MMKV.cpp std::move on a temporary object - Copy Elision

[arthurgeron]

The following warning is generated during build: gradle warning: warning: moving a temporary object prevents copy elision [-Wpessimizing-move]

This occurs in the generated MMKV.cpp on the bool MMKV::getBytes method, calls std::move on a temporary object, which causes the warning. This potentially causes efficiency issues.

The fix would be:

diff --git a/node_modules/react-native-mmkv/MMKV/Core/MMKV.cpp b/node_modules/react-native-mmkv/MMKV/Core/MMKV.cpp
index eb5b708..a81fe6f 100755
--- a/node_modules/react-native-mmkv/MMKV/Core/MMKV.cpp
+++ b/node_modules/react-native-mmkv/MMKV/Core/MMKV.cpp
@@ -701,7 +701,7 @@ bool MMKV::getBytes(MMKVKey_t key, mmkv::MMBuffer &result) {
     if (data.length() > 0) {
         try {
             CodedInputData input(data.getPtr(), data.length());
-            result = std::move(input.readData());
+            result = input.readData();
             return true;
         } catch (std::exception &exception) {
             MMKVError("%s", exception.what());

But since it's a generated file I'm not sure how/if it could be fixed in the source code.

[miiguelperes]

Any updates?

[mrousavy]

This is a warning. And can be ignored.