1736 lines
68 KiB
Rust
1736 lines
68 KiB
Rust
use super::suggest;
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use super::MethodError;
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use super::NoMatchData;
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use super::{CandidateSource, ImplSource, TraitSource};
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use crate::check::FnCtxt;
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use crate::errors::MethodCallOnUnknownType;
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use crate::hir::def::DefKind;
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use crate::hir::def_id::DefId;
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use rustc_ast as ast;
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use rustc_ast::util::lev_distance::{find_best_match_for_name, lev_distance};
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use rustc_data_structures::fx::FxHashSet;
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use rustc_data_structures::sync::Lrc;
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use rustc_hir as hir;
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use rustc_hir::def::Namespace;
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use rustc_infer::infer::canonical::OriginalQueryValues;
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use rustc_infer::infer::canonical::{Canonical, QueryResponse};
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use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
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use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
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use rustc_infer::infer::{self, InferOk, TyCtxtInferExt};
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use rustc_middle::middle::stability;
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use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
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use rustc_middle::ty::GenericParamDefKind;
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use rustc_middle::ty::{
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self, ParamEnvAnd, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness,
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};
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use rustc_session::config::nightly_options;
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use rustc_session::lint;
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use rustc_span::def_id::LocalDefId;
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use rustc_span::{symbol::Ident, Span, Symbol, DUMMY_SP};
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use rustc_trait_selection::autoderef::{self, Autoderef};
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use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
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use rustc_trait_selection::traits::query::method_autoderef::MethodAutoderefBadTy;
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use rustc_trait_selection::traits::query::method_autoderef::{
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CandidateStep, MethodAutoderefStepsResult,
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};
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use rustc_trait_selection::traits::query::CanonicalTyGoal;
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use rustc_trait_selection::traits::{self, ObligationCause};
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use std::cmp::max;
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use std::iter;
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use std::mem;
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use std::ops::Deref;
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use smallvec::{smallvec, SmallVec};
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use self::CandidateKind::*;
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pub use self::PickKind::*;
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/// Boolean flag used to indicate if this search is for a suggestion
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/// or not. If true, we can allow ambiguity and so forth.
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#[derive(Clone, Copy)]
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pub struct IsSuggestion(pub bool);
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struct ProbeContext<'a, 'tcx> {
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fcx: &'a FnCtxt<'a, 'tcx>,
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span: Span,
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mode: Mode,
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method_name: Option<Ident>,
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return_type: Option<Ty<'tcx>>,
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/// This is the OriginalQueryValues for the steps queries
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/// that are answered in steps.
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orig_steps_var_values: OriginalQueryValues<'tcx>,
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steps: Lrc<Vec<CandidateStep<'tcx>>>,
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inherent_candidates: Vec<Candidate<'tcx>>,
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extension_candidates: Vec<Candidate<'tcx>>,
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impl_dups: FxHashSet<DefId>,
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/// Collects near misses when the candidate functions are missing a `self` keyword and is only
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/// used for error reporting
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static_candidates: Vec<CandidateSource>,
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/// When probing for names, include names that are close to the
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/// requested name (by Levensthein distance)
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allow_similar_names: bool,
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/// Some(candidate) if there is a private candidate
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private_candidate: Option<(DefKind, DefId)>,
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/// Collects near misses when trait bounds for type parameters are unsatisfied and is only used
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/// for error reporting
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unsatisfied_predicates: Vec<(ty::Predicate<'tcx>, Option<ty::Predicate<'tcx>>)>,
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is_suggestion: IsSuggestion,
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}
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impl<'a, 'tcx> Deref for ProbeContext<'a, 'tcx> {
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type Target = FnCtxt<'a, 'tcx>;
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fn deref(&self) -> &Self::Target {
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&self.fcx
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}
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}
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#[derive(Debug)]
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struct Candidate<'tcx> {
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// Candidates are (I'm not quite sure, but they are mostly) basically
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// some metadata on top of a `ty::AssocItem` (without substs).
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//
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// However, method probing wants to be able to evaluate the predicates
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// for a function with the substs applied - for example, if a function
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// has `where Self: Sized`, we don't want to consider it unless `Self`
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// is actually `Sized`, and similarly, return-type suggestions want
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// to consider the "actual" return type.
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//
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// The way this is handled is through `xform_self_ty`. It contains
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// the receiver type of this candidate, but `xform_self_ty`,
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// `xform_ret_ty` and `kind` (which contains the predicates) have the
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// generic parameters of this candidate substituted with the *same set*
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// of inference variables, which acts as some weird sort of "query".
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//
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// When we check out a candidate, we require `xform_self_ty` to be
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// a subtype of the passed-in self-type, and this equates the type
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// variables in the rest of the fields.
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//
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// For example, if we have this candidate:
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// ```
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// trait Foo {
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// fn foo(&self) where Self: Sized;
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// }
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// ```
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//
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// Then `xform_self_ty` will be `&'erased ?X` and `kind` will contain
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// the predicate `?X: Sized`, so if we are evaluating `Foo` for a
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// the receiver `&T`, we'll do the subtyping which will make `?X`
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// get the right value, then when we evaluate the predicate we'll check
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// if `T: Sized`.
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xform_self_ty: Ty<'tcx>,
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xform_ret_ty: Option<Ty<'tcx>>,
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item: ty::AssocItem,
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kind: CandidateKind<'tcx>,
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import_ids: SmallVec<[LocalDefId; 1]>,
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}
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#[derive(Debug)]
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enum CandidateKind<'tcx> {
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InherentImplCandidate(
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SubstsRef<'tcx>,
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// Normalize obligations
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Vec<traits::PredicateObligation<'tcx>>,
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),
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ObjectCandidate,
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TraitCandidate(ty::TraitRef<'tcx>),
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WhereClauseCandidate(
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// Trait
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ty::PolyTraitRef<'tcx>,
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),
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}
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#[derive(Debug, PartialEq, Eq, Copy, Clone)]
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enum ProbeResult {
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NoMatch,
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BadReturnType,
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Match,
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}
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#[derive(Debug, PartialEq, Clone)]
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pub struct Pick<'tcx> {
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pub item: ty::AssocItem,
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pub kind: PickKind<'tcx>,
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pub import_ids: SmallVec<[LocalDefId; 1]>,
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// Indicates that the source expression should be autoderef'd N times
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//
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// A = expr | *expr | **expr | ...
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pub autoderefs: usize,
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// Indicates that an autoref is applied after the optional autoderefs
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//
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// B = A | &A | &mut A
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pub autoref: Option<hir::Mutability>,
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// Indicates that the source expression should be "unsized" to a
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// target type. This should probably eventually go away in favor
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// of just coercing method receivers.
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//
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// C = B | unsize(B)
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pub unsize: Option<Ty<'tcx>>,
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}
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#[derive(Clone, Debug, PartialEq, Eq)]
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pub enum PickKind<'tcx> {
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InherentImplPick,
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ObjectPick,
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TraitPick,
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WhereClausePick(
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// Trait
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ty::PolyTraitRef<'tcx>,
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),
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}
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pub type PickResult<'tcx> = Result<Pick<'tcx>, MethodError<'tcx>>;
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#[derive(PartialEq, Eq, Copy, Clone, Debug)]
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pub enum Mode {
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// An expression of the form `receiver.method_name(...)`.
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// Autoderefs are performed on `receiver`, lookup is done based on the
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// `self` argument of the method, and static methods aren't considered.
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MethodCall,
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// An expression of the form `Type::item` or `<T>::item`.
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// No autoderefs are performed, lookup is done based on the type each
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// implementation is for, and static methods are included.
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Path,
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}
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#[derive(PartialEq, Eq, Copy, Clone, Debug)]
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pub enum ProbeScope {
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// Assemble candidates coming only from traits in scope.
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TraitsInScope,
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// Assemble candidates coming from all traits.
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AllTraits,
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}
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impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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/// This is used to offer suggestions to users. It returns methods
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/// that could have been called which have the desired return
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/// type. Some effort is made to rule out methods that, if called,
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/// would result in an error (basically, the same criteria we
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/// would use to decide if a method is a plausible fit for
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/// ambiguity purposes).
