Cocos 2dx 4.x. Enable C++17 in Android Studio - c++

Question

I am trying to learn Cocos 2dx game engine. I generated a simple project with this command:
cocos new -l cpp -p com.testgame1 -d path_to_dir testgame1
Next, I try to build an android project. Everything is successful. Then I wrote a lot of code that uses C++ standard 14, 17. Example (file main.cpp):
void cocos_android_app_init(JNIEnv* env) {
LOGD("cocos_android_app_init");
std::string vec;
std::transform(std::begin(vec), std::end(vec), std::begin(vec), [](auto& elem)
{
return elem;
}
);
appDelegate.reset(new AppDelegate());
}
Here I using auto in lambda function (standart C++ 14).
I enable support for the standard in the usual way for Android Studio in build.gradle:
defaultConfig {
applicationId "com.testgame1"
minSdkVersion PROP_MIN_SDK_VERSION
targetSdkVersion PROP_TARGET_SDK_VERSION
versionCode 1
versionName "1.0"
externalNativeBuild {
cmake {
targets 'MyGame'
cppFlags "-std=c++17 -frtti -fexceptions -fsigned-char"
arguments "-DCMAKE_FIND_ROOT_PATH=", "-DANDROID_STL=c++_static", "-DANDROID_TOOLCHAIN=clang", "-DANDROID_ARM_NEON=TRUE"
}
}
ndk {
abiFilters = []
abiFilters.addAll(PROP_APP_ABI.split(':').collect{it as String})
}
}
But it doesn't have any effect. On a clean project (no Cocos 2dx game engine) everything works flawlessly.
I am getting an error in Android Studio:
..\..\..\..\jni\hellocpp\main.cpp:42:72: error: 'auto' not allowed in lambda parameter
NDK: 21.4.7075529
How to fix it?

Answer 1

In your game project folder, open up CMakeLists.txt, and add the following after the include(CocosBuildSet) statement:
set(CMAKE_CXX_STANDARD 17)
If you want to apply C++17 to the cocos2d engine code as well, then adding this may work:
set_target_properties(cocos2d PROPERTIES
CXX_STANDARD 17
CXX_STANDARD_REQUIRED YES
CXX_EXTENSIONS NO
)
Source: cocos2dx forum