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-rw-r--r--compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs700
1 files changed, 700 insertions, 0 deletions
diff --git a/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs b/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs
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index 000000000..b33729d0b
--- /dev/null
+++ b/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs
@@ -0,0 +1,700 @@
+use super::TypeErrCtxt;
+use rustc_errors::Applicability::{MachineApplicable, MaybeIncorrect};
+use rustc_errors::{pluralize, Diagnostic, MultiSpan};
+use rustc_hir::{self as hir, def::DefKind};
+use rustc_middle::traits::ObligationCauseCode;
+use rustc_middle::ty::error::ExpectedFound;
+use rustc_middle::ty::print::Printer;
+use rustc_middle::{
+ traits::ObligationCause,
+ ty::{self, error::TypeError, print::FmtPrinter, suggest_constraining_type_param, Ty},
+};
+use rustc_span::{def_id::DefId, sym, BytePos, Span, Symbol};
+
+impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+ pub fn note_and_explain_type_err(
+ &self,
+ diag: &mut Diagnostic,
+ err: TypeError<'tcx>,
+ cause: &ObligationCause<'tcx>,
+ sp: Span,
+ body_owner_def_id: DefId,
+ ) {
+ use ty::error::TypeError::*;
+ debug!("note_and_explain_type_err err={:?} cause={:?}", err, cause);
+
+ let tcx = self.tcx;
+
+ match err {
+ ArgumentSorts(values, _) | Sorts(values) => {
+ match (values.expected.kind(), values.found.kind()) {
+ (ty::Closure(..), ty::Closure(..)) => {
+ diag.note("no two closures, even if identical, have the same type");
+ diag.help("consider boxing your closure and/or using it as a trait object");
+ }
+ (ty::Alias(ty::Opaque, ..), ty::Alias(ty::Opaque, ..)) => {
+ // Issue #63167
+ diag.note("distinct uses of `impl Trait` result in different opaque types");
+ }
+ (ty::Float(_), ty::Infer(ty::IntVar(_)))
+ if let Ok(
+ // Issue #53280
+ snippet,
+ ) = tcx.sess.source_map().span_to_snippet(sp) =>
+ {
+ if snippet.chars().all(|c| c.is_digit(10) || c == '-' || c == '_') {
+ diag.span_suggestion(
+ sp,
+ "use a float literal",
+ format!("{}.0", snippet),
+ MachineApplicable,
+ );
+ }
+ }
+ (ty::Param(expected), ty::Param(found)) => {
+ let generics = tcx.generics_of(body_owner_def_id);
+ let e_span = tcx.def_span(generics.type_param(expected, tcx).def_id);
+ if !sp.contains(e_span) {
+ diag.span_label(e_span, "expected type parameter");
+ }
+ let f_span = tcx.def_span(generics.type_param(found, tcx).def_id);
+ if !sp.contains(f_span) {
+ diag.span_label(f_span, "found type parameter");
+ }
+ diag.note(
+ "a type parameter was expected, but a different one was found; \
+ you might be missing a type parameter or trait bound",
+ );
+ diag.note(
+ "for more information, visit \
+ https://doc.rust-lang.org/book/ch10-02-traits.html\
+ #traits-as-parameters",
+ );
+ }
+ (ty::Alias(ty::Projection, _), ty::Alias(ty::Projection, _)) => {
+ diag.note("an associated type was expected, but a different one was found");
+ }
+ (ty::Param(p), ty::Alias(ty::Projection, proj)) | (ty::Alias(ty::Projection, proj), ty::Param(p))
+ if tcx.def_kind(proj.def_id) != DefKind::ImplTraitPlaceholder =>
+ {
+ let p_def_id = tcx
+ .generics_of(body_owner_def_id)
+ .type_param(p, tcx)
+ .def_id;
+ let p_span = tcx.def_span(p_def_id);
+ if !sp.contains(p_span) {
+ diag.span_label(p_span, "this type parameter");
+ }
+ let hir = tcx.hir();
+ let mut note = true;
+ let parent = p_def_id
+ .as_local()
+ .and_then(|id| {
+ let local_id = hir.local_def_id_to_hir_id(id);
+ let generics = tcx.hir().find_parent(local_id)?.generics()?;
+ Some((id, generics))
+ });
+ if let Some((local_id, generics)) = parent
+ {
+ // Synthesize the associated type restriction `Add<Output = Expected>`.
