case where we have a mutable pattern to a reference as that would
|
|
// no longer be an `ImplicitSelf`.
|
|
TyKind::Rptr(_, ref mt)
|
|
if mt.ty.kind.is_implicit_self() && mt.mutbl == ast::Mutability::Mut =>
|
|
{
|
|
hir::ImplicitSelfKind::MutRef
|
|
}
|
|
TyKind::Rptr(_, ref mt) if mt.ty.kind.is_implicit_self() => {
|
|
hir::ImplicitSelfKind::ImmRef
|
|
}
|
|
_ => hir::ImplicitSelfKind::None,
|
|
}
|
|
}),
|
|
})
|
|
}
|
|
|
|
// Transforms `-> T` for `async fn` into `-> OpaqueTy { .. }`
|
|
// combined with the following definition of `OpaqueTy`:
|
|
//
|
|
// type OpaqueTy<generics_from_parent_fn> = impl Future<Output = T>;
|
|
//
|
|
// `output`: unlowered output type (`T` in `-> T`)
|
|
// `fn_def_id`: `DefId` of the parent function (used to create child impl trait definition)
|
|
// `opaque_ty_node_id`: `NodeId` of the opaque `impl Trait` type that should be created
|
|
#[tracing::instrument(level = "debug", skip(self))]
|
|
fn lower_async_fn_ret_ty(
|
|
&mut self,
|
|
output: &FnRetTy,
|
|
fn_node_id: NodeId,
|
|
opaque_ty_node_id: NodeId,
|
|
) -> hir::FnRetTy<'hir> {
|
|
let span = output.span();
|
|
|
|
let opaque_ty_span = self.mark_span_with_reason(DesugaringKind::Async, span, None);
|
|
|
|
let opaque_ty_def_id = self.local_def_id(opaque_ty_node_id);
|
|
let fn_def_id = self.local_def_id(fn_node_id);
|
|
|
|
// When we create the opaque type for this async fn, it is going to have
|
|
// to capture all the lifetimes involved in the signature (including in the
|
|
// return type). This is done by introducing lifetime parameters for:
|
|
//
|
|
// - all the explicitly declared lifetimes from the impl and function itself;
|
|
// - all the elided lifetimes in the fn arguments;
|
|
// - all the elided lifetimes in the return type.
|
|
//
|
|
// So for example in this snippet:
|
|
//
|
|
// ```rust
|
|
// impl<'a> Foo<'a> {
|
|
// async fn bar<'b>(&self, x: &'b Vec<f64>, y: &str) -> &u32 {
|
|
// // ^ '0 ^ '1 ^ '2
|
|
// // elided lifetimes used below
|
|
// }
|
|
// }
|
|
// ```
|
|
//
|
|
// we would create an opaque type like:
|
|
//
|
|
// ```
|
|
// type Bar<'a, 'b, '0, '1, '2> = impl Future<Output = &'2 u32>;
|
|
// ```
|
|
//
|
|
// and we would then desugar `bar` to the equivalent of:
|
|
//
|
|
// ```rust
|
|
// impl<'a> Foo<'a> {
|
|
// fn bar<'b, '0, '1>(&'0 self, x: &'b Vec<f64>, y: &'1 str) -> Bar<'a, 'b, '0, '1, '_>
|
|
// }
|
|
// ```
|
|
//
|
|
// Note that the final parameter to `Bar` is `'_`, not `'2` --
|
|
// this is because the elided lifetimes from the return type
|
|
// should be figured out using the ordinary elision rules, and
|
|
// this desugaring achieves that.
|
|
|
|
// Calculate all the lifetimes that should be captured
|
|
// by the opaque type. This should include all in-scope
|
|
// lifetime parameters, including those defined in-band.
|
|
|
|
// Contains the new lifetime definitions created for the TAIT (if any) generated for the
|
|
// return type.
|
|
let mut collected_lifetimes = Vec::new();
|
|
let mut new_remapping = FxHashMap::default();
|
|
|
|
let extra_lifetime_params = self.resolver.take_extra_lifetime_params(opaque_ty_node_id);
|
|
debug!(?extra_lifetime_params);
|
|
for (ident, outer_node_id, outer_res) in extra_lifetime_params {
|
|
let outer_def_id = self.local_def_id(outer_node_id);
|
|
let inner_node_id = self.next_node_id();
|
|
|
|
// Add a definition for the in scope lifetime def.