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pub fn probe_for_return_type(
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&self,
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span: Span,
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mode: Mode,
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return_type: Ty<'tcx>,
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self_ty: Ty<'tcx>,
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scope_expr_id: hir::HirId,
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) -> Vec<ty::AssocItem> {
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debug!(
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"probe(self_ty={:?}, return_type={}, scope_expr_id={})",
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self_ty, return_type, scope_expr_id
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);
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let method_names = self
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.probe_op(
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span,
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mode,
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None,
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Some(return_type),
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IsSuggestion(true),
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self_ty,
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scope_expr_id,
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ProbeScope::AllTraits,
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|probe_cx| Ok(probe_cx.candidate_method_names()),
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)
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.unwrap_or(vec![]);
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method_names
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.iter()
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.flat_map(|&method_name| {
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self.probe_op(
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span,
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mode,
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Some(method_name),
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Some(return_type),
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IsSuggestion(true),
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self_ty,
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scope_expr_id,
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ProbeScope::AllTraits,
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|probe_cx| probe_cx.pick(),
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)
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.ok()
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.map(|pick| pick.item)
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})
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.collect()
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}
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pub fn probe_for_name(
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&self,
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span: Span,
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mode: Mode,
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item_name: Ident,
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is_suggestion: IsSuggestion,
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self_ty: Ty<'tcx>,
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scope_expr_id: hir::HirId,
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scope: ProbeScope,
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) -> PickResult<'tcx> {
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debug!(
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"probe(self_ty={:?}, item_name={}, scope_expr_id={})",
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self_ty, item_name, scope_expr_id
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);
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self.probe_op(
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span,
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mode,
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Some(item_name),
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None,
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is_suggestion,
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self_ty,
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scope_expr_id,
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scope,
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|probe_cx| probe_cx.pick(),
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)
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}
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fn probe_op<OP, R>(
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&'a self,
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span: Span,
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mode: Mode,
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method_name: Option<Ident>,
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return_type: Option<Ty<'tcx>>,
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is_suggestion: IsSuggestion,
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self_ty: Ty<'tcx>,
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scope_expr_id: hir::HirId,
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scope: ProbeScope,
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op: OP,
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) -> Result<R, MethodError<'tcx>>
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where
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OP: FnOnce(ProbeContext<'a, 'tcx>) -> Result<R, MethodError<'tcx>>,
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{
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let mut orig_values = OriginalQueryValues::default();
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let param_env_and_self_ty = self.infcx.canonicalize_query(
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&ParamEnvAnd { param_env: self.param_env, value: self_ty },
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&mut orig_values,
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);
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let steps = if mode == Mode::MethodCall {
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self.tcx.method_autoderef_steps(param_env_and_self_ty)
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} else {
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self.infcx.probe(|_| {
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// Mode::Path - the deref steps is "trivial". This turns
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// our CanonicalQuery into a "trivial" QueryResponse. This
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// is a bit inefficient, but I don't think that writing
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// special handling for this "trivial case" is a good idea.
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let infcx = &self.infcx;
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let (ParamEnvAnd { param_env: _, value: self_ty }, canonical_inference_vars) =
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infcx.instantiate_canonical_with_fresh_inference_vars(
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span,
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¶m_env_and_self_ty,
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);
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debug!(
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"probe_op: Mode::Path, param_env_and_self_ty={:?} self_ty={:?}",
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param_env_and_self_ty, self_ty
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);
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MethodAutoderefStepsResult {
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steps: Lrc::new(vec![CandidateStep {
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self_ty: self.make_query_response_ignoring_pending_obligations(
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canonical_inference_vars,
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self_ty,
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),
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autoderefs: 0,
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from_unsafe_deref: false,
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unsize: false,
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}]),
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opt_bad_ty: None,
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reached_recursion_limit: false,
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}
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})
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};
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// If our autoderef loop had reached the recursion limit,
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// report an overflow error, but continue going on with
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// the truncated autoderef list.
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if steps.reached_recursion_limit {
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self.probe(|_| {
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let ty = &steps
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.steps
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.last()
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.unwrap_or_else(|| span_bug!(span, "reached the recursion limit in 0 steps?"))
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.self_ty;
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let ty = self
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.probe_instantiate_query_response(span, &orig_values, ty)
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.unwrap_or_else(|_| span_bug!(span, "instantiating {:?} failed?", ty));
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autoderef::report_autoderef_recursion_limit_error(self.tcx, span, ty.value);
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});
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}
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// If we encountered an `_` type or an error type during autoderef, this is
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// ambiguous.
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if let Some(bad_ty) = &steps.opt_bad_ty {
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if is_suggestion.0 {
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// Ambiguity was encountered during a suggestion. Just keep going.
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debug!("ProbeContext: encountered ambiguity in suggestion");
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} else if bad_ty.reached_raw_pointer && !self.tcx.features().arbitrary_self_types {
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// this case used to be allowed by the compiler,
|
|
// so we do a future-compat lint here for the 2015 edition
|
|
// (see https://github.com/rust-lang/rust/issues/46906)
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if self.tcx.sess.rust_2018() {
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self.tcx.sess.emit_err(MethodCallOnUnknownType { span });
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} else {
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self.tcx.struct_span_lint_hir(
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lint::builtin::TYVAR_BEHIND_RAW_POINTER,
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scope_expr_id,
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span,
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|lint| lint.build("type annotations needed").emit(),
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);
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}
|
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} else {
|
|
// Encountered a real ambiguity, so abort the lookup. If `ty` is not
|
|
// an `Err`, report the right "type annotations needed" error pointing
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// to it.
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let ty = &bad_ty.ty;
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let ty = self
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.probe_instantiate_query_response(span, &orig_values, ty)
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.unwrap_or_else(|_| span_bug!(span, "instantiating {:?} failed?", ty));
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|
let ty = self.structurally_resolved_type(span, ty.value);
|
|
assert!(matches!(ty.kind(), ty::Error(_)));
|
|
return Err(MethodError::NoMatch(NoMatchData::new(
|
|
Vec::new(),
|
|
Vec::new(),
|
|
Vec::new(),
|
|
None,
|
|
mode,
|
|
)));
|
|
}
|
|
}
|
|
|
|
debug!("ProbeContext: steps for self_ty={:?} are {:?}", self_ty, steps);
|
|
|
|
// this creates one big transaction so that all type variables etc
|
|
// that we create during the probe process are removed later
|
|
self.probe(|_| {
|
|
let mut probe_cx = ProbeContext::new(
|
|
self,
|
|
span,
|
|
mode,
|
|
method_name,
|
|
return_type,
|
|
orig_values,
|
|
steps.steps,
|
|
is_suggestion,
|
|
);
|
|
|
|
probe_cx.assemble_inherent_candidates();
|
|
match scope {
|
|
ProbeScope::TraitsInScope => {
|
|
probe_cx.assemble_extension_candidates_for_traits_in_scope(scope_expr_id)?