+ // FIXME: extract this logic for use in other diagnostics.
+ let (trait_ref, assoc_substs) = proj.trait_ref_and_own_substs(tcx);
+ let item_name = tcx.item_name(proj.def_id);
+ let item_args = self.format_generic_args(assoc_substs);
+
+ // Here, we try to see if there's an existing
+ // trait implementation that matches the one that
+ // we're suggesting to restrict. If so, find the
+ // "end", whether it be at the end of the trait
+ // or the end of the generic arguments.
+ let mut matching_span = None;
+ let mut matched_end_of_args = false;
+ for bound in generics.bounds_for_param(local_id) {
+ let potential_spans = bound
+ .bounds
+ .iter()
+ .find_map(|bound| {
+ let bound_trait_path = bound.trait_ref()?.path;
+ let def_id = bound_trait_path.res.opt_def_id()?;
+ let generic_args = bound_trait_path.segments.iter().last().map(|path| path.args());
+ (def_id == trait_ref.def_id).then_some((bound_trait_path.span, generic_args))
+ });
+
+ if let Some((end_of_trait, end_of_args)) = potential_spans {
+ let args_span = end_of_args.and_then(|args| args.span());
+ matched_end_of_args = args_span.is_some();
+ matching_span = args_span
+ .or_else(|| Some(end_of_trait))
+ .map(|span| span.shrink_to_hi());
+ break;
+ }
+ }
+
+ if matched_end_of_args {
+ // Append suggestion to the end of our args
+ let path = format!(", {}{} = {}",item_name, item_args, p);
+ note = !suggest_constraining_type_param(
+ tcx,
+ generics,
+ diag,
+ &format!("{}", proj.self_ty()),
+ &path,
+ None,
+ matching_span,
+ );
+ } else {
+ // Suggest adding a bound to an existing trait
+ // or if the trait doesn't exist, add the trait
+ // and the suggested bounds.
+ let path = format!("<{}{} = {}>", item_name, item_args, p);
+ note = !suggest_constraining_type_param(
+ tcx,
+ generics,
+ diag,
+ &format!("{}", proj.self_ty()),
+ &path,
+ None,
+ matching_span,
+ );
+ }
+ }
+ if note {
+ diag.note("you might be missing a type parameter or trait bound");
+ }
+ }
+ (ty::Param(p), ty::Dynamic(..) | ty::Alias(ty::Opaque, ..))
+ | (ty::Dynamic(..) | ty::Alias(ty::Opaque, ..), ty::Param(p)) => {
+ let generics = tcx.generics_of(body_owner_def_id);
+ let p_span = tcx.def_span(generics.type_param(p, tcx).def_id);
+ if !sp.contains(p_span) {
+ diag.span_label(p_span, "this type parameter");
+ }
+ diag.help("type parameters must be constrained to match other types");
+ if tcx.sess.teach(&diag.get_code().unwrap()) {
+ diag.help(
+ "given a type parameter `T` and a method `foo`:
+```
+trait Trait<T> { fn foo(&self) -> T; }
+```
+the only ways to implement method `foo` are:
+- constrain `T` with an explicit type:
+```
+impl Trait<String> for X {
+ fn foo(&self) -> String { String::new() }
+}
+```
+- add a trait bound to `T` and call a method on that trait that returns `Self`:
+```
+impl<T: std::default::Default> Trait<T> for X {
+ fn foo(&self) -> T { <T as std::default::Default>::default() }
+}
+```
+- change `foo` to return an argument of type `T`:
+```
+impl<T> Trait<T> for X {
+ fn foo(&self, x: T) -> T { x }
+}
+```",
+ );
+ }
+ diag.note(
+ "for more information, visit \
+ https://doc.rust-lang.org/book/ch10-02-traits.html\
+ #traits-as-parameters",
+ );
+ }
+ (ty::Param(p), ty::Closure(..) | ty::Generator(..)) => {
+ let generics = tcx.generics_of(body_owner_def_id);
+ let p_span = tcx.def_span(generics.type_param(p, tcx).def_id);
+ if !sp.contains(p_span) {
+ diag.span_label(p_span, "this type parameter");
+ }
+ diag.help(&format!(
+ "every closure has a distinct type and so could not always match the \
