diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs index 58cc0f62111..1821387e85f 100644 --- a/compiler/rustc_hir/src/lang_items.rs +++ b/compiler/rustc_hir/src/lang_items.rs @@ -162,6 +162,7 @@ language_item_table! { StructuralPeq, sym::structural_peq, structural_peq_trait, Target::Trait, GenericRequirement::None; Copy, sym::copy, copy_trait, Target::Trait, GenericRequirement::Exact(0); Clone, sym::clone, clone_trait, Target::Trait, GenericRequirement::None; + CloneFn, sym::clone_fn, clone_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; Sync, sym::sync, sync_trait, Target::Trait, GenericRequirement::Exact(0); DiscriminantKind, sym::discriminant_kind, discriminant_kind_trait, Target::Trait, GenericRequirement::None; /// The associated item of the `DiscriminantKind` trait. diff --git a/compiler/rustc_mir_transform/src/instsimplify.rs b/compiler/rustc_mir_transform/src/instsimplify.rs index 8209e5e2711..58fdc2d9e45 100644 --- a/compiler/rustc_mir_transform/src/instsimplify.rs +++ b/compiler/rustc_mir_transform/src/instsimplify.rs @@ -3,6 +3,7 @@ use crate::simplify::simplify_duplicate_switch_targets; use crate::take_array; use rustc_ast::attr; +use rustc_hir::LangItem; use rustc_middle::bug; use rustc_middle::mir::*; use rustc_middle::ty::layout; @@ -271,8 +272,7 @@ impl<'tcx> InstSimplifyContext<'tcx, '_> { return; } - let trait_def_id = self.tcx.trait_of_item(fn_def_id); - if trait_def_id.is_none() || trait_def_id != self.tcx.lang_items().clone_trait() { + if !self.tcx.is_lang_item(fn_def_id, LangItem::CloneFn) { return; } diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index 5ae01389116..18bc514fc98 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -557,6 +557,7 @@ symbols! { clobber_abi, clone, clone_closures, + clone_fn, clone_from, closure, closure_lifetime_binder, diff --git a/library/core/src/clone.rs b/library/core/src/clone.rs index 939b2be6dfa..76a89eaaff8 100644 --- a/library/core/src/clone.rs +++ b/library/core/src/clone.rs @@ -160,6 +160,9 @@ pub trait Clone: Sized { /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[must_use = "cloning is often expensive and is not expected to have side effects"] + // Clone::clone is special because the compiler generates MIR to implement it for some types. + // See InstanceKind::CloneShim. + #[cfg_attr(not(bootstrap), lang = "clone_fn")] fn clone(&self) -> Self; /// Performs copy-assignment from `source`.