Rollup merge of #123188 - klensy:clippy-me2, r=Nilstrieb

compiler: fix few unused_peekable and needless_pass_by_ref_mut clippy lints

This fixes few instances of `unused_peekable` and `needless_pass_by_ref_mut`. While i expected to fix more warnings, `needless_pass_by_ref_mut` produced too much for one PR, so i stopped here.

Better reviewed commit by commit, as fixes splitted by chunks.

2 files changed, 3 insertions, 6 deletions

diff --git a/compiler/rustc_mir_transform/src/coroutine.rs b/compiler/rustc_mir_transform/src/coroutine.rs
index f0a13f66555..c3f175f150d 100644
--- a/compiler/rustc_mir_transform/src/coroutine.rs
+++ b/compiler/rustc_mir_transform/src/coroutine.rs
@@ -1226,7 +1226,7 @@ fn create_coroutine_drop_shim<'tcx>(
     tcx: TyCtxt<'tcx>,
     transform: &TransformVisitor<'tcx>,
     coroutine_ty: Ty<'tcx>,
-    body: &mut Body<'tcx>,
+    body: &Body<'tcx>,
     drop_clean: BasicBlock,
 ) -> Body<'tcx> {
     let mut body = body.clone();
diff --git a/compiler/rustc_mir_transform/src/nrvo.rs b/compiler/rustc_mir_transform/src/nrvo.rs
index c3a92911bbf..232c290e0fb 100644
--- a/compiler/rustc_mir_transform/src/nrvo.rs
+++ b/compiler/rustc_mir_transform/src/nrvo.rs
@@ -84,7 +84,7 @@ impl<'tcx> MirPass<'tcx> for RenameReturnPlace {
 ///
 /// If the MIR fulfills both these conditions, this function returns the `Local` that is assigned
 /// to the return place along all possible paths through the control-flow graph.
-fn local_eligible_for_nrvo(body: &mut mir::Body<'_>) -> Option<Local> {
+fn local_eligible_for_nrvo(body: &mir::Body<'_>) -> Option<Local> {
     if IsReturnPlaceRead::run(body) {
         return None;
     }
@@ -118,10 +118,7 @@ fn local_eligible_for_nrvo(body: &mut mir::Body<'_>) -> Option<Local> {
     copied_to_return_place
 }
 
-fn find_local_assigned_to_return_place(
-    start: BasicBlock,
-    body: &mut mir::Body<'_>,
-) -> Option<Local> {
+fn find_local_assigned_to_return_place(start: BasicBlock, body: &mir::Body<'_>) -> Option<Local> {
     let mut block = start;
     let mut seen = BitSet::new_empty(body.basic_blocks.len());