Fix clippy::needless_borrow in the compiler

`x clippy compiler -Aclippy::all -Wclippy::needless_borrow --fix`.

Then I had to remove a few unnecessary parens and muts that were exposed
now.

compiler/rustc_mir_dataflow/src/elaborate_drops.rs

@@ -481,12 +481,8 @@ where
     ) -> (BasicBlock, Unwind) {
         let (succ, unwind) = self.drop_ladder_bottom();
         if !adt.is_enum() {
-            let fields = self.move_paths_for_fields(
-                self.place,
-                self.path,
-                &adt.variant(FIRST_VARIANT),
-                args,
-            );
+            let fields =
+                self.move_paths_for_fields(self.place, self.path, adt.variant(FIRST_VARIANT), args);
             self.drop_ladder(fields, succ, unwind)
         } else {
             self.open_drop_for_multivariant(adt, args, succ, unwind)
@@ -518,7 +514,7 @@ where
                     self.place,
                     ProjectionElem::Downcast(Some(variant.name), variant_index),
                 );
-                let fields = self.move_paths_for_fields(base_place, variant_path, &variant, args);
+                let fields = self.move_paths_for_fields(base_place, variant_path, variant, args);
                 values.push(discr.val);
                 if let Unwind::To(unwind) = unwind {
                     // We can't use the half-ladder from the original
@@ -859,14 +855,14 @@ where
     fn open_drop(&mut self) -> BasicBlock {
         let ty = self.place_ty(self.place);
         match ty.kind() {
-            ty::Closure(_, args) => self.open_drop_for_tuple(&args.as_closure().upvar_tys()),
+            ty::Closure(_, args) => self.open_drop_for_tuple(args.as_closure().upvar_tys()),
             // Note that `elaborate_drops` only drops the upvars of a coroutine,
             // and this is ok because `open_drop` here can only be reached
             // within that own coroutine's resume function.
             // This should only happen for the self argument on the resume function.
             // It effectively only contains upvars until the coroutine transformation runs.
             // See librustc_body/transform/coroutine.rs for more details.
-            ty::Coroutine(_, args, _) => self.open_drop_for_tuple(&args.as_coroutine().upvar_tys()),
+            ty::Coroutine(_, args, _) => self.open_drop_for_tuple(args.as_coroutine().upvar_tys()),
             ty::Tuple(fields) => self.open_drop_for_tuple(fields),
             ty::Adt(def, args) => self.open_drop_for_adt(*def, args),
             ty::Dynamic(..) => self.complete_drop(self.succ, self.unwind),

compiler/rustc_mir_dataflow/src/framework/direction.rs

@@ -196,7 +196,7 @@ impl Direction for Backward {
     {
         results.reset_to_block_entry(state, block);
 
-        vis.visit_block_end(results, &state, block_data, block);
+        vis.visit_block_end(results, state, block_data, block);
 
         // Terminator
         let loc = Location { block, statement_index: block_data.statements.len() };

compiler/rustc_mir_dataflow/src/framework/engine.rs

@@ -295,7 +295,7 @@ where
         let mut results = Results { analysis, entry_sets, _marker: PhantomData };
 
         if tcx.sess.opts.unstable_opts.dump_mir_dataflow {
-            let res = write_graphviz_results(tcx, &body, &mut results, pass_name);
+            let res = write_graphviz_results(tcx, body, &mut results, pass_name);
             if let Err(e) = res {
                 error!("Failed to write graphviz dataflow results: {}", e);
             }

compiler/rustc_mir_dataflow/src/framework/lattice.rs

@@ -342,7 +342,7 @@ impl<V: Clone> Clone for MaybeReachable<V> {
     fn clone_from(&mut self, source: &Self) {
         match (&mut *self, source) {
             (MaybeReachable::Reachable(x), MaybeReachable::Reachable(y)) => {
-                x.clone_from(&y);
+                x.clone_from(y);
             }
             _ => *self = source.clone(),
         }

compiler/rustc_mir_dataflow/src/impls/initialized.rs

@@ -409,7 +409,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeInitializedPlaces<'_, 'tcx> {
         }
 
         let enum_ = discr.place().and_then(|discr| {
-            switch_on_enum_discriminant(self.tcx, &self.body, &self.body[block], discr)
+            switch_on_enum_discriminant(self.tcx, self.body, &self.body[block], discr)
         });
 
         let Some((enum_place, enum_def)) = enum_ else {
@@ -540,7 +540,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, 'tcx> {
         }
 
         let enum_ = discr.place().and_then(|discr| {
-            switch_on_enum_discriminant(self.tcx, &self.body, &self.body[block], discr)
+            switch_on_enum_discriminant(self.tcx, self.body, &self.body[block], discr)
         });
 
         let Some((enum_place, enum_def)) = enum_ else {

compiler/rustc_mir_dataflow/src/rustc_peek.rs

@@ -34,7 +34,7 @@ impl<'tcx> MirPass<'tcx> for SanityCheck {
         }
 
         let param_env = tcx.param_env(def_id);
-        let move_data = MoveData::gather_moves(&body, tcx, param_env, |_| true);
+        let move_data = MoveData::gather_moves(body, tcx, param_env, |_| true);
         let mdpe = MoveDataParamEnv { move_data, param_env };
 
         if has_rustc_mir_with(tcx, def_id, sym::rustc_peek_maybe_init).is_some() {