use crate::errors::LifetimesOrBoundsMismatchOnTrait;
use hir::def_id::{DefId, LocalDefId};
use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
-use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId, ErrorGuaranteed};
+use rustc_errors::{
+ pluralize, struct_span_err, Applicability, DiagnosticId, ErrorGuaranteed, MultiSpan,
+};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::intravisit;
/// <'a> fn(t: &'i0 U0, m: &'a) -> Foo
///
/// This type is also the same but the name of the bound region (`'a`
-/// vs `'b`). However, the normal subtyping rules on fn types handle
+/// vs `'b`). However, the normal subtyping rules on fn types handle
/// this kind of equivalency just fine.
///
/// We now use these substitutions to ensure that all declared bounds are
//
// We then register the obligations from the impl_m and check to see
// if all constraints hold.
- hybrid_preds
- .predicates
- .extend(trait_m_predicates.instantiate_own(tcx, trait_to_placeholder_substs).predicates);
+ hybrid_preds.predicates.extend(
+ trait_m_predicates
+ .instantiate_own(tcx, trait_to_placeholder_substs)
+ .map(|(predicate, _)| predicate),
+ );
// Construct trait parameter environment and then shift it into the placeholder viewpoint.
// The key step here is to update the caller_bounds's predicates to be
debug!("compare_impl_method: caller_bounds={:?}", param_env.caller_bounds());
let impl_m_own_bounds = impl_m_predicates.instantiate_own(tcx, impl_to_placeholder_substs);
- for (predicate, span) in iter::zip(impl_m_own_bounds.predicates, impl_m_own_bounds.spans) {
+ for (predicate, span) in impl_m_own_bounds {
let normalize_cause = traits::ObligationCause::misc(span, impl_m_hir_id);
let predicate = ocx.normalize(&normalize_cause, param_env, predicate);
ty::Binder::dummy(ty::PredicateKind::WellFormed(unnormalized_impl_fty.into())),
));
}
- let emit_implied_wf_lint = || {
- infcx.tcx.struct_span_lint_hir(
- rustc_session::lint::builtin::IMPLIED_BOUNDS_ENTAILMENT,
- impl_m_hir_id,
- infcx.tcx.def_span(impl_m.def_id),
- "impl method assumes more implied bounds than the corresponding trait method",
- |lint| lint,
- );
- };
// Check that all obligations are satisfied by the implementation's
// version.
)
.map(|()| {
// If the skip-mode was successful, emit a lint.
- emit_implied_wf_lint();
+ emit_implied_wf_lint(infcx.tcx, impl_m, impl_m_hir_id, vec![]);
});
}
CheckImpliedWfMode::Skip => {
CheckImpliedWfMode::Skip,
)
.map(|()| {
+ let bad_args = extract_bad_args_for_implies_lint(
+ tcx,
+ &errors,
+ (trait_m, trait_sig),
+ // Unnormalized impl sig corresponds to the HIR types written
+ (impl_m, unnormalized_impl_sig),
+ impl_m_hir_id,
+ );
// If the skip-mode was successful, emit a lint.
- emit_implied_wf_lint();
+ emit_implied_wf_lint(tcx, impl_m, impl_m_hir_id, bad_args);
});
}
CheckImpliedWfMode::Skip => {
Ok(())
}
+fn extract_bad_args_for_implies_lint<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ errors: &[infer::RegionResolutionError<'tcx>],
+ (trait_m, trait_sig): (&ty::AssocItem, ty::FnSig<'tcx>),
+ (impl_m, impl_sig): (&ty::AssocItem, ty::FnSig<'tcx>),
+ hir_id: hir::HirId,
+) -> Vec<(Span, Option<String>)> {
+ let mut blame_generics = vec![];
+ for error in errors {
+ // Look for the subregion origin that contains an input/output type
+ let origin = match error {
+ infer::RegionResolutionError::ConcreteFailure(o, ..) => o,
+ infer::RegionResolutionError::GenericBoundFailure(o, ..) => o,
+ infer::RegionResolutionError::SubSupConflict(_, _, o, ..) => o,
+ infer::RegionResolutionError::UpperBoundUniverseConflict(.., o, _) => o,
+ };
+ // Extract (possible) input/output types from origin
+ match origin {
+ infer::SubregionOrigin::Subtype(trace) => {
+ if let Some((a, b)) = trace.values.ty() {
+ blame_generics.extend([a, b]);
+ }
+ }
+ infer::SubregionOrigin::RelateParamBound(_, ty, _) => blame_generics.push(*ty),
+ infer::SubregionOrigin::ReferenceOutlivesReferent(ty, _) => blame_generics.push(*ty),
+ _ => {}
+ }
+ }
+
+ let fn_decl = tcx.hir().fn_decl_by_hir_id(hir_id).unwrap();
+ let opt_ret_ty = match fn_decl.output {
+ hir::FnRetTy::DefaultReturn(_) => None,
+ hir::FnRetTy::Return(ty) => Some(ty),
+ };
+
+ // Map late-bound regions from trait to impl, so the names are right.