|
|
}
|
|
ProbeScope::AllTraits => probe_cx.assemble_extension_candidates_for_all_traits()?,
|
|
};
|
|
op(probe_cx)
|
|
})
|
|
}
|
|
}
|
|
|
|
pub fn provide(providers: &mut ty::query::Providers) {
|
|
providers.method_autoderef_steps = method_autoderef_steps;
|
|
}
|
|
|
|
fn method_autoderef_steps<'tcx>(
|
|
tcx: TyCtxt<'tcx>,
|
|
goal: CanonicalTyGoal<'tcx>,
|
|
) -> MethodAutoderefStepsResult<'tcx> {
|
|
debug!("method_autoderef_steps({:?})", goal);
|
|
|
|
tcx.infer_ctxt().enter_with_canonical(DUMMY_SP, &goal, |ref infcx, goal, inference_vars| {
|
|
let ParamEnvAnd { param_env, value: self_ty } = goal;
|
|
|
|
let mut autoderef = Autoderef::new(infcx, param_env, hir::CRATE_HIR_ID, DUMMY_SP, self_ty)
|
|
.include_raw_pointers()
|
|
.silence_errors();
|
|
let mut reached_raw_pointer = false;
|
|
let mut steps: Vec<_> = autoderef
|
|
.by_ref()
|
|
.map(|(ty, d)| {
|
|
let step = CandidateStep {
|
|
self_ty: infcx.make_query_response_ignoring_pending_obligations(
|
|
inference_vars.clone(),
|
|
ty,
|
|
),
|
|
autoderefs: d,
|
|
from_unsafe_deref: reached_raw_pointer,
|
|
unsize: false,
|
|
};
|
|
if let ty::RawPtr(_) = ty.kind() {
|
|
// all the subsequent steps will be from_unsafe_deref
|
|
reached_raw_pointer = true;
|
|
}
|
|
step
|
|
})
|
|
.collect();
|
|
|
|
let final_ty = autoderef.final_ty(true);
|
|
let opt_bad_ty = match final_ty.kind() {
|
|
ty::Infer(ty::TyVar(_)) | ty::Error(_) => Some(MethodAutoderefBadTy {
|
|
reached_raw_pointer,
|
|
ty: infcx
|
|
.make_query_response_ignoring_pending_obligations(inference_vars, final_ty),
|
|
}),
|
|
ty::Array(elem_ty, _) => {
|
|
let dereferences = steps.len() - 1;
|
|
|
|
steps.push(CandidateStep {
|
|
self_ty: infcx.make_query_response_ignoring_pending_obligations(
|
|
inference_vars,
|
|
infcx.tcx.mk_slice(elem_ty),
|
|
),
|
|
autoderefs: dereferences,
|
|
// this could be from an unsafe deref if we had
|
|
// a *mut/const [T; N]
|
|
from_unsafe_deref: reached_raw_pointer,
|
|
unsize: true,
|
|
});
|
|
|
|
None
|
|
}
|
|
_ => None,
|
|
};
|
|
|
|
debug!("method_autoderef_steps: steps={:?} opt_bad_ty={:?}", steps, opt_bad_ty);
|
|
|
|
MethodAutoderefStepsResult {
|
|
steps: Lrc::new(steps),
|
|
opt_bad_ty: opt_bad_ty.map(Lrc::new),
|
|
reached_recursion_limit: autoderef.reached_recursion_limit(),
|
|
}
|
|
})
|
|
}
|
|
|
|
impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
|
|
fn new(
|
|
fcx: &'a FnCtxt<'a, 'tcx>,
|
|
span: Span,
|
|
mode: Mode,
|
|
method_name: Option<Ident>,
|
|
return_type: Option<Ty<'tcx>>,
|
|
orig_steps_var_values: OriginalQueryValues<'tcx>,
|
|
steps: Lrc<Vec<CandidateStep<'tcx>>>,
|
|
is_suggestion: IsSuggestion,
|
|
) -> ProbeContext<'a, 'tcx> {
|
|
ProbeContext {
|
|
fcx,
|
|
span,
|
|
mode,
|
|
method_name,
|
|
return_type,
|
|
inherent_candidates: Vec::new(),
|
|
extension_candidates: Vec::new(),
|
|
impl_dups: FxHashSet::default(),
|
|
orig_steps_var_values,
|
|
steps,
|
|
static_candidates: Vec::new(),
|
|
allow_similar_names: false,
|
|
private_candidate: None,
|
|
unsatisfied_predicates: Vec::new(),
|
|
is_suggestion,
|
|
}
|
|
}
|
|
|
|
fn reset(&mut self) {
|
|
self.inherent_candidates.clear();
|
|
self.extension_candidates.clear();
|
|
self.impl_dups.clear();
|
|
self.static_candidates.clear();
|
|
self.private_candidate = None;
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// CANDIDATE ASSEMBLY
|
|
|
|
fn push_candidate(&mut self, candidate: Candidate<'tcx>, is_inherent: bool) {
|
|
let is_accessible = if let Some(name) = self.method_name {
|
|
let item = candidate.item;
|
|
let def_scope =
|
|
self.tcx.adjust_ident_and_get_scope(name, item.container.id(), self.body_id).1;
|
|
item.vis.is_accessible_from(def_scope, self.tcx)
|
|
} else {
|
|
true
|
|
};
|
|
if is_accessible {
|
|
if is_inherent {
|
|
self.inherent_candidates.push(candidate);
|
|
} else {
|
|
self.extension_candidates.push(candidate);
|
|
}
|
|
} else if self.private_candidate.is_none() {
|
|
self.private_candidate =
|
|
Some((candidate.item.kind.as_def_kind(), candidate.item.def_id));
|
|
}
|
|
}
|
|
|
|
fn assemble_inherent_candidates(&mut self) {
|
|
let steps = Lrc::clone(&self.steps);
|
|
for step in steps.iter() {
|
|
self.assemble_probe(&step.self_ty);
|
|
}
|
|
}
|
|
|
|
fn assemble_probe(&mut self, self_ty: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>) {
|
|
debug!("assemble_probe: self_ty={:?}", self_ty);
|
|
let lang_items = self.tcx.lang_items();
|
|
|
|
match *self_ty.value.value.kind() {
|
|
ty::Dynamic(ref data, ..) => {
|
|
if let Some(p) = data.principal() {
|
|
// Subtle: we can't use `instantiate_query_response` here: using it will
|
|
// commit to all of the type equalities assumed by inference going through
|
|
// autoderef (see the `method-probe-no-guessing` test).
|
|
//
|
|
// However, in this code, it is OK if we end up with an object type that is
|
|
// "more general" than the object type that we are evaluating. For *every*
|
|
// object type `MY_OBJECT`, a function call that goes through a trait-ref
|
|
// of the form `<MY_OBJECT as SuperTraitOf(MY_OBJECT)>::func` is a valid
|
|
// `ObjectCandidate`, and it should be discoverable "exactly" through one
|
|
// of the iterations in the autoderef loop, so there is no problem with it
|
|
// being discoverable in another one of these iterations.
|
|
//
|
|
// Using `instantiate_canonical_with_fresh_inference_vars` on our
|
|
// `Canonical<QueryResponse<Ty<'tcx>>>` and then *throwing away* the
|
|
// `CanonicalVarValues` will exactly give us such a generalization - it
|
|
// will still match the original object type, but it won't pollute our
|
|
// type variables in any form, so just do that!
|
|
let (QueryResponse { value: generalized_self_ty, .. }, _ignored_var_values) =
|
|
self.fcx
|
|
.instantiate_canonical_with_fresh_inference_vars(self.span, &self_ty);
|
|
|
|
self.assemble_inherent_candidates_from_object(generalized_self_ty);
|
|
self.assemble_inherent_impl_candidates_for_type(p.def_id());
|
|
}
|
|
}
|
|
ty::Adt(def, _) => {
|
|
self.assemble_inherent_impl_candidates_for_type(def.did);
|
|
}
|
|
ty::Foreign(did) => {
|
|
self.assemble_inherent_impl_candidates_for_type(did);
|
|
}
|
|
ty::Param(p) => {
|
|
self.assemble_inherent_candidates_from_param(p);
|
|
}
|
|
ty::Bool => {
|
|
let lang_def_id = lang_items.bool_impl();
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id);
|
|
}
|
|
ty::Char => {
|
|
let lang_def_id = lang_items.char_impl();
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id);
|
|
}
|
|
ty::Str => {
|
|
let lang_def_id = lang_items.str_impl();
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id);
|
|
|
|
let lang_def_id = lang_items.str_alloc_impl();
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id);
|
|
}
|
|
ty::Slice(_) => {
|
|
for &lang_def_id in &[
|
|
lang_items.slice_impl(),
|
|
lang_items.slice_u8_impl(),
|
|
lang_items.slice_alloc_impl(),
|
|
lang_items.slice_u8_alloc_impl(),
|
|
] {
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id);
|
|
}
|
|
}
|
|
ty::Array(_, _) => {
|
|
let lang_def_id = lang_items.array_impl();
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id);
|
|
}
|
|
ty::RawPtr(ty::TypeAndMut { ty: _, mutbl }) => {
|
|
let (lang_def_id1, lang_def_id2) = match mutbl {
|
|
hir::Mutability::Not => {
|
|
(lang_items.const_ptr_impl(), lang_items.const_slice_ptr_impl())
|
|
}
|
|
hir::Mutability::Mut => {
|
|
(lang_items.mut_ptr_impl(), lang_items.mut_slice_ptr_impl())
|
|
}
|
|
};
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id1);
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id2);
|
|
}
|
|
ty::Int(i) => {
|
|
let lang_def_id = match i {
|
|
ast::IntTy::I8 => lang_items.i8_impl(),
|
|
ast::IntTy::I16 => lang_items.i16_impl(),
|
|
ast::IntTy::I32 => lang_items.i32_impl(),
|
|
ast::IntTy::I64 => lang_items.i64_impl(),
|
|
ast::IntTy::I128 => lang_items.i128_impl(),
|
|
ast::IntTy::Isize => lang_items.isize_impl(),
|
|
};
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id);
|
|
}
|
|
ty::Uint(i) => {
|
|
let lang_def_id = match i {
|
|
ast::UintTy::U8 => lang_items.u8_impl(),
|
|
ast::UintTy::U16 => lang_items.u16_impl(),
|
|
ast::UintTy::U32 => lang_items.u32_impl(),
|
|
ast::UintTy::U64 => lang_items.u64_impl(),
|
|
ast::UintTy::U128 => lang_items.u128_impl(),
|
|
ast::UintTy::Usize => lang_items.usize_impl(),
|
|
};
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id);
|
|
}
|
|
ty::Float(f) => {
|
|
let (lang_def_id1, lang_def_id2) = match f {
|
|
ast::FloatTy::F32 => (lang_items.f32_impl(), lang_items.f32_runtime_impl()),
|
|
ast::FloatTy::F64 => (lang_items.f64_impl(), lang_items.f64_runtime_impl()),
|
|
};
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id1);
|
|
self.assemble_inherent_impl_for_primitive(lang_def_id2);
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
fn assemble_inherent_impl_for_primitive(&mut self, lang_def_id: Option<DefId>) {
|
|
if let Some(impl_def_id) = lang_def_id {
|
|
self.assemble_inherent_impl_probe(impl_def_id);
|
|
}
|
|
}
|
|
|
|
fn assemble_inherent_impl_candidates_for_type(&mut self, def_id: DefId) {
|
|
let impl_def_ids = self.tcx.at(self.span).inherent_impls(def_id);
|
|
for &impl_def_id in impl_def_ids.iter() {
|
|
self.assemble_inherent_impl_probe(impl_def_id);
|
|
}
|
|
}
|
|
|
|
fn assemble_inherent_impl_probe(&mut self, impl_def_id: DefId) {
|
|
if !self.impl_dups.insert(impl_def_id) {
|
|
return; // already visited
|
|
}
|
|
|
|
debug!("assemble_inherent_impl_probe {:?}", impl_def_id);
|
|
|
|
for item in self.impl_or_trait_item(impl_def_id) {
|
|
if !self.has_applicable_self(&item) {
|
|
// No receiver declared. Not a candidate.
