Fix transmute_undefined_repr for single element tuples

Author: Jarcho

clippy_lints/src/transmute/transmute_undefined_repr.rs

@@ -282,10 +282,11 @@ fn reduce_ty<'tcx>(cx: &LateContext<'tcx>, mut ty: Ty<'tcx>) -> ReducedTy<'tcx>
             },
             ty::Tuple(args) if args.is_empty() => ReducedTy::TypeErasure,
             ty::Tuple(args) => {
-                let Some(sized_ty) = args.iter().find(|&ty| !is_zero_sized_ty(cx, ty)) else {
+                let mut iter = args.iter();
+                let Some(sized_ty) = iter.find(|&ty| !is_zero_sized_ty(cx, ty)) else {
                     return ReducedTy::OrderedFields(ty);
                 };
-                if args.iter().all(|ty| is_zero_sized_ty(cx, ty)) {
+                if iter.all(|ty| is_zero_sized_ty(cx, ty)) {
                     ty = sized_ty;
                     continue;
                 }

tests/ui/transmute_undefined_repr.rs

@@ -87,5 +87,14 @@ fn main() {
 
         let _: *const [u8] = transmute(value::<Box<[u8]>>()); // Ok
         let _: Box<[u8]> = transmute(value::<*mut [u8]>()); // Ok
+
+        let _: Ty2<u32, u32> = transmute(value::<(Ty2<u32, u32>,)>()); // Ok
+        let _: (Ty2<u32, u32>,) = transmute(value::<Ty2<u32, u32>>()); // Ok
+
+        let _: Ty2<u32, u32> = transmute(value::<(Ty2<u32, u32>, ())>()); // Ok
+        let _: (Ty2<u32, u32>, ()) = transmute(value::<Ty2<u32, u32>>()); // Ok
+
+        let _: Ty2<u32, u32> = transmute(value::<((), Ty2<u32, u32>)>()); // Ok
+        let _: ((), Ty2<u32, u32>) = transmute(value::<Ty2<u32, u32>>()); // Ok
     }
 }