Const generic parameters aren't bounds, even if we end up erroring because of the bound that binds the parameter's type
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Oli Scherer
parent
1cb75dc4a9
commit
e4c9a8cf9b
19 changed files with 146 additions and 128 deletions
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@ -2776,97 +2776,115 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
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let mut this = "this bound";
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let mut note = None;
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let mut help = None;
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if let ty::PredicateKind::Clause(clause) = predicate.kind().skip_binder()
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&& let ty::ClauseKind::Trait(trait_pred) = clause
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{
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let def_id = trait_pred.def_id();
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let visible_item = if let Some(local) = def_id.as_local() {
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// Check for local traits being reachable.
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let vis = &tcx.resolutions(()).effective_visibilities;
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// Account for non-`pub` traits in the root of the local crate.
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let is_locally_reachable = tcx.parent(def_id).is_crate_root();
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vis.is_reachable(local) || is_locally_reachable
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} else {
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// Check for foreign traits being reachable.
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tcx.visible_parent_map(()).get(&def_id).is_some()
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};
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if tcx.is_lang_item(def_id, LangItem::Sized) {
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// Check if this is an implicit bound, even in foreign crates.
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if tcx
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.generics_of(item_def_id)
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.own_params
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.iter()
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.any(|param| tcx.def_span(param.def_id) == span)
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{
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a = "an implicit `Sized`";
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this = "the implicit `Sized` requirement on this type parameter";
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}
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if let Some(hir::Node::TraitItem(hir::TraitItem {
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generics,
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kind: hir::TraitItemKind::Type(bounds, None),
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..
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})) = tcx.hir().get_if_local(item_def_id)
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// Do not suggest relaxing if there is an explicit `Sized` obligation.
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&& !bounds.iter()
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.filter_map(|bound| bound.trait_ref())
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.any(|tr| tr.trait_def_id() == tcx.lang_items().sized_trait())
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{
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let (span, separator) = if let [.., last] = bounds {
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(last.span().shrink_to_hi(), " +")
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if let ty::PredicateKind::Clause(clause) = predicate.kind().skip_binder() {
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match clause {
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ty::ClauseKind::Trait(trait_pred) => {
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let def_id = trait_pred.def_id();
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let visible_item = if let Some(local) = def_id.as_local() {
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// Check for local traits being reachable.
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let vis = &tcx.resolutions(()).effective_visibilities;
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// Account for non-`pub` traits in the root of the local crate.
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let is_locally_reachable = tcx.parent(def_id).is_crate_root();
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vis.is_reachable(local) || is_locally_reachable
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} else {
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(generics.span.shrink_to_hi(), ":")
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// Check for foreign traits being reachable.
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tcx.visible_parent_map(()).get(&def_id).is_some()
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};
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err.span_suggestion_verbose(
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span,
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"consider relaxing the implicit `Sized` restriction",
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format!("{separator} ?Sized"),
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Applicability::MachineApplicable,
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);
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if tcx.is_lang_item(def_id, LangItem::Sized) {
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// Check if this is an implicit bound, even in foreign crates.
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if tcx
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.generics_of(item_def_id)
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.own_params
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.iter()
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.any(|param| tcx.def_span(param.def_id) == span)
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{
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a = "an implicit `Sized`";
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this =
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"the implicit `Sized` requirement on this type parameter";
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}
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if let Some(hir::Node::TraitItem(hir::TraitItem {
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generics,
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kind: hir::TraitItemKind::Type(bounds, None),
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..
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})) = tcx.hir().get_if_local(item_def_id)
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// Do not suggest relaxing if there is an explicit `Sized` obligation.
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&& !bounds.iter()
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.filter_map(|bound| bound.trait_ref())
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.any(|tr| tr.trait_def_id() == tcx.lang_items().sized_trait())
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{
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let (span, separator) = if let [.., last] = bounds {
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(last.span().shrink_to_hi(), " +")
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} else {
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(generics.span.shrink_to_hi(), ":")
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};
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err.span_suggestion_verbose(
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span,
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"consider relaxing the implicit `Sized` restriction",
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format!("{separator} ?Sized"),
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Applicability::MachineApplicable,
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);
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}
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}
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if let DefKind::Trait = tcx.def_kind(item_def_id)
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&& !visible_item
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{
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note = Some(format!(
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"`{short_item_name}` is a \"sealed trait\", because to implement it \
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you also need to implement `{}`, which is not accessible; this is \
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usually done to force you to use one of the provided types that \
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already implement it",
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with_no_trimmed_paths!(tcx.def_path_str(def_id)),
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));
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let impls_of = tcx.trait_impls_of(def_id);
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let impls = impls_of
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.non_blanket_impls()
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.values()
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.flatten()
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.chain(impls_of.blanket_impls().iter())
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.collect::<Vec<_>>();
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if !impls.is_empty() {
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let len = impls.len();
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let mut types = impls
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.iter()
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.map(|t| {
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with_no_trimmed_paths!(format!(
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" {}",
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tcx.type_of(*t).instantiate_identity(),
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))
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})
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.collect::<Vec<_>>();
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let post = if types.len() > 9 {
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types.truncate(8);
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format!("\nand {} others", len - 8)
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} else {
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String::new()
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};
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help = Some(format!(
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"the following type{} implement{} the trait:\n{}{post}",
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pluralize!(len),
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if len == 1 { "s" } else { "" },
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types.join("\n"),
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));
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}
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}
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}
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}
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if let DefKind::Trait = tcx.def_kind(item_def_id)
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&& !visible_item
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{
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note = Some(format!(
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"`{short_item_name}` is a \"sealed trait\", because to implement it \
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you also need to implement `{}`, which is not accessible; this is \
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usually done to force you to use one of the provided types that \
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already implement it",
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with_no_trimmed_paths!(tcx.def_path_str(def_id)),
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));
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let impls_of = tcx.trait_impls_of(def_id);
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let impls = impls_of
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.non_blanket_impls()
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.values()
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.flatten()
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.chain(impls_of.blanket_impls().iter())
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.collect::<Vec<_>>();
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if !impls.is_empty() {
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let len = impls.len();
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let mut types = impls
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.iter()
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.map(|t| {
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with_no_trimmed_paths!(format!(
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" {}",
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tcx.type_of(*t).instantiate_identity(),
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))
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})
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.collect::<Vec<_>>();
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let post = if types.len() > 9 {
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types.truncate(8);
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format!("\nand {} others", len - 8)
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ty::ClauseKind::ConstArgHasType(..) => {
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let descr =
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format!("required by a const generic parameter in `{item_name}`");
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if span.is_visible(sm) {
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let msg = format!(
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"required by this const generic parameter in `{short_item_name}`"
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);
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multispan.push_span_label(span, msg);
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err.span_note(multispan, descr);
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} else {
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String::new()
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};
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help = Some(format!(
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"the following type{} implement{} the trait:\n{}{post}",
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pluralize!(len),
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if len == 1 { "s" } else { "" },
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types.join("\n"),
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));
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err.span_note(tcx.def_span(item_def_id), descr);
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}
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return;
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}
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_ => (),
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}
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};
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}
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let descr = format!("required by {a} bound in `{item_name}`");
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if span.is_visible(sm) {
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let msg = format!("required by {this} in `{short_item_name}`");
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