+ caller-chosen type of parameter `{}`",
+ p
+ ));
+ }
+ (ty::Param(p), _) | (_, ty::Param(p)) => {
+ let generics = tcx.generics_of(body_owner_def_id);
+ let p_span = tcx.def_span(generics.type_param(p, tcx).def_id);
+ if !sp.contains(p_span) {
+ diag.span_label(p_span, "this type parameter");
+ }
+ }
+ (ty::Alias(ty::Projection, proj_ty), _) if tcx.def_kind(proj_ty.def_id) != DefKind::ImplTraitPlaceholder => {
+ self.expected_projection(
+ diag,
+ proj_ty,
+ values,
+ body_owner_def_id,
+ cause.code(),
+ );
+ }
+ (_, ty::Alias(ty::Projection, proj_ty)) if tcx.def_kind(proj_ty.def_id) != DefKind::ImplTraitPlaceholder => {
+ let msg = format!(
+ "consider constraining the associated type `{}` to `{}`",
+ values.found, values.expected,
+ );
+ if !(self.suggest_constraining_opaque_associated_type(
+ diag,
+ &msg,
+ proj_ty,
+ values.expected,
+ ) || self.suggest_constraint(
+ diag,
+ &msg,
+ body_owner_def_id,
+ proj_ty,
+ values.expected,
+ )) {
+ diag.help(&msg);
+ diag.note(
+ "for more information, visit \
+ https://doc.rust-lang.org/book/ch19-03-advanced-traits.html",
+ );
+ }
+ }
+ (ty::FnPtr(_), ty::FnDef(def, _))
+ if let hir::def::DefKind::Fn = tcx.def_kind(def) => {
+ diag.note(
+ "when the arguments and return types match, functions can be coerced \
+ to function pointers",
+ );
+ }
+ _ => {}
+ }
+ debug!(
+ "note_and_explain_type_err expected={:?} ({:?}) found={:?} ({:?})",
+ values.expected,
+ values.expected.kind(),
+ values.found,
+ values.found.kind(),
+ );
+ }
+ CyclicTy(ty) => {
+ // Watch out for various cases of cyclic types and try to explain.
+ if ty.is_closure() || ty.is_generator() {
+ diag.note(
+ "closures cannot capture themselves or take themselves as argument;\n\
+ this error may be the result of a recent compiler bug-fix,\n\
+ see issue #46062 <https://github.com/rust-lang/rust/issues/46062>\n\
+ for more information",
+ );
+ }
+ }
+ TargetFeatureCast(def_id) => {
+ let target_spans = tcx.get_attrs(def_id, sym::target_feature).map(|attr| attr.span);
+ diag.note(
+ "functions with `#[target_feature]` can only be coerced to `unsafe` function pointers"
+ );
+ diag.span_labels(target_spans, "`#[target_feature]` added here");
+ }
+ _ => {}
+ }
+ }
+
+ fn suggest_constraint(
+ &self,
+ diag: &mut Diagnostic,
+ msg: &str,
+ body_owner_def_id: DefId,
+ proj_ty: &ty::AliasTy<'tcx>,
+ ty: Ty<'tcx>,
+ ) -> bool {
+ let tcx = self.tcx;
+ let assoc = tcx.associated_item(proj_ty.def_id);
+ let (trait_ref, assoc_substs) = proj_ty.trait_ref_and_own_substs(tcx);
+ if let Some(item) = tcx.hir().get_if_local(body_owner_def_id) {
+ if let Some(hir_generics) = item.generics() {
+ // Get the `DefId` for the type parameter corresponding to `A` in `<A as T>::Foo`.
+ // This will also work for `impl Trait`.
+ let def_id = if let ty::Param(param_ty) = proj_ty.self_ty().kind() {
+ let generics = tcx.generics_of(body_owner_def_id);
+ generics.type_param(param_ty, tcx).def_id
+ } else {
+ return false;
+ };
+ let Some(def_id) = def_id.as_local() else {
+ return false;
+ };
+
+ // First look in the `where` clause, as this might be
+ // `fn foo<T>(x: T) where T: Trait`.
+ for pred in hir_generics.bounds_for_param(def_id) {
+ if self.constrain_generic_bound_associated_type_structured_suggestion(
+ diag,
+ &trait_ref,
+ pred.bounds,
+ assoc,
+ assoc_substs,
+ ty,
+ msg,
+ false,
+ ) {
+ return true;
+ }
+ }
+ }
+ }
+ false
+ }
+
+ /// An associated type was expected and a different type was found.
