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Make ProjectionTy::trait_ref truncate substs again
Also make sure that type arguments of associated types are printed in some error messages.
This commit is contained in:
Matthew Jasper
parent
79f6f11816
commit
dfee89f755
@ -1,5 +1,6 @@
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use crate::traits::{ObligationCause, ObligationCauseCode};
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use crate::ty::diagnostics::suggest_constraining_type_param;
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use crate::ty::print::{FmtPrinter, Printer};
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use crate::ty::{self, BoundRegionKind, Region, Ty, TyCtxt};
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use rustc_errors::Applicability::{MachineApplicable, MaybeIncorrect};
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use rustc_errors::{pluralize, DiagnosticBuilder};
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@ -400,14 +401,22 @@ impl<'tcx> TyCtxt<'tcx> {
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{
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// Synthesize the associated type restriction `Add<Output = Expected>`.
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// FIXME: extract this logic for use in other diagnostics.
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let trait_ref = proj.trait_ref(self);
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let (trait_ref, assoc_substs) = proj.trait_ref_and_own_substs(self);
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let path =
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self.def_path_str_with_substs(trait_ref.def_id, trait_ref.substs);
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let item_name = self.item_name(proj.item_def_id);
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let item_args = self.format_generic_args(assoc_substs);
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let path = if path.ends_with('>') {
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format!("{}, {} = {}>", &path[..path.len() - 1], item_name, p)
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format!(
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"{}, {}{} = {}>",
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&path[..path.len() - 1],
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item_name,
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item_args,
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p
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)
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} else {
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format!("{}<{} = {}>", path, item_name, p)
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format!("{}<{}{} = {}>", path, item_name, item_args, p)
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};
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note = !suggest_constraining_type_param(
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self,
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@ -556,7 +565,7 @@ impl<T> Trait<T> for X {
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ty: Ty<'tcx>,
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) -> bool {
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let assoc = self.associated_item(proj_ty.item_def_id);
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let trait_ref = proj_ty.trait_ref(self);
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let (trait_ref, assoc_substs) = proj_ty.trait_ref_and_own_substs(self);
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if let Some(item) = self.hir().get_if_local(body_owner_def_id) {
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if let Some(hir_generics) = item.generics() {
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// Get the `DefId` for the type parameter corresponding to `A` in `<A as T>::Foo`.
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@ -590,6 +599,7 @@ impl<T> Trait<T> for X {
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&trait_ref,
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pred.bounds,
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&assoc,
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assoc_substs,
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ty,
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msg,
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) {
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@ -607,6 +617,7 @@ impl<T> Trait<T> for X {
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&trait_ref,
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param.bounds,
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&assoc,
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assoc_substs,
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ty,
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msg,
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);
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@ -692,6 +703,7 @@ impl<T> Trait<T> for X {
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db,
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self.def_span(def_id),
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&assoc,
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proj_ty.trait_ref_and_own_substs(self).1,
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values.found,
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&msg,
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) {
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@ -856,6 +868,7 @@ fn foo(&self) -> Self::T { String::new() }
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trait_ref: &ty::TraitRef<'tcx>,
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bounds: hir::GenericBounds<'_>,
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assoc: &ty::AssocItem,
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assoc_substs: &[ty::GenericArg<'tcx>],
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ty: Ty<'tcx>,
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msg: &str,
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) -> bool {
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@ -865,7 +878,12 @@ fn foo(&self) -> Self::T { String::new() }
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// Relate the type param against `T` in `<A as T>::Foo`.
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ptr.trait_ref.trait_def_id() == Some(trait_ref.def_id)
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&& self.constrain_associated_type_structured_suggestion(
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db, ptr.span, assoc, ty, msg,
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db,
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ptr.span,
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assoc,
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assoc_substs,
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ty,
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msg,
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)
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}
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_ => false,
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@ -879,6 +897,7 @@ fn foo(&self) -> Self::T { String::new() }
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db: &mut DiagnosticBuilder<'_>,
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span: Span,
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assoc: &ty::AssocItem,
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assoc_substs: &[ty::GenericArg<'tcx>],
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ty: Ty<'tcx>,
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msg: &str,
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) -> bool {
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@ -890,11 +909,20 @@ fn foo(&self) -> Self::T { String::new() }
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let span = Span::new(pos, pos, span.ctxt());
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(span, format!(", {} = {}", assoc.ident, ty))
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} else {
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(span.shrink_to_hi(), format!("<{} = {}>", assoc.ident, ty))
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let item_args = self.format_generic_args(assoc_substs);
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(span.shrink_to_hi(), format!("<{}{} = {}>", assoc.ident, item_args, ty))
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};
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db.span_suggestion_verbose(span, msg, sugg, MaybeIncorrect);
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return true;
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}
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false
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}
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fn format_generic_args(self, args: &[ty::GenericArg<'tcx>]) -> String {
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let mut item_args = String::new();
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FmtPrinter::new(self, &mut item_args, hir::def::Namespace::TypeNS)
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.path_generic_args(Ok, args)
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.expect("could not write to `String`.");
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item_args
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}
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}
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@ -1289,8 +1289,22 @@ impl<'tcx> PolyProjectionPredicate<'tcx> {
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self.skip_binder().projection_ty.item_def_id
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}
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/// Returns the `DefId` of the trait of the associated item being projected.
