2991 lines
120 KiB
Rust
2991 lines
120 KiB
Rust
//! Conversion from AST representation of types to the `ty.rs` representation.
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//! The main routine here is `ast_ty_to_ty()`; each use is parameterized by an
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//! instance of `AstConv`.
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use crate::collect::PlaceholderHirTyCollector;
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use crate::lint;
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use crate::middle::lang_items::SizedTraitLangItem;
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use crate::middle::resolve_lifetime as rl;
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use crate::namespace::Namespace;
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use crate::require_c_abi_if_c_variadic;
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use crate::util::common::ErrorReported;
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use rustc::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS;
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use rustc::traits;
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use rustc::traits::astconv_object_safety_violations;
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use rustc::traits::error_reporting::report_object_safety_error;
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use rustc::traits::wf::object_region_bounds;
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use rustc::ty::subst::{self, InternalSubsts, Subst, SubstsRef};
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use rustc::ty::{self, Const, DefIdTree, ToPredicate, Ty, TyCtxt, TypeFoldable};
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use rustc::ty::{GenericParamDef, GenericParamDefKind};
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId};
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use rustc_hir as hir;
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use rustc_hir::def::{CtorOf, DefKind, Res};
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use rustc_hir::def_id::DefId;
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use rustc_hir::intravisit::Visitor;
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use rustc_hir::print;
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use rustc_hir::{ExprKind, GenericArg, GenericArgs};
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use rustc_span::symbol::sym;
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use rustc_span::{MultiSpan, Span, DUMMY_SP};
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use rustc_target::spec::abi;
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use smallvec::SmallVec;
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use syntax::ast;
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use syntax::feature_gate::feature_err;
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use syntax::util::lev_distance::find_best_match_for_name;
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use std::collections::BTreeSet;
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use std::iter;
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use std::slice;
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use rustc_error_codes::*;
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#[derive(Debug)]
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pub struct PathSeg(pub DefId, pub usize);
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pub trait AstConv<'tcx> {
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fn tcx<'a>(&'a self) -> TyCtxt<'tcx>;
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fn item_def_id(&self) -> Option<DefId>;
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/// Returns predicates in scope of the form `X: Foo`, where `X` is
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/// a type parameter `X` with the given id `def_id`. This is a
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/// subset of the full set of predicates.
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///
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/// This is used for one specific purpose: resolving "short-hand"
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/// associated type references like `T::Item`. In principle, we
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/// would do that by first getting the full set of predicates in
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/// scope and then filtering down to find those that apply to `T`,
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/// but this can lead to cycle errors. The problem is that we have
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/// to do this resolution *in order to create the predicates in
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/// the first place*. Hence, we have this "special pass".
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fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx>;
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/// Returns the lifetime to use when a lifetime is omitted (and not elided).
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fn re_infer(&self, param: Option<&ty::GenericParamDef>, span: Span)
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-> Option<ty::Region<'tcx>>;
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/// Returns the type to use when a type is omitted.
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fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx>;
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/// Returns `true` if `_` is allowed in type signatures in the current context.
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fn allow_ty_infer(&self) -> bool;
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/// Returns the const to use when a const is omitted.
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fn ct_infer(
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&self,
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ty: Ty<'tcx>,
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param: Option<&ty::GenericParamDef>,
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span: Span,
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) -> &'tcx Const<'tcx>;
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/// Projecting an associated type from a (potentially)
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/// higher-ranked trait reference is more complicated, because of
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/// the possibility of late-bound regions appearing in the
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/// associated type binding. This is not legal in function
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/// signatures for that reason. In a function body, we can always
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/// handle it because we can use inference variables to remove the
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/// late-bound regions.
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fn projected_ty_from_poly_trait_ref(
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&self,
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span: Span,
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item_def_id: DefId,
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item_segment: &hir::PathSegment<'_>,
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poly_trait_ref: ty::PolyTraitRef<'tcx>,
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) -> Ty<'tcx>;
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/// Normalize an associated type coming from the user.
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fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx>;
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/// Invoked when we encounter an error from some prior pass
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/// (e.g., resolve) that is translated into a ty-error. This is
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/// used to help suppress derived errors typeck might otherwise
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/// report.
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fn set_tainted_by_errors(&self);
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fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, span: Span);
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}
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pub enum SizedByDefault {
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Yes,
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No,
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}
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struct ConvertedBinding<'a, 'tcx> {
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item_name: ast::Ident,
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kind: ConvertedBindingKind<'a, 'tcx>,
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span: Span,
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}
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enum ConvertedBindingKind<'a, 'tcx> {
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Equality(Ty<'tcx>),
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Constraint(&'a [hir::GenericBound<'a>]),
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}
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#[derive(PartialEq)]
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enum GenericArgPosition {
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Type,
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Value, // e.g., functions
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MethodCall,
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}
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impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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pub fn ast_region_to_region(
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&self,
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lifetime: &hir::Lifetime,
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def: Option<&ty::GenericParamDef>,
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) -> ty::Region<'tcx> {
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let tcx = self.tcx();
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let lifetime_name = |def_id| tcx.hir().name(tcx.hir().as_local_hir_id(def_id).unwrap());
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let r = match tcx.named_region(lifetime.hir_id) {
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Some(rl::Region::Static) => tcx.lifetimes.re_static,
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Some(rl::Region::LateBound(debruijn, id, _)) => {
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let name = lifetime_name(id);
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tcx.mk_region(ty::ReLateBound(debruijn, ty::BrNamed(id, name)))
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}
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Some(rl::Region::LateBoundAnon(debruijn, index)) => {
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tcx.mk_region(ty::ReLateBound(debruijn, ty::BrAnon(index)))
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}
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Some(rl::Region::EarlyBound(index, id, _)) => {
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let name = lifetime_name(id);
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tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion { def_id: id, index, name }))
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}
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Some(rl::Region::Free(scope, id)) => {
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let name = lifetime_name(id);
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tcx.mk_region(ty::ReFree(ty::FreeRegion {
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scope,
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bound_region: ty::BrNamed(id, name),
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}))
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// (*) -- not late-bound, won't change
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}
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None => {
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self.re_infer(def, lifetime.span).unwrap_or_else(|| {
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// This indicates an illegal lifetime
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// elision. `resolve_lifetime` should have
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// reported an error in this case -- but if
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// not, let's error out.
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tcx.sess.delay_span_bug(lifetime.span, "unelided lifetime in signature");
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// Supply some dummy value. We don't have an
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// `re_error`, annoyingly, so use `'static`.
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tcx.lifetimes.re_static
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})
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}
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};
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debug!("ast_region_to_region(lifetime={:?}) yields {:?}", lifetime, r);
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r
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}
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/// Given a path `path` that refers to an item `I` with the declared generics `decl_generics`,
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/// returns an appropriate set of substitutions for this particular reference to `I`.
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pub fn ast_path_substs_for_ty(
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&self,
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span: Span,
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def_id: DefId,
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item_segment: &hir::PathSegment<'_>,
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) -> SubstsRef<'tcx> {
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let (substs, assoc_bindings, _) = self.create_substs_for_ast_path(
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span,
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def_id,
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&[],
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item_segment.generic_args(),
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item_segment.infer_args,
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None,
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);
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assoc_bindings.first().map(|b| Self::prohibit_assoc_ty_binding(self.tcx(), b.span));
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substs
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}
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/// Report error if there is an explicit type parameter when using `impl Trait`.
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fn check_impl_trait(
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tcx: TyCtxt<'_>,
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seg: &hir::PathSegment<'_>,
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generics: &ty::Generics,
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) -> bool {
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let explicit = !seg.infer_args;
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let impl_trait = generics.params.iter().any(|param| match param.kind {
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ty::GenericParamDefKind::Type {
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synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
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..
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} => true,
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_ => false,
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});
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if explicit && impl_trait {
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let spans = seg
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.generic_args()
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.args
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.iter()
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.filter_map(|arg| match arg {
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GenericArg::Type(_) => Some(arg.span()),
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_ => None,
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})
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.collect::<Vec<_>>();
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let mut err = struct_span_err! {
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tcx.sess,
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spans.clone(),
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E0632,
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"cannot provide explicit generic arguments when `impl Trait` is \
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used in argument position"
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};
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for span in spans {
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err.span_label(span, "explicit generic argument not allowed");
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}
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err.emit();
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}
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impl_trait
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}
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/// Checks that the correct number of generic arguments have been provided.
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/// Used specifically for function calls.
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pub fn check_generic_arg_count_for_call(
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tcx: TyCtxt<'_>,
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span: Span,
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def: &ty::Generics,
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seg: &hir::PathSegment<'_>,
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is_method_call: bool,
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) -> bool {
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let empty_args = hir::GenericArgs::none();
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let suppress_mismatch = Self::check_impl_trait(tcx, seg, &def);
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Self::check_generic_arg_count(
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tcx,
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span,
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def,
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if let Some(ref args) = seg.args { args } else { &empty_args },
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if is_method_call { GenericArgPosition::MethodCall } else { GenericArgPosition::Value },
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def.parent.is_none() && def.has_self, // `has_self`
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seg.infer_args || suppress_mismatch, // `infer_args`
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)
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.0
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}
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/// Checks that the correct number of generic arguments have been provided.
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/// This is used both for datatypes and function calls.
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fn check_generic_arg_count(
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tcx: TyCtxt<'_>,
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span: Span,
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def: &ty::Generics,
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args: &hir::GenericArgs<'_>,
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position: GenericArgPosition,
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has_self: bool,
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infer_args: bool,
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) -> (bool, Option<Vec<Span>>) {
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// At this stage we are guaranteed that the generic arguments are in the correct order, e.g.
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// that lifetimes will proceed types. So it suffices to check the number of each generic
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// arguments in order to validate them with respect to the generic parameters.
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let param_counts = def.own_counts();
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let arg_counts = args.own_counts();
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let infer_lifetimes = position != GenericArgPosition::Type && arg_counts.lifetimes == 0;
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let mut defaults: ty::GenericParamCount = Default::default();
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for param in &def.params {
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match param.kind {
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GenericParamDefKind::Lifetime => {}
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GenericParamDefKind::Type { has_default, .. } => {
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defaults.types += has_default as usize
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}
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GenericParamDefKind::Const => {
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// FIXME(const_generics:defaults)
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}
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};
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}
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if position != GenericArgPosition::Type && !args.bindings.is_empty() {
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AstConv::prohibit_assoc_ty_binding(tcx, args.bindings[0].span);
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}
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// Prohibit explicit lifetime arguments if late-bound lifetime parameters are present.
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let mut reported_late_bound_region_err = None;
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if !infer_lifetimes {
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if let Some(span_late) = def.has_late_bound_regions {
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let msg = "cannot specify lifetime arguments explicitly \
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if late bound lifetime parameters are present";
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let note = "the late bound lifetime parameter is introduced here";
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let span = args.args[0].span();
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if position == GenericArgPosition::Value
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&& arg_counts.lifetimes != param_counts.lifetimes
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{
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let mut err = tcx.sess.struct_span_err(span, msg);
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err.span_note(span_late, note);
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err.emit();
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reported_late_bound_region_err = Some(true);
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} else {
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let mut multispan = MultiSpan::from_span(span);
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multispan.push_span_label(span_late, note.to_string());
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tcx.lint_hir(
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lint::builtin::LATE_BOUND_LIFETIME_ARGUMENTS,
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args.args[0].id(),
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multispan,
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msg,
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);
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reported_late_bound_region_err = Some(false);
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}
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}
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}
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let check_kind_count = |kind, required, permitted, provided, offset| {
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debug!(
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"check_kind_count: kind: {} required: {} permitted: {} provided: {} offset: {}",
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kind, required, permitted, provided, offset
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);
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// We enforce the following: `required` <= `provided` <= `permitted`.
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// For kinds without defaults (e.g.., lifetimes), `required == permitted`.
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// For other kinds (i.e., types), `permitted` may be greater than `required`.
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if required <= provided && provided <= permitted {
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return (reported_late_bound_region_err.unwrap_or(false), None);
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}
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// Unfortunately lifetime and type parameter mismatches are typically styled
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// differently in diagnostics, which means we have a few cases to consider here.
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let (bound, quantifier) = if required != permitted {
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if provided < required {
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(required, "at least ")
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} else {
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// provided > permitted
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(permitted, "at most ")
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}
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} else {
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(required, "")
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};
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let mut potential_assoc_types: Option<Vec<Span>> = None;
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let (spans, label) = if required == permitted && provided > permitted {
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// In the case when the user has provided too many arguments,
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// we want to point to the unexpected arguments.
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let spans: Vec<Span> = args.args[offset + permitted..offset + provided]
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.iter()
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.map(|arg| arg.span())
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.collect();
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potential_assoc_types = Some(spans.clone());
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(spans, format!("unexpected {} argument", kind))
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} else {
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(
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vec![span],
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format!(
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"expected {}{} {} argument{}",
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quantifier,
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bound,
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kind,
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pluralize!(bound),
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),
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)
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};
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let mut err = tcx.sess.struct_span_err_with_code(
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spans.clone(),
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&format!(
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"wrong number of {} arguments: expected {}{}, found {}",
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kind, quantifier, bound, provided,
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),
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DiagnosticId::Error("E0107".into()),
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);
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for span in spans {
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err.span_label(span, label.as_str());
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}
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err.emit();
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(
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provided > required, // `suppress_error`
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potential_assoc_types,
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)
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};
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if reported_late_bound_region_err.is_none()
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&& (!infer_lifetimes || arg_counts.lifetimes > param_counts.lifetimes)
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{
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check_kind_count(
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"lifetime",
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param_counts.lifetimes,
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param_counts.lifetimes,
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arg_counts.lifetimes,
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0,
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);
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}
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// FIXME(const_generics:defaults)
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if !infer_args || arg_counts.consts > param_counts.consts {
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check_kind_count(
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"const",
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param_counts.consts,
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param_counts.consts,
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arg_counts.consts,
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arg_counts.lifetimes + arg_counts.types,
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);
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}
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// Note that type errors are currently be emitted *after* const errors.
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if !infer_args || arg_counts.types > param_counts.types - defaults.types - has_self as usize
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{
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check_kind_count(
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"type",
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param_counts.types - defaults.types - has_self as usize,
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param_counts.types - has_self as usize,
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arg_counts.types,
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arg_counts.lifetimes,
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)
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} else {
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(reported_late_bound_region_err.unwrap_or(false), None)
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}
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}
|
|
|
|
/// Creates the relevant generic argument substitutions
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|
/// corresponding to a set of generic parameters. This is a
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|
/// rather complex function. Let us try to explain the role
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|
/// of each of its parameters:
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///
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/// To start, we are given the `def_id` of the thing we are
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/// creating the substitutions for, and a partial set of
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/// substitutions `parent_substs`. In general, the substitutions
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/// for an item begin with substitutions for all the "parents" of
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/// that item -- e.g., for a method it might include the
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/// parameters from the impl.
