Could someone please assist with this NDK linker error? Been working at it for hours. NDK bug? - android-ndk

Question

I am trying to compile and link a simple enough program (basically a hello world example) all day long. I've asked the author of the library and he told me to fix my linker dependencies. Here is the relevant info:
I also tried compiling with the author's build tool and linking it as a static library, but to no avail. I have also tried all variations of the STL build environment. Am I doing anything wrong, or is something else the problem?
testbgfx.cpp
#include <SDL.h>
#include <bgfxplatform.h>
#include <bgfx.h>
int main(int argc, char* args[])
{
// SDL_Init( SDL_INIT_EVERYTHING ); Uncommenting this did nothing
SDL_Rect bounds;
SDL_GetDisplayBounds(0,&bounds);
int height = bounds.h;
int width = bounds.w;
SDL_Window* window = SDL_CreateWindow("TestApp",SDL_WINDOWPOS_UNDEFINED,SDL_WINDOWPOS_UNDEFINED,width,height,SDL_WINDOW_MAXIMIZED);
bgfx_sdlSetWindow(window);
bgfx::init();
return 0;
}
Android.mk (for client app)
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := main
LOCAL_SRC_FILES := testbgfx.cpp
# Switching to static lib did nothing
#LOCAL_STATIC_LIBRARIES := bgfx
LOCAL_SHARED_LIBRARIES := SDL2 bx bgfx
# Required for compilation
LOCAL_CXXFLAGS := $(LOCAL_CFLAGS) -D__STDC_LIMIT_MACRO -D__STDC_FORMAT_MACROS -D__STDC_CONSTANT_MACROS
LOCAL_LDLIBS := -lGLESv1_CM -lGLESv2 -llog -lc -ldl -lm -landroid -lEGL
include $(BUILD_SHARED_LIBRARY)
$(call import-module,bx)
$(call import-module,bgfx)
$(call import-module,SDL2)
The Android.mk for the bgfx library (in ndk sources directory, as required)
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := bgfx
#This did nothing
#LOCAL_C_INCLUDES += src
#Disabled those to see that would happen - nothing
#LOCAL_CFLAGS := -Wall -Wextra -g -Wa,--noexecstack -no-canonical-prefixes -ffunction-sections -Wno-psabi -Wunused-value -Wundef -fstack-protector
#LOCAL_CXXFLAGS := $(LOCAL_CFLAGS) -D__STDC_LIMIT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_CONSTANT_MACROS -MMD -MP -fPIC -std=c++0x
LOCAL_SRC_FILES := src
LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
#Enabling the following changed nothing
#LOCAL_C_INCLUDES := $(LOCAL_PATH)/3rdparty
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
# This doesn't work
#LOCAL_EXPORT_C_INCLUDES += $(LOCAL_PATH)/src/*.h
# Neither does this
#LOCAL_EXPORT_C_INCLUDES += $(wildcard $(LOCAL_PATH)/src/*h)
LOCAL_SHARED_LIBRARIES := bx
LOCAL_EXPORT_SHARED_LIBRARIES := bx
#Switching to static did nothing
#include $(BUILD_STATIC_LIBRARY)
include $(BUILD_SHARED_LIBRARY)
$(call import-modules,bx)
Android.mk for bx (utility lib depended on my bgfx, also in the ndk sources dir)
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := bx
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(BUILD_SHARED_LIBRARY)
Here is relevant error log:
/home/noob/android/android-ndk-r10d/toolchains/arm-linux-androideabi- 4.8/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++ -Wl,-soname,libmain.so -shared --sysroot=/home/noob/android/android-ndk-r10d/platforms/android-18/arch-arm ./obj/local/armeabi-v7a/objs/main/testbgfx.o ./obj/local/armeabi-v7a/libSDL2.a -lgcc ./obj/local/armeabi-v7a/libbx.so ./obj/local/armeabi-v7a/libbgfx.so ./obj/local/armeabi-v7a/libgnustl_shared.so -no-canonical-prefixes -march=armv7-a -Wl,--fix-cortex-a8 -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -mthumb -L/home/noob/android/android-ndk-r10d/platforms/android-18/arch-arm/usr/lib -lGLESv1_CM -lGLESv2 -llog -lc -ldl -lm -landroid -lEGL -Wl,--undefined=Java_org_libsdl_app_SDLActivity_nativeInit -ldl -lGLESv1_CM -lGLESv2 -llog -landroid /home/noob/android/android-ndk/sources/cxx-stl/gnu-libstdc++/4.8/libs/armeabi-v7a/libsupc++.a -lc -lm -o ./obj/local/armeabi-v7a/libmain.so
jni/src/testbgfx.cpp:18: error: undefined reference to 'bgfx::init(bgfx::RendererType::Enum, bgfx::CallbackI*, bx::ReallocatorI*)'
collect2: error: ld returned 1 exit status
make: *** [obj/local/armeabi-v7a/libmain.so] Error 1

Answer 1

The Android.mk for bgfx doesn't actually seem to be listing any source files to compile - you've only listed LOCAL_SRC_FILES := src which seems to be a directory. You need to list all the individual C/C++ source files here.