警告:/Android.mk:链接器标志中的非系统库

WARNING: .../Android.mk: non-system libraries in linker flags

本文关键字：系统库 标志 链接 Android mk 警告      更新时间：2023-10-16

运行$ANDROID_NDK_ROOT/ndk-build时收到此警告。Android.mk如下。

$ $ANDROID_NDK_ROOT/ndk-build 
WARNING:/Users/jwalton/Android-CryptoPP/jni/Android.mk:prng:
    non-system libraries in linker flags: -lcryptopp -lstlport_shared    
    This is likely to result in incorrect builds. Try using LOCAL_STATIC_LIBRARIES    
    or LOCAL_SHARED_LIBRARIES instead to list the library dependencies of the
    current module
...

然而，当我按照说明从LOCAL_LDLIBS中删除-lcryptopp -lstlport_shared时，我会得到与libstlport_shared.so中的符号相关的链接错误。以下是Android.mk文件后面的错误示例。

ndk-build究竟希望如何设置Android.mk？

为什么我必须将$(STLPORT_INCL)添加到LOCAL_C_INCLUDES，并将$(STLPORT_LIB)添加到LOCAL_LDFLAGS？为什么APP_STL := stlport_shared不能立即正确设置STL？

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
TARGET_ARCH_ABI := armeabi
TARGET_ABI      := android-9-armeabi
CRYPTOPP_INCL   := /usr/local/cryptopp-android-9/include
CRYPTOPP_LIB    := /usr/local/cryptopp-android-9/lib
STLPORT_INCL    := /opt/android-ndk-r9/sources/cxx-stl/stlport/stlport
STLPORT_LIB     := /opt/android-ndk-r9/sources/cxx-stl/stlport/libs/armeabi
APP_STL         := stlport_shared
APP_MODULES     := stlport_shared cryptopp
LOCAL_CPP_FEATURES := rtti exceptions
LOCAL_C_INCLUDES := $(CRYPTOPP_INCL) $(CRYPTOPP_INCL)/cryptopp $(STLPORT_INCL)
LOCAL_LDFLAGS  := -L $(CRYPTOPP_LIB) -L $(STLPORT_LIB)
LOCAL_LDLIBS   := -lcryptopp -lstlport_shared -llog -landroid
# LOCAL_LDLIBS   := -llog -landroid
# LOCAL_SHARED_LIBRARIES := -lcryptopp -lstlport_shared
LOCAL_MODULE    := prng
LOCAL_SRC_FILES := libprng.cpp
include $(BUILD_SHARED_LIBRARY)

以下是尝试按照建议从LOCAL_LDLIBS:中删除本地库时的错误示例

$ $ANDROID_NDK_ROOT/ndk-build 
Android NDK: WARNING: APP_PLATFORM android-14 is larger than android:minSdkVersion 9 in /Users/jwalton/Android-CryptoPP/AndroidManifest.xml    
Gdbserver      : [arm-linux-androideabi-4.6] libs/armeabi/gdbserver
Gdbsetup       : libs/armeabi/gdb.setup
Compile++ thumb  : prng <= libprng.cpp
SharedLibrary  : libprng.so
/opt/android-ndk-r9/toolchains/arm-linux-androideabi-4.6/prebuilt/darwin-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: /Users/jwalton/Android-CryptoPP/obj/local/armeabi/objs-debug/prng/libprng.o: in function std::__node_alloc::allocate(unsigned int&):/opt/android-ndk-r9/sources/cxx-stl/stlport/stlport/stl/_alloc.h:158: error: undefined reference to 'std::__node_alloc::_M_allocate(unsigned int&)'
/opt/android-ndk-r9/toolchains/arm-linux-androideabi-4.6/prebuilt/darwin-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: /Users/jwalton/Android-CryptoPP/obj/local/armeabi/objs-debug/prng/libprng.o: in function std::__node_alloc::deallocate(void*, unsigned int):/opt/android-ndk-r9/sources/cxx-stl/stlport/stlport/stl/_alloc.h:161: error: undefined reference to 'std::__node_alloc::_M_deallocate(void*, unsigned int)'
/opt/android-ndk-r9/toolchains/arm-linux-androideabi-4.6/prebuilt/darwin-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: /Users/jwalton/Android-CryptoPP/obj/local/armeabi/objs-debug/prng/libprng.o: in function std::ios_base::_M_check_exception_mask():/opt/android-ndk-r9/sources/cxx-stl/stlport/stlport/stl/_ios_base.h:193: error: undefined reference to 'std::ios_base::_M_throw_failure()'

我将"链接器标志中的非系统库"消息解释为没有使用默认系统库（在usr/lib中）的警告，这可能非常好，但也可能导致错误（不同库版本之间不兼容）。这个警告是否会让你出错完全取决于你自己。

然后，关于你试图解决它的方法，我认为你错误地使用了NDK的LOCAL_SHARED_LIBRARIES变量。

我把一个使用Assimp 的Android.mk文件的样本粘贴到这里

#------------------------------------------------------------------ Assimp
include $(CLEAR_VARS)
LOCAL_MODULE := Assimp
LOCAL_EXPORT_C_INCLUDES := $(GENERATED_INCLUDE_PATH)/assimp/include
LOCAL_SRC_FILES := $(GENERATED_PATH)/assimp/lib/libassimp.a
include $(PREBUILT_STATIC_LIBRARY)
...
LOCAL_STATIC_LIBRARIES := 
Assimp 
<Your other libs here>

正如您所看到的，我使用自定义名称声明了一个LOCAL_MODULE，设置了几个变量，然后包含了PREBUILT_STATIC_LIBRARY脚本，该脚本告诉NDK使用这个库。

然后在LOCAL_STATIC_LIBRARIES中，我列出了我使用的库及其模块名称，而不是像您在这里所做的那样，这是一个链接器标志。

在你的情况下，我认为你应该做以下事情，例如stl

include $(CLEAR_VARS)
LOCAL_MODULE := STLPortShared
LOCAL_EXPORT_C_INCLUDES := <path to stlport includes>
LOCAL_SRC_FILES := <path to stlport library>
include $(PREBUILT_SHARED_LIBRARY)
...
#Notice the name, identical to the one specified for LOCAL_MODULE
LOCAL_SHARED_LIBRARIES = STLPortShared

我认为应该这样做。当然，对每个引起麻烦的库重复这个过程，不要忘记每个库规范之间的include(CLEAR_VARS)。

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