+ ///
+ /// We perform a few different checks to see what we can suggest:
+ ///
+ /// - In the current item, look for associated functions that return the expected type and
+ /// suggest calling them. (Not a structured suggestion.)
+ /// - If any of the item's generic bounds can be constrained, we suggest constraining the
+ /// associated type to the found type.
+ /// - If the associated type has a default type and was expected inside of a `trait`, we
+ /// mention that this is disallowed.
+ /// - If all other things fail, and the error is not because of a mismatch between the `trait`
+ /// and the `impl`, we provide a generic `help` to constrain the assoc type or call an assoc
+ /// fn that returns the type.
+ fn expected_projection(
+ &self,
+ diag: &mut Diagnostic,
+ proj_ty: &ty::AliasTy<'tcx>,
+ values: ExpectedFound<Ty<'tcx>>,
+ body_owner_def_id: DefId,
+ cause_code: &ObligationCauseCode<'_>,
+ ) {
+ let tcx = self.tcx;
+
+ let msg = format!(
+ "consider constraining the associated type `{}` to `{}`",
+ values.expected, values.found
+ );
+ let body_owner = tcx.hir().get_if_local(body_owner_def_id);
+ let current_method_ident = body_owner.and_then(|n| n.ident()).map(|i| i.name);
+
+ // We don't want to suggest calling an assoc fn in a scope where that isn't feasible.
+ let callable_scope = matches!(
+ body_owner,
+ Some(
+ hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(..), .. })
+ | hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. })
+ | hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }),
+ )
+ );
+ let impl_comparison =
+ matches!(cause_code, ObligationCauseCode::CompareImplItemObligation { .. });
+ let assoc = tcx.associated_item(proj_ty.def_id);
+ if !callable_scope || impl_comparison {
+ // We do not want to suggest calling functions when the reason of the
+ // type error is a comparison of an `impl` with its `trait` or when the
+ // scope is outside of a `Body`.
+ } else {
+ // If we find a suitable associated function that returns the expected type, we don't
+ // want the more general suggestion later in this method about "consider constraining
+ // the associated type or calling a method that returns the associated type".
+ let point_at_assoc_fn = self.point_at_methods_that_satisfy_associated_type(
+ diag,
+ assoc.container_id(tcx),
+ current_method_ident,
+ proj_ty.def_id,
+ values.expected,
+ );
+ // Possibly suggest constraining the associated type to conform to the
+ // found type.
+ if self.suggest_constraint(diag, &msg, body_owner_def_id, proj_ty, values.found)
+ || point_at_assoc_fn
+ {
+ return;
+ }
+ }
+
+ self.suggest_constraining_opaque_associated_type(diag, &msg, proj_ty, values.found);
+
+ if self.point_at_associated_type(diag, body_owner_def_id, values.found) {
+ return;
+ }
+
+ if !impl_comparison {
+ // Generic suggestion when we can't be more specific.
+ if callable_scope {
+ diag.help(&format!(
+ "{} or calling a method that returns `{}`",
+ msg, values.expected
+ ));
+ } else {
+ diag.help(&msg);
+ }
+ diag.note(
+ "for more information, visit \
+ https://doc.rust-lang.org/book/ch19-03-advanced-traits.html",
+ );
+ }
+ if tcx.sess.teach(&diag.get_code().unwrap()) {
+ diag.help(
+ "given an associated type `T` and a method `foo`:
+```
+trait Trait {
+type T;
+fn foo(&self) -> Self::T;
+}
+```
+the only way of implementing method `foo` is to constrain `T` with an explicit associated type:
+```
+impl Trait for X {
+type T = String;
+fn foo(&self) -> Self::T { String::new() }
+}
+```",
+ );
+ }
+ }
+
+ /// When the expected `impl Trait` is not defined in the current item, it will come from
+ /// a return type. This can occur when dealing with `TryStream` (#71035).
