review comments
This commit is contained in:
Esteban Küber
parent
806476c840
commit
6c3a98e029
1 changed files with 73 additions and 64 deletions
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@ -24,8 +24,8 @@ impl<'a, 'tcx> FindLocalByTypeVisitor<'a, 'tcx> {
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infcx: &'a InferCtxt<'a, 'tcx>,
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target_ty: Ty<'tcx>,
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hir_map: &'a hir::map::Map<'tcx>,
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) -> FindLocalByTypeVisitor<'a, 'tcx> {
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FindLocalByTypeVisitor {
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) -> Self {
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Self {
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infcx,
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target_ty,
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hir_map,
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@ -101,6 +101,50 @@ impl<'a, 'tcx> Visitor<'tcx> for FindLocalByTypeVisitor<'a, 'tcx> {
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}
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}
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/// Suggest giving an appropriate return type to a closure expression.
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fn closure_return_type_suggestion(
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span: Span,
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err: &mut DiagnosticBuilder<'_>,
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output: &FunctionRetTy,
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body: &Body,
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name: &str,
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ret: &str,
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) {
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let (arrow, post) = match output {
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FunctionRetTy::DefaultReturn(_) => ("-> ", " "),
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_ => ("", ""),
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};
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let suggestion = match body.value.node {
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ExprKind::Block(..) => {
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vec![(output.span(), format!("{}{}{}", arrow, ret, post))]
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}
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_ => {
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vec![
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(output.span(), format!("{}{}{}{{ ", arrow, ret, post)),
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(body.value.span.shrink_to_hi(), " }".to_string()),
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]
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}
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};
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err.multipart_suggestion(
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"give this closure an explicit return type without `_` placeholders",
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suggestion,
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Applicability::HasPlaceholders,
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);
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err.span_label(span, InferCtxt::missing_type_msg(&name));
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}
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/// Given a closure signature, return a `String` containing a list of all its argument types.
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fn closure_args(fn_sig: &ty::PolyFnSig<'_>) -> String {
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fn_sig.inputs()
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.skip_binder()
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.iter()
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.next()
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.map(|args| args.tuple_fields()
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.map(|arg| arg.to_string())
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.collect::<Vec<_>>().join(", "))
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.unwrap_or_default()
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}
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impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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pub fn extract_type_name(
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&self,
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@ -160,24 +204,20 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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span
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};
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let is_named_and_not_impl_trait = |ty: Ty<'_>| {
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&ty.to_string() != "_" &&
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// FIXME: Remove this check after `impl_trait_in_bindings` is stabilized. #63527
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(!ty.is_impl_trait() || self.tcx.features().impl_trait_in_bindings)
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};
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let ty_msg = match local_visitor.found_ty {
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Some(ty::TyS { sty: ty::Closure(def_id, substs), .. }) => {
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let fn_sig = substs.closure_sig(*def_id, self.tcx);
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let args = fn_sig.inputs()
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.skip_binder()
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.iter()
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.next()
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.map(|args| args.tuple_fields()
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.map(|arg| arg.to_string())
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.collect::<Vec<_>>().join(", "))
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.unwrap_or_default();
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let args = closure_args(&fn_sig);
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let ret = fn_sig.output().skip_binder().to_string();
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format!(" for the closure `fn({}) -> {}`", args, ret)
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}
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Some(ty) if &ty.to_string() != "_" &&
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// FIXME: Remove this check after `impl_trait_in_bindings` is stabilized. #63527
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(!ty.is_impl_trait() || self.tcx.features().impl_trait_in_bindings) =>
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{
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Some(ty) if is_named_and_not_impl_trait(ty) => {
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let ty = ty_to_string(ty);
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format!(" for `{}`", ty)
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}
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@ -211,59 +251,33 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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let ret = fn_sig.output().skip_binder().to_string();
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if let Some(ExprKind::Closure(_, decl, body_id, ..)) = local_visitor.found_closure {
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let (arrow, post) = match decl.output {
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FunctionRetTy::DefaultReturn(_) => ("-> ", " "),
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_ => ("", ""),
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};
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if let Some(body) = self.tcx.hir().krate().bodies.get(body_id) {
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let suggestion = match body.value.node {
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ExprKind::Block(..) => {
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vec![(decl.output.span(), format!("{}{}{}", arrow, ret, post))]
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}
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_ => {
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vec![
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(decl.output.span(), format!("{}{}{}{{ ", arrow, ret, post)),
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(body.value.span.shrink_to_hi(), " }".to_string()),
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]
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}
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};
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err.multipart_suggestion(
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"give this closure an explicit return type without `_` placeholders",
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suggestion,
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Applicability::HasPlaceholders,
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closure_return_type_suggestion(
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span,
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&mut err,
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&decl.output,
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&body,
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&name,
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&ret,
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);
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err.span_label(span, InferCtxt::missing_type_msg(&name));
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// We don't want to give the other suggestions when the problem is the
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// closure return type.