|
|
let inner_def_id = self.create_def(
|
|
opaque_ty_def_id,
|
|
inner_node_id,
|
|
DefPathData::LifetimeNs(ident.name),
|
|
);
|
|
new_remapping.insert(outer_def_id, inner_def_id);
|
|
|
|
let inner_res = match outer_res {
|
|
// Input lifetime like `'a`:
|
|
LifetimeRes::Param { param, .. } => {
|
|
LifetimeRes::Param { param, binder: fn_node_id }
|
|
}
|
|
// Input lifetime like `'1`:
|
|
LifetimeRes::Fresh { param, .. } => {
|
|
LifetimeRes::Fresh { param, binder: fn_node_id }
|
|
}
|
|
LifetimeRes::Static | LifetimeRes::Error => continue,
|
|
res => {
|
|
panic!(
|
|
"Unexpected lifetime resolution {:?} for {:?} at {:?}",
|
|
res, ident, ident.span
|
|
)
|
|
}
|
|
};
|
|
|
|
let lifetime = Lifetime { id: outer_node_id, ident };
|
|
collected_lifetimes.push((inner_node_id, lifetime, Some(inner_res)));
|
|
}
|
|
|
|
debug!(?collected_lifetimes);
|
|
|
|
// We only want to capture the lifetimes that appear in the bounds. So visit the bounds to
|
|
// find out exactly which ones those are.
|
|
// in fn return position, like the `fn test<'a>() -> impl Debug + 'a` example,
|
|
// we only keep the lifetimes that appear in the `impl Debug` itself:
|
|
let lifetimes_to_remap = lifetime_collector::lifetimes_in_ret_ty(&self.resolver, output);
|
|
debug!(?lifetimes_to_remap);
|
|
|
|
self.with_hir_id_owner(opaque_ty_node_id, |this| {
|
|
// If this opaque type is only capturing a subset of the lifetimes (those that appear
|
|
// in bounds), then create the new lifetime parameters required and create a mapping
|
|
// from the old `'a` (on the function) to the new `'a` (on the opaque type).
|
|
collected_lifetimes.extend(
|
|
this.create_lifetime_defs(
|
|
opaque_ty_def_id,
|
|
&lifetimes_to_remap,
|
|
&mut new_remapping,
|
|
)
|
|
.into_iter()
|
|
.map(|(new_node_id, lifetime)| (new_node_id, lifetime, None)),
|
|
);
|
|
debug!(?collected_lifetimes);
|
|
debug!(?new_remapping);
|
|
|
|
// Install the remapping from old to new (if any):
|
|
this.with_remapping(new_remapping, |this| {
|
|
// We have to be careful to get elision right here. The
|
|
// idea is that we create a lifetime parameter for each
|
|
// lifetime in the return type. So, given a return type
|
|
// like `async fn foo(..) -> &[&u32]`, we lower to `impl
|
|
// Future<Output = &'1 [ &'2 u32 ]>`.
|
|
//
|
|
// Then, we will create `fn foo(..) -> Foo<'_, '_>`, and
|
|
// hence the elision takes place at the fn site.
|
|
let future_bound =
|
|
this.lower_async_fn_output_type_to_future_bound(output, fn_def_id, span);
|
|
|
|
let generic_params = this.arena.alloc_from_iter(collected_lifetimes.iter().map(
|
|
|&(new_node_id, lifetime, _)| {
|
|
let hir_id = this.lower_node_id(new_node_id);
|
|
debug_assert_ne!(this.opt_local_def_id(new_node_id), None);
|
|
|
|
let (name, kind) = if lifetime.ident.name == kw::UnderscoreLifetime {
|
|
(hir::ParamName::Fresh, hir::LifetimeParamKind::Elided)
|
|
} else {
|
|
(
|
|
hir::ParamName::Plain(lifetime.ident),
|
|
hir::LifetimeParamKind::Explicit,
|
|
)
|
|
};
|
|
|
|
hir::GenericParam {
|
|
hir_id,
|
|
name,
|
|
span: lifetime.ident.span,
|
|
pure_wrt_drop: false,
|
|
kind: hir::GenericParamKind::Lifetime { kind },
|
|
colon_span: None,
|
|
}
|
|
},
|
|
));
|
|
debug!("lower_async_fn_ret_ty: generic_params={:#?}", generic_params);
|
|
|
|
let opaque_ty_item = hir::OpaqueTy {
|
|
generics: this.arena.alloc(hir::Generics {
|
|
params: generic_params,
|
|
predicates: &[],
|
|
has_where_clause_predicates: false,
|
|
where_clause_span: this.lower_span(span),
|
|
span: this.lower_span(span),
|
|
}),
|
|
bounds: arena_vec![this; future_bound],
|
|
origin: hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
|
|
};
|
|
|
|
trace!("exist ty from async fn def id: {:#?}", opaque_ty_def_id);
|
|
this.generate_opaque_type(opaque_ty_def_id, opaque_ty_item, span, opaque_ty_span)
|
|
})
|
|
});
|
|
|
|
// As documented above, we need to create the lifetime
|
|
// arguments to our opaque type. Continuing with our example,
|
|
// we're creating the type arguments for the return type:
|
|
//
|
|
// ```
|
|
// Bar<'a, 'b, '0, '1, '_>
|
|
// ```
|
|
//
|
|
// For the "input" lifetime parameters, we wish to create
|
|
// references to the parameters themselves, including the
|
|
// "implicit" ones created from parameter types (`'a`, `'b`,
|
|
// '`0`, `'1`).
