对“_Unwind_GetIP”的未定义引用

Question

我在将 rustc 编译为 staticlib 三倍 arm-linux-androideabi 以在 Android Studio 中很好地链接时遇到了一些麻烦。

采取的步骤...

1. 通过multirust 安装 Rust
2. 为 Android API v14 构建一个 rustc
3. 使用--target=arm-linux-androideabi 构建库
4. 在 Android Studio 中添加到 jniLibs/
5. 为与 JNI 之间的钩子创建一个小的 C++ shim
6. 构建和链接（几乎）

在构建我的 crate 时，我得到以下输出：

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

所以很自然，我的 Android.mk 在使用静态库时包含这些库。

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)

在 Android Studio 中构建会得到以下输出：

: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'

线程错误 我不确定为什么会收到关于 pthread 的错误，因为我的 shim 中有 #include <pthread.h>，而这些函数在 Android's pthread 中定义。

展开错误 为此，我尝试在 shim 中包含 unwind.h，在 Android.mk 中包含 libgccunwind.a，但仍然抛出相同的错误。我找到了this thread，其中一个黑客解决方案就是在 shim 中声明原型，但是当我这样做时，我收到以下关于 unwind.h 的错误

Error:(231, 3) error: previous declaration 'void _Unwind_SetGR(_Unwind_Context*, int, _Unwind_Word)' here

所以，当我声明它们时，它能够找到它们的声明，因为它们冲突，但如果我不知道它们在哪里？我假设我的链接顺序一定有问题，但不确定如何解决它，因为在拉入 rust 创建的库后，需要的库被链接。

任何帮助将不胜感激！

编辑 1 调整了在共享库创建期间链接的 makefile。

Answer 1

LOCAL_LDLIBS 对于静态库没有意义（静态库不会被链接）。每当您在真正的二进制文件（如共享库或可执行文件）中使用该库时，都需要添加这些库。

Answer 2

解决方案恰好是构建 unwind 并包含一些可移植性标头。见模块示例here