+ fn suggest_constraining_opaque_associated_type(
+ &self,
+ diag: &mut Diagnostic,
+ msg: &str,
+ proj_ty: &ty::AliasTy<'tcx>,
+ ty: Ty<'tcx>,
+ ) -> bool {
+ let tcx = self.tcx;
+
+ let assoc = tcx.associated_item(proj_ty.def_id);
+ if let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = *proj_ty.self_ty().kind() {
+ let opaque_local_def_id = def_id.as_local();
+ let opaque_hir_ty = if let Some(opaque_local_def_id) = opaque_local_def_id {
+ match &tcx.hir().expect_item(opaque_local_def_id).kind {
+ hir::ItemKind::OpaqueTy(opaque_hir_ty) => opaque_hir_ty,
+ _ => bug!("The HirId comes from a `ty::Opaque`"),
+ }
+ } else {
+ return false;
+ };
+
+ let (trait_ref, assoc_substs) = proj_ty.trait_ref_and_own_substs(tcx);
+
+ self.constrain_generic_bound_associated_type_structured_suggestion(
+ diag,
+ &trait_ref,
+ opaque_hir_ty.bounds,
+ assoc,
+ assoc_substs,
+ ty,
+ msg,
+ true,
+ )
+ } else {
+ false
+ }
+ }
+
+ fn point_at_methods_that_satisfy_associated_type(
+ &self,
+ diag: &mut Diagnostic,
+ assoc_container_id: DefId,
+ current_method_ident: Option<Symbol>,
+ proj_ty_item_def_id: DefId,
+ expected: Ty<'tcx>,
+ ) -> bool {
+ let tcx = self.tcx;
+
+ let items = tcx.associated_items(assoc_container_id);
+ // Find all the methods in the trait that could be called to construct the
+ // expected associated type.
+ // FIXME: consider suggesting the use of associated `const`s.
+ let methods: Vec<(Span, String)> = items
+ .in_definition_order()
+ .filter(|item| {
+ ty::AssocKind::Fn == item.kind
+ && Some(item.name) != current_method_ident
+ && !tcx.is_doc_hidden(item.def_id)
+ })
+ .filter_map(|item| {
+ let method = tcx.fn_sig(item.def_id).subst_identity();
+ match *method.output().skip_binder().kind() {
+ ty::Alias(ty::Projection, ty::AliasTy { def_id: item_def_id, .. })
+ if item_def_id == proj_ty_item_def_id =>
+ {
+ Some((
+ tcx.def_span(item.def_id),
+ format!("consider calling `{}`", tcx.def_path_str(item.def_id)),
+ ))
+ }
+ _ => None,
+ }
+ })
+ .collect();
+ if !methods.is_empty() {
+ // Use a single `help:` to show all the methods in the trait that can
+ // be used to construct the expected associated type.
+ let mut span: MultiSpan =
+ methods.iter().map(|(sp, _)| *sp).collect::<Vec<Span>>().into();
+ let msg = format!(
+ "{some} method{s} {are} available that return{r} `{ty}`",
+ some = if methods.len() == 1 { "a" } else { "some" },
+ s = pluralize!(methods.len()),
+ are = pluralize!("is", methods.len()),
+ r = if methods.len() == 1 { "s" } else { "" },
+ ty = expected
+ );
+ for (sp, label) in methods.into_iter() {
+ span.push_span_label(sp, label);
+ }
+ diag.span_help(span, &msg);
+ return true;
+ }
+ false
+ }
+
+ fn point_at_associated_type(
+ &self,
+ diag: &mut Diagnostic,
+ body_owner_def_id: DefId,
+ found: Ty<'tcx>,
+ ) -> bool {
+ let tcx = self.tcx;
+
+ let Some(hir_id) = body_owner_def_id.as_local() else {
+ return false;
+ };
+ let hir_id = tcx.hir().local_def_id_to_hir_id(hir_id);
+ // When `body_owner` is an `impl` or `trait` item, look in its associated types for
+ // `expected` and point at it.
+ let parent_id = tcx.hir().get_parent_item(hir_id);
+ let item = tcx.hir().find_by_def_id(parent_id.def_id);
+
+ debug!("expected_projection parent item {:?}", item);
+
+ let param_env = tcx.param_env(body_owner_def_id);
+
+ match item {
+ Some(hir::Node::Item(hir::Item { kind: hir::ItemKind::Trait(.., items), .. })) => {
+ // FIXME: account for `#![feature(specialization)]`
+ for item in &items[..] {
+ match item.kind {
+ hir::AssocItemKind::Type => {
+ // FIXME: account for returning some type in a trait fn impl that has
+ // an assoc type as a return type (#72076).