|
|
//
|
|
// For the "output" lifetime parameters, we just want to
|
|
// generate `'_`.
|
|
let generic_args = self.arena.alloc_from_iter(collected_lifetimes.into_iter().map(
|
|
|(_, lifetime, res)| {
|
|
let id = self.next_node_id();
|
|
let span = lifetime.ident.span;
|
|
|
|
let ident = if lifetime.ident.name == kw::UnderscoreLifetime {
|
|
Ident::with_dummy_span(kw::UnderscoreLifetime)
|
|
} else {
|
|
lifetime.ident
|
|
};
|
|
|
|
let res = res.unwrap_or(
|
|
self.resolver.get_lifetime_res(lifetime.id).unwrap_or(LifetimeRes::Error),
|
|
);
|
|
let l = self.new_named_lifetime_with_res(id, span, ident, res);
|
|
hir::GenericArg::Lifetime(l)
|
|
},
|
|
));
|
|
|
|
// Create the `Foo<...>` reference itself. Note that the `type
|
|
// Foo = impl Trait` is, internally, created as a child of the
|
|
// async fn, so the *type parameters* are inherited. It's
|
|
// only the lifetime parameters that we must supply.
|
|
let opaque_ty_ref =
|
|
hir::TyKind::OpaqueDef(hir::ItemId { def_id: opaque_ty_def_id }, generic_args);
|
|
let opaque_ty = self.ty(opaque_ty_span, opaque_ty_ref);
|
|
hir::FnRetTy::Return(self.arena.alloc(opaque_ty))
|
|
}
|
|
|
|
/// Transforms `-> T` into `Future<Output = T>`.
|
|
fn lower_async_fn_output_type_to_future_bound(
|
|
&mut self,
|
|
output: &FnRetTy,
|
|
fn_def_id: LocalDefId,
|
|
span: Span,
|
|
) -> hir::GenericBound<'hir> {
|
|
// Compute the `T` in `Future<Output = T>` from the return type.
|
|
let output_ty = match output {
|
|
FnRetTy::Ty(ty) => {
|
|
// Not `OpaqueTyOrigin::AsyncFn`: that's only used for the
|
|
// `impl Future` opaque type that `async fn` implicitly
|
|
// generates.