|
|
self.record_static_candidate(ImplSource(impl_def_id));
|
|
continue;
|
|
}
|
|
|
|
let (impl_ty, impl_substs) = self.impl_ty_and_substs(impl_def_id);
|
|
let impl_ty = impl_ty.subst(self.tcx, impl_substs);
|
|
|
|
// Determine the receiver type that the method itself expects.
|
|
let xform_tys = self.xform_self_ty(&item, impl_ty, impl_substs);
|
|
|
|
// We can't use normalize_associated_types_in as it will pollute the
|
|
// fcx's fulfillment context after this probe is over.
|
|
let cause = traits::ObligationCause::misc(self.span, self.body_id);
|
|
let selcx = &mut traits::SelectionContext::new(self.fcx);
|
|
let traits::Normalized { value: (xform_self_ty, xform_ret_ty), obligations } =
|
|
traits::normalize(selcx, self.param_env, cause, &xform_tys);
|
|
debug!(
|
|
"assemble_inherent_impl_probe: xform_self_ty = {:?}/{:?}",
|
|
xform_self_ty, xform_ret_ty
|
|
);
|
|
|
|
self.push_candidate(
|
|
Candidate {
|
|
xform_self_ty,
|
|
xform_ret_ty,
|
|
item,
|
|
kind: InherentImplCandidate(impl_substs, obligations),
|
|
import_ids: smallvec![],
|
|
},
|
|
true,
|
|
);
|
|
}
|
|
}
|
|
|
|
fn assemble_inherent_candidates_from_object(&mut self, self_ty: Ty<'tcx>) {
|
|
debug!("assemble_inherent_candidates_from_object(self_ty={:?})", self_ty);
|
|
|
|
let principal = match self_ty.kind() {
|
|
ty::Dynamic(ref data, ..) => Some(data),
|
|
_ => None,
|
|
}
|
|
.and_then(|data| data.principal())
|
|
.unwrap_or_else(|| {
|
|
span_bug!(
|
|
self.span,
|
|
"non-object {:?} in assemble_inherent_candidates_from_object",
|
|
self_ty
|
|
)
|
|
});
|
|
|
|
// It is illegal to invoke a method on a trait instance that
|
|
// refers to the `Self` type. An error will be reported by
|
|
// `enforce_object_limitations()` if the method refers to the
|
|
// `Self` type anywhere other than the receiver. Here, we use
|
|
// a substitution that replaces `Self` with the object type
|
|
// itself. Hence, a `&self` method will wind up with an
|
|
// argument type like `&Trait`.
|
|
let trait_ref = principal.with_self_ty(self.tcx, self_ty);
|
|
self.elaborate_bounds(iter::once(trait_ref), |this, new_trait_ref, item| {
|
|
let new_trait_ref = this.erase_late_bound_regions(&new_trait_ref);
|
|
|
|
let (xform_self_ty, xform_ret_ty) =
|
|
this.xform_self_ty(&item, new_trait_ref.self_ty(), new_trait_ref.substs);
|
|
this.push_candidate(
|
|
Candidate {
|
|
xform_self_ty,
|
|
xform_ret_ty,
|
|
item,
|
|
kind: ObjectCandidate,
|
|
import_ids: smallvec![],
|
|
},
|
|
true,
|
|
);
|
|
});
|
|
}
|
|
|
|
fn assemble_inherent_candidates_from_param(&mut self, param_ty: ty::ParamTy) {
|
|
// FIXME: do we want to commit to this behavior for param bounds?
|
|
debug!("assemble_inherent_candidates_from_param(param_ty={:?})", param_ty);
|
|
|
|
let bounds =
|
|
self.param_env.caller_bounds().iter().map(ty::Predicate::skip_binders).filter_map(
|
|
|predicate| match predicate {
|
|
ty::PredicateAtom::Trait(trait_predicate, _) => {
|
|
match trait_predicate.trait_ref.self_ty().kind() {
|
|
ty::Param(ref p) if *p == param_ty => {
|
|
Some(ty::Binder::bind(trait_predicate.trait_ref))
|
|
}
|
|
_ => None,
|
|
}
|
|
}
|
|
ty::PredicateAtom::Subtype(..)
|
|
| ty::PredicateAtom::Projection(..)
|
|
| ty::PredicateAtom::RegionOutlives(..)
|
|
| ty::PredicateAtom::WellFormed(..)
|
|
| ty::PredicateAtom::ObjectSafe(..)
|
|
| ty::PredicateAtom::ClosureKind(..)
|
|
| ty::PredicateAtom::TypeOutlives(..)
|
|
| ty::PredicateAtom::ConstEvaluatable(..)
|
|
| ty::PredicateAtom::ConstEquate(..) => None,
|
|
},
|
|
);
|
|
|
|
self.elaborate_bounds(bounds, |this, poly_trait_ref, item| {
|
|
let trait_ref = this.erase_late_bound_regions(&poly_trait_ref);
|
|
|
|
let (xform_self_ty, xform_ret_ty) =
|
|
this.xform_self_ty(&item, trait_ref.self_ty(), trait_ref.substs);
|
|
|
|
// Because this trait derives from a where-clause, it
|
|
// should not contain any inference variables or other
|
|
// artifacts. This means it is safe to put into the
|
|
// `WhereClauseCandidate` and (eventually) into the
|
|
// `WhereClausePick`.
|
|
assert!(!trait_ref.substs.needs_infer());
|
|
|
|
this.push_candidate(
|
|
Candidate {
|
|
xform_self_ty,
|
|
xform_ret_ty,
|
|
item,
|
|
kind: WhereClauseCandidate(poly_trait_ref),
|
|
import_ids: smallvec![],
|
|
},
|
|
true,
|
|
);
|
|
});
|
|
}
|
|
|
|
// Do a search through a list of bounds, using a callback to actually
|
|
// create the candidates.
|
|
fn elaborate_bounds<F>(
|
|
&mut self,
|
|
bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
|
|
mut mk_cand: F,
|
|
) where
|
|
F: for<'b> FnMut(&mut ProbeContext<'b, 'tcx>, ty::PolyTraitRef<'tcx>, ty::AssocItem),
|
|
{
|
|
let tcx = self.tcx;
|
|
for bound_trait_ref in traits::transitive_bounds(tcx, bounds) {
|
|
debug!("elaborate_bounds(bound_trait_ref={:?})", bound_trait_ref);
|
|
for item in self.impl_or_trait_item(bound_trait_ref.def_id()) {
|
|
if !self.has_applicable_self(&item) {
|
|
self.record_static_candidate(TraitSource(bound_trait_ref.def_id()));
|
|
} else {
|
|
mk_cand(self, bound_trait_ref, item);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn assemble_extension_candidates_for_traits_in_scope(
|
|
&mut self,
|
|
expr_hir_id: hir::HirId,
|
|
) -> Result<(), MethodError<'tcx>> {
|
|
let mut duplicates = FxHashSet::default();
|
|
let opt_applicable_traits = self.tcx.in_scope_traits(expr_hir_id);
|
|
if let Some(applicable_traits) = opt_applicable_traits {
|
|
for trait_candidate in applicable_traits.iter() {
|
|
let trait_did = trait_candidate.def_id;
|
|
if duplicates.insert(trait_did) {
|
|
let result = self.assemble_extension_candidates_for_trait(
|
|
&trait_candidate.import_ids,
|
|
trait_did,
|
|
);
|
|
result?;
|
|
}
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
fn assemble_extension_candidates_for_all_traits(&mut self) -> Result<(), MethodError<'tcx>> {
|
|
let mut duplicates = FxHashSet::default();
|
|
for trait_info in suggest::all_traits(self.tcx) {
|
|
if duplicates.insert(trait_info.def_id) {
|
|
self.assemble_extension_candidates_for_trait(&smallvec![], trait_info.def_id)?;
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
pub fn matches_return_type(
|
|
&self,
|
|
method: &ty::AssocItem,
|
|
self_ty: Option<Ty<'tcx>>,
|
|
expected: Ty<'tcx>,
|
|
) -> bool {
|
|
match method.kind {
|
|
ty::AssocKind::Fn => {
|
|
let fty = self.tcx.fn_sig(method.def_id);
|
|
self.probe(|_| {
|
|
let substs = self.fresh_substs_for_item(self.span, method.def_id);
|
|
let fty = fty.subst(self.tcx, substs);
|
|
let (fty, _) =
|
|
self.replace_bound_vars_with_fresh_vars(self.span, infer::FnCall, &fty);
|
|
|
|
if let Some(self_ty) = self_ty {
|
|
if self
|
|
.at(&ObligationCause::dummy(), self.param_env)
|
|
.sup(fty.inputs()[0], self_ty)
|
|
.is_err()
|
|
{
|
|
return false;
|
|
}
|
|
}
|
|
self.can_sub(self.param_env, fty.output(), expected).is_ok()
|
|
})
|
|
}
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
fn assemble_extension_candidates_for_trait(
|
|
&mut self,
|
|
import_ids: &SmallVec<[LocalDefId; 1]>,
|
|
trait_def_id: DefId,
|
|
) -> Result<(), MethodError<'tcx>> {
|
|
debug!("assemble_extension_candidates_for_trait(trait_def_id={:?})", trait_def_id);
|
|
let trait_substs = self.fresh_item_substs(trait_def_id);
|
|
let trait_ref = ty::TraitRef::new(trait_def_id, trait_substs);
|
|
|
|
if self.tcx.is_trait_alias(trait_def_id) {
|
|
// For trait aliases, assume all super-traits are relevant.
