Rollup merge of #116257 - estebank:issue-101351, r=b-naber
Suggest trait bounds for used associated type on type param Fix #101351. When an associated type on a type parameter is used, and the type parameter isn't constrained by the correct trait, suggest the appropriate trait bound: ``` error[E0220]: associated type `Associated` not found for `T` --> file.rs:6:15 | 6 | field: T::Associated, | ^^^^^^^^^^ there is a similarly named associated type `Associated` in the trait `Foo` | help: consider restricting type parameter `T` | 5 | struct Generic<T: Foo> { | +++++ ``` When an associated type on a type parameter has a typo, suggest fixing it: ``` error[E0220]: associated type `Baa` not found for `T` --> $DIR/issue-55673.rs:9:8 | LL | T::Baa: std::fmt::Debug, | ^^^ there is a similarly named associated type `Bar` in the trait `Foo` | help: change the associated type name to use `Bar` from `Foo` | LL | T::Bar: std::fmt::Debug, | ~~~ ```
This commit is contained in:
Matthias Krüger
GitHub
commit
14663e09b7
12 changed files with 152 additions and 23 deletions
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@ -284,6 +284,7 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
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self.one_bound_for_assoc_type(
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|| traits::supertraits(tcx, trait_ref),
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trait_ref.skip_binder().print_only_trait_name(),
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None,
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binding.item_name,
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path_span,
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match binding.kind {
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@ -6,10 +6,9 @@ use crate::errors::{
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use rustc_data_structures::fx::FxHashMap;
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use rustc_errors::{pluralize, struct_span_err, Applicability, Diagnostic, ErrorGuaranteed};
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use rustc_hir as hir;
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use rustc_hir::def_id::DefId;
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use rustc_hir::def_id::{DefId, LocalDefId};
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use rustc_infer::traits::FulfillmentError;
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use rustc_middle::ty::TyCtxt;
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use rustc_middle::ty::{self, Ty};
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use rustc_middle::ty::{self, suggest_constraining_type_param, Ty, TyCtxt};
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use rustc_session::parse::feature_err;
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use rustc_span::edit_distance::find_best_match_for_name;
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use rustc_span::symbol::{sym, Ident};
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@ -102,6 +101,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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&self,
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all_candidates: impl Fn() -> I,
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ty_param_name: &str,
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ty_param_def_id: Option<LocalDefId>,
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assoc_name: Ident,
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span: Span,
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) -> ErrorGuaranteed
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@ -190,13 +190,61 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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})
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.collect::<Vec<_>>()[..]
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{
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let trait_name = self.tcx().def_path_str(*best_trait);
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let an = if suggested_name != assoc_name.name { "a similarly named" } else { "an" };
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err.span_label(
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assoc_name.span,
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format!(
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"there is a similarly named associated type `{suggested_name}` in the trait `{}`",
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self.tcx().def_path_str(*best_trait)
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"there is {an} associated type `{suggested_name}` in the \
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trait `{trait_name}`",
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),
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);
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let hir = self.tcx().hir();
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if let Some(def_id) = ty_param_def_id
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&& let parent = hir.get_parent_item(hir.local_def_id_to_hir_id(def_id))
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&& let Some(generics) = hir.get_generics(parent.def_id)
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{
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if generics.bounds_for_param(def_id)
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.flat_map(|pred| pred.bounds.iter())
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.any(|b| match b {
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hir::GenericBound::Trait(t, ..) => {
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t.trait_ref.trait_def_id().as_ref() == Some(best_trait)
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}
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_ => false,
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})
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{
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// The type param already has a bound for `trait_name`, we just need to
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// change the associated type.
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err.span_suggestion_verbose(
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assoc_name.span,
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format!(
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"change the associated type name to use `{suggested_name}` from \
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`{trait_name}`",
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),
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suggested_name.to_string(),
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Applicability::MaybeIncorrect,
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);
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} else if suggest_constraining_type_param(
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self.tcx(),
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generics,
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&mut err,
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&ty_param_name,
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&trait_name,
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None,
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None,
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)
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&& suggested_name != assoc_name.name
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{
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// We suggested constraining a type parameter, but the associated type on it
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// was also not an exact match, so we also suggest changing it.
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err.span_suggestion_verbose(
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assoc_name.span,
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"and also change the associated type name",
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suggested_name.to_string(),
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Applicability::MaybeIncorrect,
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);
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}
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}
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return err.emit();
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}
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}
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@ -1062,6 +1062,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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)
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},
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param_name,
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Some(ty_param_def_id),
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assoc_name,
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span,
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None,
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@ -1075,6 +1076,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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&self,
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all_candidates: impl Fn() -> I,
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ty_param_name: impl Display,
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ty_param_def_id: Option<LocalDefId>,
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assoc_name: Ident,
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span: Span,
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is_equality: Option<ty::Term<'tcx>>,
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@ -1096,6 +1098,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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let reported = self.complain_about_assoc_type_not_found(
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all_candidates,
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&ty_param_name.to_string(),
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ty_param_def_id,
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assoc_name,
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span,
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);
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@ -1143,30 +1146,26 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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err.span_label(
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bound_span,
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format!(
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"ambiguous `{}` from `{}`",
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assoc_name,
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"ambiguous `{assoc_name}` from `{}`",
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bound.print_only_trait_path(),
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),
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);
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if let Some(constraint) = &is_equality {
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where_bounds.push(format!(
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" T: {trait}::{assoc} = {constraint}",
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" T: {trait}::{assoc_name} = {constraint}",
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trait=bound.print_only_trait_path(),
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assoc=assoc_name,
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constraint=constraint,
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));
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} else {
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err.span_suggestion_verbose(
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span.with_hi(assoc_name.span.lo()),
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"use fully qualified syntax to disambiguate",
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format!("<{} as {}>::", ty_param_name, bound.print_only_trait_path()),
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format!("<{ty_param_name} as {}>::", bound.print_only_trait_path()),
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Applicability::MaybeIncorrect,
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);
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}
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} else {
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err.note(format!(
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"associated type `{}` could derive from `{}`",
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ty_param_name,
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"associated type `{ty_param_name}` could derive from `{}`",
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bound.print_only_trait_path(),
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));
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}
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@ -1174,8 +1173,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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if !where_bounds.is_empty() {
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err.help(format!(
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"consider introducing a new type parameter `T` and adding `where` constraints:\
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\n where\n T: {},\n{}",
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ty_param_name,
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\n where\n T: {ty_param_name},\n{}",
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where_bounds.join(",\n"),
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));
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}
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@ -1397,6 +1395,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
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)
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},
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kw::SelfUpper,
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None,
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assoc_ident,
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span,
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None,
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