|
|
let context = ImplTraitContext::ReturnPositionOpaqueTy {
|
|
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
|
|
};
|
|
self.lower_ty(ty, context)
|
|
}
|
|
FnRetTy::Default(ret_ty_span) => self.arena.alloc(self.ty_tup(*ret_ty_span, &[])),
|
|
};
|
|
|
|
// "<Output = T>"
|
|
let future_args = self.arena.alloc(hir::GenericArgs {
|
|
args: &[],
|
|
bindings: arena_vec![self; self.output_ty_binding(span, output_ty)],
|
|
parenthesized: false,
|
|
span_ext: DUMMY_SP,
|
|
});
|
|
|
|
hir::GenericBound::LangItemTrait(
|
|
// ::std::future::Future<future_params>
|
|
hir::LangItem::Future,
|
|
self.lower_span(span),
|
|
self.next_id(),
|
|
future_args,
|
|
)
|
|
}
|
|
|
|
#[instrument(level = "trace", skip(self))]
|
|
fn lower_param_bound(
|
|
&mut self,
|
|
tpb: &GenericBound,
|
|
itctx: ImplTraitContext,
|
|
) -> hir::GenericBound<'hir> {
|
|
match tpb {
|
|
GenericBound::Trait(p, modifier) => hir::GenericBound::Trait(
|
|
self.lower_poly_trait_ref(p, itctx),
|
|
self.lower_trait_bound_modifier(*modifier),
|
|
),
|
|
GenericBound::Outlives(lifetime) => {
|
|
hir::GenericBound::Outlives(self.lower_lifetime(lifetime))
|
|
}
|
|
}
|
|
}
|
|
|
|
fn lower_lifetime(&mut self, l: &Lifetime) -> hir::Lifetime {
|
|
let span = self.lower_span(l.ident.span);
|
|
let ident = self.lower_ident(l.ident);
|
|
self.new_named_lifetime(l.id, l.id, span, ident)
|
|
}
|
|
|
|
#[tracing::instrument(level = "debug", skip(self))]
|
|
fn new_named_lifetime_with_res(
|
|
&mut self,
|
|
id: NodeId,
|
|
span: Span,
|
|
ident: Ident,
|
|
res: LifetimeRes,
|
|
) -> hir::Lifetime {
|
|
let name = match res {
|
|
LifetimeRes::Param { param, .. } => {
|
|
let p_name = ParamName::Plain(ident);
|
|
let param = self.resolver.get_remapped_def_id(param);
|
|
|
|
hir::LifetimeName::Param(param, p_name)
|
|
}
|
|
LifetimeRes::Fresh { param, .. } => {
|
|
debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
|
|
let param = self.local_def_id(param);
|
|
|
|
hir::LifetimeName::Param(param, ParamName::Fresh)
|
|
}
|
|
LifetimeRes::Infer => hir::LifetimeName::Infer,
|
|
LifetimeRes::Static => hir::LifetimeName::Static,
|
|
LifetimeRes::Error => hir::LifetimeName::Error,
|
|
res => panic!("Unexpected lifetime resolution {:?} for {:?} at {:?}", res, ident, span),
|
|
};
|
|
|
|
debug!(?name);
|
|
hir::Lifetime { hir_id: self.lower_node_id(id), span: self.lower_span(span), name }
|
|
}
|
|
|
|
#[tracing::instrument(level = "debug", skip(self))]
|
|
fn new_named_lifetime(
|
|
&mut self,
|
|
id: NodeId,
|
|
new_id: NodeId,
|
|
span: Span,
|
|
ident: Ident,
|
|
) -> hir::Lifetime {
|
|
let res = self.resolver.get_lifetime_res(id).unwrap_or(LifetimeRes::Error);
|
|
self.new_named_lifetime_with_res(new_id, span, ident, res)
|
|
}
|
|
|
|
fn lower_generic_params_mut<'s>(
|
|
&'s mut self,
|
|
params: &'s [GenericParam],
|
|
) -> impl Iterator<Item = hir::GenericParam<'hir>> + Captures<'a> + Captures<'s> {
|
|
params.iter().map(move |param| self.lower_generic_param(param))
|
|
}
|
|
|
|
fn lower_generic_params(&mut self, params: &[GenericParam]) -> &'hir [hir::GenericParam<'hir>] {
|
|
self.arena.alloc_from_iter(self.lower_generic_params_mut(params))
|
|
}
|
|
|
|
#[instrument(level = "trace", skip(self))]
|
|
fn lower_generic_param(&mut self, param: &GenericParam) -> hir::GenericParam<'hir> {
|
|
let (name, kind) = self.lower_generic_param_kind(param);
|
|
|
|
let hir_id = self.lower_node_id(param.id);
|
|
self.lower_attrs(hir_id, ¶m.attrs);
|
|
hir::GenericParam {
|
|
hir_id,
|
|
name,
|
|
span: self.lower_span(param.span()),
|
|
pure_wrt_drop: self.tcx.sess.contains_name(¶m.attrs, sym::may_dangle),
|
|
kind,
|
|
colon_span: param.colon_span.map(|s| self.lower_span(s)),
|
|
}
|
|
}
|
|
|
|
fn lower_generic_param_kind(
|
|
&mut self,
|
|
param: &GenericParam,
|
|
) -> (hir::ParamName, hir::GenericParamKind<'hir>) {
|
|
match param.kind {
|
|
GenericParamKind::Lifetime => {
|
|
// AST resolution emitted an error on those parameters, so we lower them using
|
|
// `ParamName::Error`.
