diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index b29c7d9f253..6665329d114 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -103,7 +103,7 @@ mod zst_offset; use bind_instead_of_map::BindInsteadOfMap; use clippy_utils::consts::{constant, Constant}; use clippy_utils::diagnostics::{span_lint, span_lint_and_help}; -use clippy_utils::ty::{contains_adt_constructor, implements_trait, is_copy, is_type_diagnostic_item}; +use clippy_utils::ty::{contains_ty_adt_constructor_opaque, implements_trait, is_copy, is_type_diagnostic_item}; use clippy_utils::{contains_return, is_trait_method, iter_input_pats, meets_msrv, msrvs, return_ty}; use if_chain::if_chain; use rustc_hir as hir; @@ -3394,36 +3394,10 @@ impl<'tcx> LateLintPass<'tcx> for Methods { if let hir::ImplItemKind::Fn(_, _) = impl_item.kind { let ret_ty = return_ty(cx, impl_item.hir_id()); - // walk the return type and check for Self (this does not check associated types) - if let Some(self_adt) = self_ty.ty_adt_def() { - if contains_adt_constructor(ret_ty, self_adt) { - return; - } - } else if ret_ty.contains(self_ty) { + if contains_ty_adt_constructor_opaque(cx, ret_ty, self_ty) { return; } - // if return type is impl trait, check the associated types - if let ty::Opaque(def_id, _) = *ret_ty.kind() { - // one of the associated types must be Self - for &(predicate, _span) in cx.tcx.explicit_item_bounds(def_id) { - if let ty::PredicateKind::Projection(projection_predicate) = predicate.kind().skip_binder() { - let assoc_ty = match projection_predicate.term.unpack() { - ty::TermKind::Ty(ty) => ty, - ty::TermKind::Const(_c) => continue, - }; - // walk the associated type and check for Self - if let Some(self_adt) = self_ty.ty_adt_def() { - if contains_adt_constructor(assoc_ty, self_adt) { - return; - } - } else if assoc_ty.contains(self_ty) { - return; - } - } - } - } - if name == "new" && ret_ty != self_ty { span_lint( cx, diff --git a/clippy_utils/src/ty.rs b/clippy_utils/src/ty.rs index f4a135f2b5b..2dd8c826ab3 100644 --- a/clippy_utils/src/ty.rs +++ b/clippy_utils/src/ty.rs @@ -59,6 +59,58 @@ pub fn contains_adt_constructor<'tcx>(ty: Ty<'tcx>, adt: AdtDef<'tcx>) -> bool { }) } +/// Walks into `ty` and returns `true` if any inner type is an instance of the given type, or adt +/// constructor of the same type. +/// +/// This method also recurses into opaque type predicates, so call it with `impl Trait` and `U` +/// will also return `true`. +pub fn contains_ty_adt_constructor_opaque<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, needle: Ty<'tcx>) -> bool { + ty.walk().any(|inner| match inner.unpack() { + GenericArgKind::Type(inner_ty) => { + if inner_ty == needle { + return true; + } + + if inner_ty.ty_adt_def() == needle.ty_adt_def() { + return true; + } + + if let ty::Opaque(def_id, _) = *inner_ty.kind() { + for &(predicate, _span) in cx.tcx.explicit_item_bounds(def_id) { + match predicate.kind().skip_binder() { + // For `impl Trait`, it will register a predicate of `T: Trait`, so we go through + // and check substituions to find `U`. + ty::PredicateKind::Trait(trait_predicate) => { + if trait_predicate + .trait_ref + .substs + .types() + .skip(1) // Skip the implicit `Self` generic parameter + .any(|ty| contains_ty_adt_constructor_opaque(cx, ty, needle)) + { + return true; + } + }, + // For `impl Trait`, it will register a predicate of `::Assoc = U`, + // so we check the term for `U`. + ty::PredicateKind::Projection(projection_predicate) => { + if let ty::TermKind::Ty(ty) = projection_predicate.term.unpack() { + if contains_ty_adt_constructor_opaque(cx, ty, needle) { + return true; + } + }; + }, + _ => (), + } + } + } + + false + }, + GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => false, + }) +} + /// Resolves `::Item` for `T` /// Do not invoke without first verifying that the type implements `Iterator` pub fn get_iterator_item_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option> { diff --git a/tests/ui/new_ret_no_self.rs b/tests/ui/new_ret_no_self.rs index 2f315ffe298..f69982d63a8 100644 --- a/tests/ui/new_ret_no_self.rs +++ b/tests/ui/new_ret_no_self.rs @@ -350,3 +350,53 @@ impl RetOtherSelf { RetOtherSelf(RetOtherSelfWrapper(t)) } } + +mod issue7344 { + struct RetImplTraitSelf(T); + + impl RetImplTraitSelf { + // should not trigger lint + fn new(t: T) -> impl Into { + Self(t) + } + } + + struct RetImplTraitNoSelf(T); + + impl RetImplTraitNoSelf { + // should trigger lint + fn new(t: T) -> impl Into { + 1 + } + } + + trait Trait2 {} + impl Trait2 for () {} + + struct RetImplTraitSelf2(T); + + impl RetImplTraitSelf2 { + // should not trigger lint + fn new(t: T) -> impl Trait2<(), Self> { + unimplemented!() + } + } + + struct RetImplTraitNoSelf2(T); + + impl RetImplTraitNoSelf2 { + // should trigger lint + fn new(t: T) -> impl Trait2<(), i32> { + unimplemented!() + } + } + + struct RetImplTraitSelfAdt<'a>(&'a str); + + impl<'a> RetImplTraitSelfAdt<'a> { + // should not trigger lint + fn new<'b: 'a>(s: &'b str) -> impl Into> { + RetImplTraitSelfAdt(s) + } + } +} diff --git a/tests/ui/new_ret_no_self.stderr b/tests/ui/new_ret_no_self.stderr index 8217bc6187f..bc13be47927 100644 --- a/tests/ui/new_ret_no_self.stderr +++ b/tests/ui/new_ret_no_self.stderr @@ -76,5 +76,21 @@ LL | | unimplemented!(); LL | | } | |_________^ -error: aborting due to 10 previous errors +error: methods called `new` usually return `Self` + --> $DIR/new_ret_no_self.rs:368:9 + | +LL | / fn new(t: T) -> impl Into { +LL | | 1 +LL | | } + | |_________^ + +error: methods called `new` usually return `Self` + --> $DIR/new_ret_no_self.rs:389:9 + | +LL | / fn new(t: T) -> impl Trait2<(), i32> { +LL | | unimplemented!() +LL | | } + | |_________^ + +error: aborting due to 12 previous errors