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#[inline]
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pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
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pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
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self.skip_binder().projection_ty.trait_def_id(tcx)
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}
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#[inline]
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pub fn projection_self_ty(&self) -> Binder<Ty<'tcx>> {
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self.map_bound(|predicate| predicate.projection_ty.self_ty())
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}
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/// Get the [PolyTraitRef] required for this projection to be well formed.
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/// Note that for generic associated types the predicates of the associated
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/// type also need to be checked.
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#[inline]
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pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
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// Note: unlike with `TraitRef::to_poly_trait_ref()`,
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// `self.0.trait_ref` is permitted to have escaping regions.
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// This is because here `self` has a `Binder` and so does our
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@ -17,7 +17,7 @@ use rustc_hir as hir;
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use rustc_hir::def_id::DefId;
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use rustc_index::vec::Idx;
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use rustc_macros::HashStable;
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use rustc_span::symbol::{kw, Ident, Symbol};
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use rustc_span::symbol::{kw, Symbol};
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use rustc_target::abi::VariantIdx;
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use rustc_target::spec::abi;
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use std::borrow::Cow;
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@ -1112,20 +1112,35 @@ pub struct ProjectionTy<'tcx> {
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}
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impl<'tcx> ProjectionTy<'tcx> {
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pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
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tcx.associated_item(self.item_def_id).container.id()
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}
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/// Extracts the underlying trait reference and own substs from this projection.
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/// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
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/// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
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pub fn trait_ref_and_own_substs(
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&self,
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tcx: TyCtxt<'tcx>,
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) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
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let def_id = tcx.associated_item(self.item_def_id).container.id();
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let trait_generics = tcx.generics_of(def_id);
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(
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ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
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&self.substs[trait_generics.count()..],
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)
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}
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/// Extracts the underlying trait reference from this projection.
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/// For example, if this is a projection of `<T as Iterator>::Item`,
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/// then this function would return a `T: Iterator` trait reference.
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///
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/// WARNING: This will drop the substs for generic associated types
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/// consider calling [Self::trait_ref_and_own_substs] to get those
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/// as well.
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pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
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// FIXME: This method probably shouldn't exist at all, since it's not
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// clear what this method really intends to do. Be careful when
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// using this method since the resulting TraitRef additionally
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// contains the substs for the assoc_item, which strictly speaking
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// is not correct
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let def_id = tcx.associated_item(self.item_def_id).container.id();
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// Include substitutions for generic arguments of associated types
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let assoc_item = tcx.associated_item(self.item_def_id);
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let substs_assoc_item = self.substs.truncate_to(tcx, tcx.generics_of(assoc_item.def_id));
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ty::TraitRef { def_id, substs: substs_assoc_item }
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let def_id = self.trait_def_id(tcx);
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ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
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}
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pub fn self_ty(&self) -> Ty<'tcx> {
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@ -1589,8 +1589,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
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self.emit_inference_failure_err(body_id, span, a.into(), vec![], ErrorCode::E0282)
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}
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ty::PredicateKind::Projection(data) => {
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let trait_ref = bound_predicate.rebind(data).to_poly_trait_ref(self.tcx);
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let self_ty = trait_ref.skip_binder().self_ty();
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let self_ty = data.projection_ty.self_ty();
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let ty = data.ty;
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if predicate.references_error() {
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return;
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@ -779,14 +779,11 @@ impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>
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self,
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interner: &RustInterner<'tcx>,
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) -> chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>> {
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let trait_ref = self.projection_ty.trait_ref(interner.tcx);
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let (trait_ref, own_substs) = self.projection_ty.trait_ref_and_own_substs(interner.tcx);
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chalk_solve::rust_ir::AliasEqBound {
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trait_bound: trait_ref.lower_into(interner),
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associated_ty_id: chalk_ir::AssocTypeId(self.projection_ty.item_def_id),
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parameters: self.projection_ty.substs[trait_ref.substs.len()..]
