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Make Clone::clone a lang item #128170

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Merged
merged 1 commit into from
Jul 26, 2024
Merged

Make Clone::clone a lang item #128170

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1 change: 1 addition & 0 deletions compiler/rustc_hir/src/lang_items.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -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.
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4 changes: 2 additions & 2 deletions compiler/rustc_mir_transform/src/instsimplify.rs
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Expand Up @@ -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;
Expand Down Expand Up @@ -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;
}

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1 change: 1 addition & 0 deletions compiler/rustc_span/src/symbol.rs
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Expand Up @@ -557,6 +557,7 @@ symbols! {
clobber_abi,
clone,
clone_closures,
clone_fn,
clone_from,
closure,
closure_lifetime_binder,
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3 changes: 3 additions & 0 deletions library/core/src/clone.rs
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Expand Up @@ -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")]
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suggestion: include a comment about what makes Clone::clone special to the compiler.

fn clone(&self) -> Self;

/// Performs copy-assignment from `source`.
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