--- /dev/null
+use crate::astconv::AstConv;
+use crate::errors::{ManualImplementation, MissingTypeParams};
+use rustc_data_structures::fx::FxHashMap;
+use rustc_errors::{pluralize, struct_span_err, Applicability, ErrorGuaranteed};
+use rustc_hir as hir;
+use rustc_hir::def_id::DefId;
+use rustc_middle::ty;
+use rustc_session::parse::feature_err;
+use rustc_span::lev_distance::find_best_match_for_name;
+use rustc_span::symbol::{sym, Ident};
+use rustc_span::{Span, Symbol, DUMMY_SP};
+
+use std::collections::BTreeSet;
+
+impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
+ /// On missing type parameters, emit an E0393 error and provide a structured suggestion using
+ /// the type parameter's name as a placeholder.
+ pub(crate) fn complain_about_missing_type_params(
+ &self,
+ missing_type_params: Vec<Symbol>,
+ def_id: DefId,
+ span: Span,
+ empty_generic_args: bool,
+ ) {
+ if missing_type_params.is_empty() {
+ return;
+ }
+
+ self.tcx().sess.emit_err(MissingTypeParams {
+ span,
+ def_span: self.tcx().def_span(def_id),
+ span_snippet: self.tcx().sess.source_map().span_to_snippet(span).ok(),
+ missing_type_params,
+ empty_generic_args,
+ });
+ }
+
+ /// When the code is using the `Fn` traits directly, instead of the `Fn(A) -> B` syntax, emit
+ /// an error and attempt to build a reasonable structured suggestion.
+ pub(crate) fn complain_about_internal_fn_trait(
+ &self,
+ span: Span,
+ trait_def_id: DefId,
+ trait_segment: &'_ hir::PathSegment<'_>,
+ is_impl: bool,
+ ) {
+ if self.tcx().features().unboxed_closures {
+ return;
+ }
+
+ let trait_def = self.tcx().trait_def(trait_def_id);
+ if !trait_def.paren_sugar {
+ if trait_segment.args().parenthesized {
+ // For now, require that parenthetical notation be used only with `Fn()` etc.
+ let mut err = feature_err(
+ &self.tcx().sess.parse_sess,
+ sym::unboxed_closures,
+ span,
+ "parenthetical notation is only stable when used with `Fn`-family traits",
+ );
+ err.emit();
+ }
+
+ return;
+ }
+
+ let sess = self.tcx().sess;
+
+ if !trait_segment.args().parenthesized {
+ // For now, require that parenthetical notation be used only with `Fn()` etc.
+ let mut err = feature_err(
+ &sess.parse_sess,
+ sym::unboxed_closures,
+ span,
+ "the precise format of `Fn`-family traits' type parameters is subject to change",
+ );
+ // Do not suggest the other syntax if we are in trait impl:
+ // the desugaring would contain an associated type constraint.
+ if !is_impl {
+ let args = trait_segment
+ .args
+ .as_ref()
+ .and_then(|args| args.args.get(0))
+ .and_then(|arg| match arg {
+ hir::GenericArg::Type(ty) => match ty.kind {
+ hir::TyKind::Tup(t) => t
+ .iter()
+ .map(|e| sess.source_map().span_to_snippet(e.span))
+ .collect::<Result<Vec<_>, _>>()
+ .map(|a| a.join(", ")),
+ _ => sess.source_map().span_to_snippet(ty.span),
+ }
+ .map(|s| format!("({})", s))
+ .ok(),
+ _ => None,
+ })
+ .unwrap_or_else(|| "()".to_string());
+ let ret = trait_segment
+ .args()
+ .bindings
+ .iter()
+ .find_map(|b| match (b.ident.name == sym::Output, &b.kind) {
+ (true, hir::TypeBindingKind::Equality { term }) => {
+ let span = match term {
+ hir::Term::Ty(ty) => ty.span,
+ hir::Term::Const(c) => self.tcx().hir().span(c.hir_id),
+ };
+ sess.source_map().span_to_snippet(span).ok()
+ }
+ _ => None,
+ })
+ .unwrap_or_else(|| "()".to_string());
+ err.span_suggestion(
+ span,
+ "use parenthetical notation instead",
+ format!("{}{} -> {}", trait_segment.ident, args, ret),
+ Applicability::MaybeIncorrect,
+ );
+ }
+ err.emit();
+ }
+
+ if is_impl {
+ let trait_name = self.tcx().def_path_str(trait_def_id);
+ self.tcx().sess.emit_err(ManualImplementation { span, trait_name });
+ }
+ }
+
+ pub(crate) fn complain_about_assoc_type_not_found<I>(
+ &self,
+ all_candidates: impl Fn() -> I,
+ ty_param_name: &str,
+ assoc_name: Ident,
+ span: Span,
+ ) -> ErrorGuaranteed
+ where
+ I: Iterator<Item = ty::PolyTraitRef<'tcx>>,
+ {
+ // The fallback span is needed because `assoc_name` might be an `Fn()`'s `Output` without a
+ // valid span, so we point at the whole path segment instead.