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///
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/// Therefore, the method begins by walking down these parents,
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/// starting with the outermost parent and proceed inwards until
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/// it reaches `def_id`. For each parent `P`, it will check `parent_substs`
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/// first to see if the parent's substitutions are listed in there. If so,
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/// we can append those and move on. Otherwise, it invokes the
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|
/// three callback functions:
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///
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/// - `args_for_def_id`: given the `DefId` `P`, supplies back the
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/// generic arguments that were given to that parent from within
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|
/// the path; so e.g., if you have `<T as Foo>::Bar`, the `DefId`
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|
/// might refer to the trait `Foo`, and the arguments might be
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/// `[T]`. The boolean value indicates whether to infer values
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/// for arguments whose values were not explicitly provided.
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/// - `provided_kind`: given the generic parameter and the value from `args_for_def_id`,
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/// instantiate a `GenericArg`.
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/// - `inferred_kind`: if no parameter was provided, and inference is enabled, then
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/// creates a suitable inference variable.
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|
pub fn create_substs_for_generic_args<'b>(
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tcx: TyCtxt<'tcx>,
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def_id: DefId,
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parent_substs: &[subst::GenericArg<'tcx>],
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has_self: bool,
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self_ty: Option<Ty<'tcx>>,
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args_for_def_id: impl Fn(DefId) -> (Option<&'b GenericArgs<'b>>, bool),
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provided_kind: impl Fn(&GenericParamDef, &GenericArg<'_>) -> subst::GenericArg<'tcx>,
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|
mut inferred_kind: impl FnMut(
|
|
Option<&[subst::GenericArg<'tcx>]>,
|
|
&GenericParamDef,
|
|
bool,
|
|
) -> subst::GenericArg<'tcx>,
|
|
) -> SubstsRef<'tcx> {
|
|
// Collect the segments of the path; we need to substitute arguments
|
|
// for parameters throughout the entire path (wherever there are
|
|
// generic parameters).
|
|
let mut parent_defs = tcx.generics_of(def_id);
|
|
let count = parent_defs.count();
|
|
let mut stack = vec![(def_id, parent_defs)];
|
|
while let Some(def_id) = parent_defs.parent {
|
|
parent_defs = tcx.generics_of(def_id);
|
|
stack.push((def_id, parent_defs));
|
|
}
|
|
|
|
// We manually build up the substitution, rather than using convenience
|
|
// methods in `subst.rs`, so that we can iterate over the arguments and
|
|
// parameters in lock-step linearly, instead of trying to match each pair.
|
|
let mut substs: SmallVec<[subst::GenericArg<'tcx>; 8]> = SmallVec::with_capacity(count);
|
|
|
|
// Iterate over each segment of the path.
|
|
while let Some((def_id, defs)) = stack.pop() {
|
|
let mut params = defs.params.iter().peekable();
|
|
|
|
// If we have already computed substitutions for parents, we can use those directly.
|
|
while let Some(¶m) = params.peek() {
|
|
if let Some(&kind) = parent_substs.get(param.index as usize) {
|
|
substs.push(kind);
|
|
params.next();
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
// `Self` is handled first, unless it's been handled in `parent_substs`.
|
|
if has_self {
|
|
if let Some(¶m) = params.peek() {
|
|
if param.index == 0 {
|
|
if let GenericParamDefKind::Type { .. } = param.kind {
|
|
substs.push(
|
|
self_ty
|
|
.map(|ty| ty.into())
|
|
.unwrap_or_else(|| inferred_kind(None, param, true)),
|
|
);
|
|
params.next();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Check whether this segment takes generic arguments and the user has provided any.
|
|
let (generic_args, infer_args) = args_for_def_id(def_id);
|
|
|
|
let mut args =
|
|
generic_args.iter().flat_map(|generic_args| generic_args.args.iter()).peekable();
|
|
|
|
loop {
|
|
// We're going to iterate through the generic arguments that the user
|
|
// provided, matching them with the generic parameters we expect.
|
|
// Mismatches can occur as a result of elided lifetimes, or for malformed
|
|
// input. We try to handle both sensibly.
|
|
match (args.peek(), params.peek()) {
|
|
(Some(&arg), Some(¶m)) => {
|
|
match (arg, ¶m.kind) {
|
|
(GenericArg::Lifetime(_), GenericParamDefKind::Lifetime)
|
|
| (GenericArg::Type(_), GenericParamDefKind::Type { .. })
|
|
| (GenericArg::Const(_), GenericParamDefKind::Const) => {
|
|
substs.push(provided_kind(param, arg));
|
|
args.next();
|
|
params.next();
|
|
}
|
|
(GenericArg::Type(_), GenericParamDefKind::Lifetime)
|
|
| (GenericArg::Const(_), GenericParamDefKind::Lifetime) => {
|
|
// We expected a lifetime argument, but got a type or const
|
|
// argument. That means we're inferring the lifetimes.
|
|
substs.push(inferred_kind(None, param, infer_args));
|
|
params.next();
|
|
}
|
|
(_, _) => {
|
|
// We expected one kind of parameter, but the user provided
|
|
// another. This is an error, but we need to handle it
|
|
// gracefully so we can report sensible errors.
|
|
// In this case, we're simply going to infer this argument.
|
|
args.next();
|
|
}
|
|
}
|
|
}
|
|
(Some(_), None) => {
|
|
// We should never be able to reach this point with well-formed input.
|
|
// Getting to this point means the user supplied more arguments than
|
|
// there are parameters.
|
|
args.next();
|
|
}
|
|
(None, Some(¶m)) => {
|
|
// If there are fewer arguments than parameters, it means
|
|
// we're inferring the remaining arguments.
|
|
substs.push(inferred_kind(Some(&substs), param, infer_args));
|
|
args.next();
|
|
params.next();
|
|
}
|
|
(None, None) => break,
|
|
}
|
|
}
|
|
}
|
|
|
|
tcx.intern_substs(&substs)
|
|
}
|
|
|
|
/// Given the type/lifetime/const arguments provided to some path (along with
|
|
/// an implicit `Self`, if this is a trait reference), returns the complete
|
|
/// set of substitutions. This may involve applying defaulted type parameters.
|
|
/// Also returns back constriants on associated types.
|
|
///
|
|
/// Example:
|
|
///
|
|
/// ```
|
|
/// T: std::ops::Index<usize, Output = u32>
|
|
/// ^1 ^^^^^^^^^^^^^^2 ^^^^3 ^^^^^^^^^^^4
|
|
/// ```
|
|
///
|
|
/// 1. The `self_ty` here would refer to the type `T`.
|
|
/// 2. The path in question is the path to the trait `std::ops::Index`,
|
|
/// which will have been resolved to a `def_id`
|
|
/// 3. The `generic_args` contains info on the `<...>` contents. The `usize` type
|
|
/// parameters are returned in the `SubstsRef`, the associated type bindings like
|
|
/// `Output = u32` are returned in the `Vec<ConvertedBinding...>` result.
|
|
///
|
|
/// Note that the type listing given here is *exactly* what the user provided.
|
|
///
|
|
/// For (generic) associated types
|
|
///
|
|
/// ```
|
|
/// <Vec<u8> as Iterable<u8>>::Iter::<'a>
|
|
/// ```
|
|
///
|
|
/// We have the parent substs are the substs for the parent trait:
|
|
/// `[Vec<u8>, u8]` and `generic_args` are the arguments for the associated
|
|
/// type itself: `['a]`. The returned `SubstsRef` concatenates these two
|
|
/// lists: `[Vec<u8>, u8, 'a]`.
|
|
fn create_substs_for_ast_path<'a>(
|
|
&self,
|
|
span: Span,
|
|
def_id: DefId,
|
|
parent_substs: &[subst::GenericArg<'tcx>],
|
|
generic_args: &'a hir::GenericArgs<'_>,
|
|
infer_args: bool,
|
|
self_ty: Option<Ty<'tcx>>,
|
|
) -> (SubstsRef<'tcx>, Vec<ConvertedBinding<'a, 'tcx>>, Option<Vec<Span>>) {
|
|
// If the type is parameterized by this region, then replace this
|
|
// region with the current anon region binding (in other words,
|
|
// whatever & would get replaced with).
|
|
debug!(
|
|
"create_substs_for_ast_path(def_id={:?}, self_ty={:?}, \
|
|
generic_args={:?})",
|
|
def_id, self_ty, generic_args
|
|
);
|
|
|
|
let tcx = self.tcx();
|
|
let generic_params = tcx.generics_of(def_id);
|
|
|
|
if generic_params.has_self {
|
|
if generic_params.parent.is_some() {
|
|
// The parent is a trait so it should have at least one subst
|
|
// for the `Self` type.
|
|
assert!(!parent_substs.is_empty())
|
|
} else {
|
|
// This item (presumably a trait) needs a self-type.
|
|
assert!(self_ty.is_some());
|
|
}
|
|
} else {
|
|
assert!(self_ty.is_none() && parent_substs.is_empty());
|
|
}
|
|
|
|
let (_, potential_assoc_types) = Self::check_generic_arg_count(
|
|
tcx,
|
|
span,
|
|
&generic_params,
|
|
&generic_args,
|
|
GenericArgPosition::Type,
|
|
self_ty.is_some(),
|
|
infer_args,
|
|
);
|
|
|
|
let is_object = self_ty.map_or(false, |ty| ty == self.tcx().types.trait_object_dummy_self);
|
|
let default_needs_object_self = |param: &ty::GenericParamDef| {
|
|
if let GenericParamDefKind::Type { has_default, .. } = param.kind {
|
|
if is_object && has_default {
|
|
let self_param = tcx.types.self_param;
|
|
if tcx.at(span).type_of(param.def_id).walk().any(|ty| ty == self_param) {
|
|
// There is no suitable inference default for a type parameter
|
|
// that references self, in an object type.
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
false
|
|
};
|
|
|
|
let mut missing_type_params = vec![];
|
|
let substs = Self::create_substs_for_generic_args(
|
|
tcx,
|
|
def_id,
|
|
parent_substs,
|
|
self_ty.is_some(),
|
|
self_ty,
|
|
// Provide the generic args, and whether types should be inferred.
|
|
|_| (Some(generic_args), infer_args),
|
|
// Provide substitutions for parameters for which (valid) arguments have been provided.
|
|
|param, arg| match (¶m.kind, arg) {
|
|
(GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
|
|
self.ast_region_to_region(<, Some(param)).into()
|
|
}
|
|
(GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
|
|
self.ast_ty_to_ty(&ty).into()
|
|
}
|
|
(GenericParamDefKind::Const, GenericArg::Const(ct)) => {
|
|
self.ast_const_to_const(&ct.value, tcx.type_of(param.def_id)).into()
|
|
}
|
|
_ => unreachable!(),
|
|
},
|
|
// Provide substitutions for parameters for which arguments are inferred.
|
|
|substs, param, infer_args| {
|
|
match param.kind {
|
|
GenericParamDefKind::Lifetime => tcx.lifetimes.re_static.into(),
|
|
GenericParamDefKind::Type { has_default, .. } => {
|
|
if !infer_args && has_default {
|
|
// No type parameter provided, but a default exists.
|
|
|
|
// If we are converting an object type, then the
|
|
// `Self` parameter is unknown. However, some of the
|
|
// other type parameters may reference `Self` in their
|
|
// defaults. This will lead to an ICE if we are not
|
|
// careful!
|
|
if default_needs_object_self(param) {
|
|
missing_type_params.push(param.name.to_string());
|
|
tcx.types.err.into()
|
|
} else {
|
|
// This is a default type parameter.
|
|
self.normalize_ty(
|
|
span,
|
|
tcx.at(span).type_of(param.def_id).subst_spanned(
|
|
tcx,
|
|
substs.unwrap(),
|
|
Some(span),
|
|
),
|
|
)
|
|
.into()
|
|
}
|
|
} else if infer_args {
|
|
// No type parameters were provided, we can infer all.
|
|
let param =
|
|
if !default_needs_object_self(param) { Some(param) } else { None };
|
|
self.ty_infer(param, span).into()
|
|
} else {
|
|
// We've already errored above about the mismatch.
|
|
tcx.types.err.into()
|
|
}
|
|
}
|
|
GenericParamDefKind::Const => {
|
|
// FIXME(const_generics:defaults)
|
|
if infer_args {
|
|
// No const parameters were provided, we can infer all.
|
|
let ty = tcx.at(span).type_of(param.def_id);
|
|
self.ct_infer(ty, Some(param), span).into()
|
|
} else {
|
|
// We've already errored above about the mismatch.
|
|
tcx.consts.err.into()
|
|
}
|
|
}
|
|
}
|
|
},
|
|
);
|
|
|
|
self.complain_about_missing_type_params(
|
|
missing_type_params,
|
|
def_id,
|
|
span,
|
|
generic_args.args.is_empty(),
|
|
);
|
|
|
|
// Convert associated-type bindings or constraints into a separate vector.
|
|
// Example: Given this:
|
|
//
|
|
// T: Iterator<Item = u32>
|
|
//
|
|
// The `T` is passed in as a self-type; the `Item = u32` is
|
|
// not a "type parameter" of the `Iterator` trait, but rather
|
|
// a restriction on `<T as Iterator>::Item`, so it is passed
|
|
// back separately.
|
|
let assoc_bindings = generic_args
|
|
.bindings
|
|
.iter()
|
|
.map(|binding| {
|
|
let kind = match binding.kind {
|
|
hir::TypeBindingKind::Equality { ref ty } => {
|
|
ConvertedBindingKind::Equality(self.ast_ty_to_ty(ty))
|
|
}
|
|
hir::TypeBindingKind::Constraint { ref bounds } => {
|
|
ConvertedBindingKind::Constraint(bounds)
|
|
}
|
|
};
|
|
ConvertedBinding { item_name: binding.ident, kind, span: binding.span }
|
|
})
|
|
.collect();
|
|
|
|
debug!(
|
|
"create_substs_for_ast_path(generic_params={:?}, self_ty={:?}) -> {:?}",
|
|
generic_params, self_ty, substs
|
|
);
|
|
|
|
(substs, assoc_bindings, potential_assoc_types)
|
|
}
|
|
|
|
crate fn create_substs_for_associated_item(
|
|
&self,
|
|
tcx: TyCtxt<'tcx>,
|
|
span: Span,
|
|
item_def_id: DefId,
|
|
item_segment: &hir::PathSegment<'_>,
|
|
parent_substs: SubstsRef<'tcx>,
|
|
) -> SubstsRef<'tcx> {
|
|
if tcx.generics_of(item_def_id).params.is_empty() {
|
|
self.prohibit_generics(slice::from_ref(item_segment));
|
|
|
|
parent_substs
|
|
} else {
|
|
self.create_substs_for_ast_path(
|
|
span,
|
|
item_def_id,
|
|
parent_substs,
|
|
item_segment.generic_args(),
|
|
item_segment.infer_args,
|
|
None,
|
|
)
|
|
.0
|
|
}
|
|
}
|
|
|
|
/// On missing type parameters, emit an E0393 error and provide a structured suggestion using
|
|
/// the type parameter's name as a placeholder.
