review comments
This commit is contained in:
Esteban Küber
parent
2c998aa8bb
commit
794b644f0b
@ -17,6 +17,7 @@
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#![feature(crate_visibility_modifier)]
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#![feature(or_patterns)]
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#![feature(str_strip)]
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#![feature(option_zip)]
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#![recursion_limit = "512"] // For rustdoc
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#[macro_use]
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@ -388,7 +388,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
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// which is somewhat confusing.
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self.suggest_restricting_param_bound(
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&mut err,
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&trait_ref,
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trait_ref,
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obligation.cause.body_id,
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);
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} else {
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@ -27,7 +27,7 @@ pub trait InferCtxtExt<'tcx> {
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fn suggest_restricting_param_bound(
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&self,
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err: &mut DiagnosticBuilder<'_>,
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trait_ref: &ty::PolyTraitRef<'_>,
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trait_ref: ty::PolyTraitRef<'_>,
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body_id: hir::HirId,
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);
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@ -168,103 +168,96 @@ fn suggest_restriction(
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err: &mut DiagnosticBuilder<'_>,
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fn_sig: Option<&hir::FnSig<'_>>,
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projection: Option<&ty::ProjectionTy<'_>>,
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trait_ref: &ty::PolyTraitRef<'_>,
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trait_ref: ty::PolyTraitRef<'_>,
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) {
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let span = generics.where_clause.span_for_predicates_or_empty_place();
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if !span.from_expansion() && span.desugaring_kind().is_none() {
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// Given `fn foo(t: impl Trait)` where `Trait` requires assoc type `A`...
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if let Some((name, fn_sig)) = fn_sig.and_then(|sig| {
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projection.and_then(|p| {
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// Shenanigans to get the `Trait` from the `impl Trait`.
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match p.self_ty().kind {
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ty::Param(param) => {
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// `fn foo(t: impl Trait)`
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// ^^^^^ get this string
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param
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.name
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.as_str()
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.strip_prefix("impl")
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.map(|s| (s.trim_start().to_string(), sig))
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}
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_ => None,
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}
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})
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}) {
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// We know we have an `impl Trait` that doesn't satisfy a required projection.
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if span.from_expansion() || span.desugaring_kind().is_some() {
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return;
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}
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// Given `fn foo(t: impl Trait)` where `Trait` requires assoc type `A`...
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if let Some((name, fn_sig)) =
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fn_sig.zip(projection).and_then(|(sig, p)| match p.self_ty().kind {
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// Shenanigans to get the `Trait` from the `impl Trait`.
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ty::Param(param) => {
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// `fn foo(t: impl Trait)`
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// ^^^^^ get this string
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param.name.as_str().strip_prefix("impl").map(|s| (s.trim_start().to_string(), sig))
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}
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_ => None,
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})
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{
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// We know we have an `impl Trait` that doesn't satisfy a required projection.
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// Find all of the ocurrences of `impl Trait` for `Trait` in the function arguments'
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// types. There should be at least one, but there might be *more* than one. In that
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// case we could just ignore it and try to identify which one needs the restriction,
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// but instead we choose to suggest replacing all instances of `impl Trait` with `T`
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// where `T: Trait`.
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let mut ty_spans = vec![];
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let impl_name = format!("impl {}", name);
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for input in fn_sig.decl.inputs {
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if let hir::TyKind::Path(hir::QPath::Resolved(
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None,
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hir::Path { segments: [segment], .. },
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)) = input.kind
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{
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if segment.ident.as_str() == impl_name.as_str() {
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// `fn foo(t: impl Trait)`
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// ^^^^^^^^^^ get this to suggest
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// `T` instead
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// Find all of the ocurrences of `impl Trait` for `Trait` in the function arguments'
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// types. There should be at least one, but there might be *more* than one. In that
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// case we could just ignore it and try to identify which one needs the restriction,
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// but instead we choose to suggest replacing all instances of `impl Trait` with `T`
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// where `T: Trait`.
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let mut ty_spans = vec![];
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let impl_name = format!("impl {}", name);
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for input in fn_sig.decl.inputs {
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if let hir::TyKind::Path(hir::QPath::Resolved(
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None,
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hir::Path { segments: [segment], .. },
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)) = input.kind
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{
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if segment.ident.as_str() == impl_name.as_str() {
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// `fn foo(t: impl Trait)`
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// ^^^^^^^^^^ get this to suggest
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// `T` instead
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// There might be more than one `impl Trait`.