|
|
let param_name =
|
|
if let Some(LifetimeRes::Error) = self.resolver.get_lifetime_res(param.id) {
|
|
ParamName::Error
|
|
} else {
|
|
let ident = self.lower_ident(param.ident);
|
|
ParamName::Plain(ident)
|
|
};
|
|
let kind =
|
|
hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Explicit };
|
|
|
|
(param_name, kind)
|
|
}
|
|
GenericParamKind::Type { ref default, .. } => {
|
|
let kind = hir::GenericParamKind::Type {
|
|
default: default.as_ref().map(|x| {
|
|
self.lower_ty(x, ImplTraitContext::Disallowed(ImplTraitPosition::Type))
|
|
}),
|
|
synthetic: false,
|
|
};
|
|
|
|
(hir::ParamName::Plain(self.lower_ident(param.ident)), kind)
|
|
}
|
|
GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
|
|
let ty = self.lower_ty(&ty, ImplTraitContext::Disallowed(ImplTraitPosition::Type));
|
|
let default = default.as_ref().map(|def| self.lower_anon_const(def));
|
|
(
|
|
hir::ParamName::Plain(self.lower_ident(param.ident)),
|
|
hir::GenericParamKind::Const { ty, default },
|
|
)
|
|
}
|
|
}
|
|
}
|
|
|
|
fn lower_trait_ref(&mut self, p: &TraitRef, itctx: ImplTraitContext) -> hir::TraitRef<'hir> {
|
|
let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit, itctx) {
|
|
hir::QPath::Resolved(None, path) => path,
|
|
qpath => panic!("lower_trait_ref: unexpected QPath `{:?}`", qpath),
|
|
};
|
|
hir::TraitRef { path, hir_ref_id: self.lower_node_id(p.ref_id) }
|
|
}
|
|
|
|
#[tracing::instrument(level = "debug", skip(self))]
|
|
fn lower_poly_trait_ref(
|
|
&mut self,
|
|
p: &PolyTraitRef,
|
|
itctx: ImplTraitContext,
|
|
) -> hir::PolyTraitRef<'hir> {
|
|
let bound_generic_params =
|
|
self.lower_lifetime_binder(p.trait_ref.ref_id, &p.bound_generic_params);
|
|
let trait_ref = self.lower_trait_ref(&p.trait_ref, itctx);
|
|
hir::PolyTraitRef { bound_generic_params, trait_ref, span: self.lower_span(p.span) }
|
|
}
|
|
|
|
fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext) -> hir::MutTy<'hir> {
|
|
hir::MutTy { ty: self.lower_ty(&mt.ty, itctx), mutbl: mt.mutbl }
|
|
}
|
|
|
|
fn lower_param_bounds(
|
|
&mut self,
|
|
bounds: &[GenericBound],
|
|
itctx: ImplTraitContext,
|
|
) -> hir::GenericBounds<'hir> {
|
|
self.arena.alloc_from_iter(self.lower_param_bounds_mut(bounds, itctx))
|
|
}
|
|
|
|
fn lower_param_bounds_mut<'s>(
|
|
&'s mut self,
|
|
bounds: &'s [GenericBound],
|
|
itctx: ImplTraitContext,
|
|
) -> impl Iterator<Item = hir::GenericBound<'hir>> + Captures<'s> + Captures<'a> {
|
|
bounds.iter().map(move |bound| self.lower_param_bound(bound, itctx))
|
|
}
|
|
|
|
fn lower_generic_and_bounds(
|
|
&mut self,
|
|
node_id: NodeId,
|
|
span: Span,
|
|
ident: Ident,
|
|
bounds: &[GenericBound],
|
|
) -> (hir::GenericParam<'hir>, Option<hir::WherePredicate<'hir>>, hir::TyKind<'hir>) {
|
|
// Add a definition for the in-band `Param`.
|
|
let def_id = self.local_def_id(node_id);
|
|
|
|
// Set the name to `impl Bound1 + Bound2`.