+ let span = if assoc_name.span != DUMMY_SP { assoc_name.span } else { span };
+ let mut err = struct_span_err!(
+ self.tcx().sess,
+ span,
+ E0220,
+ "associated type `{}` not found for `{}`",
+ assoc_name,
+ ty_param_name
+ );
+
+ let all_candidate_names: Vec<_> = all_candidates()
+ .flat_map(|r| self.tcx().associated_items(r.def_id()).in_definition_order())
+ .filter_map(
+ |item| if item.kind == ty::AssocKind::Type { Some(item.name) } else { None },
+ )
+ .collect();
+
+ if let (Some(suggested_name), true) = (
+ find_best_match_for_name(&all_candidate_names, assoc_name.name, None),
+ assoc_name.span != DUMMY_SP,
+ ) {
+ err.span_suggestion(
+ assoc_name.span,
+ "there is an associated type with a similar name",
+ suggested_name,
+ Applicability::MaybeIncorrect,
+ );
+ return err.emit();
+ }
+
+ // If we didn't find a good item in the supertraits (or couldn't get
+ // the supertraits), like in ItemCtxt, then look more generally from
+ // all visible traits. If there's one clear winner, just suggest that.
+
+ let visible_traits: Vec<_> = self
+ .tcx()
+ .all_traits()
+ .filter(|trait_def_id| {
+ let viz = self.tcx().visibility(*trait_def_id);
+ if let Some(def_id) = self.item_def_id() {
+ viz.is_accessible_from(def_id, self.tcx())
+ } else {
+ viz.is_visible_locally()
+ }
+ })
+ .collect();
+
+ let wider_candidate_names: Vec<_> = visible_traits
+ .iter()
+ .flat_map(|trait_def_id| {
+ self.tcx().associated_items(*trait_def_id).in_definition_order()
+ })
+ .filter_map(
+ |item| if item.kind == ty::AssocKind::Type { Some(item.name) } else { None },
+ )
+ .collect();
+
+ if let (Some(suggested_name), true) = (
+ find_best_match_for_name(&wider_candidate_names, assoc_name.name, None),
+ assoc_name.span != DUMMY_SP,
+ ) {
+ if let [best_trait] = visible_traits
+ .iter()
+ .filter(|trait_def_id| {
+ self.tcx()
+ .associated_items(*trait_def_id)
+ .filter_by_name_unhygienic(suggested_name)
+ .any(|item| item.kind == ty::AssocKind::Type)
+ })
+ .collect::<Vec<_>>()[..]
+ {
+ err.span_label(
+ assoc_name.span,
+ format!(
+ "there is a similarly named associated type `{suggested_name}` in the trait `{}`",
+ self.tcx().def_path_str(*best_trait)
+ ),
+ );
+ return err.emit();
+ }
+ }
+
+ err.span_label(span, format!("associated type `{}` not found", assoc_name));
+ err.emit()
+ }
+
+ /// When there are any missing associated types, emit an E0191 error and attempt to supply a
+ /// reasonable suggestion on how to write it. For the case of multiple associated types in the
+ /// same trait bound have the same name (as they come from different supertraits), we instead
+ /// emit a generic note suggesting using a `where` clause to constraint instead.
+ pub(crate) fn complain_about_missing_associated_types(
+ &self,
+ associated_types: FxHashMap<Span, BTreeSet<DefId>>,
+ potential_assoc_types: Vec<Span>,
+ trait_bounds: &[hir::PolyTraitRef<'_>],
+ ) {
+ if associated_types.values().all(|v| v.is_empty()) {
+ return;
+ }
+ let tcx = self.tcx();
+ // FIXME: Marked `mut` so that we can replace the spans further below with a more
+ // appropriate one, but this should be handled earlier in the span assignment.
+ let mut associated_types: FxHashMap<Span, Vec<_>> = associated_types
+ .into_iter()
+ .map(|(span, def_ids)| {
+ (span, def_ids.into_iter().map(|did| tcx.associated_item(did)).collect())
+ })
+ .collect();
+ let mut names = vec![];
+
+ // Account for things like `dyn Foo + 'a`, like in tests `issue-22434.rs` and
+ // `issue-22560.rs`.
+ let mut trait_bound_spans: Vec<Span> = vec![];
+ for (span, items) in &associated_types {
+ if !items.is_empty() {
+ trait_bound_spans.push(*span);
+ }
+ for assoc_item in items {
+ let trait_def_id = assoc_item.container_id(tcx);
+ names.push(format!(
+ "`{}` (from trait `{}`)",
+ assoc_item.name,
+ tcx.def_path_str(trait_def_id),
+ ));
+ }
+ }
+ if let ([], [bound]) = (&potential_assoc_types[..], &trait_bounds) {
+ match bound.trait_ref.path.segments {
+ // FIXME: `trait_ref.path.span` can point to a full path with multiple
+ // segments, even though `trait_ref.path.segments` is of length `1`. Work
+ // around that bug here, even though it should be fixed elsewhere.