|
|
fn complain_about_missing_type_params(
|
|
&self,
|
|
missing_type_params: Vec<String>,
|
|
def_id: DefId,
|
|
span: Span,
|
|
empty_generic_args: bool,
|
|
) {
|
|
if missing_type_params.is_empty() {
|
|
return;
|
|
}
|
|
let display =
|
|
missing_type_params.iter().map(|n| format!("`{}`", n)).collect::<Vec<_>>().join(", ");
|
|
let mut err = struct_span_err!(
|
|
self.tcx().sess,
|
|
span,
|
|
E0393,
|
|
"the type parameter{} {} must be explicitly specified",
|
|
pluralize!(missing_type_params.len()),
|
|
display,
|
|
);
|
|
err.span_label(
|
|
self.tcx().def_span(def_id),
|
|
&format!(
|
|
"type parameter{} {} must be specified for this",
|
|
pluralize!(missing_type_params.len()),
|
|
display,
|
|
),
|
|
);
|
|
let mut suggested = false;
|
|
if let (Ok(snippet), true) = (
|
|
self.tcx().sess.source_map().span_to_snippet(span),
|
|
// Don't suggest setting the type params if there are some already: the order is
|
|
// tricky to get right and the user will already know what the syntax is.
|
|
empty_generic_args,
|
|
) {
|
|
if snippet.ends_with('>') {
|
|
// The user wrote `Trait<'a, T>` or similar. To provide an accurate suggestion
|
|
// we would have to preserve the right order. For now, as clearly the user is
|
|
// aware of the syntax, we do nothing.
|
|
} else {
|
|
// The user wrote `Iterator`, so we don't have a type we can suggest, but at
|
|
// least we can clue them to the correct syntax `Iterator<Type>`.
|
|
err.span_suggestion(
|
|
span,
|
|
&format!(
|
|
"set the type parameter{plural} to the desired type{plural}",
|
|
plural = pluralize!(missing_type_params.len()),
|
|
),
|
|
format!("{}<{}>", snippet, missing_type_params.join(", ")),
|
|
Applicability::HasPlaceholders,
|
|
);
|
|
suggested = true;
|
|
}
|
|
}
|
|
if !suggested {
|
|
err.span_label(
|
|
span,
|
|
format!(
|
|
"missing reference{} to {}",
|
|
pluralize!(missing_type_params.len()),
|
|
display,
|
|
),
|
|
);
|
|
}
|
|
err.note(&format!(
|
|
"because of the default `Self` reference, type parameters must be \
|
|
specified on object types"
|
|
));
|
|
err.emit();
|
|
}
|
|
|
|
/// Instantiates the path for the given trait reference, assuming that it's
|
|
/// bound to a valid trait type. Returns the `DefId` of the defining trait.
|
|
/// The type _cannot_ be a type other than a trait type.
|
|
///
|
|
/// If the `projections` argument is `None`, then assoc type bindings like `Foo<T = X>`
|
|
/// are disallowed. Otherwise, they are pushed onto the vector given.
|
|
pub fn instantiate_mono_trait_ref(
|
|
&self,
|
|
trait_ref: &hir::TraitRef<'_>,
|
|
self_ty: Ty<'tcx>,
|
|
) -> ty::TraitRef<'tcx> {
|
|
self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1);
|
|
|
|
self.ast_path_to_mono_trait_ref(
|
|
trait_ref.path.span,
|
|
trait_ref.trait_def_id(),
|
|
self_ty,
|
|
trait_ref.path.segments.last().unwrap(),
|
|
)
|
|
}
|
|
|
|
/// The given trait-ref must actually be a trait.
|
|
pub(super) fn instantiate_poly_trait_ref_inner(
|
|
&self,
|
|
trait_ref: &hir::TraitRef<'_>,
|
|
span: Span,
|
|
self_ty: Ty<'tcx>,
|
|
bounds: &mut Bounds<'tcx>,
|
|
speculative: bool,
|
|
) -> Option<Vec<Span>> {
|
|
let trait_def_id = trait_ref.trait_def_id();
|
|
|
|
debug!("instantiate_poly_trait_ref({:?}, def_id={:?})", trait_ref, trait_def_id);
|
|
|
|
self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1);
|
|
|
|
let path_span = if let [segment] = &trait_ref.path.segments[..] {
|
|
// FIXME: `trait_ref.path.span` can point to a full path with multiple
|
|
// segments, even though `trait_ref.path.segments` is of length `1`. Work
|
|
// around that bug here, even though it should be fixed elsewhere.
|
|
// This would otherwise cause an invalid suggestion. For an example, look at
|
|
// `src/test/ui/issues/issue-28344.rs`.
|
|
segment.ident.span
|
|
} else {
|
|
trait_ref.path.span
|
|
};
|
|
let (substs, assoc_bindings, potential_assoc_types) = self.create_substs_for_ast_trait_ref(
|
|
path_span,
|
|
trait_def_id,
|
|
self_ty,
|
|
trait_ref.path.segments.last().unwrap(),
|
|
);
|
|
let poly_trait_ref = ty::Binder::bind(ty::TraitRef::new(trait_def_id, substs));
|
|
|
|
bounds.trait_bounds.push((poly_trait_ref, span));
|
|
|
|
let mut dup_bindings = FxHashMap::default();
|
|
for binding in &assoc_bindings {
|
|
// Specify type to assert that error was already reported in `Err` case.
|
|
let _: Result<_, ErrorReported> = self.add_predicates_for_ast_type_binding(
|
|
trait_ref.hir_ref_id,
|
|
poly_trait_ref,
|
|
binding,
|
|
bounds,
|
|
speculative,
|
|
&mut dup_bindings,
|
|
span,
|
|
);
|
|
// Okay to ignore `Err` because of `ErrorReported` (see above).
|
|
}
|
|
|
|
debug!(
|
|
"instantiate_poly_trait_ref({:?}, bounds={:?}) -> {:?}",
|
|
trait_ref, bounds, poly_trait_ref
|
|
);
|
|
potential_assoc_types
|
|
}
|
|
|
|
/// Given a trait bound like `Debug`, applies that trait bound the given self-type to construct
|
|
/// a full trait reference. The resulting trait reference is returned. This may also generate
|
|
/// auxiliary bounds, which are added to `bounds`.
|
|
///
|
|
/// Example:
|
|
///
|
|
/// ```
|
|
/// poly_trait_ref = Iterator<Item = u32>
|
|
/// self_ty = Foo
|
|
/// ```
|
|
///
|
|
/// this would return `Foo: Iterator` and add `<Foo as Iterator>::Item = u32` into `bounds`.
|
|
///
|
|
/// **A note on binders:** against our usual convention, there is an implied bounder around
|
|
/// the `self_ty` and `poly_trait_ref` parameters here. So they may reference bound regions.
|
|
/// If for example you had `for<'a> Foo<'a>: Bar<'a>`, then the `self_ty` would be `Foo<'a>`
|
|
/// where `'a` is a bound region at depth 0. Similarly, the `poly_trait_ref` would be
|
|
/// `Bar<'a>`. The returned poly-trait-ref will have this binder instantiated explicitly,
|
|
/// however.
|
|
pub fn instantiate_poly_trait_ref(
|
|
&self,
|
|
poly_trait_ref: &hir::PolyTraitRef<'_>,
|
|
self_ty: Ty<'tcx>,
|
|
bounds: &mut Bounds<'tcx>,
|
|
) -> Option<Vec<Span>> {
|
|
self.instantiate_poly_trait_ref_inner(
|
|
&poly_trait_ref.trait_ref,
|
|
poly_trait_ref.span,
|
|
self_ty,
|
|
bounds,
|
|
false,
|
|
)
|
|
}
|
|
|
|
fn ast_path_to_mono_trait_ref(
|
|
&self,
|
|
span: Span,
|
|
trait_def_id: DefId,
|
|
self_ty: Ty<'tcx>,
|
|
trait_segment: &hir::PathSegment<'_>,
|
|
) -> ty::TraitRef<'tcx> {
|
|
let (substs, assoc_bindings, _) =
|
|
self.create_substs_for_ast_trait_ref(span, trait_def_id, self_ty, trait_segment);
|
|
assoc_bindings.first().map(|b| AstConv::prohibit_assoc_ty_binding(self.tcx(), b.span));
|
|
ty::TraitRef::new(trait_def_id, substs)
|
|
}
|
|
|
|
/// When the code is using the `Fn` traits directly, instead of the `Fn(A) -> B` syntax, emit
|
|
/// an error and attempt to build a reasonable structured suggestion.
|
|
fn complain_about_internal_fn_trait(
|
|
&self,
|
|
span: Span,
|
|
trait_def_id: DefId,
|
|
trait_segment: &'a hir::PathSegment<'a>,
|
|
) {
|
|
let trait_def = self.tcx().trait_def(trait_def_id);
|
|
|
|
if !self.tcx().features().unboxed_closures
|
|
&& trait_segment.generic_args().parenthesized != trait_def.paren_sugar
|
|
{
|
|
// For now, require that parenthetical notation be used only with `Fn()` etc.
|
|
let (msg, sugg) = if trait_def.paren_sugar {
|
|
(
|
|
"the precise format of `Fn`-family traits' type parameters is subject to \
|
|
change",
|
|
Some(format!(
|
|
"{}{} -> {}",
|
|
trait_segment.ident,
|
|
trait_segment
|
|
.args
|
|
.as_ref()
|
|
.and_then(|args| args.args.get(0))
|
|
.and_then(|arg| match arg {
|
|
hir::GenericArg::Type(ty) => {
|
|
Some(print::to_string(print::NO_ANN, |s| s.print_type(ty)))
|
|
}
|
|
_ => None,
|
|
})
|
|
.unwrap_or_else(|| "()".to_string()),
|
|
trait_segment
|
|
.generic_args()
|
|
.bindings
|
|
.iter()
|
|
.filter_map(|b| match (b.ident.as_str() == "Output", &b.kind) {
|
|
(true, hir::TypeBindingKind::Equality { ty }) => {
|
|
Some(print::to_string(print::NO_ANN, |s| s.print_type(ty)))
|
|
}
|
|
_ => None,
|
|
})
|
|
.next()
|
|
.unwrap_or_else(|| "()".to_string()),
|
|
)),
|
|
)
|
|
} else {
|
|
("parenthetical notation is only stable when used with `Fn`-family traits", None)
|
|
};
|
|
let sess = &self.tcx().sess.parse_sess;
|
|
let mut err = feature_err(sess, sym::unboxed_closures, span, msg);
|
|
if let Some(sugg) = sugg {
|
|
let msg = "use parenthetical notation instead";
|
|
err.span_suggestion(span, msg, sugg, Applicability::MaybeIncorrect);
|
|
}
|
|
err.emit();
|
|
}
|
|
}
|
|
|
|
fn create_substs_for_ast_trait_ref<'a>(
|
|
&self,
|
|
span: Span,
|
|
trait_def_id: DefId,
|
|
self_ty: Ty<'tcx>,
|
|
trait_segment: &'a hir::PathSegment<'a>,
|
|
) -> (SubstsRef<'tcx>, Vec<ConvertedBinding<'a, 'tcx>>, Option<Vec<Span>>) {
|
|
debug!("create_substs_for_ast_trait_ref(trait_segment={:?})", trait_segment);
|
|
|
|
self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment);
|
|
|
|
self.create_substs_for_ast_path(
|
|
span,
|
|
trait_def_id,
|
|
&[],
|
|
trait_segment.generic_args(),
|
|
trait_segment.infer_args,
|
|
Some(self_ty),
|
|
)
|
|
}
|
|
|
|
fn trait_defines_associated_type_named(
|
|
&self,
|
|
trait_def_id: DefId,
|
|
assoc_name: ast::Ident,
|
|
) -> bool {
|
|
self.tcx().associated_items(trait_def_id).any(|item| {
|
|
item.kind == ty::AssocKind::Type
|
|
&& self.tcx().hygienic_eq(assoc_name, item.ident, trait_def_id)
|
|
})
|
|
}
|
|
|
|
// Returns `true` if a bounds list includes `?Sized`.
|
|
pub fn is_unsized(&self, ast_bounds: &[hir::GenericBound<'_>], span: Span) -> bool {
|
|
let tcx = self.tcx();
|
|
|
|
// Try to find an unbound in bounds.
|
|
let mut unbound = None;
|
|
for ab in ast_bounds {
|
|
if let &hir::GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = ab {
|
|
if unbound.is_none() {
|
|
unbound = Some(&ptr.trait_ref);
|
|
} else {
|
|
struct_span_err!(
|
|
tcx.sess,
|
|
span,
|
|
E0203,
|
|
"type parameter has more than one relaxed default \
|
|
bound, only one is supported"
|
|
)
|
|
.emit();
|
|
}
|
|
}
|
|
}
|
|
|
|
let kind_id = tcx.lang_items().require(SizedTraitLangItem);
|
|
match unbound {
|
|
Some(tpb) => {
|
|
// FIXME(#8559) currently requires the unbound to be built-in.
|
|
if let Ok(kind_id) = kind_id {
|
|
if tpb.path.res != Res::Def(DefKind::Trait, kind_id) {
|
|
tcx.sess.span_warn(
|
|
span,
|
|
"default bound relaxed for a type parameter, but \
|
|
this does nothing because the given bound is not \
|
|
a default; only `?Sized` is supported",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
_ if kind_id.is_ok() => {
|
|
return false;
|
|
}
|
|
// No lang item for `Sized`, so we can't add it as a bound.
|
|
None => {}
|
|
}
|
|
|
|
true
|
|
}
|
|
|
|
/// This helper takes a *converted* parameter type (`param_ty`)
|
|
/// and an *unconverted* list of bounds:
|
|
///
|
|
/// ```
|
|
/// fn foo<T: Debug>
|
|
/// ^ ^^^^^ `ast_bounds` parameter, in HIR form
|
|
/// |
|
|
/// `param_ty`, in ty form
|
|
/// ```
|
|
///
|
|
/// It adds these `ast_bounds` into the `bounds` structure.
|
|
///
|
|
/// **A note on binders:** there is an implied binder around
|
|
/// `param_ty` and `ast_bounds`. See `instantiate_poly_trait_ref`
|
|
/// for more details.
|
|
fn add_bounds(
|
|
&self,
|
|
param_ty: Ty<'tcx>,
|
|
ast_bounds: &[hir::GenericBound<'_>],
|
|
bounds: &mut Bounds<'tcx>,
|
|
) {
|
|
let mut trait_bounds = Vec::new();
|
|
let mut region_bounds = Vec::new();
|
|
|
|
for ast_bound in ast_bounds {
|
|
match *ast_bound {
|
|
hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::None) => {
|
|
trait_bounds.push(b)
|
|
}
|
|
hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => {}
|
|
hir::GenericBound::Outlives(ref l) => region_bounds.push(l),
|
|
}
|
|
}
|
|
|
|
for bound in trait_bounds {
|
|
let _ = self.instantiate_poly_trait_ref(bound, param_ty, bounds);
|
|
}
|
|
|
|
bounds.region_bounds.extend(
|
|
region_bounds.into_iter().map(|r| (self.ast_region_to_region(r, None), r.span)),
|
|
);
|
|
}
|
|
|
|
/// Translates a list of bounds from the HIR into the `Bounds` data structure.
|
|
/// The self-type for the bounds is given by `param_ty`.