|
|
let param = hir::GenericParam {
|
|
hir_id: self.lower_node_id(node_id),
|
|
name: ParamName::Plain(self.lower_ident(ident)),
|
|
pure_wrt_drop: false,
|
|
span: self.lower_span(span),
|
|
kind: hir::GenericParamKind::Type { default: None, synthetic: true },
|
|
colon_span: None,
|
|
};
|
|
|
|
let preds = self.lower_generic_bound_predicate(
|
|
ident,
|
|
node_id,
|
|
&GenericParamKind::Type { default: None },
|
|
bounds,
|
|
ImplTraitContext::Universal,
|
|
hir::PredicateOrigin::ImplTrait,
|
|
);
|
|
|
|
let ty = hir::TyKind::Path(hir::QPath::Resolved(
|
|
None,
|
|
self.arena.alloc(hir::Path {
|
|
span: self.lower_span(span),
|
|
res: Res::Def(DefKind::TyParam, def_id.to_def_id()),
|
|
segments: arena_vec![self; hir::PathSegment::from_ident(self.lower_ident(ident))],
|
|
}),
|
|
));
|
|
|
|
(param, preds, ty)
|
|
}
|
|
|
|
/// Lowers a block directly to an expression, presuming that it
|
|
/// has no attributes and is not targeted by a `break`.
|
|
fn lower_block_expr(&mut self, b: &Block) -> hir::Expr<'hir> {
|
|
let block = self.lower_block(b, false);
|
|
self.expr_block(block, AttrVec::new())
|
|
}
|
|
|
|
fn lower_array_length(&mut self, c: &AnonConst) -> hir::ArrayLen {
|
|
match c.value.kind {
|
|
ExprKind::Underscore => {
|
|
if self.tcx.features().generic_arg_infer {
|
|
hir::ArrayLen::Infer(self.lower_node_id(c.id), c.value.span)
|
|
} else {
|
|
feature_err(
|
|
&self.tcx.sess.parse_sess,
|
|
sym::generic_arg_infer,
|
|
c.value.span,
|
|
"using `_` for array lengths is unstable",
|
|
)
|
|
.stash(c.value.span, StashKey::UnderscoreForArrayLengths);
|
|
hir::ArrayLen::Body(self.lower_anon_const(c))
|
|
}
|
|
}
|
|
_ => hir::ArrayLen::Body(self.lower_anon_const(c)),
|
|
}
|
|
}
|
|
|
|
fn lower_anon_const(&mut self, c: &AnonConst) -> hir::AnonConst {
|
|
self.with_new_scopes(|this| hir::AnonConst {
|
|
hir_id: this.lower_node_id(c.id),
|
|
body: this.lower_const_body(c.value.span, Some(&c.value)),
|
|
})
|
|
}
|
|
|
|
fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
|
|
match u {
|
|
CompilerGenerated => hir::UnsafeSource::CompilerGenerated,
|
|
UserProvided => hir::UnsafeSource::UserProvided,
|
|
}
|
|
}
|
|
|
|
fn lower_trait_bound_modifier(&mut self, f: TraitBoundModifier) -> hir::TraitBoundModifier {
|
|
match f {
|
|
TraitBoundModifier::None => hir::TraitBoundModifier::None,
|
|
TraitBoundModifier::MaybeConst => hir::TraitBoundModifier::MaybeConst,
|
|
|
|
// `MaybeConstMaybe` will cause an error during AST validation, but we need to pick a
|
|
// placeholder for compilation to proceed.
|
|
TraitBoundModifier::MaybeConstMaybe | TraitBoundModifier::Maybe => {
|
|
hir::TraitBoundModifier::Maybe
|
|
}
|
|
}
|
|
}
|
|
|
|
// Helper methods for building HIR.
