c++ - cpprestsdk : Undefined symbols for architecture x86_64

Question

我已经访问了所有其他问题，但据我所知，没有一个是我的问题。

在 MacBook Pro 16GB 内存 Intel Core I7 上运行 OS X El Capitan 10.11.6

我也运行过 brew doctor，但没有发现任何会导致此问题的问题。下面是我的 CMakeLists.txt 文件:

cmake_minimum_required(VERSION 3.0.0)
project(WebClient VERSION 0.0.0)

include(CheckCXXCompilerFlag)
CHECK_CXX_COMPILER_FLAG("-std=c++14" COMPLIER_SUPPORTS_CXX14)
CHECK_CXX_COMPILER_FLAG("-std=c++0x" COMPLIER_SUPPORTS_CXX0X)
if(COMPLIER_SUPPORTS_CXX14)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
elseif(COMPILER_SUPPORTS_CXX0X)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
else()
    message(STATUS "The compiler ${CMAKE_CXX_COMPILER} has no C++14 support.
                    Please use a different C++ compiler.")
endif()

FIND_PACKAGE( Boost 1.62 COMPONENTS program_options REQUIRED )
INCLUDE_DIRECTORIES( ${Boost_INCLUDE_DIR} )

set(OPT_CPPFLAGS "-I/usr/local/opt/openssl/include -I/usr/local/opt/libiconv/include")
set(OPT_LDFLAGS "-v -lcpprest -lboost_system -L/usr/local/opt/openssl/lib -L/usr/local/opt/libiconv/lib -lcrypto -lssl")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OPT_CPPFLAGS} -v -g -O3 -fno-common -stdlib=libc++")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OPT_LDFLAGS}")

add_executable(anyExecutable webclient.cpp)

TARGET_LINK_LIBRARIES( anyExecutable ${Boost_LIBRARIES} )

include(CPack)

我使用 brew 安装了 cpprestsdk/2.8.0，其中还包括 boost/1.62.0 和 openssl/1.0.2j 以及 libiconv/1.14。我的代码来自 wiki cpprestsdk 上的教程。

#include <cpprest/http_client.h>
#include <cpprest/filestream.h>
#include <atomic>

using namespace utility;                    // Common utilities like string conversions
using namespace web;                        // Common features like URIs.
using namespace web::http;                  // Common HTTP functionality
using namespace web::http::client;          // HTTP client features
using namespace concurrency::streams;       // Asynchronous streams

int main(int argc, char* argv[]) {
  auto fileStream = std::make_shared<ostream>();

  // Open stream to output file.
  pplx::task<void> requestTask = fstream::open_ostream( U("results.xml") ).then(
    [=](ostream outFile) {
        *fileStream = outFile;

        // