Point at method chains on E0271
errors
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parent
984eab57f7
commit
294944dfec
3 changed files with 138 additions and 89 deletions
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@ -352,6 +352,14 @@ pub trait TypeErrCtxtExt<'tcx> {
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param_env: ty::ParamEnv<'tcx>,
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err: &mut Diagnostic,
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);
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fn probe_assoc_types_at_expr(
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&self,
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type_diffs: &[TypeError<'tcx>],
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span: Span,
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prev_ty: Ty<'tcx>,
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body_id: hir::HirId,
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param_env: ty::ParamEnv<'tcx>,
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) -> Vec<Option<(Span, (DefId, Ty<'tcx>))>>;
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}
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fn predicate_constraint(generics: &hir::Generics<'_>, pred: ty::Predicate<'_>) -> (Span, String) {
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@ -3152,23 +3160,37 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
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if let ObligationCauseCode::ExprBindingObligation(def_id, _, _, idx) = parent_code.deref()
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&& let predicates = self.tcx.predicates_of(def_id).instantiate_identity(self.tcx)
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&& let Some(pred) = predicates.predicates.get(*idx)
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&& let Ok(trait_pred) = pred.kind().try_map_bound(|pred| match pred {
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{
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if let Ok(trait_pred) = pred.kind().try_map_bound(|pred| match pred {
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ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => Ok(trait_pred),
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_ => Err(()),
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})
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{
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let mut c = CollectAllMismatches {
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infcx: self.infcx,
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param_env,
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errors: vec![],
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};
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if let Ok(trait_predicate) = predicate.kind().try_map_bound(|pred| match pred {
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ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => Ok(trait_pred),
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_ => Err(()),
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}) {
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&& let Ok(trait_predicate) = predicate.kind().try_map_bound(|pred| match pred {
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ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => Ok(trait_pred),
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_ => Err(()),
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})
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{
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let mut c = CollectAllMismatches {
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infcx: self.infcx,
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param_env,
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errors: vec![],
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};
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if let Ok(_) = c.relate(trait_pred, trait_predicate) {
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type_diffs = c.errors;
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}
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} else if let ty::PredicateKind::Clause(
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ty::Clause::Projection(proj)
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) = pred.kind().skip_binder()
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&& let ty::PredicateKind::Clause(
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ty::Clause::Projection(projection)
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) = predicate.kind().skip_binder()
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{
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type_diffs = vec![
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Sorts(ty::error::ExpectedFound {
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expected: self.tcx.mk_ty(ty::Alias(ty::Projection, proj.projection_ty)),
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found: projection.term.ty().unwrap(),
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}),
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];
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}
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}
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if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind
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@ -3221,10 +3243,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
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let tcx = self.tcx;
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let mut print_root_expr = true;
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let mut assocs = vec![];
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// We still want to point at the different methods even if there hasn't
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// been a change of assoc type.
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let mut call_spans = vec![];
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let mut expr = expr;
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let mut prev_ty = self.resolve_vars_if_possible(
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typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error()),
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@ -3234,63 +3254,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
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// vec![1, 2, 3].iter().map(mapper).sum<i32>()
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// ^^^^^^ ^^^^^^^^^^^
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expr = rcvr_expr;
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let mut assocs_in_this_method = Vec::with_capacity(type_diffs.len());
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call_spans.push(span);
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let ocx = ObligationCtxt::new_in_snapshot(self.infcx);
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for diff in &type_diffs {
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let Sorts(expected_found) = diff else { continue; };
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let ty::Alias(ty::Projection, proj) = expected_found.expected.kind() else { continue; };
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let origin =
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TypeVariableOrigin { kind: TypeVariableOriginKind::TypeInference, span };
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let trait_def_id = proj.trait_def_id(self.tcx);
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// Make `Self` be equivalent to the type of the call chain
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// expression we're looking at now, so that we can tell what
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// for example `Iterator::Item` is at this point in the chain.
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let substs = InternalSubsts::for_item(self.tcx, trait_def_id, |param, _| {
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match param.kind {
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ty::GenericParamDefKind::Type { .. } => {
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if param.index == 0 {
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return prev_ty.into();
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}
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}
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ty::GenericParamDefKind::Lifetime
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| ty::GenericParamDefKind::Const { .. } => {}
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}
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self.var_for_def(span, param)
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});
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// This will hold the resolved type of the associated type, if the
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// current expression implements the trait that associated type is
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// in. For example, this would be what `Iterator::Item` is here.
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let ty_var = self.infcx.next_ty_var(origin);
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// This corresponds to `<ExprTy as Iterator>::Item = _`.
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let projection = ty::Binder::dummy(ty::PredicateKind::Clause(
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ty::Clause::Projection(ty::ProjectionPredicate {
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projection_ty: tcx.mk_alias_ty(proj.def_id, substs),
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term: ty_var.into(),
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}),
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));
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// Add `<ExprTy as Iterator>::Item = _` obligation.
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ocx.register_obligation(Obligation::misc(
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self.tcx,
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span,
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expr.hir_id,
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param_env,
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projection,
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));
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if ocx.select_where_possible().is_empty() {
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// `ty_var` now holds the type that `Item` is for `ExprTy`.
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let ty_var = self.resolve_vars_if_possible(ty_var);
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assocs_in_this_method.push(Some((span, (proj.def_id, ty_var))));
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} else {
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// `<ExprTy as Iterator>` didn't select, so likely we've
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// reached the end of the iterator chain, like the originating
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// `Vec<_>`.
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// Keep the space consistent for later zipping.
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assocs_in_this_method.push(None);
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}
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}
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let assocs_in_this_method =
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self.probe_assoc_types_at_expr(&type_diffs, span, prev_ty, expr.hir_id, param_env);
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assocs.push(assocs_in_this_method);
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prev_ty = self.resolve_vars_if_possible(
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typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error()),
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@ -3300,17 +3265,32 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
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&& let hir::Path { res: hir::def::Res::Local(hir_id), .. } = path
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&& let Some(hir::Node::Pat(binding)) = self.tcx.hir().find(*hir_id)
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&& let parent_hir_id = self.tcx.hir().get_parent_node(binding.hir_id)
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&& let Some(hir::Node::Local(local)) = self.tcx.hir().find(parent_hir_id)
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&& let Some(binding_expr) = local.init
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&& let Some(parent) = self.tcx.hir().find(parent_hir_id)
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{
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// We've reached the root of the method call chain and it is a
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// binding. Get the binding creation and try to continue the chain.
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expr = binding_expr;
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// We've reached the root of the method call chain...
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if let hir::Node::Local(local) = parent
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&& let Some(binding_expr) = local.init
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{
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// ...and it is a binding. Get the binding creation and continue the chain.
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expr = binding_expr;
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}
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if let hir::Node::Param(param) = parent {
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// ...and it is a an fn argument.
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let prev_ty = self.resolve_vars_if_possible(
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typeck_results.node_type_opt(param.hir_id).unwrap_or(tcx.ty_error()),
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);
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let assocs_in_this_method = self.probe_assoc_types_at_expr(&type_diffs, param.ty_span, prev_ty, param.hir_id, param_env);
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if assocs_in_this_method.iter().any(|a| a.is_some()) {
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assocs.push(assocs_in_this_method);
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print_root_expr = false;
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}
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break;
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}
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}
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}
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// We want the type before deref coercions, otherwise we talk about `&[_]`
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// instead of `Vec<_>`.