|
|
let bounds = iter::once(trait_ref.to_poly_trait_ref());
|
|
self.elaborate_bounds(bounds, |this, new_trait_ref, item| {
|
|
let new_trait_ref = this.erase_late_bound_regions(&new_trait_ref);
|
|
|
|
let (xform_self_ty, xform_ret_ty) =
|
|
this.xform_self_ty(&item, new_trait_ref.self_ty(), new_trait_ref.substs);
|
|
this.push_candidate(
|
|
Candidate {
|
|
xform_self_ty,
|
|
xform_ret_ty,
|
|
item,
|
|
import_ids: import_ids.clone(),
|
|
kind: TraitCandidate(new_trait_ref),
|
|
},
|
|
false,
|
|
);
|
|
});
|
|
} else {
|
|
debug_assert!(self.tcx.is_trait(trait_def_id));
|
|
for item in self.impl_or_trait_item(trait_def_id) {
|
|
// Check whether `trait_def_id` defines a method with suitable name.
|
|
if !self.has_applicable_self(&item) {
|
|
debug!("method has inapplicable self");
|
|
self.record_static_candidate(TraitSource(trait_def_id));
|
|
continue;
|
|
}
|
|
|
|
let (xform_self_ty, xform_ret_ty) =
|
|
self.xform_self_ty(&item, trait_ref.self_ty(), trait_substs);
|
|
self.push_candidate(
|
|
Candidate {
|
|
xform_self_ty,
|
|
xform_ret_ty,
|
|
item,
|
|
import_ids: import_ids.clone(),
|
|
kind: TraitCandidate(trait_ref),
|
|
},
|
|
false,
|
|
);
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
fn candidate_method_names(&self) -> Vec<Ident> {
|
|
let mut set = FxHashSet::default();
|
|
let mut names: Vec<_> = self
|
|
.inherent_candidates
|
|
.iter()
|
|
.chain(&self.extension_candidates)
|
|
.filter(|candidate| {
|
|
if let Some(return_ty) = self.return_type {
|
|
self.matches_return_type(&candidate.item, None, return_ty)
|
|
} else {
|
|
true
|
|
}
|
|
})
|
|
.map(|candidate| candidate.item.ident)
|
|
.filter(|&name| set.insert(name))
|
|
.collect();
|
|
|
|
// Sort them by the name so we have a stable result.
|
|
names.sort_by_cached_key(|n| n.as_str());
|
|
names
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// THE ACTUAL SEARCH
|
|
|
|
fn pick(mut self) -> PickResult<'tcx> {
|
|
assert!(self.method_name.is_some());
|
|
|
|
if let Some(r) = self.pick_core() {
|
|
return r;
|
|
}
|
|
|
|
debug!("pick: actual search failed, assemble diagnostics");
|
|
|
|
let static_candidates = mem::take(&mut self.static_candidates);
|
|
let private_candidate = self.private_candidate.take();
|
|
let unsatisfied_predicates = mem::take(&mut self.unsatisfied_predicates);
|
|
|
|
// things failed, so lets look at all traits, for diagnostic purposes now:
|
|
self.reset();
|
|
|
|
let span = self.span;
|
|
let tcx = self.tcx;
|
|
|
|
self.assemble_extension_candidates_for_all_traits()?;
|
|
|
|
let out_of_scope_traits = match self.pick_core() {
|
|
Some(Ok(p)) => vec![p.item.container.id()],
|
|
//Some(Ok(p)) => p.iter().map(|p| p.item.container().id()).collect(),
|
|
Some(Err(MethodError::Ambiguity(v))) => v
|
|
.into_iter()
|
|
.map(|source| match source {
|
|
TraitSource(id) => id,
|
|
ImplSource(impl_id) => match tcx.trait_id_of_impl(impl_id) {
|
|
Some(id) => id,
|
|
None => span_bug!(span, "found inherent method when looking at traits"),
|
|
},
|
|
})
|
|
.collect(),
|
|
Some(Err(MethodError::NoMatch(NoMatchData {
|
|
out_of_scope_traits: others, ..
|
|
}))) => {
|
|
assert!(others.is_empty());
|
|
vec![]
|
|
}
|
|
_ => vec![],
|
|
};
|
|
|
|
if let Some((kind, def_id)) = private_candidate {
|
|
return Err(MethodError::PrivateMatch(kind, def_id, out_of_scope_traits));
|
|
}
|
|
let lev_candidate = self.probe_for_lev_candidate()?;
|
|
|
|
Err(MethodError::NoMatch(NoMatchData::new(
|
|
static_candidates,
|
|
unsatisfied_predicates,
|
|
out_of_scope_traits,
|
|
lev_candidate,
|
|
self.mode,
|
|
)))
|
|
}
|
|
|
|
fn pick_core(&mut self) -> Option<PickResult<'tcx>> {
|
|
let steps = self.steps.clone();
|
|
|
|
// find the first step that works
|
|
steps
|
|
.iter()
|
|
.filter(|step| {
|
|
debug!("pick_core: step={:?}", step);
|
|
// skip types that are from a type error or that would require dereferencing
|
|
// a raw pointer
|
|
!step.self_ty.references_error() && !step.from_unsafe_deref
|
|
})
|
|
.flat_map(|step| {
|
|
let InferOk { value: self_ty, obligations: _ } = self
|
|
.fcx
|
|
.probe_instantiate_query_response(
|
|
self.span,
|
|
&self.orig_steps_var_values,
|
|
&step.self_ty,
|
|
)
|
|
.unwrap_or_else(|_| {
|
|
span_bug!(self.span, "{:?} was applicable but now isn't?", step.self_ty)
|
|
});
|
|
self.pick_by_value_method(step, self_ty).or_else(|| {
|
|
self.pick_autorefd_method(step, self_ty, hir::Mutability::Not)
|
|
.or_else(|| self.pick_autorefd_method(step, self_ty, hir::Mutability::Mut))
|
|
})
|
|
})
|
|
.next()
|
|
}
|
|
|
|
fn pick_by_value_method(
|
|
&mut self,
|
|
step: &CandidateStep<'tcx>,
|
|
self_ty: Ty<'tcx>,
|
|
) -> Option<PickResult<'tcx>> {
|
|
//! For each type `T` in the step list, this attempts to find a
|
|
//! method where the (transformed) self type is exactly `T`. We
|
|
//! do however do one transformation on the adjustment: if we
|
|
//! are passing a region pointer in, we will potentially
|
|
//! *reborrow* it to a shorter lifetime. This allows us to
|
|
//! transparently pass `&mut` pointers, in particular, without
|
|
//! consuming them for their entire lifetime.