|
|
///
|
|
/// Example:
|
|
///
|
|
/// ```
|
|
/// fn foo<T: Bar + Baz>() { }
|
|
/// ^ ^^^^^^^^^ ast_bounds
|
|
/// param_ty
|
|
/// ```
|
|
///
|
|
/// The `sized_by_default` parameter indicates if, in this context, the `param_ty` should be
|
|
/// considered `Sized` unless there is an explicit `?Sized` bound. This would be true in the
|
|
/// example above, but is not true in supertrait listings like `trait Foo: Bar + Baz`.
|
|
///
|
|
/// `span` should be the declaration size of the parameter.
|
|
pub fn compute_bounds(
|
|
&self,
|
|
param_ty: Ty<'tcx>,
|
|
ast_bounds: &[hir::GenericBound<'_>],
|
|
sized_by_default: SizedByDefault,
|
|
span: Span,
|
|
) -> Bounds<'tcx> {
|
|
let mut bounds = Bounds::default();
|
|
|
|
self.add_bounds(param_ty, ast_bounds, &mut bounds);
|
|
bounds.trait_bounds.sort_by_key(|(t, _)| t.def_id());
|
|
|
|
bounds.implicitly_sized = if let SizedByDefault::Yes = sized_by_default {
|
|
if !self.is_unsized(ast_bounds, span) { Some(span) } else { None }
|
|
} else {
|
|
None
|
|
};
|
|
|
|
bounds
|
|
}
|
|
|
|
/// Given an HIR binding like `Item = Foo` or `Item: Foo`, pushes the corresponding predicates
|
|
/// onto `bounds`.
|
|
///
|
|
/// **A note on binders:** given something like `T: for<'a> Iterator<Item = &'a u32>`, the
|
|
/// `trait_ref` here will be `for<'a> T: Iterator`. The `binding` data however is from *inside*
|
|
/// the binder (e.g., `&'a u32`) and hence may reference bound regions.
|
|
fn add_predicates_for_ast_type_binding(
|
|
&self,
|
|
hir_ref_id: hir::HirId,
|
|
trait_ref: ty::PolyTraitRef<'tcx>,
|
|
binding: &ConvertedBinding<'_, 'tcx>,
|
|
bounds: &mut Bounds<'tcx>,
|
|
speculative: bool,
|
|
dup_bindings: &mut FxHashMap<DefId, Span>,
|
|
path_span: Span,
|
|
) -> Result<(), ErrorReported> {
|
|
let tcx = self.tcx();
|
|
|
|
if !speculative {
|
|
// Given something like `U: SomeTrait<T = X>`, we want to produce a
|
|
// predicate like `<U as SomeTrait>::T = X`. This is somewhat
|
|
// subtle in the event that `T` is defined in a supertrait of
|
|
// `SomeTrait`, because in that case we need to upcast.
|
|
//
|
|
// That is, consider this case:
|
|
//
|
|
// ```
|
|
// trait SubTrait: SuperTrait<int> { }
|
|
// trait SuperTrait<A> { type T; }
|
|
//
|
|
// ... B: SubTrait<T = foo> ...
|
|
// ```
|
|
//
|
|
// We want to produce `<B as SuperTrait<int>>::T == foo`.
|
|
|
|
// Find any late-bound regions declared in `ty` that are not
|
|
// declared in the trait-ref. These are not well-formed.
|
|
//
|
|
// Example:
|
|
//
|
|
// for<'a> <T as Iterator>::Item = &'a str // <-- 'a is bad
|
|
// for<'a> <T as FnMut<(&'a u32,)>>::Output = &'a str // <-- 'a is ok
|
|
if let ConvertedBindingKind::Equality(ty) = binding.kind {
|
|
let late_bound_in_trait_ref =
|
|
tcx.collect_constrained_late_bound_regions(&trait_ref);
|
|
let late_bound_in_ty =
|
|
tcx.collect_referenced_late_bound_regions(&ty::Binder::bind(ty));
|
|
debug!("late_bound_in_trait_ref = {:?}", late_bound_in_trait_ref);
|
|
debug!("late_bound_in_ty = {:?}", late_bound_in_ty);
|
|
for br in late_bound_in_ty.difference(&late_bound_in_trait_ref) {
|
|
let br_name = match *br {
|
|
ty::BrNamed(_, name) => name,
|
|
_ => {
|
|
span_bug!(
|
|
binding.span,
|
|
"anonymous bound region {:?} in binding but not trait ref",
|
|
br
|
|
);
|
|
}
|
|
};
|
|
struct_span_err!(
|
|
tcx.sess,
|
|
binding.span,
|
|
E0582,
|
|
"binding for associated type `{}` references lifetime `{}`, \
|
|
which does not appear in the trait input types",
|
|
binding.item_name,
|
|
br_name
|
|
)
|
|
.emit();
|
|
}
|
|
}
|
|
}
|
|
|
|
let candidate =
|
|
if self.trait_defines_associated_type_named(trait_ref.def_id(), binding.item_name) {
|
|
// Simple case: X is defined in the current trait.
|
|
trait_ref
|
|
} else {
|
|
// Otherwise, we have to walk through the supertraits to find
|
|
// those that do.
|
|
self.one_bound_for_assoc_type(
|
|
|| traits::supertraits(tcx, trait_ref),
|
|
&trait_ref.print_only_trait_path().to_string(),
|
|
binding.item_name,
|
|
path_span,
|
|
match binding.kind {
|
|
ConvertedBindingKind::Equality(ty) => Some(ty.to_string()),
|
|
_ => None,
|
|
},
|
|
)?
|
|
};
|
|
|
|
let (assoc_ident, def_scope) =
|
|
tcx.adjust_ident_and_get_scope(binding.item_name, candidate.def_id(), hir_ref_id);
|
|
let assoc_ty = tcx
|
|
.associated_items(candidate.def_id())
|
|
.find(|i| i.kind == ty::AssocKind::Type && i.ident.modern() == assoc_ident)
|
|
.expect("missing associated type");
|
|
|
|
if !assoc_ty.vis.is_accessible_from(def_scope, tcx) {
|
|
let msg = format!("associated type `{}` is private", binding.item_name);
|
|
tcx.sess.span_err(binding.span, &msg);
|
|
}
|
|
tcx.check_stability(assoc_ty.def_id, Some(hir_ref_id), binding.span);
|
|
|
|
if !speculative {
|
|
dup_bindings
|
|
.entry(assoc_ty.def_id)
|
|
.and_modify(|prev_span| {
|
|
struct_span_err!(
|
|
self.tcx().sess,
|
|
binding.span,
|
|
E0719,
|
|
"the value of the associated type `{}` (from trait `{}`) \
|
|
is already specified",
|
|
binding.item_name,
|
|
tcx.def_path_str(assoc_ty.container.id())
|
|
)
|
|
.span_label(binding.span, "re-bound here")
|
|
.span_label(*prev_span, format!("`{}` bound here first", binding.item_name))
|
|
.emit();
|
|
})
|
|
.or_insert(binding.span);
|
|
}
|
|
|
|
match binding.kind {
|
|
ConvertedBindingKind::Equality(ref ty) => {
|
|
// "Desugar" a constraint like `T: Iterator<Item = u32>` this to
|
|
// the "projection predicate" for:
|
|
//
|
|
// `<T as Iterator>::Item = u32`
|
|
bounds.projection_bounds.push((
|
|
candidate.map_bound(|trait_ref| ty::ProjectionPredicate {
|
|
projection_ty: ty::ProjectionTy::from_ref_and_name(
|
|
tcx,
|
|
trait_ref,
|
|
binding.item_name,
|
|
),
|
|
ty,
|
|
}),
|
|
binding.span,
|
|
));
|
|
}
|
|
ConvertedBindingKind::Constraint(ast_bounds) => {
|
|
// "Desugar" a constraint like `T: Iterator<Item: Debug>` to
|
|
//
|
|
// `<T as Iterator>::Item: Debug`
|
|
//
|
|
// Calling `skip_binder` is okay, because `add_bounds` expects the `param_ty`
|
|
// parameter to have a skipped binder.
|
|
let param_ty = tcx.mk_projection(assoc_ty.def_id, candidate.skip_binder().substs);
|
|
self.add_bounds(param_ty, ast_bounds, bounds);
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
fn ast_path_to_ty(
|
|
&self,
|
|
span: Span,
|
|
did: DefId,
|
|
item_segment: &hir::PathSegment<'_>,
|
|
) -> Ty<'tcx> {
|
|
let substs = self.ast_path_substs_for_ty(span, did, item_segment);
|
|
self.normalize_ty(span, self.tcx().at(span).type_of(did).subst(self.tcx(), substs))
|
|
}
|
|
|
|
fn conv_object_ty_poly_trait_ref(
|
|
&self,
|
|
span: Span,
|
|
trait_bounds: &[hir::PolyTraitRef<'_>],
|
|
lifetime: &hir::Lifetime,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx();
|
|
|
|
let mut bounds = Bounds::default();
|
|
let mut potential_assoc_types = Vec::new();
|
|
let dummy_self = self.tcx().types.trait_object_dummy_self;
|
|
for trait_bound in trait_bounds.iter().rev() {
|
|
let cur_potential_assoc_types =
|
|
self.instantiate_poly_trait_ref(trait_bound, dummy_self, &mut bounds);
|
|
potential_assoc_types.extend(cur_potential_assoc_types.into_iter().flatten());
|
|
}
|
|
|
|
// Expand trait aliases recursively and check that only one regular (non-auto) trait
|
|
// is used and no 'maybe' bounds are used.
|
|
let expanded_traits =
|
|
traits::expand_trait_aliases(tcx, bounds.trait_bounds.iter().cloned());
|
|
let (mut auto_traits, regular_traits): (Vec<_>, Vec<_>) =
|
|
expanded_traits.partition(|i| tcx.trait_is_auto(i.trait_ref().def_id()));
|
|
if regular_traits.len() > 1 {
|
|
let first_trait = ®ular_traits[0];
|
|
let additional_trait = ®ular_traits[1];
|
|
let mut err = struct_span_err!(
|
|
tcx.sess,
|
|
additional_trait.bottom().1,
|
|
E0225,
|
|
"only auto traits can be used as additional traits in a trait object"
|
|
);
|
|
additional_trait.label_with_exp_info(
|
|
&mut err,
|
|
"additional non-auto trait",
|
|
"additional use",
|
|
);
|
|
first_trait.label_with_exp_info(&mut err, "first non-auto trait", "first use");
|
|
err.emit();
|
|
}
|
|
|
|
if regular_traits.is_empty() && auto_traits.is_empty() {
|
|
struct_span_err!(
|
|
tcx.sess,
|
|
span,
|
|
E0224,
|
|
"at least one trait is required for an object type"
|
|
)
|
|
.emit();
|
|
return tcx.types.err;
|
|
}
|
|
|
|
// Check that there are no gross object safety violations;
|
|
// most importantly, that the supertraits don't contain `Self`,
|
|
// to avoid ICEs.
|
|
for item in ®ular_traits {
|
|
let object_safety_violations =
|
|
astconv_object_safety_violations(tcx, item.trait_ref().def_id());
|
|
if !object_safety_violations.is_empty() {
|
|
report_object_safety_error(
|
|
tcx,
|
|
span,
|
|
item.trait_ref().def_id(),
|
|
object_safety_violations,
|
|
)
|
|
.emit();
|
|
return tcx.types.err;
|
|
}
|
|
}
|
|
|
|
// Use a `BTreeSet` to keep output in a more consistent order.
|
|
let mut associated_types: FxHashMap<Span, BTreeSet<DefId>> = FxHashMap::default();
|
|
|
|
let regular_traits_refs_spans = bounds
|
|
.trait_bounds
|
|
.into_iter()
|
|
.filter(|(trait_ref, _)| !tcx.trait_is_auto(trait_ref.def_id()));
|
|
|
|
for (base_trait_ref, span) in regular_traits_refs_spans {
|
|
for trait_ref in traits::elaborate_trait_ref(tcx, base_trait_ref) {
|
|
debug!(
|
|
"conv_object_ty_poly_trait_ref: observing object predicate `{:?}`",
|
|
trait_ref
|
|
);
|
|
match trait_ref {
|
|
ty::Predicate::Trait(pred) => {
|
|
associated_types.entry(span).or_default().extend(
|
|
tcx.associated_items(pred.def_id())
|
|
.filter(|item| item.kind == ty::AssocKind::Type)
|
|
.map(|item| item.def_id),
|
|
);
|
|
}
|
|
ty::Predicate::Projection(pred) => {
|
|
// A `Self` within the original bound will be substituted with a
|
|
// `trait_object_dummy_self`, so check for that.
|
|
let references_self = pred.skip_binder().ty.walk().any(|t| t == dummy_self);
|
|
|
|
// If the projection output contains `Self`, force the user to
|
|
// elaborate it explicitly to avoid a lot of complexity.
|
|
//
|
|
// The "classicaly useful" case is the following:
|
|
// ```
|
|
// trait MyTrait: FnMut() -> <Self as MyTrait>::MyOutput {
|
|
// type MyOutput;
|
|
// }
|
|
// ```
|
|
//
|
|
// Here, the user could theoretically write `dyn MyTrait<Output = X>`,
|
|
// but actually supporting that would "expand" to an infinitely-long type
|
|
// `fix $ τ → dyn MyTrait<MyOutput = X, Output = <τ as MyTrait>::MyOutput`.
|
|
//
|
|
// Instead, we force the user to write
|
|
// `dyn MyTrait<MyOutput = X, Output = X>`, which is uglier but works. See
|
|
// the discussion in #56288 for alternatives.
|
|
if !references_self {
|
|
// Include projections defined on supertraits.
|
|
bounds.projection_bounds.push((pred, span));
|
|
}
|
|
}
|
|
_ => (),
|
|
}
|
|
}
|
|
}
|
|
|
|
for (projection_bound, _) in &bounds.projection_bounds {
|
|
for (_, def_ids) in &mut associated_types {
|
|
def_ids.remove(&projection_bound.projection_def_id());
|
|
}
|
|
}
|
|
|
|
self.complain_about_missing_associated_types(
|
|
associated_types,
|
|
potential_assoc_types,
|
|
trait_bounds,
|
|
);
|
|
|
|
// De-duplicate auto traits so that, e.g., `dyn Trait + Send + Send` is the same as
|
|
// `dyn Trait + Send`.
|
|
auto_traits.sort_by_key(|i| i.trait_ref().def_id());
|
|
auto_traits.dedup_by_key(|i| i.trait_ref().def_id());
|
|
debug!("regular_traits: {:?}", regular_traits);
|
|
debug!("auto_traits: {:?}", auto_traits);
|
|
|
|
// Transform a `PolyTraitRef` into a `PolyExistentialTraitRef` by
|
|
// removing the dummy `Self` type (`trait_object_dummy_self`).
|
|
let trait_ref_to_existential = |trait_ref: ty::TraitRef<'tcx>| {
|
|
if trait_ref.self_ty() != dummy_self {
|
|
// FIXME: There appears to be a missing filter on top of `expand_trait_aliases`,
|
|
// which picks up non-supertraits where clauses - but also, the object safety
|
|
// completely ignores trait aliases, which could be object safety hazards. We
|
|
// `delay_span_bug` here to avoid an ICE in stable even when the feature is
|
|
// disabled. (#66420)
|
|
tcx.sess.delay_span_bug(
|
|
DUMMY_SP,
|
|
&format!(
|
|
"trait_ref_to_existential called on {:?} with non-dummy Self",
|
|
trait_ref,
|
|
),
|
|
);
|
|
}
|
|
ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref)
|
|
};
|
|
|
|
// Erase the `dummy_self` (`trait_object_dummy_self`) used above.
