Undefined reference to '_Unwind_GetIP' - makefile

Question

I'm having a bit of trouble getting a rustc compiled staticlib for triple, arm-linux-androideabi, to link up nicely within Android Studio.
Steps taken...
Install Rust via multirust
Build a rustc for Android API v14
Build lib with --target=arm-linux-androideabi
Add to jniLibs/ within Android Studio
Create a little C++ shim for hooks to/from JNI
Build and link (almost)
When building my crate, I get the following output:
note: link against the following native artifacts when linking
against this static library
note: the order and any duplication can be significant on some platforms,
and so may need to be preserved
note: library: c
note: library: m
note: library: dl
note: library: log
note: library: gcc
note: library: c
note: library: m
So naturally, my Android.mk includes these libs when using the staticlib.
Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := hydrogen
LOCAL_SRC_FILES := ../jniLibs/$(TARGET_ARCH_ABI)/libhydrogen.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := hydrogen-android
LOCAL_SRC_FILES := shim.cpp
LOCAL_STATIC_LIBRARIES := hydrogen
LOCAL_LDLIBS := -lc -lm -ldl -llog -lgcc -lc -lm
include $(BUILD_SHARED_LIBRARY)
Building in Android Studio gives me the following output:
:app:buildCppShim
Android NDK: WARNING:/Android.mk:hydrogen: non-system libraries in linker flags: -lgcc -lgccunwind
Android NDK: This is likely to result in incorrect builds. Try using LOCAL_STATIC_LIBRARIES
Android NDK: or LOCAL_SHARED_LIBRARIES instead to list the library dependencies of the
Android NDK: current module
[armeabi] Compile++ thumb: hydrogen-android <= shim.cpp
[armeabi] SharedLibrary : libhydrogen-android.so
[snipped]function sync::rwlock::StaticRwLock::read::ha5ec9717ccd1ed83Lxp: error: undefined reference to 'pthread_rwlock_rdlock'
[snipped]function sys_common::rwlock::RWLock::read::h7f3d472c79e2e1e2Z1q: error: undefined reference to 'pthread_rwlock_rdlock'
[snipped]function sys_common::rwlock::RWLock::read_unlock::hd7d67e9c5c47b9f5B2q: error: undefined reference to 'pthread_rwlock_unlock'
[snipped]function sync::rwlock::StaticRwLock::try_read::hddd396186cced62f8xp: error: undefined reference to 'pthread_rwlock_tryrdlock'
[snipped]function sys_common::rwlock::RWLock::try_read::ha5aede723e91a3c881q: error: undefined reference to 'pthread_rwlock_tryrdlock'
[snipped]function sync::rwlock::StaticRwLock::write::h787666bb30e75d28Ryp: error: undefined reference to 'pthread_rwlock_wrlock'
[snipped]function sys_common::rwlock::RWLock::write::h0273da9a7ade68c0i2q: error: undefined reference to 'pthread_rwlock_wrlock'
[snipped]function sync..rwlock..RwLockWriteGuard$LT$$LP$$RP$$GT$::drop.34348::h4c8fbe45843b9a01: error: undefined reference to 'pthread_rwlock_unlock'
[snipped]function sync::rwlock::StaticRwLock::try_write::h5d30a7fdd53c86b4ezp: error: undefined reference to 'pthread_rwlock_trywrlock'
[snipped]function sys_common::rwlock::RWLock::try_write::h0ec4bcc0cb460718r2q: error: undefined reference to 'pthread_rwlock_trywrlock'
[snipped]function sync::rwlock::StaticRwLock::destroy::ha1e9f51e62905aedXzp: error: undefined reference to 'pthread_rwlock_destroy'
[snipped]function sys_common::rwlock::RWLock::destroy::h602ce773ff2356e6T2q: error: undefined reference to 'pthread_rwlock_destroy'
[snipped]function sys::rwlock::RWLock::read::h241f5fdff06a76ab00u: error: undefined reference to 'pthread_rwlock_rdlock'
[snipped]function sys::rwlock::RWLock::write::h48034b52e6491ea4h3u: error: undefined reference to 'pthread_rwlock_wrlock'
~/bin/rust/src/compiler-rt/lib/builtins/gcc_personality_v0.c
Error:(206) undefined reference to '_Unwind_GetIP'
Error:(273) undefined reference to '_Unwind_SetGR'
Error:(274) undefined reference to '_Unwind_SetGR'
Error:(275) undefined reference to '_Unwind_SetIP'
pthread errors
I'm not sure why I received the errors about pthread, because I have #include <pthread.h> in my shim, and these functions are defined in Android's pthread.
unwind errors
For this, I've tried including unwind.h in the shim and libgccunwind.a in the Android.mk, but still throws the same errors. I found this thread where a hack-solution was to just declare the prototypes in the shim, but when I do this, I receive the following errors about unwind.h
Error:(231, 3) error: previous declaration 'void _Unwind_SetGR(_Unwind_Context*, int, _Unwind_Word)' here
So, it is able to find their declarations when I declare them, because they conflict, but has no idea where they are if I do not? I'm assuming it has to be something wrong with my linking order, but unsure of how to solve it, because the required libs are linked against after pulling in the rust created lib.
Any help would be greatly appreciated!
Edit 1
Adjusted makefile to link during Shared Library creation.

Answer 1

LOCAL_LDLIBS is meaningless for a static library (static libraries don't get linked). You need to add those libraries whenever you use that library in a real binary (like a shared library or executable).

Answer 2

The solution happened to be building unwind and including some portability headers. See module example here