CODEWITHSUNDEEP
androidc++11android-ndk
Rajveer
Rajveer

Reputation: 857

Android NDK r9b and compiling C++11

I'm trying to compile some C++11 code using NDK r9b, however no matter what I try it doesn't work. Compiling without C++11 features works fine.

Here is my Application.mk:

NDK_TOOLCHAIN_VERSION := 4.8
APP_STL := gnustl_static

Here is my Android.mk:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

FILE_LIST := $(wildcard $(LOCAL_PATH)/*.cpp)

LOCAL_CPPFLAGS := -std=c++11 -pthread -frtti -fexceptions
LOCAL_MODULE    := RAGEAndroid
LOCAL_SRC_FILES := jni.c $(FILE_LIST:$(LOCAL_PATH)/%=%)
LOCAL_LDLIBS    := -llog -lm -landroid -lGLESv3

include $(BUILD_SHARED_LIBRARY)

I have tried setting the following too without luck:

LOCAL_CFLAGS := -D__GXX_EXPERIMENTAL_CXX0X__
LOCAL_CPPFLAGS := -std=gnu++11 -pthread -frtti -fexceptions

I have ensured that Eclipse has the following paths in C++ general->Paths and Symbols

(ndk path)/sources/cxx-stl/gnu-libstdc++/4.8/include
(ndk path)/sources/cxx-stl/gnu-libstdc++/4.8/libs/armeabi/include

I have one C file (jni.c) and a couple of test cpp/hpp. Everything compiles fine without any C++11 features, and including something like <thread> or <memory> doesn't cause any complaints, however when actually creating a std::thread object I get "Type 'std::thread' could not be resolved". This also happens with other features I am trying to use (std::unique_ptr, std::shared_ptr, std::move() e.t.c).

I've read many topics on getting C++11 to compile but nothing seems to work, I believe I've missed something but can't figure out what it is. Any help would be appreciated!

EDIT: If I print __cplusplus it shows 201103L, so it looks like it's using the correct version.

EDIT 2: std::atomic seems to work fine.

Upvotes: 6

Views: 9748

Answers (2)

Dono
Dono

Reputation: 128

May be you need to inverse the line:

LOCAL_MODULE    := RAGEAndroid

with the line:

LOCAL_CPPFLAGS := -std=c++11 -pthread -frtti -fexceptions

To say these flags need to be use on the current module (RageAndroid), not the previous module.

By the way, in my project I need to indicate c++11 with the line above (c++0x<->c++11) (otherwise it didn't work here).

LOCAL_CPPFLAGS  := -std=c++0x

Upvotes: 0

Alex Cohn
Alex Cohn

Reputation: 57203

I'm sorry, the following should have been a comment, not answer - because I don't know what's wrong in your code, but here is what you can do to figure out yourself:

Here's my minimal Android.mk:

LOCAL_PATH      := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE    := hello-jni
LOCAL_SRC_FILES := HelloJni.cpp
LOCAL_LDLIBS    := -llog
include $(BUILD_SHARED_LIBRARY)

Application.mk

APP_CPPFLAGS := -std=c++11
NDK_TOOLCHAIN_VERSION=4.8
APP_STL=gnustl_static

And here is the minimal HelloJni.cpp

#include <jni.h>
#include <thread>

void doSomeWork( void )
{
    __android_log_print(ANDROID_LOG_DEBUG, "HelloJni", "hello from thread...");
    return;
}

extern "C" 
jstring 
Java_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env,
                                              jobject thiz )
{
    std::thread t( doSomeWork );
    t.join();
    return env->NewStringUTF("Hello from JNI !");
}

It builds clean in r9b on my Mac. One thing to check: run ndk-build V=1 and make sure that the link step is similar to 

~/android-ndk-r9b/toolchains/arm-linux-androideabi-4.8/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-g++ -Wl,-soname,libhello-jni.so -shared --sysroot=~/android-ndk-r9b/platforms/android-17/arch-arm ./obj/local/armeabi/objs-debug/hello-jni/HelloJni.o ~/android-ndk-r9b/sources/cxx-stl/gnu-libstdc++/4.8/libs/armeabi/libgnustl_static.a -lgcc -no-canonical-prefixes  -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now  -L~/android-ndk-r9b/platforms/android-17/arch-arm/usr/lib -llog -lc -lm -o ./obj/local/armeabi/libhello-jni.so

and check output of command

~/android-ndk-r9b/toolchains/arm-linux-androideabi-4.8/prebuilt/darwin-x86/bin/arm-linux-androideabi-nm -C ~/android-ndk-r9b/sources/cxx-stl/gnu-libstdc++/4.8/libs/armeabi/libgnustl_static.a  | grep std::thread

Here is what I get:

00000000 T std::thread::_M_start_thread(std::shared_ptr<std::thread::_Impl_base>)
00000000 T std::thread::hardware_concurrency()
00000000 T std::thread::join()
00000000 T std::thread::detach()

Upvotes: 3

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