diff options
6 files changed, 136 insertions, 14 deletions
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs index 40a27c9aebe..f6dbbeb51ca 100644 --- a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs +++ b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs @@ -32,8 +32,8 @@ use rustc_middle::ty::print::{ }; use rustc_middle::ty::{ self, AdtKind, GenericArgs, InferTy, IsSuggestable, Ty, TyCtxt, TypeFoldable, TypeFolder, - TypeSuperFoldable, TypeVisitableExt, TypeckResults, Upcast, suggest_arbitrary_trait_bound, - suggest_constraining_type_param, + TypeSuperFoldable, TypeSuperVisitable, TypeVisitableExt, TypeVisitor, TypeckResults, Upcast, + suggest_arbitrary_trait_bound, suggest_constraining_type_param, }; use rustc_middle::{bug, span_bug}; use rustc_span::def_id::LocalDefId; @@ -263,6 +263,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { _ => (false, None), }; + let mut finder = ParamFinder { .. }; + finder.visit_binder(&trait_pred); + // FIXME: Add check for trait bound that is already present, particularly `?Sized` so we // don't suggest `T: Sized + ?Sized`. loop { @@ -411,6 +414,26 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { } } + hir::Node::TraitItem(hir::TraitItem { + generics, + kind: hir::TraitItemKind::Fn(..), + .. + }) + | hir::Node::ImplItem(hir::ImplItem { + generics, + trait_item_def_id: None, + kind: hir::ImplItemKind::Fn(..), + .. + }) if finder.can_suggest_bound(generics) => { + // Missing generic type parameter bound. + suggest_arbitrary_trait_bound( + self.tcx, + generics, + err, + trait_pred, + associated_ty, + ); + } hir::Node::Item(hir::Item { kind: hir::ItemKind::Struct(_, generics, _) @@ -423,7 +446,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { | hir::ItemKind::Const(_, generics, _, _) | hir::ItemKind::TraitAlias(_, generics, _), .. - }) if !param_ty => { + }) if finder.can_suggest_bound(generics) => { // Missing generic type parameter bound. if suggest_arbitrary_trait_bound( self.tcx, @@ -5068,8 +5091,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { // Suggesting `T: ?Sized` is only valid in an ADT if `T` is only used in a // borrow. `struct S<'a, T: ?Sized>(&'a T);` is valid, `struct S<T: ?Sized>(T);` // is not. Look for invalid "bare" parameter uses, and suggest using indirection. - let mut visitor = - FindTypeParam { param: param.name.ident().name, invalid_spans: vec![], nested: false }; + let mut visitor = FindTypeParam { param: param.name.ident().name, .. }; visitor.visit_item(item); if visitor.invalid_spans.is_empty() { return false; @@ -5228,7 +5250,7 @@ fn hint_missing_borrow<'tcx>( /// Used to suggest replacing associated types with an explicit type in `where` clauses. #[derive(Debug)] pub struct SelfVisitor<'v> { - pub paths: Vec<&'v hir::Ty<'v>>, + pub paths: Vec<&'v hir::Ty<'v>> = Vec::new(), pub name: Option<Symbol>, } @@ -5599,7 +5621,7 @@ fn point_at_assoc_type_restriction<G: EmissionGuarantee>( ); // Search for the associated type `Self::{name}`, get // its type and suggest replacing the bound with it. - let mut visitor = SelfVisitor { paths: vec![], name: Some(name) }; + let mut visitor = SelfVisitor { name: Some(name), .. }; visitor.visit_trait_ref(trait_ref); for path in visitor.paths { err.span_suggestion_verbose( @@ -5610,7 +5632,7 @@ fn point_at_assoc_type_restriction<G: EmissionGuarantee>( ); } } else { - let mut visitor = SelfVisitor { paths: vec![], name: None }; + let mut visitor = SelfVisitor { name: None, .. }; visitor.visit_trait_ref(trait_ref); let span: MultiSpan = visitor.paths.iter().map(|p| p.span).collect::<Vec<Span>>().into(); @@ -5640,8 +5662,8 @@ fn get_deref_type_and_refs(mut ty: Ty<'_>) -> (Ty<'_>, Vec<hir::Mutability>) { /// `param: ?Sized` would be a valid constraint. struct FindTypeParam { param: rustc_span::Symbol, - invalid_spans: Vec<Span>, - nested: bool, + invalid_spans: Vec<Span> = Vec::new(), + nested: bool = false, } impl<'v> Visitor<'v> for FindTypeParam { @@ -5679,3 +5701,38 @@ impl<'v> Visitor<'v> for FindTypeParam { } } } + +/// Look for type parameters in predicates. We use this to identify whether a bound is suitable in +/// on a given item. +struct ParamFinder { + params: Vec<Symbol> = Vec::new(), +} + +impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ParamFinder { + fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result { + match t.kind() { + ty::Param(p) => self.params.push(p.name), + _ => {} + } + t.super_visit_with(self) + } +} + +impl ParamFinder { + /// Whether the `hir::Generics` of the