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ty_spans.push(input.span);
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}
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// There might be more than one `impl Trait`.
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ty_spans.push(input.span);
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}
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}
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// The type param `T: Trait` we will suggest to introduce.
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let type_param = format!("{}: {}", "T", name);
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// FIXME: modify the `trait_ref` instead of string shenanigans.
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// Turn `<impl Trait as Foo>::Bar: Qux` into `<T as Foo>::Bar: Qux`.
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let pred = trait_ref.without_const().to_predicate().to_string();
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let pred = pred.replace(&impl_name, "T");
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let mut sugg = vec![
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match generics
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.params
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.iter()
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.filter(|p| match p.kind {
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hir::GenericParamKind::Type {
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synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
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..
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} => false,
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_ => true,
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})
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.last()
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{
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// `fn foo(t: impl Trait)`
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// ^ suggest `<T: Trait>` here
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None => (generics.span, format!("<{}>", type_param)),
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// `fn foo<A>(t: impl Trait)`
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// ^^^ suggest `<A, T: Trait>` here
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Some(param) => (param.span.shrink_to_hi(), format!(", {}", type_param)),
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},
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// `fn foo(t: impl Trait)`
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// ^ suggest `where <T as Trait>::A: Bound`
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predicate_constraint(generics, pred),
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];
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sugg.extend(ty_spans.into_iter().map(|s| (s, "T".to_string())));
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// Suggest `fn foo<T: Trait>(t: T) where <T as Trait>::A: Bound`.
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err.multipart_suggestion(
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"introduce a type parameter with a trait bound instead of using \
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`impl Trait`",
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sugg,
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Applicability::MaybeIncorrect,
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);
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} else {
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// Trivial case: `T` needs an extra bound: `T: Bound`.
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let (sp, s) = predicate_constraint(
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generics,
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trait_ref.without_const().to_predicate().to_string(),
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);
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let appl = Applicability::MachineApplicable;
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err.span_suggestion(sp, &format!("consider further restricting {}", msg), s, appl);
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}
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// The type param `T: Trait` we will suggest to introduce.
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let type_param = format!("{}: {}", "T", name);
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// FIXME: modify the `trait_ref` instead of string shenanigans.
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// Turn `<impl Trait as Foo>::Bar: Qux` into `<T as Foo>::Bar: Qux`.
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let pred = trait_ref.without_const().to_predicate().to_string();
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let pred = pred.replace(&impl_name, "T");
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let mut sugg = vec![
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match generics
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.params
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.iter()
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.filter(|p| match p.kind {
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hir::GenericParamKind::Type {
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synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
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..
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} => false,
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_ => true,
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})
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.last()
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{
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// `fn foo(t: impl Trait)`
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// ^ suggest `<T: Trait>` here
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None => (generics.span, format!("<{}>", type_param)),
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// `fn foo<A>(t: impl Trait)`
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// ^^^ suggest `<A, T: Trait>` here
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Some(param) => (param.span.shrink_to_hi(), format!(", {}", type_param)),
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},
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// `fn foo(t: impl Trait)`
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// ^ suggest `where <T as Trait>::A: Bound`
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predicate_constraint(generics, pred),
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];
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sugg.extend(ty_spans.into_iter().map(|s| (s, "T".to_string())));
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// Suggest `fn foo<T: Trait>(t: T) where <T as Trait>::A: Bound`.
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err.multipart_suggestion(
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"introduce a type parameter with a trait bound instead of using \
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`impl Trait`",
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sugg,
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Applicability::MaybeIncorrect,
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);
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} else {
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// Trivial case: `T` needs an extra bound: `T: Bound`.
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let (sp, s) =
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predicate_constraint(generics, trait_ref.without_const().to_predicate().to_string());
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let appl = Applicability::MachineApplicable;
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err.span_suggestion(sp, &format!("consider further restricting {}", msg), s, appl);
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}
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}
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@ -272,7 +265,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
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fn suggest_restricting_param_bound(
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&self,
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mut err: &mut DiagnosticBuilder<'_>,
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trait_ref: &ty::PolyTraitRef<'_>,
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trait_ref: ty::PolyTraitRef<'_>,
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body_id: hir::HirId,
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) {
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let self_ty = trait_ref.self_ty();
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