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.iter()
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.map(|arg| arg.lower_into(interner))
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.collect(),
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parameters: own_substs.iter().map(|arg| arg.lower_into(interner)).collect(),
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value: self.ty.lower_into(interner),
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}
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}
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@ -208,7 +208,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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});
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// Even if we can't infer the full signature, we may be able to
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// infer the kind. This can occur if there is a trait-reference
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// infer the kind. This can occur when we elaborate a predicate
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// like `F : Fn<A>`. Note that due to subtyping we could encounter
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// many viable options, so pick the most restrictive.
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let expected_kind = self
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@ -234,11 +234,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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debug!("deduce_sig_from_projection({:?})", projection);
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let trait_ref = projection.to_poly_trait_ref(tcx);
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let trait_def_id = projection.trait_def_id(tcx);
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let is_fn = tcx.fn_trait_kind_from_lang_item(trait_ref.def_id()).is_some();
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let is_fn = tcx.fn_trait_kind_from_lang_item(trait_def_id).is_some();
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let gen_trait = tcx.require_lang_item(LangItem::Generator, cause_span);
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let is_gen = gen_trait == trait_ref.def_id();
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let is_gen = gen_trait == trait_def_id;
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if !is_fn && !is_gen {
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debug!("deduce_sig_from_projection: not fn or generator");
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return None;
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@ -256,7 +256,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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}
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let input_tys = if is_fn {
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let arg_param_ty = trait_ref.skip_binder().substs.type_at(1);
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let arg_param_ty = projection.skip_binder().projection_ty.substs.type_at(1);
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let arg_param_ty = self.resolve_vars_if_possible(arg_param_ty);
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debug!("deduce_sig_from_projection: arg_param_ty={:?}", arg_param_ty);
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@ -662,9 +662,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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};
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// Check that this is a projection from the `Future` trait.
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let trait_ref = predicate.projection_ty.trait_ref(self.tcx);
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let trait_def_id = predicate.projection_ty.trait_def_id(self.tcx);
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let future_trait = self.tcx.require_lang_item(LangItem::Future, Some(cause_span));
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if trait_ref.def_id != future_trait {
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if trait_def_id != future_trait {
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debug!("deduce_future_output_from_projection: not a future");
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return None;
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}
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@ -769,9 +769,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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.filter_map(move |obligation| {
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let bound_predicate = obligation.predicate.kind();
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match bound_predicate.skip_binder() {
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ty::PredicateKind::Projection(data) => {
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Some((bound_predicate.rebind(data).to_poly_trait_ref(self.tcx), obligation))
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}
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ty::PredicateKind::Projection(data) => Some((
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bound_predicate.rebind(data).required_poly_trait_ref(self.tcx),
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obligation,
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)),
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ty::PredicateKind::Trait(data, _) => {
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Some((bound_predicate.rebind(data).to_poly_trait_ref(), obligation))
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}
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@ -24,6 +24,7 @@ use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
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use rustc_trait_selection::traits::Obligation;
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use std::cmp::Ordering;
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use std::iter;
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use super::probe::Mode;
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use super::{CandidateSource, MethodError, NoMatchData};
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@ -649,21 +650,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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ty::PredicateKind::Projection(pred) => {
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let pred = bound_predicate.rebind(pred);
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// `<Foo as Iterator>::Item = String`.
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let trait_ref =
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pred.skip_binder().projection_ty.trait_ref(self.tcx);
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let assoc = self
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.tcx
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.associated_item(pred.skip_binder().projection_ty.item_def_id);
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let ty = pred.skip_binder().ty;
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let obligation = format!("{}::{} = {}", trait_ref, assoc.ident, ty);
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let quiet = format!(
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"<_ as {}>::{} = {}",
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trait_ref.print_only_trait_path(),
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assoc.ident,
