diff options
| -rw-r--r-- | clippy_lints/src/derive.rs | 87 | ||||
| -rw-r--r-- | tests/ui/derive.rs | 21 | ||||
| -rw-r--r-- | tests/ui/derive.stderr | 30 |
3 files changed, 89 insertions, 49 deletions
diff --git a/clippy_lints/src/derive.rs b/clippy_lints/src/derive.rs index 834136f910d..9fad85f8ef4 100644 --- a/clippy_lints/src/derive.rs +++ b/clippy_lints/src/derive.rs @@ -1,6 +1,6 @@ use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_then}; use clippy_utils::paths; -use clippy_utils::ty::is_copy; +use clippy_utils::ty::{implements_trait, is_copy}; use clippy_utils::{get_trait_def_id, is_allowed, is_automatically_derived, match_def_path}; use if_chain::if_chain; use rustc_hir::def_id::DefId; @@ -12,7 +12,7 @@ use rustc_lint::{LateContext, LateLintPass}; use rustc_middle::hir::map::Map; use rustc_middle::ty::{self, Ty}; use rustc_session::{declare_lint_pass, declare_tool_lint}; -use rustc_span::source_map::Span; +use rustc_span::{def_id::LOCAL_CRATE, source_map::Span}; declare_clippy_lint! { /// **What it does:** Checks for deriving `Hash` but implementing `PartialEq` @@ -293,48 +293,53 @@ fn check_ord_partial_ord<'tcx>( /// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint. fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) { - if cx - .tcx - .lang_items() - .clone_trait() - .map_or(false, |id| Some(id) == trait_ref.trait_def_id()) - { - if !is_copy(cx, ty) { + let clone_id = match cx.tcx.lang_items().clone_trait() { + Some(id) if trait_ref.trait_def_id() == Some(id) => id, + _ => return, + }; + let copy_id = match cx.tcx.lang_items().copy_trait() { + Some(id) => id, + None => return, + }; + let (ty_adt, ty_subs) = match *ty.kind() { + // Unions can't derive clone. + ty::Adt(adt, subs) if !adt.is_union() => (adt, subs), + _ => return, + }; + // If the current self type doesn't implement Copy (due to generic constraints), search to see if + // there's a Copy impl for any instance of the adt. + if !is_copy(cx, ty) { + if ty_subs.non_erasable_generics().next().is_some() { + let has_copy_impl = cx + .tcx + .all_local_trait_impls(LOCAL_CRATE) + .get(©_id) + .map_or(false, |impls| { + impls + .iter() + .any(|&id| matches!(cx.tcx.type_of(id).kind(), ty::Adt(adt, _) if ty_adt.did == adt.did)) + }); + if !has_copy_impl { + return; + } + } else { return; } - - match *ty.kind() { - ty::Adt(def, _) if def.is_union() => return, - - // Some types are not Clone by default but could be cloned “by hand” if necessary - ty::Adt(def, substs) => { - for variant in &def.variants { - for field in &variant.fields { - if let ty::FnDef(..) = field.ty(cx.tcx, substs).kind() { - return; - } - } - for subst in substs { - if let ty::subst::GenericArgKind::Type(subst) = subst.unpack() { - if let ty::Param(_) = subst.kind() { - return; - } - } - } - } - }, - _ => (), - } - - span_lint_and_note( - cx, - EXPL_IMPL_CLONE_ON_COPY, - item.span, - "you are implementing `Clone` explicitly on a `Copy` type", - Some(item.span), - "consider deriving `Clone` or removing `Copy`", - ); } + // Derive constrains all generic types to requiring Clone. Check if any type is not constrained for + // this impl. + if ty_subs.types().any(|ty| !implements_trait(cx, ty, clone_id, &[])) { + return; + } + + span_lint_and_note( + cx, + EXPL_IMPL_CLONE_ON_COPY, + item.span, + "you are implementing `Clone` explicitly on a `Copy` type", + Some(item.span), + "consider deriving `Clone` or removing `Copy`", + ); } /// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint. diff --git a/tests/ui/derive.rs b/tests/ui/derive.rs index 8fcb0e8b28d..4e46bf13991 100644 --- a/tests/ui/derive.rs +++ b/tests/ui/derive.rs @@ -35,7 +35,6 @@ impl<'a> Clone for Lt<'a> { } } -// Ok, `Clone` cannot be derived because of the big array #[derive(Copy)] struct BigArray { a: [u8; 65], @@ -47,7 +46,6 @@ impl Clone for BigArray { } } -// Ok, function pointers are not always Clone #[derive(Copy)] struct FnPtr { a: fn() -> !, @@ -59,7 +57,7 @@ impl Clone for FnPtr { } } -// Ok, generics +// Ok, Clone trait impl doesn't have constrained generics. #[derive(Copy)] struct Generic<T> { a: T, @@ -71,4 +69,21 @@ impl<T> Clone for Generic<T> { } } +#[derive(Copy)] +struct Generic2<T>(T); +impl<T: Clone> Clone for Generic2<T> { + fn clone(&self) -> Self { + Self(self.0.clone()) + } +} + +// Ok, Clone trait impl doesn't have constrained generics. +#[derive(Copy)] +struct GenericRef<'a, T, U>(T, &'a U); +impl<T: Clone, U> Clone for GenericRef<'_, T, U> { + fn clone(&self) -> Self { + Self(self.0.clone(), self.1) + } +} + fn main() {} diff --git a/tests/ui/derive.stderr b/tests/ui/derive.stderr index 1328a9b3107..82a70ceecc3 100644 --- a/tests/ui/derive.stderr +++ b/tests/ui/derive.stderr @@ -40,7 +40,7 @@ LL | | } | |_^ error: you are implementing `Clone` explicitly on a `Copy` type - --> $DIR/derive.rs:44:1 + --> $DIR/derive.rs:43:1 | LL | / impl Clone for BigArray { LL | | fn clone(&self) -> Self { @@ -50,7 +50,7 @@ LL | | } | |_^ | note: consider deriving `Clone` or removing `Copy` - --> $DIR/derive.rs:44:1 + --> $DIR/derive.rs:43:1 | LL | / impl Clone for BigArray { LL | | fn clone(&self) -> Self { @@ -60,7 +60,7 @@ LL | | } | |_^ error: you are implementing `Clone` explicitly on a `Copy` type - --> $DIR/derive.rs:56:1 + --> $DIR/derive.rs:54:1 | LL | / impl Clone for FnPtr { LL | | fn clone(&self) -> Self { @@ -70,7 +70,7 @@ LL | | } | |_^ | note: consider deriving `Clone` or removing `Copy` - --> $DIR/derive.rs:56:1 + --> $DIR/derive.rs:54:1 | LL | / impl Clone for FnPtr { LL | | fn clone(&self) -> Self { @@ -79,5 +79,25 @@ LL | | } LL | | } | |_^ -error: aborting due to 4 previous errors +error: you are implementing `Clone` explicitly on a `Copy` type + --> $DIR/derive.rs:74:1 + | +LL | / impl<T: Clone> Clone for Generic2<T> { +LL | | fn clone(&self) -> Self { +LL | | Self(self.0.clone()) +LL | | } +LL | | } + | |_^ + | +note: consider deriving `Clone` or removing `Copy` + --> $DIR/derive.rs:74:1 + | +LL | / impl<T: Clone> Clone for Generic2<T> { +LL | | fn clone(&self) -> Self { +LL | | Self(self.0.clone()) +LL | | } +LL | | } + | |_^ + +error: aborting due to 5 previous errors |