|
|
|
|
fn stmt(&mut self, span: Span, kind: hir::StmtKind<'hir>) -> hir::Stmt<'hir> {
|
|
hir::Stmt { span: self.lower_span(span), kind, hir_id: self.next_id() }
|
|
}
|
|
|
|
fn stmt_expr(&mut self, span: Span, expr: hir::Expr<'hir>) -> hir::Stmt<'hir> {
|
|
self.stmt(span, hir::StmtKind::Expr(self.arena.alloc(expr)))
|
|
}
|
|
|
|
fn stmt_let_pat(
|
|
&mut self,
|
|
attrs: Option<&'hir [Attribute]>,
|
|
span: Span,
|
|
init: Option<&'hir hir::Expr<'hir>>,
|
|
pat: &'hir hir::Pat<'hir>,
|
|
source: hir::LocalSource,
|
|
) -> hir::Stmt<'hir> {
|
|
let hir_id = self.next_id();
|
|
if let Some(a) = attrs {
|
|
debug_assert!(!a.is_empty());
|
|
self.attrs.insert(hir_id.local_id, a);
|
|
}
|
|
let local = hir::Local {
|
|
hir_id,
|
|
init,
|
|
pat,
|
|
els: None,
|
|
source,
|
|
span: self.lower_span(span),
|
|
ty: None,
|
|
};
|
|
self.stmt(span, hir::StmtKind::Local(self.arena.alloc(local)))
|
|
}
|
|
|
|
fn block_expr(&mut self, expr: &'hir hir::Expr<'hir>) -> &'hir hir::Block<'hir> {
|
|
self.block_all(expr.span, &[], Some(expr))
|
|
}
|
|
|
|
fn block_all(
|
|
&mut self,
|
|
span: Span,
|
|
stmts: &'hir [hir::Stmt<'hir>],
|
|
expr: Option<&'hir hir::Expr<'hir>>,
|
|
) -> &'hir hir::Block<'hir> {
|
|
let blk = hir::Block {
|
|
stmts,
|
|
expr,
|
|
hir_id: self.next_id(),
|
|
rules: hir::BlockCheckMode::DefaultBlock,
|
|
span: self.lower_span(span),
|
|
targeted_by_break: false,
|
|
};
|
|
self.arena.alloc(blk)
|
|
}
|
|
|
|
fn pat_cf_continue(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> {
|
|
let field = self.single_pat_field(span, pat);
|
|
self.pat_lang_item_variant(span, hir::LangItem::ControlFlowContinue, field, None)
|
|
}
|
|
|
|
fn pat_cf_break(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> {
|
|
let field = self.single_pat_field(span, pat);
|
|
self.pat_lang_item_variant(span, hir::LangItem::ControlFlowBreak, field, None)
|
|
}
|
|
|
|
fn pat_some(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> {
|
|
let field = self.single_pat_field(span, pat);
|
|
self.pat_lang_item_variant(span, hir::LangItem::OptionSome, field, None)
|
|
}
|
|
|
|
fn pat_none(&mut self, span: Span) -> &'hir hir::Pat<'hir> {
|
|
self.pat_lang_item_variant(span, hir::LangItem::OptionNone, &[], None)
|
|
}
|
|
|
|
fn single_pat_field(
|
|
&mut self,
|
|
span: Span,
|
|
pat: &'hir hir::Pat<'hir>,
|
|
) -> &'hir [hir::PatField<'hir>] {
|
|
let field = hir::PatField {
|
|
hir_id: self.next_id(),
|
|
ident: Ident::new(sym::integer(0), self.lower_span(span)),
|
|
is_shorthand: false,
|
|
pat,
|
|
span: self.lower_span(span),
|
|
};
|
|
arena_vec![self; field]
|
|
}
|
|
|
|
fn pat_lang_item_variant(
|
|
&mut self,
|
|
span: Span,
|
|
lang_item: hir::LangItem,
|
|
fields: &'hir [hir::PatField<'hir>],
|
|
hir_id: Option<hir::HirId>,
|
|
) -> &'hir hir::Pat<'hir> {
|
|
let qpath = hir::QPath::LangItem(lang_item, self.lower_span(span), hir_id);
|
|
self.pat(span, hir::PatKind::Struct(qpath, fields, false))
|
|
}
|
|
|
|
fn pat_ident(&mut self, span: Span, ident: Ident) -> (&'hir hir::Pat<'hir>, hir::HirId) {
|
|
self.pat_ident_binding_mode(span, ident, hir::BindingAnnotation::Unannotated)
|
|
}
|
|
|
|
fn pat_ident_mut(&mut self, span: Span, ident: Ident) -> (hir::Pat<'hir>, hir::HirId) {
|
|
self.pat_ident_binding_mode_mut(span, ident, hir::BindingAnnotation::Unannotated)
|
|
}
|
|
|
|
fn pat_ident_binding_mode(
|
|
&mut self,
|
|
span: Span,
