我有一个Go库,为COpenImageIO库提供绑定(OpenImageiGO).我一直很乐意通过标准动态链接到libOpenImageIO来构建我的绑定,但现在我正试图静态链接.我遇到了一个问题,无论我尝试哪种标志组合,外部链接器都会因大量“未定义的引用”错误而失败.我似乎记得在过去提到过这个问题,并说链接器看到符号的顺序存在问题.但我似乎无法再找到这些信息.
这是我最近的构建尝试的一个简短示例,试图将其与boost,OpenColorIO和OpenImageIO的静态构建相链接：
$export CGO_CPPFLAGS="\
-I/path/to/boost/include \
-I/path/to/OpenColorIO/include \
-I/path/to/OpenImageIO/include"
$export CGO_LDFLAGS="\
-L/path/to/boost/lib -lboost_thread_static -lboost_system_static \
-L/path/to/OpenColorIO/lib -lopencolorio \
-L/path/to/OpenImageIO/lib -lOpenImageIO"
$go build -v -x --ldflags '-extldflags "-static"' github.com/justinfx/openimageigo
...
CGO_LDFLAGS="/path/to/boost/lib/libboost_system_static.a" "/path/to/boost/lib/libboost_thread_static.a" "/path/to/OpenColorIO/lib/libopencolorio.a" "/path/to/OpenImageIO/lib/libOpenImageIO.a" "-lstdc++" /vol/apps/go/1.3.0/pkg/tool/linux_amd64/cgo -objdir $WORK/github.com/justinfx/openimageigo/_obj/ -- -I/path/to/boost/include -I/path/to/OpenColorIO/include -I/path/to/OpenImageIO/include -I./cpp -I $WORK/github.com/justinfx/openimageigo/_obj/ -I/path/to/boost/include -I/path/to/OpenColorIO/include -I/path/to/OpenImageIO/include color.go imagebuf.go imagebufalgo.go imagecache.go imageinput.go imageoutput.go imagespec.go oiio.go roi.go
...
/usr/bin/g++ -I . -fPIC -m64 -pthread -fmessage-length=0 -I/path/to/boost/include -I/path/to/OpenColorIO/include -I/path/to/OpenImageIO/include -I./cpp -I $WORK/github.com/justinfx/openimageigo/_obj/ -g -O2 -o $WORK/github.com/justinfx/openimageigo/_obj/all.cpp.o -c ./all.cpp
/usr/bin/g++ -I . -fPIC -m64 -pthread -fmessage-length=0 -o $WORK/github.com/justinfx/openimageigo/_obj/_cgo_.o $WORK/github.com/justinfx/openimageigo/_obj/_cgo_main.o $WORK/github.com/justinfx/openimageigo/_obj/_cgo_export.o $WORK/github.com/justinfx/openimageigo/_obj/color.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/imagebuf.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/imagebufalgo.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/imagecache.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/imageinput.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/imageoutput.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/imagespec.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/oiio.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/roi.cgo2.o $WORK/github.com/justinfx/openimageigo/_obj/all.cpp.o /path/to/boost/lib/libboost_system_static.a /path/to/boost/lib/libboost_thread_static.a /path/to/OpenColorIO/lib/libopencolorio.a /path/to/OpenImageIO/lib/libOpenImageIO.a -lstdc++
这里有一些樱桃挑选的错误,因为它是一个非常长的输出：
/path/to/OpenImageIO/lib/libOpenImageIO.a(OpenImageIO_dist^src^libOpenImageIO^color_ocio.cpp.o): In function `ColorConfig':
/path/to/OpenImageIO/OpenImageIO_dist/src/libOpenImageIO/color_ocio.cpp:141: undefined reference to `OpenColorIO::v1::SetLoggingLevel(OpenColorIO::v1::LoggingLevel)'
...
/path/to/OpenImageIO/lib/libOpenImageIO.a(OpenImageIO_dist^src^libOpenImageIO^imagebufalgo_copy.cpp.o): In function `boost::shared_mutex::lock()':
/path/to/boost/include/boost/thread/pthread/shared_mutex.hpp:138: undefined reference to `boost::this_thread::disable_interruption::~disable_interruption()'
OpenImageIO似乎无法找到OpenColorIO的引用.并且,OpenImageIO似乎无法找到提升的参考.看起来链接期间发生事情的顺序并不是OpenColorIO或OpenCmageIO可用的提升符号,所以我得到了一堆符号错误.
我希望我做一些简单而愚蠢的事情,可以在我的构建过程中纠正.但是与外部库的cgo静态链接似乎比默认的动态链接方法更复杂.
更新#1
@ james-henstridge给出的答案是正确的,除了最后一次打嗝之外,我几乎完全建成了.我正在获取OpenColorIO所需的yaml-cpp失败的引用,即使它看起来我的订单正确.
这是我最新的env,我已经完成了所有必须添加的显式静态库：
$export CGO_CPPFLAGS="-I/usr/local/include -I/usr/include"
$export CGO_LDFLAGS="\
-L/usr/local/lib \
-L/usr/lib \
-L/usr/lib/x86_64-linux-gnu \
-lOpenImageIO \
-lHalf -lIex -lfreetype -lIlmThread -lImath -lIlmImf -lIlmThread \
-lOpenColorIO \
-lyaml-cpp -ltinyxml \
-lboost_regex -lboost_filesystem -lboost_thread -lboost_system \
-ltiff -lgif -lpng -ljpeg -lz \
-lrt -ldl"
$go test -v -x --ldflags '-extldflags "-static"' github.com/justinfx/openimageigo
...
/home/justin/src/OpenColorIO/src/core/OCIOYaml.cpp:329: undefined reference to `YAML::Node::begin() const'
...
/home/justin/src/OpenColorIO/build/ext/dist/include/yaml-cpp/nodereadimpl.h:79: undefined reference to `YAML::Node::GetScalar(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&) const'
...
/usr/local/lib/libOpenColorIO.a(OCIOYaml.cpp.o): In function `_FindFromNodeAtIndex':
/home/justin/src/OpenColorIO/build/ext/dist/include/yaml-cpp/nodeutil.h:53: undefined reference to `YAML::Node::FindAtIndex(unsigned long) const'
collect2: ld returned 1 exit status
更新#2
没关系更新#1.它与OpenColorIO特别相关,而不是一般问题.
解决方法:
当您链接静态库时,-l标志的顺序很重要.如果使用-lfoo -lbar -lbaz进行链接,则只能在libbar.a和libbaz.a中搜索libbar.a所需的任何符号.即使libfoo.a包含您所追求的符号,链接器也无法找到它们.
发生的事情是,对于每个库,链接器解压缩归档并添加包含之前引用的符号引用的符号的目标文件.如果不需要存档中的特定目标文件,则忽略该文件.
解决方法是确保每个库在链接器标志中依赖于它之前列出.如果存在任何依赖循环(不应该存在),则可能需要两次列出库.