|
|
|
|
if step.unsize {
|
|
return None;
|
|
}
|
|
|
|
self.pick_method(self_ty).map(|r| {
|
|
r.map(|mut pick| {
|
|
pick.autoderefs = step.autoderefs;
|
|
|
|
// Insert a `&*` or `&mut *` if this is a reference type:
|
|
if let ty::Ref(_, _, mutbl) = *step.self_ty.value.value.kind() {
|
|
pick.autoderefs += 1;
|
|
pick.autoref = Some(mutbl);
|
|
}
|
|
|
|
pick
|
|
})
|
|
})
|
|
}
|
|
|
|
fn pick_autorefd_method(
|
|
&mut self,
|
|
step: &CandidateStep<'tcx>,
|
|
self_ty: Ty<'tcx>,
|
|
mutbl: hir::Mutability,
|
|
) -> Option<PickResult<'tcx>> {
|
|
let tcx = self.tcx;
|
|
|
|
// In general, during probing we erase regions.
|
|
let region = tcx.lifetimes.re_erased;
|
|
|
|
let autoref_ty = tcx.mk_ref(region, ty::TypeAndMut { ty: self_ty, mutbl });
|
|
self.pick_method(autoref_ty).map(|r| {
|
|
r.map(|mut pick| {
|
|
pick.autoderefs = step.autoderefs;
|
|
pick.autoref = Some(mutbl);
|
|
pick.unsize = step.unsize.then_some(self_ty);
|
|
pick
|
|
})
|
|
})
|
|
}
|
|
|
|
fn pick_method(&mut self, self_ty: Ty<'tcx>) -> Option<PickResult<'tcx>> {
|
|
debug!("pick_method(self_ty={})", self.ty_to_string(self_ty));
|
|
|
|
let mut possibly_unsatisfied_predicates = Vec::new();
|
|
let mut unstable_candidates = Vec::new();
|
|
|
|
for (kind, candidates) in
|
|
&[("inherent", &self.inherent_candidates), ("extension", &self.extension_candidates)]
|
|
{
|
|
debug!("searching {} candidates", kind);
|
|
let res = self.consider_candidates(
|
|
self_ty,
|
|
candidates.iter(),
|
|
&mut possibly_unsatisfied_predicates,
|
|
Some(&mut unstable_candidates),
|
|
);
|
|
if let Some(pick) = res {
|
|
if !self.is_suggestion.0 && !unstable_candidates.is_empty() {
|
|
if let Ok(p) = &pick {
|
|
// Emit a lint if there are unstable candidates alongside the stable ones.
|
|
//
|
|
// We suppress warning if we're picking the method only because it is a
|
|
// suggestion.
|
|
self.emit_unstable_name_collision_hint(p, &unstable_candidates);
|
|
}
|
|
}
|
|
return Some(pick);
|
|
}
|
|
}
|
|
|
|
debug!("searching unstable candidates");
|
|
let res = self.consider_candidates(
|
|
self_ty,
|
|
unstable_candidates.into_iter().map(|(c, _)| c),
|
|
&mut possibly_unsatisfied_predicates,
|
|
None,
|
|
);
|
|
if res.is_none() {
|
|
self.unsatisfied_predicates.extend(possibly_unsatisfied_predicates);
|
|
}
|
|
res
|
|
}
|
|
|
|
fn consider_candidates<'b, ProbesIter>(
|
|
&self,
|
|
self_ty: Ty<'tcx>,
|
|
probes: ProbesIter,
|
|
possibly_unsatisfied_predicates: &mut Vec<(
|
|
ty::Predicate<'tcx>,
|
|
Option<ty::Predicate<'tcx>>,
|
|
)>,
|
|
unstable_candidates: Option<&mut Vec<(&'b Candidate<'tcx>, Symbol)>>,
|
|
) -> Option<PickResult<'tcx>>
|
|
where
|
|
ProbesIter: Iterator<Item = &'b Candidate<'tcx>> + Clone,
|
|
{
|
|
let mut applicable_candidates: Vec<_> = probes
|
|
.clone()
|
|
.map(|probe| {
|
|
(probe, self.consider_probe(self_ty, probe, possibly_unsatisfied_predicates))
|
|
})
|
|
.filter(|&(_, status)| status != ProbeResult::NoMatch)
|
|
.collect();
|
|
|
|
debug!("applicable_candidates: {:?}", applicable_candidates);
|
|
|
|
if applicable_candidates.len() > 1 {
|
|
if let Some(pick) = self.collapse_candidates_to_trait_pick(&applicable_candidates[..]) {
|
|
return Some(Ok(pick));
|
|
}
|
|
}
|
|
|
|
if let Some(uc) = unstable_candidates {
|
|
applicable_candidates.retain(|&(p, _)| {
|
|
if let stability::EvalResult::Deny { feature, .. } =
|
|
self.tcx.eval_stability(p.item.def_id, None, self.span)
|
|
{
|
|
uc.push((p, feature));
|
|
return false;
|
|
}
|
|
true
|
|
});
|
|
}
|
|
|
|
if applicable_candidates.len() > 1 {
|
|
let sources = probes.map(|p| self.candidate_source(p, self_ty)).collect();
|
|
return Some(Err(MethodError::Ambiguity(sources)));
|
|
}
|
|
|
|
applicable_candidates.pop().map(|(probe, status)| {
|
|
if status == ProbeResult::Match {
|
|
Ok(probe.to_unadjusted_pick())
|
|
} else {
|
|
Err(MethodError::BadReturnType)
|
|
}
|
|
})
|
|
}
|
|
|
|
fn emit_unstable_name_collision_hint(
|
|
&self,
|
|
stable_pick: &Pick<'_>,
|
|
unstable_candidates: &[(&Candidate<'tcx>, Symbol)],
|
|
) {
|
|
self.tcx.struct_span_lint_hir(
|
|
lint::builtin::UNSTABLE_NAME_COLLISIONS,
|
|
self.fcx.body_id,
|
|
self.span,
|
|
|lint| {
|
|
let mut diag = lint.build(
|
|
"a method with this name may be added to the standard library in the future",
|
|
);
|
|
// FIXME: This should be a `span_suggestion` instead of `help`
|
|
// However `self.span` only
|
|
// highlights the method name, so we can't use it. Also consider reusing the code from
|
|
// `report_method_error()`.
|
|
diag.help(&format!(
|
|
"call with fully qualified syntax `{}(...)` to keep using the current method",
|
|
self.tcx.def_path_str(stable_pick.item.def_id),
|
|
));
|
|
|
|
if nightly_options::is_nightly_build() {
|
|
for (candidate, feature) in unstable_candidates {
|
|
diag.help(&format!(
|
|
"add `#![feature({})]` to the crate attributes to enable `{}`",
|
|
feature,
|
|
self.tcx.def_path_str(candidate.item.def_id),
|
|
));
|
|
}
|
|
}
|
|
|
|
diag.emit();
|
|
},
|
|
);
|
|
}
|
|
|
|
fn select_trait_candidate(
|
|
&self,
|
|
trait_ref: ty::TraitRef<'tcx>,
|
|
) -> traits::SelectionResult<'tcx, traits::Selection<'tcx>> {
|
|
let cause = traits::ObligationCause::misc(self.span, self.body_id);
|
|
let predicate = trait_ref.to_poly_trait_ref().to_poly_trait_predicate();
|
|
let obligation = traits::Obligation::new(cause, self.param_env, predicate);
|
|
traits::SelectionContext::new(self).select(&obligation)
|
|
}
|
|
|
|
fn candidate_source(&self, candidate: &Candidate<'tcx>, self_ty: Ty<'tcx>) -> CandidateSource {
|
|
match candidate.kind {
|
|
InherentImplCandidate(..) => ImplSource(candidate.item.container.id()),
|
|
ObjectCandidate | WhereClauseCandidate(_) => TraitSource(candidate.item.container.id()),
|
|
TraitCandidate(trait_ref) => self.probe(|_| {
|
|
let _ = self
|
|
.at(&ObligationCause::dummy(), self.param_env)
|
|
.sup(candidate.xform_self_ty, self_ty);
|
|
match self.select_trait_candidate(trait_ref) {
|
|
Ok(Some(traits::ImplSource::ImplSourceUserDefined(ref impl_data))) => {
|
|
// If only a single impl matches, make the error message point
|
|
// to that impl.
|
|
ImplSource(impl_data.impl_def_id)
|
|
}
|
|
_ => TraitSource(candidate.item.container.id()),
|
|
}
|
|
}),
|
|
}
|
|
}
|
|
|
|
fn consider_probe(
|
|
&self,
|
|
self_ty: Ty<'tcx>,
|
|
probe: &Candidate<'tcx>,
|
|
possibly_unsatisfied_predicates: &mut Vec<(
|
|
ty::Predicate<'tcx>,
|
|
Option<ty::Predicate<'tcx>>,
|
|
)>,
|
|
) -> ProbeResult {
|
|
debug!("consider_probe: self_ty={:?} probe={:?}", self_ty, probe);
|
|
|
|
self.probe(|_| {
|
|
// First check that the self type can be related.