+ let mapping = std::iter::zip(
+ tcx.fn_sig(trait_m.def_id).bound_vars(),
+ tcx.fn_sig(impl_m.def_id).bound_vars(),
+ )
+ .filter_map(|(impl_bv, trait_bv)| {
+ if let ty::BoundVariableKind::Region(impl_bv) = impl_bv
+ && let ty::BoundVariableKind::Region(trait_bv) = trait_bv
+ {
+ Some((impl_bv, trait_bv))
+ } else {
+ None
+ }
+ })
+ .collect();
+
+ // For each arg, see if it was in the "blame" of any of the region errors.
+ // If so, then try to produce a suggestion to replace the argument type with
+ // one from the trait.
+ let mut bad_args = vec![];
+ for (idx, (ty, hir_ty)) in
+ std::iter::zip(impl_sig.inputs_and_output, fn_decl.inputs.iter().chain(opt_ret_ty))
+ .enumerate()
+ {
+ let expected_ty = trait_sig.inputs_and_output[idx]
+ .fold_with(&mut RemapLateBound { tcx, mapping: &mapping });
+ if blame_generics.iter().any(|blame| ty.contains(*blame)) {
+ let expected_ty_sugg = expected_ty.to_string();
+ bad_args.push((
+ hir_ty.span,
+ // Only suggest something if it actually changed.
+ (expected_ty_sugg != ty.to_string()).then_some(expected_ty_sugg),
+ ));
+ }
+ }
+
+ bad_args
+}
+
+struct RemapLateBound<'a, 'tcx> {
+ tcx: TyCtxt<'tcx>,
+ mapping: &'a FxHashMap<ty::BoundRegionKind, ty::BoundRegionKind>,
+}
+
+impl<'tcx> TypeFolder<'tcx> for RemapLateBound<'_, 'tcx> {
+ fn tcx(&self) -> TyCtxt<'tcx> {
+ self.tcx
+ }
+
+ fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
+ if let ty::ReFree(fr) = *r {
+ self.tcx.mk_region(ty::ReFree(ty::FreeRegion {
+ bound_region: self
+ .mapping
+ .get(&fr.bound_region)
+ .copied()
+ .unwrap_or(fr.bound_region),
+ ..fr
+ }))
+ } else {
+ r
+ }
+ }
+}
+
+fn emit_implied_wf_lint<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ impl_m: &ty::AssocItem,
+ hir_id: hir::HirId,
+ bad_args: Vec<(Span, Option<String>)>,
+) {
+ let span: MultiSpan = if bad_args.is_empty() {
+ tcx.def_span(impl_m.def_id).into()
+ } else {
+ bad_args.iter().map(|(span, _)| *span).collect::<Vec<_>>().into()
+ };
+ tcx.struct_span_lint_hir(
+ rustc_session::lint::builtin::IMPLIED_BOUNDS_ENTAILMENT,
+ hir_id,
+ span,
+ "impl method assumes more implied bounds than the corresponding trait method",
+ |lint| {
+ let bad_args: Vec<_> =
+ bad_args.into_iter().filter_map(|(span, sugg)| Some((span, sugg?))).collect();
+ if !bad_args.is_empty() {
+ lint.multipart_suggestion(
+ format!(
+ "replace {} type{} to make the impl signature compatible",
+ pluralize!("this", bad_args.len()),
+ pluralize!(bad_args.len())
+ ),
+ bad_args,
+ Applicability::MaybeIncorrect,
+ );
+ }
+ lint
+ },
+ );
+}
+
#[derive(Debug, PartialEq, Eq)]
enum CheckImpliedWfMode {
/// Checks implied well-formedness of the impl method. If it fails, we will
) -> Result<&'tcx FxHashMap<DefId, Ty<'tcx>>, ErrorGuaranteed> {
let impl_m = tcx.opt_associated_item(def_id).unwrap();
let trait_m = tcx.opt_associated_item(impl_m.trait_item_def_id.unwrap()).unwrap();
- let impl_trait_ref = tcx.impl_trait_ref(impl_m.impl_container(tcx).unwrap()).unwrap();
+ let impl_trait_ref =
+ tcx.impl_trait_ref(impl_m.impl_container(tcx).unwrap()).unwrap().subst_identity();
let param_env = tcx.param_env(def_id);
// First, check a few of the same things as `compare_impl_method`,
match infcx.fully_resolve(ty) {
Ok(ty) => {
// `ty` contains free regions that we created earlier while liberating the
- // trait fn signature. However, projection normalization expects `ty` to
+ // trait fn signature. However, projection normalization expects `ty` to
// contains `def_id`'s early-bound regions.
