diff options
| -rw-r--r-- | clippy_lints/src/implied_bounds_in_impls.rs | 170 |
1 files changed, 96 insertions, 74 deletions
diff --git a/clippy_lints/src/implied_bounds_in_impls.rs b/clippy_lints/src/implied_bounds_in_impls.rs index 165dc2548e1..120ab5a034e 100644 --- a/clippy_lints/src/implied_bounds_in_impls.rs +++ b/clippy_lints/src/implied_bounds_in_impls.rs @@ -50,6 +50,93 @@ declare_clippy_lint! { } declare_lint_pass!(ImpliedBoundsInImpls => [IMPLIED_BOUNDS_IN_IMPLS]); +#[allow(clippy::too_many_arguments)] +fn emit_lint( + cx: &LateContext<'_>, + poly_trait: &rustc_hir::PolyTraitRef<'_>, + opaque_ty: &rustc_hir::OpaqueTy<'_>, + index: usize, + implied_bindings: &[rustc_hir::TypeBinding<'_>], + implied_by_bindings: &[rustc_hir::TypeBinding<'_>], + implied_by_args: &[GenericArg<'_>], + implied_by_span: Span, +) { + let implied_by = snippet(cx, implied_by_span, ".."); + + span_lint_and_then( + cx, + IMPLIED_BOUNDS_IN_IMPLS, + poly_trait.span, + &format!("this bound is already specified as the supertrait of `{implied_by}`"), + |diag| { + // If we suggest removing a bound, we may also need extend the span + // to include the `+` token that is ahead or behind, + // so we don't end up with something like `impl + B` or `impl A + ` + + let implied_span_extended = if let Some(next_bound) = opaque_ty.bounds.get(index + 1) { + poly_trait.span.to(next_bound.span().shrink_to_lo()) + } else if index > 0 + && let Some(prev_bound) = opaque_ty.bounds.get(index - 1) + { + prev_bound.span().shrink_to_hi().to(poly_trait.span.shrink_to_hi()) + } else { + poly_trait.span + }; + + let mut sugg = vec![(implied_span_extended, String::new())]; + + // We also might need to include associated type binding that were specified in the implied bound, + // but omitted in the implied-by bound: + // `fn f() -> impl Deref<Target = u8> + DerefMut` + // If we're going to suggest removing `Deref<..>`, we'll need to put `<Target = u8>` on `DerefMut` + let omitted_assoc_tys: Vec<_> = implied_bindings + .iter() + .filter(|binding| !implied_by_bindings.iter().any(|b| b.ident == binding.ident)) + .collect(); + + if !omitted_assoc_tys.is_empty() { + // `<>` needs to be added if there aren't yet any generic arguments or bindings + let needs_angle_brackets = implied_by_args.is_empty() && implied_by_bindings.is_empty(); + let insert_span = match (implied_by_args, implied_by_bindings) { + ([.., arg], [.., binding]) => arg.span().max(binding.span).shrink_to_hi(), + ([.., arg], []) => arg.span().shrink_to_hi(), + ([], [.., binding]) => binding.span.shrink_to_hi(), + ([], []) => implied_by_span.shrink_to_hi(), + }; + + let mut associated_tys_sugg = if needs_angle_brackets { + "<".to_owned() + } else { + // If angle brackets aren't needed (i.e., there are already generic arguments or bindings), + // we need to add a comma: + // `impl A<B, C >` + // ^ if we insert `Assoc=i32` without a comma here, that'd be invalid syntax: + // `impl A<B, C Assoc=i32>` + ", ".to_owned() + }; + + for (index, binding) in omitted_assoc_tys.into_iter().enumerate() { + if index > 0 { + associated_tys_sugg += ", "; + } + associated_tys_sugg += &snippet(cx, binding.span, ".."); + } + if needs_angle_brackets { + associated_tys_sugg += ">"; + } + sugg.push((insert_span, associated_tys_sugg)); + } + + diag.multipart_suggestion_with_style( + "try removing this bound", + sugg, + Applicability::MachineApplicable, + SuggestionStyle::ShowAlways, + ); + }, + ); +} + /// Tries to "resolve" a type. /// The index passed to this function must start with `Self=0`, i.e. it must be a valid /// type parameter index. @@ -189,80 +276,15 @@ fn check(cx: &LateContext<'_>, decl: &FnDecl<'_>) { }) }) { - let implied_by = snippet(cx, implied_by_span, ".."); - span_lint_and_then( - cx, IMPLIED_BOUNDS_IN_IMPLS, - poly_trait.span, - &format!("this bound is already specified as the supertrait of `{implied_by}`"), - |diag| { - // If we suggest removing a bound, we may also need extend the span - // to include the `+` token that is ahead or behind, - // so we don't end up with something like `impl + B` or `impl A + ` - - let implied_span_extended = if let Some(next_bound) = opaque_ty.bounds.get(index + 1) { - poly_trait.span.to(next_bound.span().shrink_to_lo()) - } else if index > 0 - && let Some(prev_bound) = opaque_ty.bounds.get(index - 1) - { - prev_bound.span().shrink_to_hi().to(poly_trait.span.shrink_to_hi()) - } else { - poly_trait.span - }; - - let mut sugg = vec![ - (implied_span_extended, String::new()), - ]; - - // We also might need to include associated type binding that were specified in the implied bound, - // but omitted in the implied-by bound: - // `fn f() -> impl Deref<Target = u8> + DerefMut` - // If we're going to suggest removing `Deref<..>`, we'll need to put `<Target = u8>` on `DerefMut` - let omitted_assoc_tys: Vec<_> = implied_bindings - .iter() - .filter(|binding| { - implied_by_bindings - .iter() - // TODO: is checking idents enough for stuff like `<Target: Sized> == <Target = u8>` - .find(|b| b.ident == binding.ident) - .is_none() - }) - .collect(); - - if !omitted_assoc_tys.is_empty() { - // `<>` needs to be added if there aren't yet any generic arguments or bindings - let needs_angle_brackets = implied_by_args.is_empty() && implied_by_bindings.is_empty(); - let insert_span = match (implied_by_args, implied_by_bindings) { - ([.., arg], [.., binding]) => arg.span().max(binding.span).shrink_to_hi(), - ([.., arg], []) => arg.span().shrink_to_hi(), - ([], [.., binding]) => binding.span.shrink_to_hi(), - ([], []) => implied_by_span.shrink_to_hi(), - }; - - let mut associated_tys_sugg = if needs_angle_brackets { - "<".to_owned() - } else { - // If angle brackets aren't needed (i.e., there are already generic arguments or bindings), - // we need to add a comma: - // `impl A<B, C >` - // ^ if we insert `Assoc=i32` without a comma here, that'd be invalid syntax: - // `impl A<B, C Assoc=i32>` - ", ".to_owned() - }; - - for (index, binding) in omitted_assoc_tys.into_iter().enumerate() { - if index > 0 { - associated_tys_sugg += ", "; - } - associated_tys_sugg += &snippet(cx, binding.span, ".."); - } - if needs_angle_brackets { - associated_tys_sugg += ">"; - } - sugg.push((insert_span, associated_tys_sugg)); - } - - diag.multipart_suggestion_with_style("try removing this bound", sugg, Applicability::MachineApplicable, SuggestionStyle::ShowAlways); - } + emit_lint( + cx, + poly_trait, + opaque_ty, + index, + implied_bindings, + implied_by_bindings, + implied_by_args, + implied_by_span ); } } |