无法编译具有snappy支持的leveldb

Question

我正试图在mac x high上构建支持https://github.com/google/leveldb压缩的https://github.com/google/snappy，以便以后在XCode项目中使用，我正在遍历自述的标准编译过程，用于这两个项目。这包括通过cmake为两个项目构建项目。对于snappy项目，程序是平滑的，所有的构建和安装都是完美无缺的。但是，对于leveldb，我无法使cmake找到以前通过make install安装的snappy库。我不明白如何调试cmake并找到它查找库的位置。

任何帮助都是非常感谢的。

以下是这两种构建的结果：

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编辑

下面是一个输出，看起来/usr/local/lib在列表中

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另一个编辑

我试着按照sel-fish提供的解决方案运行sel-fish。但是，如果出现以下输出失败：

Undefined symbols for architecture x86_64:
  "std::__1::__vector_base_common<true>::__throw_length_error() const", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  "std::logic_error::logic_error(char const*)", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  "std::length_error::~length_error()", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::resize(unsigned long, char)", referenced from:
      snappy::Uncompress(char const*, unsigned long, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) in libsnappy.a(snappy.cc.o)
      snappy::Compress(char const*, unsigned long, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) in libsnappy.a(snappy.cc.o)
  "std::terminate()", referenced from:
      ___clang_call_terminate in libsnappy.a(snappy.cc.o)
  "typeinfo for std::length_error", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  "vtable for __cxxabiv1::__class_type_info", referenced from:
      typeinfo for snappy::Sink in libsnappy.a(snappy-sinksource.cc.o)
      typeinfo for snappy::Source in libsnappy.a(snappy-sinksource.cc.o)
  NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
  "vtable for __cxxabiv1::__si_class_type_info", referenced from:
      typeinfo for snappy::ByteArraySource in libsnappy.a(snappy-sinksource.cc.o)
      typeinfo for snappy::UncheckedByteArraySink in libsnappy.a(snappy-sinksource.cc.o)
  NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
  "vtable for std::length_error", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
  "operator delete[](void*)", referenced from:
      snappy::Compress(snappy::Source*, snappy::Sink*) in libsnappy.a(snappy.cc.o)
      snappy::SnappySinkAllocator::Deleter(void*, char const*, unsigned long) in libsnappy.a(snappy.cc.o)
  "operator delete(void*)", referenced from:
      snappy::UncompressAsMuchAsPossible(snappy::Source*, snappy::Sink*) in libsnappy.a(snappy.cc.o)
      snappy::Uncompress(snappy::Source*, snappy::Sink*) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
      snappy::ByteArraySource::~ByteArraySource() in libsnappy.a(snappy-sinksource.cc.o)
      snappy::UncheckedByteArraySink::~UncheckedByteArraySink() in libsnappy.a(snappy-sinksource.cc.o)
  "operator new[](unsigned long)", referenced from:
      snappy::internal::WorkingMemory::GetHashTable(unsigned long, int*) in libsnappy.a(snappy.cc.o)
      snappy::Compress(snappy::Source*, snappy::Sink*) in libsnappy.a(snappy.cc.o)
      snappy::SnappyScatteredWriter<snappy::SnappySinkAllocator>::SlowAppend(char const*, unsigned long) in libsnappy.a(snappy.cc.o)
  "operator new(unsigned long)", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  "___cxa_allocate_exception", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  "___cxa_begin_catch", referenced from:
      ___clang_call_terminate in libsnappy.a(snappy.cc.o)
  "___cxa_free_exception", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  "___cxa_pure_virtual", referenced from:
      vtable for snappy::Sink in libsnappy.a(snappy-sinksource.cc.o)
      vtable for snappy::Source in libsnappy.a(snappy-sinksource.cc.o)
  "___cxa_throw", referenced from:
      void std::__1::vector<snappy::SnappySinkAllocator::Datablock, std::__1::allocator<snappy::SnappySinkAllocator::Datablock> >::__push_back_slow_path<snappy::SnappySinkAllocator::Datablock const>(snappy::SnappySinkAllocator::Datablock const&) in libsnappy.a(snappy.cc.o)
      void std::__1::vector<char*, std::__1::allocator<char*> >::__push_back_slow_path<char* const>(char* const&) in libsnappy.a(snappy.cc.o)
  "___gxx_personality_v0", referenced from:
      snappy::GetUncompressedLength(snappy::Source*, unsigned int*) in libsnappy.a(snappy.cc.o)
      snappy::Compress(snappy::Source*, snappy::Sink*) in libsnappy.a(snappy.cc.o)
      snappy::RawUncompressToIOVec(char const*, unsigned long, iovec const*, unsigned long) in libsnappy.a(snappy.cc.o)
      snappy::RawUncompressToIOVec(snappy::Source*, iovec const*, unsigned long) in libsnappy.a(snappy.cc.o)
      snappy::RawUncompress(char const*, unsigned long, char*) in libsnappy.a(snappy.cc.o)
      snappy::RawUncompress(snappy::Source*, char*) in libsnappy.a(snappy.cc.o)
      snappy::Uncompress(char const*, unsigned long, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) in libsnappy.a(snappy.cc.o)
      ...
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Answer 1

看来你的链接器找不到/usr/local/lib/libsnappy.a。

clang -Xlinker -v，试图运行 /usr/local/lib，确保/usr/local/lib存在于Library search paths中

clang -Xlinker -v

@(#)PROGRAM:ld  PROJECT:ld64-278.4
configured to support archs: armv6 armv7 armv7s arm64 i386 x86_64 x86_64h armv6m armv7k armv7m armv7em (tvOS)
Library search paths:
    /usr/lib
    /usr/local/lib

通常，它会存在。那就试试sudo update_dyld_shared_cache。

谈到调试cmake，您可以使用像--debug-output这样的标志

cmake --debug-output --trace --debug-trycompile ..

更新

check_library_exists(snappy snappy_compress "" HAVE_SNAPPY)

实际上，按照下面的操作，它将尝试链接snappy并查找该函数是否存在：

cc  -DCHECK_FUNCTION_EXISTS=snappy_compress -Wl,-search_paths_first -Wl,-headerpad_max_install_names -o check_snappy_exist CheckFunctionExists.c -lsnappy

CheckFunctionExists.c的来源，您可以找到这里。

我认为这会简化问题。

Answer 2

我已经用brew完成了安装brew的工作。同样重要的是将XCode中的路径添加到User Header Search Paths中，如下所示：

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