Auto merge of #108339 - GuillaumeGomez:rollup-4z02kas, r=GuillaumeGomez

Rollup of 8 pull requests

Successful merges:

 - #108110 (Move some `InferCtxt` methods to `EvalCtxt` in new solver)
 - #108168 (Fix ICE on type alias in recursion)
 - #108230 (Convert a hard-warning about named static lifetimes into lint "unused_lifetimes")
 - #108239 (Fix overlapping spans in removing extra arguments)
 - #108246 (Add an InstCombine for redundant casts)
 - #108264 (no-fail-fast support for tool testsuites)
 - #108310 (rustdoc: Fix duplicated attributes for first reexport)
 - #108318 (Remove unused FileDesc::get_cloexec)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 9 insertions, 0 deletions

diff --git a/compiler/rustc_mir_transform/src/instcombine.rs b/compiler/rustc_mir_transform/src/instcombine.rs
index 0534e688703..3896f0e57ea 100644
--- a/compiler/rustc_mir_transform/src/instcombine.rs
+++ b/compiler/rustc_mir_transform/src/instcombine.rs
@@ -30,6 +30,7 @@ impl<'tcx> MirPass<'tcx> for InstCombine {
                         ctx.combine_bool_cmp(&statement.source_info, rvalue);
                         ctx.combine_ref_deref(&statement.source_info, rvalue);
                         ctx.combine_len(&statement.source_info, rvalue);
+                        ctx.combine_cast(&statement.source_info, rvalue);
                     }
                     _ => {}
                 }
@@ -142,6 +143,14 @@ impl<'tcx> InstCombineContext<'tcx, '_> {
         }
     }
 
+    fn combine_cast(&self, _source_info: &SourceInfo, rvalue: &mut Rvalue<'tcx>) {
+        if let Rvalue::Cast(_kind, operand, ty) = rvalue {
+            if operand.ty(self.local_decls, self.tcx) == *ty {
+                *rvalue = Rvalue::Use(operand.clone());
+            }
+        }
+    }
+
     fn combine_primitive_clone(
         &self,
         terminator: &mut Terminator<'tcx>,