|
|
let existential_trait_refs = regular_traits
|
|
.iter()
|
|
.map(|i| i.trait_ref().map_bound(|trait_ref| trait_ref_to_existential(trait_ref)));
|
|
let existential_projections = bounds.projection_bounds.iter().map(|(bound, _)| {
|
|
bound.map_bound(|b| {
|
|
let trait_ref = trait_ref_to_existential(b.projection_ty.trait_ref(tcx));
|
|
ty::ExistentialProjection {
|
|
ty: b.ty,
|
|
item_def_id: b.projection_ty.item_def_id,
|
|
substs: trait_ref.substs,
|
|
}
|
|
})
|
|
});
|
|
|
|
// Calling `skip_binder` is okay because the predicates are re-bound.
|
|
let regular_trait_predicates = existential_trait_refs
|
|
.map(|trait_ref| ty::ExistentialPredicate::Trait(*trait_ref.skip_binder()));
|
|
let auto_trait_predicates = auto_traits
|
|
.into_iter()
|
|
.map(|trait_ref| ty::ExistentialPredicate::AutoTrait(trait_ref.trait_ref().def_id()));
|
|
let mut v = regular_trait_predicates
|
|
.chain(auto_trait_predicates)
|
|
.chain(
|
|
existential_projections
|
|
.map(|x| ty::ExistentialPredicate::Projection(*x.skip_binder())),
|
|
)
|
|
.collect::<SmallVec<[_; 8]>>();
|
|
v.sort_by(|a, b| a.stable_cmp(tcx, b));
|
|
v.dedup();
|
|
let existential_predicates = ty::Binder::bind(tcx.mk_existential_predicates(v.into_iter()));
|
|
|
|
// Use explicitly-specified region bound.
|
|
let region_bound = if !lifetime.is_elided() {
|
|
self.ast_region_to_region(lifetime, None)
|
|
} else {
|
|
self.compute_object_lifetime_bound(span, existential_predicates).unwrap_or_else(|| {
|
|
if tcx.named_region(lifetime.hir_id).is_some() {
|
|
self.ast_region_to_region(lifetime, None)
|
|
} else {
|
|
self.re_infer(None, span).unwrap_or_else(|| {
|
|
struct_span_err!(
|
|
tcx.sess,
|
|
span,
|
|
E0228,
|
|
"the lifetime bound for this object type cannot be deduced \
|
|
from context; please supply an explicit bound"
|
|
)
|
|
.emit();
|
|
tcx.lifetimes.re_static
|
|
})
|
|
}
|
|
})
|
|
};
|
|
debug!("region_bound: {:?}", region_bound);
|
|
|
|
let ty = tcx.mk_dynamic(existential_predicates, region_bound);
|
|
debug!("trait_object_type: {:?}", ty);
|
|
ty
|
|
}
|
|
|
|
/// When there are any missing associated types, emit an E0191 error and attempt to supply a
|
|
/// reasonable suggestion on how to write it. For the case of multiple associated types in the
|
|
/// same trait bound have the same name (as they come from different super-traits), we instead
|
|
/// emit a generic note suggesting using a `where` clause to constraint instead.
|
|
fn complain_about_missing_associated_types(
|
|
&self,
|
|
associated_types: FxHashMap<Span, BTreeSet<DefId>>,
|
|
potential_assoc_types: Vec<Span>,
|
|
trait_bounds: &[hir::PolyTraitRef<'_>],
|
|
) {
|
|
if !associated_types.values().any(|v| v.len() > 0) {
|
|
return;
|
|
}
|
|
let tcx = self.tcx();
|
|
// FIXME: Marked `mut` so that we can replace the spans further below with a more
|
|
// appropriate one, but this should be handled earlier in the span assignment.
|
|
let mut associated_types: FxHashMap<Span, Vec<_>> = associated_types
|
|
.into_iter()
|
|
.map(|(span, def_ids)| {
|
|
(span, def_ids.into_iter().map(|did| tcx.associated_item(did)).collect())
|
|
})
|
|
.collect();
|
|
let mut names = vec![];
|
|
|
|
// Account for things like `dyn Foo + 'a`, like in tests `issue-22434.rs` and
|
|
// `issue-22560.rs`.
|
|
let mut trait_bound_spans: Vec<Span> = vec![];
|
|
for (span, items) in &associated_types {
|
|
if !items.is_empty() {
|
|
trait_bound_spans.push(*span);
|
|
}
|
|
for assoc_item in items {
|
|
let trait_def_id = assoc_item.container.id();
|
|
names.push(format!(
|
|
"`{}` (from trait `{}`)",
|
|
assoc_item.ident,
|
|
tcx.def_path_str(trait_def_id),
|
|
));
|
|
}
|
|
}
|
|
|
|
match (&potential_assoc_types[..], &trait_bounds) {
|
|
([], [bound]) => match &bound.trait_ref.path.segments[..] {
|
|
// FIXME: `trait_ref.path.span` can point to a full path with multiple
|
|
// segments, even though `trait_ref.path.segments` is of length `1`. Work
|
|
// around that bug here, even though it should be fixed elsewhere.
|
|
// This would otherwise cause an invalid suggestion. For an example, look at
|
|
// `src/test/ui/issues/issue-28344.rs` where instead of the following:
|
|
//
|
|
// error[E0191]: the value of the associated type `Output`
|
|
// (from trait `std::ops::BitXor`) must be specified
|
|
// --> $DIR/issue-28344.rs:4:17
|
|
// |
|
|
// LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8);
|
|
// | ^^^^^^ help: specify the associated type:
|
|
// | `BitXor<Output = Type>`
|
|
//
|
|
// we would output:
|
|
//
|
|
// error[E0191]: the value of the associated type `Output`
|
|
// (from trait `std::ops::BitXor`) must be specified
|
|
// --> $DIR/issue-28344.rs:4:17
|
|
// |
|
|
// LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8);
|
|
// | ^^^^^^^^^^^^^ help: specify the associated type:
|
|
// | `BitXor::bitor<Output = Type>`
|
|
[segment] if segment.args.is_none() => {
|
|
trait_bound_spans = vec![segment.ident.span];
|
|
associated_types = associated_types
|
|
.into_iter()
|
|
.map(|(_, items)| (segment.ident.span, items))
|
|
.collect();
|
|
}
|
|
_ => {}
|
|
},
|
|
_ => {}
|
|
}
|
|
names.sort();
|
|
trait_bound_spans.sort();
|
|
let mut err = struct_span_err!(
|
|
tcx.sess,
|
|
trait_bound_spans,
|
|
E0191,
|
|
"the value of the associated type{} {} must be specified",
|
|
pluralize!(names.len()),
|
|
names.join(", "),
|
|
);
|
|
let mut suggestions = vec![];
|
|
let mut types_count = 0;
|
|
let mut where_constraints = vec![];
|
|
for (span, assoc_items) in &associated_types {
|
|
let mut names: FxHashMap<_, usize> = FxHashMap::default();
|
|
for item in assoc_items {
|
|
types_count += 1;
|
|
*names.entry(item.ident.name).or_insert(0) += 1;
|
|
}
|
|
let mut dupes = false;
|
|
for item in assoc_items {
|
|
let prefix = if names[&item.ident.name] > 1 {
|
|
let trait_def_id = item.container.id();
|
|
dupes = true;
|
|
format!("{}::", tcx.def_path_str(trait_def_id))
|
|
} else {
|
|
String::new()
|
|
};
|
|
if let Some(sp) = tcx.hir().span_if_local(item.def_id) {
|
|
err.span_label(sp, format!("`{}{}` defined here", prefix, item.ident));
|
|
}
|
|
}
|
|
if potential_assoc_types.len() == assoc_items.len() {
|
|
// Only suggest when the amount of missing associated types equals the number of
|
|
// extra type arguments present, as that gives us a relatively high confidence
|
|
// that the user forgot to give the associtated type's name. The canonical
|
|
// example would be trying to use `Iterator<isize>` instead of
|
|
// `Iterator<Item = isize>`.
|
|
for (potential, item) in potential_assoc_types.iter().zip(assoc_items.iter()) {
|
|
if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(*potential) {
|
|
suggestions.push((*potential, format!("{} = {}", item.ident, snippet)));
|
|
}
|
|
}
|
|
} else if let (Ok(snippet), false) =
|
|
(tcx.sess.source_map().span_to_snippet(*span), dupes)
|
|
{
|
|
let types: Vec<_> =
|
|
assoc_items.iter().map(|item| format!("{} = Type", item.ident)).collect();
|
|
let code = if snippet.ends_with(">") {
|
|
// The user wrote `Trait<'a>` or similar and we don't have a type we can
|
|
// suggest, but at least we can clue them to the correct syntax
|
|
// `Trait<'a, Item = Type>` while accounting for the `<'a>` in the
|
|
// suggestion.
|
|
format!("{}, {}>", &snippet[..snippet.len() - 1], types.join(", "))
|
|
} else {
|
|
// The user wrote `Iterator`, so we don't have a type we can suggest, but at
|
|
// least we can clue them to the correct syntax `Iterator<Item = Type>`.
|
|
format!("{}<{}>", snippet, types.join(", "))
|
|
};
|
|
suggestions.push((*span, code));
|
|
} else if dupes {
|
|
where_constraints.push(*span);
|
|
}
|
|
}
|
|
let where_msg = "consider introducing a new type parameter, adding `where` constraints \
|
|
using the fully-qualified path to the associated types";
|
|
if !where_constraints.is_empty() && suggestions.is_empty() {
|
|
// If there are duplicates associated type names and a single trait bound do not
|
|
// use structured suggestion, it means that there are multiple super-traits with
|
|
// the same associated type name.
|
|
err.help(where_msg);
|
|
}
|
|
if suggestions.len() != 1 {
|
|
// We don't need this label if there's an inline suggestion, show otherwise.
|
|
for (span, assoc_items) in &associated_types {
|
|
let mut names: FxHashMap<_, usize> = FxHashMap::default();
|
|
for item in assoc_items {
|
|
types_count += 1;
|
|
*names.entry(item.ident.name).or_insert(0) += 1;
|
|
}
|
|
let mut label = vec![];
|
|
for item in assoc_items {
|
|
let postfix = if names[&item.ident.name] > 1 {
|
|
let trait_def_id = item.container.id();
|
|
format!(" (from trait `{}`)", tcx.def_path_str(trait_def_id))
|
|
} else {
|
|
String::new()
|
|
};
|
|
label.push(format!("`{}`{}", item.ident, postfix));
|
|
}
|
|
if !label.is_empty() {
|
|
err.span_label(
|
|
*span,
|
|
format!(
|
|
"associated type{} {} must be specified",
|
|
pluralize!(label.len()),
|
|
label.join(", "),
|
|
),
|
|
);
|
|
}
|
|
}
|
|
}
|
|
if !suggestions.is_empty() {
|
|
err.multipart_suggestion(
|
|
&format!("specify the associated type{}", pluralize!(types_count)),
|
|
suggestions,
|
|
Applicability::HasPlaceholders,
|
|
);
|
|
if !where_constraints.is_empty() {
|
|
err.span_help(where_constraints, where_msg);
|
|
}
|
|
}
|
|
err.emit();
|
|
}
|
|
|
|
fn report_ambiguous_associated_type(
|
|
&self,
|
|
span: Span,
|
|
type_str: &str,
|
|
trait_str: &str,
|
|
name: ast::Name,
|
|
) {
|
|
let mut err = struct_span_err!(self.tcx().sess, span, E0223, "ambiguous associated type");
|
|
if let (Some(_), Ok(snippet)) = (
|
|
self.tcx().sess.confused_type_with_std_module.borrow().get(&span),
|
|
self.tcx().sess.source_map().span_to_snippet(span),
|
|
) {
|
|
err.span_suggestion(
|
|
span,
|
|
"you are looking for the module in `std`, not the primitive type",
|
|
format!("std::{}", snippet),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else {
|
|
err.span_suggestion(
|
|
span,
|
|
"use fully-qualified syntax",
|
|
format!("<{} as {}>::{}", type_str, trait_str, name),
|
|
Applicability::HasPlaceholders,
|
|
);
|
|
}
|
|
err.emit();
|
|
}
|
|
|
|
// Search for a bound on a type parameter which includes the associated item
|
|
// given by `assoc_name`. `ty_param_def_id` is the `DefId` of the type parameter
|
|
// This function will fail if there are no suitable bounds or there is
|
|
// any ambiguity.
|
|
fn find_bound_for_assoc_item(
|
|
&self,
|
|
ty_param_def_id: DefId,
|
|
assoc_name: ast::Ident,
|
|
span: Span,
|
|
) -> Result<ty::PolyTraitRef<'tcx>, ErrorReported> {
|
|
let tcx = self.tcx();
|
|
|
|
debug!(
|
|
"find_bound_for_assoc_item(ty_param_def_id={:?}, assoc_name={:?}, span={:?})",
|
|
ty_param_def_id, assoc_name, span,
|
|
);
|
|
|
|
let predicates = &self.get_type_parameter_bounds(span, ty_param_def_id).predicates;
|
|
|
|
debug!("find_bound_for_assoc_item: predicates={:#?}", predicates);
|
|
|
|
let param_hir_id = tcx.hir().as_local_hir_id(ty_param_def_id).unwrap();
|
|
let param_name = tcx.hir().ty_param_name(param_hir_id);
|
|
self.one_bound_for_assoc_type(
|
|
|| {
|
|
traits::transitive_bounds(
|
|
tcx,
|
|
predicates.iter().filter_map(|(p, _)| p.to_opt_poly_trait_ref()),
|
|
)
|
|
},
|
|
¶m_name.as_str(),
|
|
assoc_name,
|
|
span,
|
|
None,
|
|
)
|
|
}
|
|
|
|
// Checks that `bounds` contains exactly one element and reports appropriate
|
|
// errors otherwise.
|
|
fn one_bound_for_assoc_type<I>(
|
|
&self,
|
|
all_candidates: impl Fn() -> I,
|
|
ty_param_name: &str,
|
|
assoc_name: ast::Ident,
|
|
span: Span,
|
|
is_equality: Option<String>,
|
|
) -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
|
|
where
|
|
I: Iterator<Item = ty::PolyTraitRef<'tcx>>,
|
|
{
|
|
let mut matching_candidates = all_candidates()
|
|
.filter(|r| self.trait_defines_associated_type_named(r.def_id(), assoc_name));
|
|
|
|
let bound = match matching_candidates.next() {
|
|
Some(bound) => bound,
|
|
None => {
|
|
self.complain_about_assoc_type_not_found(
|
|
all_candidates,
|
|
ty_param_name,
|
|
assoc_name,
|
|
span,
|
|
);
|
|
return Err(ErrorReported);
|
|
}
|
|
};
|
|
|
|
debug!("one_bound_for_assoc_type: bound = {:?}", bound);
|
|
|
|
if let Some(bound2) = matching_candidates.next() {
|
|
debug!("one_bound_for_assoc_type: bound2 = {:?}", bound2);
|
|
|
|
let bounds = iter::once(bound).chain(iter::once(bound2)).chain(matching_candidates);
|
|
let mut err = if is_equality.is_some() {
|
|
// More specific Error Index entry.