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ty
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let projection_ty = pred.skip_binder().projection_ty;
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let substs_with_infer_self = tcx.mk_substs(
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iter::once(tcx.mk_ty_var(ty::TyVid { index: 0 }).into())
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.chain(projection_ty.substs.iter().skip(1)),
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);
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bound_span_label(trait_ref.self_ty(), &obligation, &quiet);
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Some((obligation, trait_ref.self_ty()))
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let quiet_projection_ty = ty::ProjectionTy {
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substs: substs_with_infer_self,
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item_def_id: projection_ty.item_def_id,
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};
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let ty = pred.skip_binder().ty;
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let obligation = format!("{} = {}", projection_ty, ty);
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let quiet = format!("{} = {}", quiet_projection_ty, ty);
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bound_span_label(projection_ty.self_ty(), &obligation, &quiet);
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Some((obligation, projection_ty.self_ty()))
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}
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ty::PredicateKind::Trait(poly_trait_ref, _) => {
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let p = poly_trait_ref.trait_ref;
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@ -0,0 +1,17 @@
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// Test that correct syntax is used in suggestion to constrain associated type
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#![feature(generic_associated_types)]
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//~^ WARNING the feature `generic_associated_types` is incomplete
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trait X {
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type Y<T>;
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}
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fn f<T: X>(a: T::Y<i32>) {
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//~^ HELP consider constraining the associated type `<T as X>::Y<i32>` to `Vec<i32>`
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//~| SUGGESTION Y<i32> = Vec<i32>>
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let b: Vec<i32> = a;
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//~^ ERROR mismatched types
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}
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fn main() {}
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@ -0,0 +1,27 @@
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warning: the feature `generic_associated_types` is incomplete and may not be safe to use and/or cause compiler crashes
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--> $DIR/constraint-assoc-type-suggestion.rs:3:12
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|
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LL | #![feature(generic_associated_types)]
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| ^^^^^^^^^^^^^^^^^^^^^^^^
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|
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= note: `#[warn(incomplete_features)]` on by default
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= note: see issue #44265 <https://github.com/rust-lang/rust/issues/44265> for more information
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error[E0308]: mismatched types
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--> $DIR/constraint-assoc-type-suggestion.rs:13:23
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|
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LL | let b: Vec<i32> = a;
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| -------- ^ expected struct `Vec`, found associated type
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| |
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| expected due to this
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|
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= note: expected struct `Vec<i32>`
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found associated type `<T as X>::Y<i32>`
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help: consider constraining the associated type `<T as X>::Y<i32>` to `Vec<i32>`
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|
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LL | fn f<T: X<Y<i32> = Vec<i32>>>(a: T::Y<i32>) {
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| ^^^^^^^^^^^^^^^^^^^
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|
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error: aborting due to previous error; 1 warning emitted
|
||||
|
||||
For more information about this error, try `rustc --explain E0308`.
|
||||
@ -0,0 +1,35 @@
|
||||
// Test that the predicate printed in an unresolved method error prints the
|
||||
// generics for a generic associated type.
|
||||
|
||||
#![feature(generic_associated_types)]
|
||||
//~^ WARNING the feature `generic_associated_types` is incomplete
|
||||
//~| NOTE `#[warn(incomplete_features)]` on by default
|
||||
//~| NOTE see issue #44265
|
||||
|
||||
trait X {
|
||||
type Y<T>;
|
||||
}
|
||||
|
||||
trait M {
|
||||
fn f(&self) {}
|
||||
}
|
||||
|
||||
impl<T: X<Y<i32> = i32>> M for T {}
|
||||
|
||||
struct S;
|
||||
//~^ NOTE method `f` not found for this
|
||||
//~| NOTE doesn't satisfy `<S as X>::Y<i32> = i32`
|
||||
//~| NOTE doesn't satisfy `S: M`
|
||||
|
||||
impl X for S {
|
||||
type Y<T> = bool;
|
||||
}
|
||||
|
||||
fn f(a: S) {
|
||||
a.f();
|
||||
//~^ ERROR the method `f` exists for struct `S`, but its trait bounds were not satisfied
|
||||
//~| NOTE method cannot be called on `S` due to unsatisfied trait bounds
|
||||
//~| NOTE the following trait bounds were not satisfied:
|
||||
}
|
||||
|
||||
fn main() {}
|
||||
@ -0,0 +1,29 @@
|
||||
warning: the feature `generic_associated_types` is incomplete and may not be safe to use and/or cause compiler crashes
|
||||
--> $DIR/method-unsatified-assoc-type-predicate.rs:4:12
|
||||
|
|
||||
LL | #![feature(generic_associated_types)]
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
= note: `#[warn(incomplete_features)]` on by default
|
||||
= note: see issue #44265 <https://github.com/rust-lang/rust/issues/44265> for more information
|
||||
|
||||
error[E0599]: the method `f` exists for struct `S`, but its trait bounds were not satisfied
|
||||
--> $DIR/method-unsatified-assoc-type-predicate.rs:29:7
|
||||
|
|
||||
LL | struct S;
|
||||
| ---------
|
||||
| |
|
||||
| method `f` not found for this
|
||||
| doesn't satisfy `<S as X>::Y<i32> = i32`
|
||||
| doesn't satisfy `S: M`
|
||||
...
|
||||
LL | a.f();
|
||||
| ^ method cannot be called on `S` due to unsatisfied trait bounds
|
||||
|
|
||||
= note: the following trait bounds were not satisfied:
|
||||
`<S as X>::Y<i32> = i32`
|
||||
which is required by `S: M`
|
||||
|
||||
error: aborting due to previous error; 1 warning emitted
|
||||
|
||||
For more information about this error, try `rustc --explain E0599`.
|
||||
Loading…
Reference in New Issue
Block a user