+ // This would otherwise cause an invalid suggestion. For an example, look at
+ // `src/test/ui/issues/issue-28344.rs` where instead of the following:
+ //
+ // error[E0191]: the value of the associated type `Output`
+ // (from trait `std::ops::BitXor`) must be specified
+ // --> $DIR/issue-28344.rs:4:17
+ // |
+ // LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8);
+ // | ^^^^^^ help: specify the associated type:
+ // | `BitXor<Output = Type>`
+ //
+ // we would output:
+ //
+ // error[E0191]: the value of the associated type `Output`
+ // (from trait `std::ops::BitXor`) must be specified
+ // --> $DIR/issue-28344.rs:4:17
+ // |
+ // LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8);
+ // | ^^^^^^^^^^^^^ help: specify the associated type:
+ // | `BitXor::bitor<Output = Type>`
+ [segment] if segment.args.is_none() => {
+ trait_bound_spans = vec![segment.ident.span];
+ associated_types = associated_types
+ .into_iter()
+ .map(|(_, items)| (segment.ident.span, items))
+ .collect();
+ }
+ _ => {}
+ }
+ }
+ names.sort();
+ trait_bound_spans.sort();
+ let mut err = struct_span_err!(
+ tcx.sess,
+ trait_bound_spans,
+ E0191,
+ "the value of the associated type{} {} must be specified",
+ pluralize!(names.len()),
+ names.join(", "),
+ );
+ let mut suggestions = vec![];
+ let mut types_count = 0;
+ let mut where_constraints = vec![];
+ let mut already_has_generics_args_suggestion = false;
+ for (span, assoc_items) in &associated_types {
+ let mut names: FxHashMap<_, usize> = FxHashMap::default();
+ for item in assoc_items {
+ types_count += 1;
+ *names.entry(item.name).or_insert(0) += 1;
+ }
+ let mut dupes = false;
+ for item in assoc_items {
+ let prefix = if names[&item.name] > 1 {
+ let trait_def_id = item.container_id(tcx);
+ dupes = true;
+ format!("{}::", tcx.def_path_str(trait_def_id))
+ } else {
+ String::new()
+ };
+ if let Some(sp) = tcx.hir().span_if_local(item.def_id) {
+ err.span_label(sp, format!("`{}{}` defined here", prefix, item.name));
+ }
+ }
+ if potential_assoc_types.len() == assoc_items.len() {
+ // When the amount of missing associated types equals the number of
+ // extra type arguments present. A suggesting to replace the generic args with
+ // associated types is already emitted.
+ already_has_generics_args_suggestion = true;
+ } else if let (Ok(snippet), false) =
+ (tcx.sess.source_map().span_to_snippet(*span), dupes)
+ {
+ let types: Vec<_> =
+ assoc_items.iter().map(|item| format!("{} = Type", item.name)).collect();
+ let code = if snippet.ends_with('>') {
+ // The user wrote `Trait<'a>` or similar and we don't have a type we can
+ // suggest, but at least we can clue them to the correct syntax
+ // `Trait<'a, Item = Type>` while accounting for the `<'a>` in the
+ // suggestion.
+ format!("{}, {}>", &snippet[..snippet.len() - 1], types.join(", "))
+ } else {
+ // The user wrote `Iterator`, so we don't have a type we can suggest, but at
+ // least we can clue them to the correct syntax `Iterator<Item = Type>`.
+ format!("{}<{}>", snippet, types.join(", "))
+ };
+ suggestions.push((*span, code));
+ } else if dupes {
+ where_constraints.push(*span);
+ }
+ }
+ let where_msg = "consider introducing a new type parameter, adding `where` constraints \
+ using the fully-qualified path to the associated types";
+ if !where_constraints.is_empty() && suggestions.is_empty() {
+ // If there are duplicates associated type names and a single trait bound do not
+ // use structured suggestion, it means that there are multiple supertraits with
+ // the same associated type name.
+ err.help(where_msg);
+ }
+ if suggestions.len() != 1 || already_has_generics_args_suggestion {
+ // We don't need this label if there's an inline suggestion, show otherwise.
+ for (span, assoc_items) in &associated_types {
+ let mut names: FxHashMap<_, usize> = FxHashMap::default();
+ for item in assoc_items {
+ types_count += 1;
+ *names.entry(item.name).or_insert(0) += 1;
+ }
+ let mut label = vec![];
+ for item in assoc_items {
+ let postfix = if names[&item.name] > 1 {
+ let trait_def_id = item.container_id(tcx);
+ format!(" (from trait `{}`)", tcx.def_path_str(trait_def_id))
+ } else {
+ String::new()
+ };
+ label.push(format!("`{}`{}", item.name, postfix));
+ }
+ if !label.is_empty() {
+ err.span_label(
+ *span,
+ format!(
+ "associated type{} {} must be specified",
+ pluralize!(label.len()),
+ label.join(", "),
+ ),
+ );
+ }
+ }
+ }
+ if !suggestions.is_empty() {
+ err.multipart_suggestion(
+ &format!("specify the associated type{}", pluralize!(types_count)),
+ suggestions,
+ Applicability::HasPlaceholders,
+ );
+ if !where_constraints.is_empty() {
+ err.span_help(where_constraints, where_msg);
+ }
+ }
+ err.emit();
+ }
+}
projects / rustc.git / blobdiff