|
|
struct_span_err!(
|
|
self.tcx().sess,
|
|
span,
|
|
E0222,
|
|
"ambiguous associated type `{}` in bounds of `{}`",
|
|
assoc_name,
|
|
ty_param_name
|
|
)
|
|
} else {
|
|
struct_span_err!(
|
|
self.tcx().sess,
|
|
span,
|
|
E0221,
|
|
"ambiguous associated type `{}` in bounds of `{}`",
|
|
assoc_name,
|
|
ty_param_name
|
|
)
|
|
};
|
|
err.span_label(span, format!("ambiguous associated type `{}`", assoc_name));
|
|
|
|
let mut where_bounds = vec![];
|
|
for bound in bounds {
|
|
let bound_span = self
|
|
.tcx()
|
|
.associated_items(bound.def_id())
|
|
.find(|item| {
|
|
item.kind == ty::AssocKind::Type
|
|
&& self.tcx().hygienic_eq(assoc_name, item.ident, bound.def_id())
|
|
})
|
|
.and_then(|item| self.tcx().hir().span_if_local(item.def_id));
|
|
|
|
if let Some(bound_span) = bound_span {
|
|
err.span_label(
|
|
bound_span,
|
|
format!(
|
|
"ambiguous `{}` from `{}`",
|
|
assoc_name,
|
|
bound.print_only_trait_path(),
|
|
),
|
|
);
|
|
if let Some(constraint) = &is_equality {
|
|
where_bounds.push(format!(
|
|
" T: {trait}::{assoc} = {constraint}",
|
|
trait=bound.print_only_trait_path(),
|
|
assoc=assoc_name,
|
|
constraint=constraint,
|
|
));
|
|
} else {
|
|
err.span_suggestion(
|
|
span,
|
|
"use fully qualified syntax to disambiguate",
|
|
format!(
|
|
"<{} as {}>::{}",
|
|
ty_param_name,
|
|
bound.print_only_trait_path(),
|
|
assoc_name,
|
|
),
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
}
|
|
} else {
|
|
err.note(&format!(
|
|
"associated type `{}` could derive from `{}`",
|
|
ty_param_name,
|
|
bound.print_only_trait_path(),
|
|
));
|
|
}
|
|
}
|
|
if !where_bounds.is_empty() {
|
|
err.help(&format!(
|
|
"consider introducing a new type parameter `T` and adding `where` constraints:\
|
|
\n where\n T: {},\n{}",
|
|
ty_param_name,
|
|
where_bounds.join(",\n"),
|
|
));
|
|
}
|
|
err.emit();
|
|
if !where_bounds.is_empty() {
|
|
return Err(ErrorReported);
|
|
}
|
|
}
|
|
return Ok(bound);
|
|
}
|
|
|
|
fn complain_about_assoc_type_not_found<I>(
|
|
&self,
|
|
all_candidates: impl Fn() -> I,
|
|
ty_param_name: &str,
|
|
assoc_name: ast::Ident,
|
|
span: Span,
|
|
) where
|
|
I: Iterator<Item = ty::PolyTraitRef<'tcx>>,
|
|
{
|
|
// The fallback span is needed because `assoc_name` might be an `Fn()`'s `Output` without a
|
|
// valid span, so we point at the whole path segment instead.
|
|
let span = if assoc_name.span != DUMMY_SP { assoc_name.span } else { span };
|
|
let mut err = struct_span_err!(
|
|
self.tcx().sess,
|
|
span,
|
|
E0220,
|
|
"associated type `{}` not found for `{}`",
|
|
assoc_name,
|
|
ty_param_name
|
|
);
|
|
|
|
let all_candidate_names: Vec<_> = all_candidates()
|
|
.map(|r| self.tcx().associated_items(r.def_id()))
|
|
.flatten()
|
|
.filter_map(
|
|
|item| if item.kind == ty::AssocKind::Type { Some(item.ident.name) } else { None },
|
|
)
|
|
.collect();
|
|
|
|
if let (Some(suggested_name), true) = (
|
|
find_best_match_for_name(all_candidate_names.iter(), &assoc_name.as_str(), None),
|
|
assoc_name.span != DUMMY_SP,
|
|
) {
|
|
err.span_suggestion(
|
|
assoc_name.span,
|
|
"there is an associated type with a similar name",
|
|
suggested_name.to_string(),
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
} else {
|
|
err.span_label(span, format!("associated type `{}` not found", assoc_name));
|
|
}
|
|
|
|
err.emit();
|
|
}
|
|
|
|
// Create a type from a path to an associated type.
|
|
// For a path `A::B::C::D`, `qself_ty` and `qself_def` are the type and def for `A::B::C`
|
|
// and item_segment is the path segment for `D`. We return a type and a def for
|
|
// the whole path.
|
|
// Will fail except for `T::A` and `Self::A`; i.e., if `qself_ty`/`qself_def` are not a type
|
|
// parameter or `Self`.
|
|
pub fn associated_path_to_ty(
|
|
&self,
|
|
hir_ref_id: hir::HirId,
|
|
span: Span,
|
|
qself_ty: Ty<'tcx>,
|
|
qself_res: Res,
|
|
assoc_segment: &hir::PathSegment<'_>,
|
|
permit_variants: bool,
|
|
) -> Result<(Ty<'tcx>, DefKind, DefId), ErrorReported> {
|
|
let tcx = self.tcx();
|
|
let assoc_ident = assoc_segment.ident;
|
|
|
|
debug!("associated_path_to_ty: {:?}::{}", qself_ty, assoc_ident);
|
|
|
|
// Check if we have an enum variant.
|
|
let mut variant_resolution = None;
|
|
if let ty::Adt(adt_def, _) = qself_ty.kind {
|
|
if adt_def.is_enum() {
|
|
let variant_def = adt_def
|
|
.variants
|
|
.iter()
|
|
.find(|vd| tcx.hygienic_eq(assoc_ident, vd.ident, adt_def.did));
|
|
if let Some(variant_def) = variant_def {
|
|
if permit_variants {
|
|
tcx.check_stability(variant_def.def_id, Some(hir_ref_id), span);
|
|
self.prohibit_generics(slice::from_ref(assoc_segment));
|
|
return Ok((qself_ty, DefKind::Variant, variant_def.def_id));
|
|
} else {
|
|
variant_resolution = Some(variant_def.def_id);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Find the type of the associated item, and the trait where the associated
|
|
// item is declared.
|
|
let bound = match (&qself_ty.kind, qself_res) {
|
|
(_, Res::SelfTy(Some(_), Some(impl_def_id))) => {
|
|
// `Self` in an impl of a trait -- we have a concrete self type and a
|
|
// trait reference.
|
|
let trait_ref = match tcx.impl_trait_ref(impl_def_id) {
|
|
Some(trait_ref) => trait_ref,
|
|
None => {
|
|
// A cycle error occurred, most likely.
|
|
return Err(ErrorReported);
|
|
}
|
|
};
|
|
|
|
self.one_bound_for_assoc_type(
|
|
|| traits::supertraits(tcx, ty::Binder::bind(trait_ref)),
|
|
"Self",
|
|
assoc_ident,
|
|
span,
|
|
None,
|
|
)?
|
|
}
|
|
(&ty::Param(_), Res::SelfTy(Some(param_did), None))
|
|
| (&ty::Param(_), Res::Def(DefKind::TyParam, param_did)) => {
|
|
self.find_bound_for_assoc_item(param_did, assoc_ident, span)?
|
|
}
|
|
_ => {
|
|
if variant_resolution.is_some() {
|
|
// Variant in type position
|
|
let msg = format!("expected type, found variant `{}`", assoc_ident);
|
|
tcx.sess.span_err(span, &msg);
|
|
} else if qself_ty.is_enum() {
|
|
let mut err = tcx.sess.struct_span_err(
|
|
assoc_ident.span,
|
|
&format!("no variant `{}` in enum `{}`", assoc_ident, qself_ty),
|
|
);
|
|
|
|
let adt_def = qself_ty.ty_adt_def().expect("enum is not an ADT");
|
|
if let Some(suggested_name) = find_best_match_for_name(
|
|
adt_def.variants.iter().map(|variant| &variant.ident.name),
|
|
&assoc_ident.as_str(),
|
|
None,
|
|
) {
|
|
err.span_suggestion(
|
|
assoc_ident.span,
|
|
"there is a variant with a similar name",
|
|
suggested_name.to_string(),
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
} else {
|
|
err.span_label(
|
|
assoc_ident.span,
|
|
format!("variant not found in `{}`", qself_ty),
|
|
);
|
|
}
|
|
|
|
if let Some(sp) = tcx.hir().span_if_local(adt_def.did) {
|
|
let sp = tcx.sess.source_map().def_span(sp);
|
|
err.span_label(sp, format!("variant `{}` not found here", assoc_ident));
|
|
}
|
|
|
|
err.emit();
|
|
} else if !qself_ty.references_error() {
|
|
// Don't print `TyErr` to the user.
|
|
self.report_ambiguous_associated_type(
|
|
span,
|
|
&qself_ty.to_string(),
|
|
"Trait",
|
|
assoc_ident.name,
|
|
);
|
|
}
|
|
return Err(ErrorReported);
|
|
}
|
|
};
|
|
|
|
let trait_did = bound.def_id();
|
|
let (assoc_ident, def_scope) =
|
|
tcx.adjust_ident_and_get_scope(assoc_ident, trait_did, hir_ref_id);
|
|
let item = tcx
|
|
.associated_items(trait_did)
|
|
.find(|i| Namespace::from(i.kind) == Namespace::Type && i.ident.modern() == assoc_ident)
|
|
.expect("missing associated type");
|
|
|
|
let ty = self.projected_ty_from_poly_trait_ref(span, item.def_id, assoc_segment, bound);
|
|
let ty = self.normalize_ty(span, ty);
|
|
|
|
let kind = DefKind::AssocTy;
|
|
if !item.vis.is_accessible_from(def_scope, tcx) {
|
|
let msg = format!("{} `{}` is private", kind.descr(item.def_id), assoc_ident);
|
|
tcx.sess.span_err(span, &msg);
|
|
}
|
|
tcx.check_stability(item.def_id, Some(hir_ref_id), span);
|
|
|
|
if let Some(variant_def_id) = variant_resolution {
|
|
let mut err = tcx.struct_span_lint_hir(
|
|
AMBIGUOUS_ASSOCIATED_ITEMS,
|
|
hir_ref_id,
|
|
span,
|
|
"ambiguous associated item",
|
|
);
|
|
|
|
let mut could_refer_to = |kind: DefKind, def_id, also| {
|
|
let note_msg = format!(
|
|
"`{}` could{} refer to {} defined here",
|
|
assoc_ident,
|
|
also,
|
|
kind.descr(def_id)
|
|
);
|
|
err.span_note(tcx.def_span(def_id), ¬e_msg);
|
|
};
|
|
could_refer_to(DefKind::Variant, variant_def_id, "");
|
|
could_refer_to(kind, item.def_id, " also");
|
|
|
|
err.span_suggestion(
|
|
span,
|
|
"use fully-qualified syntax",
|
|
format!("<{} as {}>::{}", qself_ty, tcx.item_name(trait_did), assoc_ident),
|
|
Applicability::MachineApplicable,
|
|
)
|
|
.emit();
|
|
}
|
|
|
|
Ok((ty, kind, item.def_id))
|
|
}
|
|
|
|
fn qpath_to_ty(
|
|
&self,
|
|
span: Span,
|
|
opt_self_ty: Option<Ty<'tcx>>,
|
|
item_def_id: DefId,
|
|
trait_segment: &hir::PathSegment<'_>,
|
|
item_segment: &hir::PathSegment<'_>,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx();
|
|
|
|
let trait_def_id = tcx.parent(item_def_id).unwrap();
|
|
|
|
debug!("qpath_to_ty: trait_def_id={:?}", trait_def_id);
|
|
|
|
let self_ty = if let Some(ty) = opt_self_ty {
|
|
ty
|
|
} else {
|
|
let path_str = tcx.def_path_str(trait_def_id);
|
|
|
|
let def_id = self.item_def_id();
|
|
|
|
debug!("qpath_to_ty: self.item_def_id()={:?}", def_id);
|
|
|
|
let parent_def_id = def_id
|
|
.and_then(|def_id| tcx.hir().as_local_hir_id(def_id))
|
|
.map(|hir_id| tcx.hir().get_parent_did(hir_id));
|
|
|
|
debug!("qpath_to_ty: parent_def_id={:?}", parent_def_id);
|
|
|
|
// If the trait in segment is the same as the trait defining the item,
|
|
// use the `<Self as ..>` syntax in the error.
|
|
let is_part_of_self_trait_constraints = def_id == Some(trait_def_id);
|
|
let is_part_of_fn_in_self_trait = parent_def_id == Some(trait_def_id);
|
|
|
|
let type_name = if is_part_of_self_trait_constraints || is_part_of_fn_in_self_trait {
|
|
"Self"
|
|
} else {
|
|
"Type"
|
|
};
|
|
|
|
self.report_ambiguous_associated_type(
|
|
span,
|
|
type_name,
|
|
&path_str,
|
|
item_segment.ident.name,
|
|
);
|
|
return tcx.types.err;
|
|
};
|
|
|
|
debug!("qpath_to_ty: self_type={:?}", self_ty);
|
|
|
|
let trait_ref = self.ast_path_to_mono_trait_ref(span, trait_def_id, self_ty, trait_segment);
|
|
|
|
let item_substs = self.create_substs_for_associated_item(
|
|
tcx,
|
|
span,
|
|
item_def_id,
|
|
item_segment,
|
|
trait_ref.substs,
|
|
);
|
|
|
|
debug!("qpath_to_ty: trait_ref={:?}", trait_ref);
|
|
|
|
self.normalize_ty(span, tcx.mk_projection(item_def_id, item_substs))
|
|
}
|
|
|
|
pub fn prohibit_generics<'a, T: IntoIterator<Item = &'a hir::PathSegment<'a>>>(
|
|
&self,
|
|
segments: T,
|
|
) -> bool {
|
|
let mut has_err = false;
|
|
for segment in segments {
|
|
let (mut err_for_lt, mut err_for_ty, mut err_for_ct) = (false, false, false);
|
|
for arg in segment.generic_args().args {
|
|
let (span, kind) = match arg {
|
|
hir::GenericArg::Lifetime(lt) => {
|
|
if err_for_lt {
|
|
continue;
|
|
}
|
|
err_for_lt = true;
|
|
has_err = true;
|
|
(lt.span, "lifetime")
|
|
}
|
|
hir::GenericArg::Type(ty) => {
|
|
if err_for_ty {
|
|
continue;
|
|
}
|
|
err_for_ty = true;
|
|
has_err = true;
|
|
(ty.span, "type")
|
|
}
|
|
hir::GenericArg::Const(ct) => {
|
|
if err_for_ct {
|
|
continue;
|
|
}
|
|
err_for_ct = true;
|
|
(ct.span, "const")
|
|
}
|
|
};
|
|
let mut err = struct_span_err!(
|
|
self.tcx().sess,
|
|
span,
|
|
E0109,
|
|
"{} arguments are not allowed for this type",
|
|
kind,
|
|
);
|
|
err.span_label(span, format!("{} argument not allowed", kind));
|
|
err.emit();
|
|
if err_for_lt && err_for_ty && err_for_ct {
|
|
break;
|
|
}
|
|
}
|
|
for binding in segment.generic_args().bindings {
|
|
has_err = true;
|
|
Self::prohibit_assoc_ty_binding(self.tcx(), binding.span);
|
|
break;
|
|
}
|
|
}
|
|
has_err
|
|
}
|
|
|
|
pub fn prohibit_assoc_ty_binding(tcx: TyCtxt<'_>, span: Span) {
|
|
let mut err = struct_span_err!(
|
|
tcx.sess,
|
|
span,
|
|
E0229,
|
|
"associated type bindings are not allowed here"
|
|
);
|
|
err.span_label(span, "associated type not allowed here").emit();
|
|
}
|
|
|
|
// FIXME(eddyb, varkor) handle type paths here too, not just value ones.