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if let Some(ty) = typeck_results.expr_ty_opt(expr) {
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if let Some(ty) = typeck_results.expr_ty_opt(expr) && print_root_expr {
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let ty = with_forced_trimmed_paths!(self.ty_to_string(ty));
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// Point at the root expression
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// vec![1, 2, 3].iter().map(mapper).sum<i32>()
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@ -3324,7 +3304,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
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let Some(prev_assoc_in_method) = assocs.peek() else {
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for entry in assocs_in_method {
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let Some((span, (assoc, ty))) = entry else { continue; };
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if type_diffs.iter().any(|diff| {
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if primary_spans.is_empty() || type_diffs.iter().any(|diff| {
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let Sorts(expected_found) = diff else { return false; };
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self.can_eq(param_env, expected_found.found, ty).is_ok()
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}) {
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@ -3380,13 +3360,6 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
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}
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}
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}
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for span in call_spans {
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if span_labels.iter().find(|(s, _)| *s == span).is_none() {
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// Ensure we are showing the entire chain, even if the assoc types
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// haven't changed.
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span_labels.push((span, String::new()));
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}
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}
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if !primary_spans.is_empty() {
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let mut multi_span: MultiSpan = primary_spans.into();
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for (span, label) in span_labels {
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@ -3394,13 +3367,70 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
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}
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err.span_note(
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multi_span,
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format!(
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"the method call chain might not have had the expected \
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associated types",
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),
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format!("the method call chain might not have had the expected associated types"),
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);
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}
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}
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fn probe_assoc_types_at_expr(
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&self,
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type_diffs: &[TypeError<'tcx>],
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span: Span,
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prev_ty: Ty<'tcx>,
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body_id: hir::HirId,
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param_env: ty::ParamEnv<'tcx>,
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) -> Vec<Option<(Span, (DefId, Ty<'tcx>))>> {
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let ocx = ObligationCtxt::new_in_snapshot(self.infcx);
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let mut assocs_in_this_method = Vec::with_capacity(type_diffs.len());
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for diff in type_diffs {
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let Sorts(expected_found) = diff else { continue; };
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let ty::Alias(ty::Projection, proj) = expected_found.expected.kind() else { continue; };
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let origin = TypeVariableOrigin { kind: TypeVariableOriginKind::TypeInference, span };
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let trait_def_id = proj.trait_def_id(self.tcx);
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// Make `Self` be equivalent to the type of the call chain
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// expression we're looking at now, so that we can tell what
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// for example `Iterator::Item` is at this point in the chain.
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let substs = InternalSubsts::for_item(self.tcx, trait_def_id, |param, _| {
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match param.kind {
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ty::GenericParamDefKind::Type { .. } => {
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if param.index == 0 {
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return prev_ty.into();
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}
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}
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ty::GenericParamDefKind::Lifetime | ty::GenericParamDefKind::Const { .. } => {}
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}
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self.var_for_def(span, param)
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});
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// This will hold the resolved type of the associated type, if the
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// current expression implements the trait that associated type is
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// in. For example, this would be what `Iterator::Item` is here.
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let ty_var = self.infcx.next_ty_var(origin);
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// This corresponds to `<ExprTy as Iterator>::Item = _`.
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let projection = ty::Binder::dummy(ty::PredicateKind::Clause(ty::Clause::Projection(
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ty::ProjectionPredicate {
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projection_ty: self.tcx.mk_alias_ty(proj.def_id, substs),
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term: ty_var.into(),
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},
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)));
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// Add `<ExprTy as Iterator>::Item = _` obligation.
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ocx.register_obligation(Obligation::misc(
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self.tcx, span, body_id, param_env, projection,
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));
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if ocx.select_where_possible().is_empty() {
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// `ty_var` now holds the type that `Item` is for `ExprTy`.
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let ty_var = self.resolve_vars_if_possible(ty_var);
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assocs_in_this_method.push(Some((span, (proj.def_id, ty_var))));
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} else {
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// `<ExprTy as Iterator>` didn't select, so likely we've
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// reached the end of the iterator chain, like the originating
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// `Vec<_>`.
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// Keep the space consistent for later zipping.
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assocs_in_this_method.push(None);
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}
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}
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assocs_in_this_method
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}
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}
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/// Add a hint to add a missing borrow or remove an unnecessary one.
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