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return err;
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}
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}
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// This shouldn't be reachable, but just in case we leave a reasonable fallback.
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let args = fn_sig.inputs()
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.skip_binder()
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.iter()
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.next()
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.map(|args| args.tuple_fields()
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.map(|arg| arg.to_string())
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.collect::<Vec<_>>().join(", "))
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.unwrap_or_default();
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let args = closure_args(&fn_sig);
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// This suggestion is incomplete, as the user will get further type inference
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// errors due to the `_` placeholders and the introduction of `Box`, but it does
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// nudge them in the right direction.
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format!("a boxed closure type like `Box<dyn Fn({}) -> {}>`", args, ret)
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}
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Some(ty) if &ty.to_string() != "_" &&
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name == "_" &&
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// FIXME: Remove this check after `impl_trait_in_bindings` is stabilized. #63527
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(!ty.is_impl_trait() || self.tcx.features().impl_trait_in_bindings) =>
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{
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Some(ty) if is_named_and_not_impl_trait(ty) && name == "_" => {
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let ty = ty_to_string(ty);
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format!("the explicit type `{}`, with the type parameters specified", ty)
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}
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Some(ty) if &ty.to_string() != "_" &&
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ty.to_string() != name &&
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// FIXME: Remove this check after `impl_trait_in_bindings` is stabilized. #63527
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(!ty.is_impl_trait() || self.tcx.features().impl_trait_in_bindings) =>
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{
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Some(ty) if is_named_and_not_impl_trait(ty) && ty.to_string() != name => {
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let ty = ty_to_string(ty);
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format!(
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"the explicit type `{}`, where the type parameter `{}` is specified",
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@ -296,25 +310,20 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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format!("consider giving this closure parameter {}", suffix),
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);
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} else if let Some(pattern) = local_visitor.found_local_pattern {
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if let Some(simple_ident) = pattern.simple_ident() {
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let msg = if let Some(simple_ident) = pattern.simple_ident() {
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match pattern.span.desugaring_kind() {
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None => {
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err.span_label(
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pattern.span,
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format!("consider giving `{}` {}", simple_ident, suffix),
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);
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format!("consider giving `{}` {}", simple_ident, suffix)
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}
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Some(DesugaringKind::ForLoop) => {
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err.span_label(
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pattern.span,
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"the element type for this iterator is not specified".to_string(),
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);
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"the element type for this iterator is not specified".to_string()
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}
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_ => {}
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_ => format!("this needs {}", suffix),
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}
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} else {
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err.span_label(pattern.span, format!("consider giving this pattern {}", suffix));
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}
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format!("consider giving this pattern {}", suffix)
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};
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err.span_label(pattern.span, msg);
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}
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if !err.span.span_labels().iter().any(|span_label| {
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span_label.label.is_some() && span_label.span == span
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