|
|
pub fn def_ids_for_value_path_segments(
|
|
&self,
|
|
segments: &[hir::PathSegment<'_>],
|
|
self_ty: Option<Ty<'tcx>>,
|
|
kind: DefKind,
|
|
def_id: DefId,
|
|
) -> Vec<PathSeg> {
|
|
// We need to extract the type parameters supplied by the user in
|
|
// the path `path`. Due to the current setup, this is a bit of a
|
|
// tricky-process; the problem is that resolve only tells us the
|
|
// end-point of the path resolution, and not the intermediate steps.
|
|
// Luckily, we can (at least for now) deduce the intermediate steps
|
|
// just from the end-point.
|
|
//
|
|
// There are basically five cases to consider:
|
|
//
|
|
// 1. Reference to a constructor of a struct:
|
|
//
|
|
// struct Foo<T>(...)
|
|
//
|
|
// In this case, the parameters are declared in the type space.
|
|
//
|
|
// 2. Reference to a constructor of an enum variant:
|
|
//
|
|
// enum E<T> { Foo(...) }
|
|
//
|
|
// In this case, the parameters are defined in the type space,
|
|
// but may be specified either on the type or the variant.
|
|
//
|
|
// 3. Reference to a fn item or a free constant:
|
|
//
|
|
// fn foo<T>() { }
|
|
//
|
|
// In this case, the path will again always have the form
|
|
// `a::b::foo::<T>` where only the final segment should have
|
|
// type parameters. However, in this case, those parameters are
|
|
// declared on a value, and hence are in the `FnSpace`.
|
|
//
|
|
// 4. Reference to a method or an associated constant:
|
|
//
|
|
// impl<A> SomeStruct<A> {
|
|
// fn foo<B>(...)
|
|
// }
|
|
//
|
|
// Here we can have a path like
|
|
// `a::b::SomeStruct::<A>::foo::<B>`, in which case parameters
|
|
// may appear in two places. The penultimate segment,
|
|
// `SomeStruct::<A>`, contains parameters in TypeSpace, and the
|
|
// final segment, `foo::<B>` contains parameters in fn space.
|
|
//
|
|
// The first step then is to categorize the segments appropriately.
|
|
|
|
let tcx = self.tcx();
|
|
|
|
assert!(!segments.is_empty());
|
|
let last = segments.len() - 1;
|
|
|
|
let mut path_segs = vec![];
|
|
|
|
match kind {
|
|
// Case 1. Reference to a struct constructor.
|
|
DefKind::Ctor(CtorOf::Struct, ..) => {
|
|
// Everything but the final segment should have no
|
|
// parameters at all.
|
|
let generics = tcx.generics_of(def_id);
|
|
// Variant and struct constructors use the
|
|
// generics of their parent type definition.
|
|
let generics_def_id = generics.parent.unwrap_or(def_id);
|
|
path_segs.push(PathSeg(generics_def_id, last));
|
|
}
|
|
|
|
// Case 2. Reference to a variant constructor.
|
|
DefKind::Ctor(CtorOf::Variant, ..) | DefKind::Variant => {
|
|
let adt_def = self_ty.map(|t| t.ty_adt_def().unwrap());
|
|
let (generics_def_id, index) = if let Some(adt_def) = adt_def {
|
|
debug_assert!(adt_def.is_enum());
|
|
(adt_def.did, last)
|
|
} else if last >= 1 && segments[last - 1].args.is_some() {
|
|
// Everything but the penultimate segment should have no
|
|
// parameters at all.
|
|
let mut def_id = def_id;
|
|
|
|
// `DefKind::Ctor` -> `DefKind::Variant`
|
|
if let DefKind::Ctor(..) = kind {
|
|
def_id = tcx.parent(def_id).unwrap()
|
|
}
|
|
|
|
// `DefKind::Variant` -> `DefKind::Enum`
|
|
let enum_def_id = tcx.parent(def_id).unwrap();
|
|
(enum_def_id, last - 1)
|
|
} else {
|
|
// FIXME: lint here recommending `Enum::<...>::Variant` form
|
|
// instead of `Enum::Variant::<...>` form.
|
|
|
|
// Everything but the final segment should have no
|
|
// parameters at all.
|
|
let generics = tcx.generics_of(def_id);
|
|
// Variant and struct constructors use the
|
|
// generics of their parent type definition.
|
|
(generics.parent.unwrap_or(def_id), last)
|
|
};
|
|
path_segs.push(PathSeg(generics_def_id, index));
|
|
}
|
|
|
|
// Case 3. Reference to a top-level value.
|
|
DefKind::Fn | DefKind::Const | DefKind::ConstParam | DefKind::Static => {
|
|
path_segs.push(PathSeg(def_id, last));
|
|
}
|
|
|
|
// Case 4. Reference to a method or associated const.
|
|
DefKind::Method | DefKind::AssocConst => {
|
|
if segments.len() >= 2 {
|
|
let generics = tcx.generics_of(def_id);
|
|
path_segs.push(PathSeg(generics.parent.unwrap(), last - 1));
|
|
}
|
|
path_segs.push(PathSeg(def_id, last));
|
|
}
|
|
|
|
kind => bug!("unexpected definition kind {:?} for {:?}", kind, def_id),
|
|
}
|
|
|
|
debug!("path_segs = {:?}", path_segs);
|
|
|
|
path_segs
|
|
}
|
|
|
|
// Check a type `Path` and convert it to a `Ty`.
|
|
pub fn res_to_ty(
|
|
&self,
|
|
opt_self_ty: Option<Ty<'tcx>>,
|
|
path: &hir::Path<'_>,
|
|
permit_variants: bool,
|
|
) -> Ty<'tcx> {
|
|
let tcx = self.tcx();
|
|
|
|
debug!(
|
|
"res_to_ty(res={:?}, opt_self_ty={:?}, path_segments={:?})",
|
|
path.res, opt_self_ty, path.segments
|
|
);
|
|
|
|
let span = path.span;
|
|
match path.res {
|
|
Res::Def(DefKind::OpaqueTy, did) => {
|
|
// Check for desugared `impl Trait`.
|
|
assert!(ty::is_impl_trait_defn(tcx, did).is_none());
|
|
let item_segment = path.segments.split_last().unwrap();
|
|
self.prohibit_generics(item_segment.1);
|
|
let substs = self.ast_path_substs_for_ty(span, did, item_segment.0);
|
|
self.normalize_ty(span, tcx.mk_opaque(did, substs))
|
|
}
|
|
Res::Def(DefKind::Enum, did)
|
|
| Res::Def(DefKind::TyAlias, did)
|
|
| Res::Def(DefKind::Struct, did)
|
|
| Res::Def(DefKind::Union, did)
|
|
| Res::Def(DefKind::ForeignTy, did) => {
|
|
assert_eq!(opt_self_ty, None);
|
|
self.prohibit_generics(path.segments.split_last().unwrap().1);
|
|
self.ast_path_to_ty(span, did, path.segments.last().unwrap())
|
|
}
|
|
Res::Def(kind @ DefKind::Variant, def_id) if permit_variants => {
|
|
// Convert "variant type" as if it were a real type.
|
|
// The resulting `Ty` is type of the variant's enum for now.
|
|
assert_eq!(opt_self_ty, None);
|
|
|
|
let path_segs =
|
|
self.def_ids_for_value_path_segments(&path.segments, None, kind, def_id);
|
|
let generic_segs: FxHashSet<_> =
|
|
path_segs.iter().map(|PathSeg(_, index)| index).collect();
|
|
self.prohibit_generics(path.segments.iter().enumerate().filter_map(
|
|
|(index, seg)| {
|
|
if !generic_segs.contains(&index) { Some(seg) } else { None }
|
|
},
|
|
));
|
|
|
|
let PathSeg(def_id, index) = path_segs.last().unwrap();
|
|
self.ast_path_to_ty(span, *def_id, &path.segments[*index])
|
|
}
|
|
Res::Def(DefKind::TyParam, def_id) => {
|
|
assert_eq!(opt_self_ty, None);
|
|
self.prohibit_generics(path.segments);
|
|
|
|
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
|
|
let item_id = tcx.hir().get_parent_node(hir_id);
|
|
let item_def_id = tcx.hir().local_def_id(item_id);
|
|
let generics = tcx.generics_of(item_def_id);
|
|
let index = generics.param_def_id_to_index[&def_id];
|
|
tcx.mk_ty_param(index, tcx.hir().name(hir_id))
|
|
}
|
|
Res::SelfTy(Some(_), None) => {
|
|
// `Self` in trait or type alias.
|
|
assert_eq!(opt_self_ty, None);
|
|
self.prohibit_generics(path.segments);
|
|
tcx.types.self_param
|
|
}
|
|
Res::SelfTy(_, Some(def_id)) => {
|
|
// `Self` in impl (we know the concrete type).
|
|
assert_eq!(opt_self_ty, None);
|
|
self.prohibit_generics(path.segments);
|
|
// Try to evaluate any array length constants.
|
|
self.normalize_ty(span, tcx.at(span).type_of(def_id))
|
|
}
|
|
Res::Def(DefKind::AssocTy, def_id) => {
|
|
debug_assert!(path.segments.len() >= 2);
|
|
self.prohibit_generics(&path.segments[..path.segments.len() - 2]);
|
|
self.qpath_to_ty(
|
|
span,
|
|
opt_self_ty,
|
|
def_id,
|
|
&path.segments[path.segments.len() - 2],
|
|
path.segments.last().unwrap(),
|
|
)
|
|
}
|
|
Res::PrimTy(prim_ty) => {
|
|
assert_eq!(opt_self_ty, None);
|
|
self.prohibit_generics(path.segments);
|
|
match prim_ty {
|
|
hir::PrimTy::Bool => tcx.types.bool,
|
|
hir::PrimTy::Char => tcx.types.char,
|
|
hir::PrimTy::Int(it) => tcx.mk_mach_int(it),
|
|
hir::PrimTy::Uint(uit) => tcx.mk_mach_uint(uit),
|
|
hir::PrimTy::Float(ft) => tcx.mk_mach_float(ft),
|
|
hir::PrimTy::Str => tcx.mk_str(),
|
|
}
|
|
}
|
|
Res::Err => {
|
|
self.set_tainted_by_errors();
|
|
return self.tcx().types.err;
|
|
}
|
|
_ => span_bug!(span, "unexpected resolution: {:?}", path.res),
|
|
}
|
|
}
|
|
|
|
/// Parses the programmer's textual representation of a type into our
|
|
/// internal notion of a type.
|
|
pub fn ast_ty_to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
|
|
debug!("ast_ty_to_ty(id={:?}, ast_ty={:?} ty_ty={:?})", ast_ty.hir_id, ast_ty, ast_ty.kind);
|
|
|
|
let tcx = self.tcx();
|
|
|
|
let result_ty = match ast_ty.kind {
|
|
hir::TyKind::Slice(ref ty) => tcx.mk_slice(self.ast_ty_to_ty(&ty)),
|
|
hir::TyKind::Ptr(ref mt) => {
|
|
tcx.mk_ptr(ty::TypeAndMut { ty: self.ast_ty_to_ty(&mt.ty), mutbl: mt.mutbl })
|
|
}
|
|
hir::TyKind::Rptr(ref region, ref mt) => {
|
|
let r = self.ast_region_to_region(region, None);
|
|
debug!("ast_ty_to_ty: r={:?}", r);
|
|
let t = self.ast_ty_to_ty(&mt.ty);
|
|
tcx.mk_ref(r, ty::TypeAndMut { ty: t, mutbl: mt.mutbl })
|
|
}
|
|
hir::TyKind::Never => tcx.types.never,
|
|
hir::TyKind::Tup(ref fields) => {
|
|
tcx.mk_tup(fields.iter().map(|t| self.ast_ty_to_ty(&t)))
|
|
}
|
|
hir::TyKind::BareFn(ref bf) => {
|
|
require_c_abi_if_c_variadic(tcx, &bf.decl, bf.abi, ast_ty.span);
|
|
tcx.mk_fn_ptr(self.ty_of_fn(bf.unsafety, bf.abi, &bf.decl, &[], None))
|
|
}
|
|
hir::TyKind::TraitObject(ref bounds, ref lifetime) => {
|
|
self.conv_object_ty_poly_trait_ref(ast_ty.span, bounds, lifetime)
|
|
}
|
|
hir::TyKind::Path(hir::QPath::Resolved(ref maybe_qself, ref path)) => {
|
|
debug!("ast_ty_to_ty: maybe_qself={:?} path={:?}", maybe_qself, path);
|
|
let opt_self_ty = maybe_qself.as_ref().map(|qself| self.ast_ty_to_ty(qself));
|
|
self.res_to_ty(opt_self_ty, path, false)
|
|
}
|
|
hir::TyKind::Def(item_id, ref lifetimes) => {
|
|
let did = tcx.hir().local_def_id(item_id.id);
|
|
self.impl_trait_ty_to_ty(did, lifetimes)
|
|
}
|
|
hir::TyKind::Path(hir::QPath::TypeRelative(ref qself, ref segment)) => {
|
|
debug!("ast_ty_to_ty: qself={:?} segment={:?}", qself, segment);
|
|
let ty = self.ast_ty_to_ty(qself);
|
|
|
|
let res = if let hir::TyKind::Path(hir::QPath::Resolved(_, ref path)) = qself.kind {
|
|
path.res
|
|
} else {
|
|
Res::Err
|
|
};
|
|
self.associated_path_to_ty(ast_ty.hir_id, ast_ty.span, ty, res, segment, false)
|
|
.map(|(ty, _, _)| ty)
|
|
.unwrap_or(tcx.types.err)
|
|
}
|
|
hir::TyKind::Array(ref ty, ref length) => {
|
|
let length = self.ast_const_to_const(length, tcx.types.usize);
|
|
let array_ty = tcx.mk_ty(ty::Array(self.ast_ty_to_ty(&ty), length));
|
|
self.normalize_ty(ast_ty.span, array_ty)
|
|
}
|
|
hir::TyKind::Typeof(ref _e) => {
|
|
struct_span_err!(
|
|
tcx.sess,
|
|
ast_ty.span,
|
|
E0516,
|
|
"`typeof` is a reserved keyword but unimplemented"
|
|
)
|
|
.span_label(ast_ty.span, "reserved keyword")
|
|
.emit();
|
|
|
|
tcx.types.err
|
|
}
|
|
hir::TyKind::Infer => {
|
|
// Infer also appears as the type of arguments or return
|
|
// values in a ExprKind::Closure, or as
|
|
// the type of local variables. Both of these cases are
|
|
// handled specially and will not descend into this routine.
