Rollup merge of #128170 - saethlin:clone-fn, r=compiler-errors

Make Clone::clone a lang item

I want to absorb all the logic for picking whether an Instance is LocalCopy or GloballyShared into one place. As part of this, I wanted to identify Clone shims inside `cross_crate_inlinable` and found that rather tricky. `@compiler-errors` suggested that I add a lang item for `Clone::clone` because that would produce other cleanups in the compiler.

That sounds good to me, but I have looked and I've only been able to find one.

r? compiler-errors

1 files changed, 2 insertions, 2 deletions

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;
         }