Merge pull request #10390 from marjoleinheyndrickx/wunused-parameters

avoid unused-parameter warning for c++

src/google/protobuf/arena.h

@@ -438,6 +438,7 @@ class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final {
 
     template <typename U>
     static Arena* GetOwningArena(Rank1, const U* p) {
+      (void) p;
       return nullptr;
     }
 
@@ -468,6 +469,7 @@ class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final {
 
     template <typename U>
     static Arena* GetArenaForAllocation(Rank2, const U* p) {
+      (void) p;
       return nullptr;
     }