let id_substs = InternalSubsts::identity_for_item(tcx, def_id);
debug!(?id_substs, ?substs);
// Must have same number of early-bound lifetime parameters.
// Unfortunately, if the user screws up the bounds, then this
- // will change classification between early and late. E.g.,
+ // will change classification between early and late. E.g.,
// if in trait we have `<'a,'b:'a>`, and in impl we just have
// `<'a,'b>`, then we have 2 early-bound lifetime parameters
// in trait but 0 in the impl. But if we report "expected 2
impl_trait_ref: ty::TraitRef<'tcx>,
) -> Result<(), ErrorGuaranteed> {
// Try to give more informative error messages about self typing
- // mismatches. Note that any mismatch will also be detected
+ // mismatches. Note that any mismatch will also be detected
// below, where we construct a canonical function type that
- // includes the self parameter as a normal parameter. It's just
+ // includes the self parameter as a normal parameter. It's just
// that the error messages you get out of this code are a bit more
// inscrutable, particularly for cases where one method has no
// self.
) -> Result<(), ErrorGuaranteed> {
let impl_const_item = tcx.associated_item(impl_const_item_def);
let trait_const_item = tcx.associated_item(trait_const_item_def);
- let impl_trait_ref = tcx.impl_trait_ref(impl_const_item.container_id(tcx)).unwrap();
+ let impl_trait_ref =
+ tcx.impl_trait_ref(impl_const_item.container_id(tcx)).unwrap().subst_identity();
debug!("compare_const_impl(impl_trait_ref={:?})", impl_trait_ref);
let impl_c_span = tcx.def_span(impl_const_item_def.to_def_id());
check_region_bounds_on_impl_item(tcx, impl_ty, trait_ty, false)?;
let impl_ty_own_bounds = impl_ty_predicates.instantiate_own(tcx, impl_substs);
-
- if impl_ty_own_bounds.is_empty() {
+ if impl_ty_own_bounds.len() == 0 {
// Nothing to check.
return Ok(());
}
// associated type in the trait are assumed.
let impl_predicates = tcx.predicates_of(impl_ty_predicates.parent.unwrap());
let mut hybrid_preds = impl_predicates.instantiate_identity(tcx);
- hybrid_preds
- .predicates
- .extend(trait_ty_predicates.instantiate_own(tcx, trait_to_impl_substs).predicates);
+ hybrid_preds.predicates.extend(
+ trait_ty_predicates
+ .instantiate_own(tcx, trait_to_impl_substs)
+ .map(|(predicate, _)| predicate),
+ );
debug!("compare_type_predicate_entailment: bounds={:?}", hybrid_preds);
debug!("compare_type_predicate_entailment: caller_bounds={:?}", param_env.caller_bounds());
- assert_eq!(impl_ty_own_bounds.predicates.len(), impl_ty_own_bounds.spans.len());
- for (span, predicate) in std::iter::zip(impl_ty_own_bounds.spans, impl_ty_own_bounds.predicates)
- {
+ for (predicate, span) in impl_ty_own_bounds {
let cause = ObligationCause::misc(span, impl_ty_hir_id);
let predicate = ocx.normalize(&cause, param_env, predicate);
projects / rust.git / blobdiff