|
|
let sub_obligations = match self
|
|
.at(&ObligationCause::dummy(), self.param_env)
|
|
.sup(probe.xform_self_ty, self_ty)
|
|
{
|
|
Ok(InferOk { obligations, value: () }) => obligations,
|
|
Err(_) => {
|
|
debug!("--> cannot relate self-types");
|
|
return ProbeResult::NoMatch;
|
|
}
|
|
};
|
|
|
|
let mut result = ProbeResult::Match;
|
|
let selcx = &mut traits::SelectionContext::new(self);
|
|
let cause = traits::ObligationCause::misc(self.span, self.body_id);
|
|
|
|
// If so, impls may carry other conditions (e.g., where
|
|
// clauses) that must be considered. Make sure that those
|
|
// match as well (or at least may match, sometimes we
|
|
// don't have enough information to fully evaluate).
|
|
match probe.kind {
|
|
InherentImplCandidate(ref substs, ref ref_obligations) => {
|
|
// Check whether the impl imposes obligations we have to worry about.
|
|
let impl_def_id = probe.item.container.id();
|
|
let impl_bounds = self.tcx.predicates_of(impl_def_id);
|
|
let impl_bounds = impl_bounds.instantiate(self.tcx, substs);
|
|
let traits::Normalized { value: impl_bounds, obligations: norm_obligations } =
|
|
traits::normalize(selcx, self.param_env, cause.clone(), &impl_bounds);
|
|
|
|
// Convert the bounds into obligations.
|
|
let impl_obligations =
|
|
traits::predicates_for_generics(cause, self.param_env, impl_bounds);
|
|
|
|
let candidate_obligations = impl_obligations
|
|
.chain(norm_obligations.into_iter())
|
|
.chain(ref_obligations.iter().cloned());
|
|
// Evaluate those obligations to see if they might possibly hold.
|
|
for o in candidate_obligations {
|
|
let o = self.resolve_vars_if_possible(&o);
|
|
if !self.predicate_may_hold(&o) {
|
|
result = ProbeResult::NoMatch;
|
|
possibly_unsatisfied_predicates.push((o.predicate, None));
|
|
}
|
|
}
|
|
}
|
|
|
|
ObjectCandidate | WhereClauseCandidate(..) => {
|
|
// These have no additional conditions to check.
|
|
}
|
|
|
|
TraitCandidate(trait_ref) => {
|
|
let predicate = trait_ref.without_const().to_predicate(self.tcx);
|
|
let obligation = traits::Obligation::new(cause, self.param_env, predicate);
|
|
if !self.predicate_may_hold(&obligation) {
|
|
result = ProbeResult::NoMatch;
|
|
if self.probe(|_| {
|
|
match self.select_trait_candidate(trait_ref) {
|
|
Err(_) => return true,
|
|
Ok(Some(impl_source))
|
|
if !impl_source.borrow_nested_obligations().is_empty() =>
|
|
{
|
|
for obligation in impl_source.borrow_nested_obligations() {
|
|
// Determine exactly which obligation wasn't met, so
|
|
// that we can give more context in the error.
|
|
if !self.predicate_may_hold(&obligation) {
|
|
let o = self.resolve_vars_if_possible(obligation);
|
|
let predicate =
|
|
self.resolve_vars_if_possible(&predicate);
|
|
let p = if predicate == o.predicate {
|
|
// Avoid "`MyStruct: Foo` which is required by
|
|
// `MyStruct: Foo`" in E0599.
|
|
None
|
|
} else {
|
|
Some(predicate)
|
|
};
|
|
possibly_unsatisfied_predicates.push((o.predicate, p));
|
|
}
|
|
}
|
|
}
|
|
_ => {
|
|
// Some nested subobligation of this predicate
|
|
// failed.
|
|
let predicate = self.resolve_vars_if_possible(&predicate);
|
|
possibly_unsatisfied_predicates.push((predicate, None));
|
|
}
|
|
}
|
|
false
|
|
}) {
|
|
// This candidate's primary obligation doesn't even
|
|
// select - don't bother registering anything in
|
|
// `potentially_unsatisfied_predicates`.
|
|
return ProbeResult::NoMatch;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Evaluate those obligations to see if they might possibly hold.
|
|
for o in sub_obligations {
|
|
let o = self.resolve_vars_if_possible(&o);
|
|
if !self.predicate_may_hold(&o) {
|
|
result = ProbeResult::NoMatch;
|
|
possibly_unsatisfied_predicates.push((o.predicate, None));
|
|
}
|
|
}
|
|
|
|
if let ProbeResult::Match = result {
|
|
if let (Some(return_ty), Some(xform_ret_ty)) =
|
|
(self.return_type, probe.xform_ret_ty)
|
|
{
|
|
let xform_ret_ty = self.resolve_vars_if_possible(&xform_ret_ty);
|
|
debug!(
|
|
"comparing return_ty {:?} with xform ret ty {:?}",
|
|
return_ty, probe.xform_ret_ty
|
|
);
|
|
if self
|
|
.at(&ObligationCause::dummy(), self.param_env)
|
|
.sup(return_ty, xform_ret_ty)
|
|
.is_err()
|
|
{
|
|
return ProbeResult::BadReturnType;
|
|
}
|
|
}
|
|
}
|
|
|
|
result
|
|
})
|
|
}
|
|
|
|
/// Sometimes we get in a situation where we have multiple probes that are all impls of the
|
|
/// same trait, but we don't know which impl to use. In this case, since in all cases the
|
|
/// external interface of the method can be determined from the trait, it's ok not to decide.
|
|
/// We can basically just collapse all of the probes for various impls into one where-clause
|
|
/// probe. This will result in a pending obligation so when more type-info is available we can
|
|
/// make the final decision.
|
|
///
|
|
/// Example (`src/test/ui/method-two-trait-defer-resolution-1.rs`):
|
|
///
|
|
/// ```
|
|
/// trait Foo { ... }
|
|
/// impl Foo for Vec<i32> { ... }
|
|
/// impl Foo for Vec<usize> { ... }
|
|
/// ```
|
|
///
|
|
/// Now imagine the receiver is `Vec<_>`. It doesn't really matter at this time which impl we
|
|
/// use, so it's ok to just commit to "using the method from the trait Foo".
|
|
fn collapse_candidates_to_trait_pick(
|
|
&self,
|
|
probes: &[(&Candidate<'tcx>, ProbeResult)],
|
|
) -> Option<Pick<'tcx>> {
|
|
// Do all probes correspond to the same trait?
|
|
let container = probes[0].0.item.container;
|
|
if let ty::ImplContainer(_) = container {
|
|
return None;
|
|
}
|
|
if probes[1..].iter().any(|&(p, _)| p.item.container != container) {
|
|
return None;
|
|
}
|
|
|
|
// FIXME: check the return type here somehow.
|
|
// If so, just use this trait and call it a day.
|
|
Some(Pick {
|
|
item: probes[0].0.item,
|
|
kind: TraitPick,
|
|
import_ids: probes[0].0.import_ids.clone(),
|
|
autoderefs: 0,
|
|
autoref: None,
|
|
unsize: None,
|
|
})
|
|
}
|
|
|
|
/// Similarly to `probe_for_return_type`, this method attempts to find the best matching
|
|
/// candidate method where the method name may have been misspelt. Similarly to other
|
|
/// Levenshtein based suggestions, we provide at most one such suggestion.
|
|
fn probe_for_lev_candidate(&mut self) -> Result<Option<ty::AssocItem>, MethodError<'tcx>> {
|
|
debug!("probing for method names similar to {:?}", self.method_name);
|
|
|
|
let steps = self.steps.clone();
|
|
self.probe(|_| {
|
|
let mut pcx = ProbeContext::new(
|
|
self.fcx,
|
|
self.span,
|
|
self.mode,
|
|
self.method_name,
|
|
self.return_type,
|
|
self.orig_steps_var_values.clone(),
|
|
steps,
|
|
IsSuggestion(true),
|
|
);
|
|
pcx.allow_similar_names = true;
|
|
pcx.assemble_inherent_candidates();
|
|
|
|
let method_names = pcx.candidate_method_names();
|
|
pcx.allow_similar_names = false;
|
|
let applicable_close_candidates: Vec<ty::AssocItem> = method_names
|
|
.iter()
|
|
.filter_map(|&method_name| {
|
|
pcx.reset();
|
|
pcx.method_name = Some(method_name);
|
|
pcx.assemble_inherent_candidates();
|
|
pcx.pick_core().and_then(|pick| pick.ok()).map(|pick| pick.item)
|
|
})
|
|
.collect();
|
|
|
|
if applicable_close_candidates.is_empty() {
|
|
Ok(None)
|
|
} else {
|
|
let best_name = {
|
|
let names = applicable_close_candidates.iter().map(|cand| &cand.ident.name);
|
|
find_best_match_for_name(names, self.method_name.unwrap().name, None)
|
|
}
|
|
.unwrap();
|
|
Ok(applicable_close_candidates
|
|
.into_iter()
|
|
.find(|method| method.ident.name == best_name))
|
|
}
|
|
})
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// MISCELLANY
|
|
fn has_applicable_self(&self, item: &ty::AssocItem) -> bool {
|
|
// "Fast track" -- check for usage of sugar when in method call
|
|
// mode.