+ if let hir::Defaultness::Default { has_value: true } =
+ tcx.impl_defaultness(item.id.owner_id)
+ {
+ let assoc_ty = tcx.type_of(item.id.owner_id).subst_identity();
+ if self.infcx.can_eq(param_env, assoc_ty, found) {
+ diag.span_label(
+ item.span,
+ "associated type defaults can't be assumed inside the \
+ trait defining them",
+ );
+ return true;
+ }
+ }
+ }
+ _ => {}
+ }
+ }
+ }
+ Some(hir::Node::Item(hir::Item {
+ kind: hir::ItemKind::Impl(hir::Impl { items, .. }),
+ ..
+ })) => {
+ for item in &items[..] {
+ if let hir::AssocItemKind::Type = item.kind {
+ let assoc_ty = tcx.type_of(item.id.owner_id).subst_identity();
+
+ if self.infcx.can_eq(param_env, assoc_ty, found) {
+ diag.span_label(item.span, "expected this associated type");
+ return true;
+ }
+ }
+ }
+ }
+ _ => {}
+ }
+ false
+ }
+
+ /// Given a slice of `hir::GenericBound`s, if any of them corresponds to the `trait_ref`
+ /// requirement, provide a structured suggestion to constrain it to a given type `ty`.
+ ///
+ /// `is_bound_surely_present` indicates whether we know the bound we're looking for is
+ /// inside `bounds`. If that's the case then we can consider `bounds` containing only one
+ /// trait bound as the one we're looking for. This can help in cases where the associated
+ /// type is defined on a supertrait of the one present in the bounds.
+ fn constrain_generic_bound_associated_type_structured_suggestion(
+ &self,
+ diag: &mut Diagnostic,
+ trait_ref: &ty::TraitRef<'tcx>,
+ bounds: hir::GenericBounds<'_>,
+ assoc: ty::AssocItem,
+ assoc_substs: &[ty::GenericArg<'tcx>],
+ ty: Ty<'tcx>,
+ msg: &str,
+ is_bound_surely_present: bool,
+ ) -> bool {
+ // FIXME: we would want to call `resolve_vars_if_possible` on `ty` before suggesting.
+
+ let trait_bounds = bounds.iter().filter_map(|bound| match bound {
+ hir::GenericBound::Trait(ptr, hir::TraitBoundModifier::None) => Some(ptr),
+ _ => None,
+ });
+
+ let matching_trait_bounds = trait_bounds
+ .clone()
+ .filter(|ptr| ptr.trait_ref.trait_def_id() == Some(trait_ref.def_id))
+ .collect::<Vec<_>>();
+
+ let span = match &matching_trait_bounds[..] {
+ &[ptr] => ptr.span,
+ &[] if is_bound_surely_present => match &trait_bounds.collect::<Vec<_>>()[..] {
+ &[ptr] => ptr.span,
+ _ => return false,
+ },
+ _ => return false,
+ };
+
+ self.constrain_associated_type_structured_suggestion(
+ diag,
+ span,
+ assoc,
+ assoc_substs,
+ ty,
+ msg,
+ )
+ }
+
+ /// Given a span corresponding to a bound, provide a structured suggestion to set an
+ /// associated type to a given type `ty`.
+ fn constrain_associated_type_structured_suggestion(
+ &self,
+ diag: &mut Diagnostic,
+ span: Span,
+ assoc: ty::AssocItem,
+ assoc_substs: &[ty::GenericArg<'tcx>],
+ ty: Ty<'tcx>,
+ msg: &str,
+ ) -> bool {
+ let tcx = self.tcx;
+
+ if let Ok(has_params) =
+ tcx.sess.source_map().span_to_snippet(span).map(|snippet| snippet.ends_with('>'))
+ {
+ let (span, sugg) = if has_params {
+ let pos = span.hi() - BytePos(1);
+ let span = Span::new(pos, pos, span.ctxt(), span.parent());
+ (span, format!(", {} = {}", assoc.ident(tcx), ty))
+ } else {
+ let item_args = self.format_generic_args(assoc_substs);
+ (span.shrink_to_hi(), format!("<{}{} = {}>", assoc.ident(tcx), item_args, ty))
+ };
+ diag.span_suggestion_verbose(span, msg, sugg, MaybeIncorrect);
+ return true;
+ }
+ false
+ }
+
+ pub fn format_generic_args(&self, args: &[ty::GenericArg<'tcx>]) -> String {
+ FmtPrinter::new(self.tcx, hir::def::Namespace::TypeNS)
+ .path_generic_args(Ok, args)
+ .expect("could not write to `String`.")
+ .into_buffer()
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-21 10:09:08 +0000