|
|
ident: Ident,
|
|
bm: hir::BindingAnnotation,
|
|
) -> (&'hir hir::Pat<'hir>, hir::HirId) {
|
|
let (pat, hir_id) = self.pat_ident_binding_mode_mut(span, ident, bm);
|
|
(self.arena.alloc(pat), hir_id)
|
|
}
|
|
|
|
fn pat_ident_binding_mode_mut(
|
|
&mut self,
|
|
span: Span,
|
|
ident: Ident,
|
|
bm: hir::BindingAnnotation,
|
|
) -> (hir::Pat<'hir>, hir::HirId) {
|
|
let hir_id = self.next_id();
|
|
|
|
(
|
|
hir::Pat {
|
|
hir_id,
|
|
kind: hir::PatKind::Binding(bm, hir_id, self.lower_ident(ident), None),
|
|
span: self.lower_span(span),
|
|
default_binding_modes: true,
|
|
},
|
|
hir_id,
|
|
)
|
|
}
|
|
|
|
fn pat(&mut self, span: Span, kind: hir::PatKind<'hir>) -> &'hir hir::Pat<'hir> {
|
|
self.arena.alloc(hir::Pat {
|
|
hir_id: self.next_id(),
|
|
kind,
|
|
span: self.lower_span(span),
|
|
default_binding_modes: true,
|
|
})
|
|
}
|
|
|
|
fn pat_without_dbm(&mut self, span: Span, kind: hir::PatKind<'hir>) -> hir::Pat<'hir> {
|
|
hir::Pat {
|
|
hir_id: self.next_id(),
|
|
kind,
|
|
span: self.lower_span(span),
|
|
default_binding_modes: false,
|
|
}
|
|
}
|
|
|
|
fn ty_path(
|
|
&mut self,
|
|
mut hir_id: hir::HirId,
|
|
span: Span,
|
|
qpath: hir::QPath<'hir>,
|
|
) -> hir::Ty<'hir> {
|
|
let kind = match qpath {
|
|
hir::QPath::Resolved(None, path) => {
|
|
// Turn trait object paths into `TyKind::TraitObject` instead.
|
|
match path.res {
|
|
Res::Def(DefKind::Trait | DefKind::TraitAlias, _) => {
|
|
let principal = hir::PolyTraitRef {
|
|
bound_generic_params: &[],
|
|
trait_ref: hir::TraitRef { path, hir_ref_id: hir_id },
|
|
span: self.lower_span(span),
|
|
};
|
|
|
|
// The original ID is taken by the `PolyTraitRef`,
|
|
// so the `Ty` itself needs a different one.
|
|
hir_id = self.next_id();
|
|
hir::TyKind::TraitObject(
|
|
arena_vec![self; principal],
|
|
self.elided_dyn_bound(span),
|
|
TraitObjectSyntax::None,
|
|
)
|
|
}
|
|
_ => hir::TyKind::Path(hir::QPath::Resolved(None, path)),
|
|
}
|
|
}
|
|
_ => hir::TyKind::Path(qpath),
|
|
};
|
|
|
|
hir::Ty { hir_id, kind, span: self.lower_span(span) }
|
|
}
|
|
|
|
/// Invoked to create the lifetime argument(s) for an elided trait object
|
|
/// bound, like the bound in `Box<dyn Debug>`. This method is not invoked
|
|
/// when the bound is written, even if it is written with `'_` like in
|
|
/// `Box<dyn Debug + '_>`. In those cases, `lower_lifetime` is invoked.
|
|
fn elided_dyn_bound(&mut self, span: Span) -> hir::Lifetime {
|
|
let r = hir::Lifetime {
|
|
hir_id: self.next_id(),
|
|
span: self.lower_span(span),
|
|
name: hir::LifetimeName::ImplicitObjectLifetimeDefault,
|
|
};
|
|
debug!("elided_dyn_bound: r={:?}", r);
|
|
r
|
|
}
|
|
}
|
|
|
|
/// Helper struct for delayed construction of GenericArgs.
|
|
struct GenericArgsCtor<'hir> {
|
|
args: SmallVec<[hir::GenericArg<'hir>; 4]>,
|
|
bindings: &'hir [hir::TypeBinding<'hir>],
|
|
parenthesized: bool,
|
|
span: Span,
|
|
}
|
|
|
|
impl<'hir> GenericArgsCtor<'hir> {
|
|
fn is_empty(&self) -> bool {
|
|
self.args.is_empty() && self.bindings.is_empty() && !self.parenthesized
|
|
}
|
|
|
|
fn into_generic_args(self, this: &LoweringContext<'_, 'hir>) -> &'hir hir::GenericArgs<'hir> {
|
|
let ga = hir::GenericArgs {
|
|
args: this.arena.alloc_from_iter(self.args),
|
|
bindings: self.bindings,
|
|
parenthesized: self.parenthesized,
|
|
span_ext: this.lower_span(self.span),
|
|
};
|
|
this.arena.alloc(ga)
|
|
}
|
|
}
|