|
|
//
|
|
// In Path mode (i.e., resolving a value like `T::next`), consider any
|
|
// associated value (i.e., methods, constants) but not types.
|
|
match self.mode {
|
|
Mode::MethodCall => item.fn_has_self_parameter,
|
|
Mode::Path => match item.kind {
|
|
ty::AssocKind::Type => false,
|
|
ty::AssocKind::Fn | ty::AssocKind::Const => true,
|
|
},
|
|
}
|
|
// FIXME -- check for types that deref to `Self`,
|
|
// like `Rc<Self>` and so on.
|
|
//
|
|
// Note also that the current code will break if this type
|
|
// includes any of the type parameters defined on the method
|
|
// -- but this could be overcome.
|
|
}
|
|
|
|
fn record_static_candidate(&mut self, source: CandidateSource) {
|
|
self.static_candidates.push(source);
|
|
}
|
|
|
|
fn xform_self_ty(
|
|
&self,
|
|
item: &ty::AssocItem,
|
|
impl_ty: Ty<'tcx>,
|
|
substs: SubstsRef<'tcx>,
|
|
) -> (Ty<'tcx>, Option<Ty<'tcx>>) {
|
|
if item.kind == ty::AssocKind::Fn && self.mode == Mode::MethodCall {
|
|
let sig = self.xform_method_sig(item.def_id, substs);
|
|
(sig.inputs()[0], Some(sig.output()))
|
|
} else {
|
|
(impl_ty, None)
|
|
}
|
|
}
|
|
|
|
fn xform_method_sig(&self, method: DefId, substs: SubstsRef<'tcx>) -> ty::FnSig<'tcx> {
|
|
let fn_sig = self.tcx.fn_sig(method);
|
|
debug!("xform_self_ty(fn_sig={:?}, substs={:?})", fn_sig, substs);
|
|
|
|
assert!(!substs.has_escaping_bound_vars());
|
|
|
|
// It is possible for type parameters or early-bound lifetimes
|
|
// to appear in the signature of `self`. The substitutions we
|
|
// are given do not include type/lifetime parameters for the
|
|
// method yet. So create fresh variables here for those too,
|
|
// if there are any.
|
|
let generics = self.tcx.generics_of(method);
|
|
assert_eq!(substs.len(), generics.parent_count as usize);
|
|
|
|
// Erase any late-bound regions from the method and substitute
|
|
// in the values from the substitution.
|
|
let xform_fn_sig = self.erase_late_bound_regions(&fn_sig);
|
|
|
|
if generics.params.is_empty() {
|
|
xform_fn_sig.subst(self.tcx, substs)
|
|
} else {
|
|
let substs = InternalSubsts::for_item(self.tcx, method, |param, _| {
|
|
let i = param.index as usize;
|
|
if i < substs.len() {
|
|
substs[i]
|
|
} else {
|
|
match param.kind {
|
|
GenericParamDefKind::Lifetime => {
|
|
// In general, during probe we erase regions.
|
|
self.tcx.lifetimes.re_erased.into()
|
|
}
|
|
GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => {
|
|
self.var_for_def(self.span, param)
|
|
}
|
|
}
|
|
}
|
|
});
|
|
xform_fn_sig.subst(self.tcx, substs)
|
|
}
|
|
}
|
|
|
|
/// Gets the type of an impl and generate substitutions with placeholders.
|
|
fn impl_ty_and_substs(&self, impl_def_id: DefId) -> (Ty<'tcx>, SubstsRef<'tcx>) {
|
|
(self.tcx.type_of(impl_def_id), self.fresh_item_substs(impl_def_id))
|
|
}
|
|
|
|
fn fresh_item_substs(&self, def_id: DefId) -> SubstsRef<'tcx> {
|
|
InternalSubsts::for_item(self.tcx, def_id, |param, _| match param.kind {
|
|
GenericParamDefKind::Lifetime => self.tcx.lifetimes.re_erased.into(),
|
|
GenericParamDefKind::Type { .. } => self
|
|
.next_ty_var(TypeVariableOrigin {
|
|
kind: TypeVariableOriginKind::SubstitutionPlaceholder,
|
|
span: self.tcx.def_span(def_id),
|
|
})
|
|
.into(),
|
|
GenericParamDefKind::Const { .. } => {
|
|
let span = self.tcx.def_span(def_id);
|
|
let origin = ConstVariableOrigin {
|
|
kind: ConstVariableOriginKind::SubstitutionPlaceholder,
|
|
span,
|
|
};
|
|
self.next_const_var(self.tcx.type_of(param.def_id), origin).into()
|
|
}
|
|
})
|
|
}
|
|
|
|
/// Replaces late-bound-regions bound by `value` with `'static` using
|
|
/// `ty::erase_late_bound_regions`.
|
|
///
|
|
/// This is only a reasonable thing to do during the *probe* phase, not the *confirm* phase, of
|
|
/// method matching. It is reasonable during the probe phase because we don't consider region
|
|
/// relationships at all. Therefore, we can just replace all the region variables with 'static
|
|
/// rather than creating fresh region variables. This is nice for two reasons:
|
|
///
|
|
/// 1. Because the numbers of the region variables would otherwise be fairly unique to this
|
|
/// particular method call, it winds up creating fewer types overall, which helps for memory
|
|
/// usage. (Admittedly, this is a rather small effect, though measurable.)
|
|
///
|
|
/// 2. It makes it easier to deal with higher-ranked trait bounds, because we can replace any
|
|
/// late-bound regions with 'static. Otherwise, if we were going to replace late-bound
|
|
/// regions with actual region variables as is proper, we'd have to ensure that the same
|
|
/// region got replaced with the same variable, which requires a bit more coordination
|
|
/// and/or tracking the substitution and
|
|
/// so forth.
|
|
fn erase_late_bound_regions<T>(&self, value: &ty::Binder<T>) -> T
|
|
where
|
|
T: TypeFoldable<'tcx>,
|
|
{
|
|
self.tcx.erase_late_bound_regions(value)
|
|
}
|
|
|
|
/// Finds the method with the appropriate name (or return type, as the case may be). If
|
|
/// `allow_similar_names` is set, find methods with close-matching names.
|
|
fn impl_or_trait_item(&self, def_id: DefId) -> Vec<ty::AssocItem> {
|
|
if let Some(name) = self.method_name {
|
|
if self.allow_similar_names {
|
|
let max_dist = max(name.as_str().len(), 3) / 3;
|
|
self.tcx
|
|
.associated_items(def_id)
|
|
.in_definition_order()
|
|
.filter(|x| {
|
|
let dist = lev_distance(&*name.as_str(), &x.ident.as_str());
|
|
x.kind.namespace() == Namespace::ValueNS && dist > 0 && dist <= max_dist
|
|
})
|
|
.copied()
|
|
.collect()
|
|
} else {
|
|
self.fcx
|
|
.associated_item(def_id, name, Namespace::ValueNS)
|
|
.map_or(Vec::new(), |x| vec![x])
|
|
}
|
|
} else {
|
|
self.tcx.associated_items(def_id).in_definition_order().copied().collect()
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> Candidate<'tcx> {
|
|
fn to_unadjusted_pick(&self) -> Pick<'tcx> {
|
|
Pick {
|
|
item: self.item,
|
|
kind: match self.kind {
|
|
InherentImplCandidate(..) => InherentImplPick,
|
|
ObjectCandidate => ObjectPick,
|
|
TraitCandidate(_) => TraitPick,
|
|
WhereClauseCandidate(ref trait_ref) => {
|
|
// Only trait derived from where-clauses should
|
|
// appear here, so they should not contain any
|
|
// inference variables or other artifacts. This
|
|
// means they are safe to put into the
|
|
// `WhereClausePick`.
|
|
assert!(
|
|
!trait_ref.skip_binder().substs.needs_infer()
|
|
&& !trait_ref.skip_binder().substs.has_placeholders()
|
|
);
|
|
|
|
WhereClausePick(*trait_ref)
|
|
}
|
|
},
|
|
import_ids: self.import_ids.clone(),
|
|
autoderefs: 0,
|
|
autoref: None,
|
|
unsize: None,
|
|
}
|
|
}
|
|
}
|