current item can suggest the evaluated bound because its + /// references to type parameters are present in the generics. + fn can_suggest_bound(&self, generics: &hir::Generics<'_>) -> bool { + if self.params.is_empty() { + // There are no references to type parameters at all, so suggesting the bound + // would be reasonable. + return true; + } + generics.params.iter().any(|p| match p.name { + hir::ParamName::Plain(p_name) => { + // All of the parameters in the bound can be referenced in the current item. + self.params.iter().any(|p| *p == p_name.name || *p == kw::SelfUpper) + } + _ => true, + }) + } +} diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs index e2b22f7bab7..fc0cf8f140a 100644 --- a/compiler/rustc_trait_selection/src/lib.rs +++ b/compiler/rustc_trait_selection/src/lib.rs @@ -19,6 +19,7 @@ #![feature(assert_matches)] #![feature(associated_type_defaults)] #![feature(box_patterns)] +#![feature(default_field_values)] #![feature(if_let_guard)] #![feature(iter_intersperse)] #![feature(iterator_try_reduce)] diff --git a/tests/ui/const-generics/failing_goal_with_repeat_expr_anon_const.stderr b/tests/ui/const-generics/failing_goal_with_repeat_expr_anon_const.stderr index 12de4f1dc30..cf5b55a0ce2 100644 --- a/tests/ui/const-generics/failing_goal_with_repeat_expr_anon_const.stderr +++ b/tests/ui/const-generics/failing_goal_with_repeat_expr_anon_const.stderr @@ -21,10 +21,6 @@ LL | [0u8; std::mem::size_of::<Self::A>()] == Self::P; | ^^ no implementation for `[u8; std::mem::size_of::<Self::A>()] == <Self as T>::A` | = help: the trait `PartialEq<<Self as T>::A>` is not implemented for `[u8; std::mem::size_of::<Self::A>()]` -help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement - | -LL | pub trait T where [u8; std::mem::size_of::<Self::A>()]: PartialEq<<Self as T>::A> { - | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ error: aborting due to 3 previous errors diff --git a/tests/ui/traits/bound/suggest-complex-bound-on-method.fixed b/tests/ui/traits/bound/suggest-complex-bound-on-method.fixed new file mode 100644 index 00000000000..719835af0a9 --- /dev/null +++ b/tests/ui/traits/bound/suggest-complex-bound-on-method.fixed @@ -0,0 +1,23 @@ +//@ run-rustfix +#![allow(dead_code)] +struct Application; +// https://github.com/rust-lang/rust/issues/144734 +trait Trait { + type Error: std::error::Error; + + fn run(&self) -> Result<(), Self::Error>; +} + +#[derive(Debug)] +enum ApplicationError { + Quit, +} + +impl Application { + fn thing<T: Trait>(&self, t: T) -> Result<(), ApplicationError> where ApplicationError: From<<T as Trait>::Error> { + t.run()?; //~ ERROR E0277 + Ok(()) + } +} + +fn main() {} diff --git a/tests/ui/traits/bound/suggest-complex-bound-on-method.rs b/tests/ui/traits/bound/suggest-complex-bound-on-method.rs new file mode 100644 index 00000000000..39cec571242 --- /dev/null +++ b/tests/ui/traits/bound/suggest-complex-bound-on-method.rs @@ -0,0 +1,23 @@ +//@ run-rustfix +#![allow(dead_code)] +struct Application; +// https://github.com/rust-lang/rust/issues/144734 +trait Trait { + type Error: std::error::Error; + + fn run(&self) -> Result<(), Self::Error>; +} + +#[derive(Debug)] +enum ApplicationError { + Quit, +} + +impl Application { + fn thing<T: Trait>(&self, t: T) -> Result<(), ApplicationError> { + t.run()?; //~ ERROR E0277 + Ok(()) + } +} + +fn main() {} diff --git a/tests/ui/traits/bound/suggest-complex-bound-on-method.stderr b/tests/ui/traits/bound/suggest-complex-bound-on-method.stderr new file mode 100644 index 00000000000..ac45f049541 --- /dev/null +++ b/tests/ui/traits/bound/suggest-complex-bound-on-method.stderr @@ -0,0 +1,22 @@ +error[E0277]: `?` couldn't convert the error to `ApplicationError` + --> $DIR/suggest-complex-bound-on-method.rs:18:16 + | +LL | t.run()?; + | -----^ the trait `From<<T as Trait>::Error>` is not implemented for `ApplicationError` + | | + | this can't be annotated with `?` because it has type `Result<_, <T as Trait>::Error>` + | +note: `ApplicationError` needs to implement `From<<T as Trait>::Error>` + --> $DIR/suggest-complex-bound-on-method.rs:12:1 + | +LL | enum ApplicationError { + | ^^^^^^^^^^^^^^^^^^^^^ + = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait +help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement + | +LL | fn thing<T: Trait>(&self, t: T) -> Result<(), ApplicationError> where ApplicationError: From<<T as Trait>::Error> { + | +++++++++++++++++++++++++++++++++++++++++++++++++ + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0277`. |