|
|
self.ty_infer(None, ast_ty.span)
|
|
}
|
|
hir::TyKind::Err => tcx.types.err,
|
|
};
|
|
|
|
debug!("ast_ty_to_ty: result_ty={:?}", result_ty);
|
|
|
|
self.record_ty(ast_ty.hir_id, result_ty, ast_ty.span);
|
|
result_ty
|
|
}
|
|
|
|
/// Returns the `DefId` of the constant parameter that the provided expression is a path to.
|
|
pub fn const_param_def_id(&self, expr: &hir::Expr<'_>) -> Option<DefId> {
|
|
// Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
|
|
// currently have to be wrapped in curly brackets, so it's necessary to special-case.
|
|
let expr = match &expr.kind {
|
|
ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
|
|
block.expr.as_ref().unwrap()
|
|
}
|
|
_ => expr,
|
|
};
|
|
|
|
match &expr.kind {
|
|
ExprKind::Path(hir::QPath::Resolved(_, path)) => match path.res {
|
|
Res::Def(DefKind::ConstParam, did) => Some(did),
|
|
_ => None,
|
|
},
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
pub fn ast_const_to_const(
|
|
&self,
|
|
ast_const: &hir::AnonConst,
|
|
ty: Ty<'tcx>,
|
|
) -> &'tcx ty::Const<'tcx> {
|
|
debug!("ast_const_to_const(id={:?}, ast_const={:?})", ast_const.hir_id, ast_const);
|
|
|
|
let tcx = self.tcx();
|
|
let def_id = tcx.hir().local_def_id(ast_const.hir_id);
|
|
|
|
let mut const_ = ty::Const {
|
|
val: ty::ConstKind::Unevaluated(def_id, InternalSubsts::identity_for_item(tcx, def_id)),
|
|
ty,
|
|
};
|
|
|
|
let expr = &tcx.hir().body(ast_const.body).value;
|
|
if let Some(def_id) = self.const_param_def_id(expr) {
|
|
// Find the name and index of the const parameter by indexing the generics of the
|
|
// parent item and construct a `ParamConst`.
|
|
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
|
|
let item_id = tcx.hir().get_parent_node(hir_id);
|
|
let item_def_id = tcx.hir().local_def_id(item_id);
|
|
let generics = tcx.generics_of(item_def_id);
|
|
let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(hir_id)];
|
|
let name = tcx.hir().name(hir_id);
|
|
const_.val = ty::ConstKind::Param(ty::ParamConst::new(index, name));
|
|
}
|
|
|
|
tcx.mk_const(const_)
|
|
}
|
|
|
|
pub fn impl_trait_ty_to_ty(
|
|
&self,
|
|
def_id: DefId,
|
|
lifetimes: &[hir::GenericArg<'_>],
|
|
) -> Ty<'tcx> {
|
|
debug!("impl_trait_ty_to_ty(def_id={:?}, lifetimes={:?})", def_id, lifetimes);
|
|
let tcx = self.tcx();
|
|
|
|
let generics = tcx.generics_of(def_id);
|
|
|
|
debug!("impl_trait_ty_to_ty: generics={:?}", generics);
|
|
let substs = InternalSubsts::for_item(tcx, def_id, |param, _| {
|
|
if let Some(i) = (param.index as usize).checked_sub(generics.parent_count) {
|
|
// Our own parameters are the resolved lifetimes.
|
|
match param.kind {
|
|
GenericParamDefKind::Lifetime => {
|
|
if let hir::GenericArg::Lifetime(lifetime) = &lifetimes[i] {
|
|
self.ast_region_to_region(lifetime, None).into()
|
|
} else {
|
|
bug!()
|
|
}
|
|
}
|
|
_ => bug!(),
|
|
}
|
|
} else {
|
|
// Replace all parent lifetimes with `'static`.
|
|
match param.kind {
|
|
GenericParamDefKind::Lifetime => tcx.lifetimes.re_static.into(),
|
|
_ => tcx.mk_param_from_def(param),
|
|
}
|
|
}
|
|
});
|
|
debug!("impl_trait_ty_to_ty: substs={:?}", substs);
|
|
|
|
let ty = tcx.mk_opaque(def_id, substs);
|
|
debug!("impl_trait_ty_to_ty: {}", ty);
|
|
ty
|
|
}
|
|
|
|
pub fn ty_of_arg(&self, ty: &hir::Ty<'_>, expected_ty: Option<Ty<'tcx>>) -> Ty<'tcx> {
|
|
match ty.kind {
|
|
hir::TyKind::Infer if expected_ty.is_some() => {
|
|
self.record_ty(ty.hir_id, expected_ty.unwrap(), ty.span);
|
|
expected_ty.unwrap()
|
|
}
|
|
_ => self.ast_ty_to_ty(ty),
|
|
}
|
|
}
|
|
|
|
pub fn ty_of_fn(
|
|
&self,
|
|
unsafety: hir::Unsafety,
|
|
abi: abi::Abi,
|
|
decl: &hir::FnDecl<'_>,
|
|
generic_params: &[hir::GenericParam<'_>],
|
|
ident_span: Option<Span>,
|
|
) -> ty::PolyFnSig<'tcx> {
|
|
debug!("ty_of_fn");
|
|
|
|
let tcx = self.tcx();
|
|
|
|
// We proactively collect all the infered type params to emit a single error per fn def.
|
|
let mut visitor = PlaceholderHirTyCollector::default();
|
|
for ty in decl.inputs {
|
|
visitor.visit_ty(ty);
|
|
}
|
|
let input_tys = decl.inputs.iter().map(|a| self.ty_of_arg(a, None));
|
|
let output_ty = match decl.output {
|
|
hir::FunctionRetTy::Return(ref output) => {
|
|
visitor.visit_ty(output);
|
|
self.ast_ty_to_ty(output)
|
|
}
|
|
hir::FunctionRetTy::DefaultReturn(..) => tcx.mk_unit(),
|
|
};
|
|
|
|
debug!("ty_of_fn: output_ty={:?}", output_ty);
|
|
|
|
let bare_fn_ty =
|
|
ty::Binder::bind(tcx.mk_fn_sig(input_tys, output_ty, decl.c_variadic, unsafety, abi));
|
|
|
|
if !self.allow_ty_infer() {
|
|
// We always collect the spans for placeholder types when evaluating `fn`s, but we
|
|
// only want to emit an error complaining about them if infer types (`_`) are not
|
|
// allowed. `allow_ty_infer` gates this behavior.
|
|
crate::collect::placeholder_type_error(
|
|
tcx,
|
|
ident_span.map(|sp| sp.shrink_to_hi()).unwrap_or(DUMMY_SP),
|
|
generic_params,
|
|
visitor.0,
|
|
ident_span.is_some(),
|
|
);
|
|
}
|
|
|
|
// Find any late-bound regions declared in return type that do
|
|
// not appear in the arguments. These are not well-formed.
|
|
//
|
|
// Example:
|
|
// for<'a> fn() -> &'a str <-- 'a is bad
|
|
// for<'a> fn(&'a String) -> &'a str <-- 'a is ok
|
|
let inputs = bare_fn_ty.inputs();
|
|
let late_bound_in_args =
|
|
tcx.collect_constrained_late_bound_regions(&inputs.map_bound(|i| i.to_owned()));
|
|
let output = bare_fn_ty.output();
|
|
let late_bound_in_ret = tcx.collect_referenced_late_bound_regions(&output);
|
|
for br in late_bound_in_ret.difference(&late_bound_in_args) {
|
|
let lifetime_name = match *br {
|
|
ty::BrNamed(_, name) => format!("lifetime `{}`,", name),
|
|
ty::BrAnon(_) | ty::BrEnv => "an anonymous lifetime".to_string(),
|
|
};
|
|
let mut err = struct_span_err!(
|
|
tcx.sess,
|
|
decl.output.span(),
|
|
E0581,
|
|
"return type references {} \
|
|
which is not constrained by the fn input types",
|
|
lifetime_name
|
|
);
|
|
if let ty::BrAnon(_) = *br {
|
|
// The only way for an anonymous lifetime to wind up
|
|
// in the return type but **also** be unconstrained is
|
|
// if it only appears in "associated types" in the
|
|
// input. See #47511 for an example. In this case,
|
|
// though we can easily give a hint that ought to be
|
|
// relevant.
|
|
err.note(
|
|
"lifetimes appearing in an associated type \
|
|
are not considered constrained",
|
|
);
|
|
}
|
|
err.emit();
|
|
}
|
|
|
|
bare_fn_ty
|
|
}
|
|
|
|
/// Given the bounds on an object, determines what single region bound (if any) we can
|
|
/// use to summarize this type. The basic idea is that we will use the bound the user
|
|
/// provided, if they provided one, and otherwise search the supertypes of trait bounds
|
|
/// for region bounds. It may be that we can derive no bound at all, in which case
|
|
/// we return `None`.
|
|
fn compute_object_lifetime_bound(
|
|
&self,
|
|
span: Span,
|
|
existential_predicates: ty::Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>,
|
|
) -> Option<ty::Region<'tcx>> // if None, use the default
|
|
{
|
|
let tcx = self.tcx();
|
|
|
|
debug!("compute_opt_region_bound(existential_predicates={:?})", existential_predicates);
|
|
|
|
// No explicit region bound specified. Therefore, examine trait
|
|
// bounds and see if we can derive region bounds from those.
|
|
let derived_region_bounds = object_region_bounds(tcx, existential_predicates);
|
|
|
|
// If there are no derived region bounds, then report back that we
|
|
// can find no region bound. The caller will use the default.
|
|
if derived_region_bounds.is_empty() {
|
|
return None;
|
|
}
|
|
|
|
// If any of the derived region bounds are 'static, that is always
|
|
// the best choice.
|
|
if derived_region_bounds.iter().any(|&r| ty::ReStatic == *r) {
|
|
return Some(tcx.lifetimes.re_static);
|
|
}
|
|
|
|
// Determine whether there is exactly one unique region in the set
|
|
// of derived region bounds. If so, use that. Otherwise, report an
|
|
// error.
|
|
let r = derived_region_bounds[0];
|
|
if derived_region_bounds[1..].iter().any(|r1| r != *r1) {
|
|
struct_span_err!(
|
|
tcx.sess,
|
|
span,
|
|
E0227,
|
|
"ambiguous lifetime bound, explicit lifetime bound required"
|
|
)
|
|
.emit();
|
|
}
|
|
return Some(r);
|
|
}
|
|
}
|
|
|
|
/// Collects together a list of bounds that are applied to some type,
|
|
/// after they've been converted into `ty` form (from the HIR
|
|
/// representations). These lists of bounds occur in many places in
|
|
/// Rust's syntax:
|
|
///
|
|
/// ```
|
|
/// trait Foo: Bar + Baz { }
|
|
/// ^^^^^^^^^ supertrait list bounding the `Self` type parameter
|
|
///
|
|
/// fn foo<T: Bar + Baz>() { }
|
|
/// ^^^^^^^^^ bounding the type parameter `T`
|
|
///
|
|
/// impl dyn Bar + Baz
|
|
/// ^^^^^^^^^ bounding the forgotten dynamic type
|
|
/// ```
|
|
///
|
|
/// Our representation is a bit mixed here -- in some cases, we
|
|
/// include the self type (e.g., `trait_bounds`) but in others we do
|
|
#[derive(Default, PartialEq, Eq, Clone, Debug)]
|
|
pub struct Bounds<'tcx> {
|
|
/// A list of region bounds on the (implicit) self type. So if you
|
|
/// had `T: 'a + 'b` this might would be a list `['a, 'b]` (but
|
|
/// the `T` is not explicitly included).
|
|
pub region_bounds: Vec<(ty::Region<'tcx>, Span)>,
|
|
|
|
/// A list of trait bounds. So if you had `T: Debug` this would be
|
|
/// `T: Debug`. Note that the self-type is explicit here.
|
|
pub trait_bounds: Vec<(ty::PolyTraitRef<'tcx>, Span)>,
|
|
|
|
/// A list of projection equality bounds. So if you had `T:
|
|
/// Iterator<Item = u32>` this would include `<T as
|
|
/// Iterator>::Item => u32`. Note that the self-type is explicit
|
|
/// here.
|
|
pub projection_bounds: Vec<(ty::PolyProjectionPredicate<'tcx>, Span)>,
|
|
|
|
/// `Some` if there is *no* `?Sized` predicate. The `span`
|
|
/// is the location in the source of the `T` declaration which can
|
|
/// be cited as the source of the `T: Sized` requirement.
|
|
pub implicitly_sized: Option<Span>,
|
|
}
|
|
|
|
impl<'tcx> Bounds<'tcx> {
|
|
/// Converts a bounds list into a flat set of predicates (like
|
|
/// where-clauses). Because some of our bounds listings (e.g.,
|
|
/// regions) don't include the self-type, you must supply the
|
|
/// self-type here (the `param_ty` parameter).
|
|
pub fn predicates(
|
|
&self,
|
|
tcx: TyCtxt<'tcx>,
|
|
param_ty: Ty<'tcx>,
|
|
) -> Vec<(ty::Predicate<'tcx>, Span)> {
|
|
// If it could be sized, and is, add the `Sized` predicate.
|
|
let sized_predicate = self.implicitly_sized.and_then(|span| {
|
|
tcx.lang_items().sized_trait().map(|sized| {
|
|
let trait_ref = ty::Binder::bind(ty::TraitRef {
|
|
def_id: sized,
|
|
substs: tcx.mk_substs_trait(param_ty, &[]),
|
|
});
|
|
(trait_ref.to_predicate(), span)
|
|
})
|
|
});
|
|
|
|
sized_predicate
|
|
.into_iter()
|
|
.chain(
|
|
self.region_bounds
|
|
.iter()
|
|
.map(|&(region_bound, span)| {
|
|
// Account for the binder being introduced below; no need to shift `param_ty`
|
|
// because, at present at least, it either only refers to early-bound regions,
|
|
// or it's a generic associated type that deliberately has escaping bound vars.
|
|
let region_bound = ty::fold::shift_region(tcx, region_bound, 1);
|
|
let outlives = ty::OutlivesPredicate(param_ty, region_bound);
|
|
(ty::Binder::bind(outlives).to_predicate(), span)
|
|
})
|
|
.chain(
|
|
self.trait_bounds
|
|
.iter()
|
|
.map(|&(bound_trait_ref, span)| (bound_trait_ref.to_predicate(), span)),
|
|
)
|
|
.chain(
|
|
self.projection_bounds
|
|
.iter()
|
|
.map(|&(projection, span)| (projection.to_predicate(), span)),
|
|
),
|
|
)
|
|
.collect()
|
|
}
|
|
}
|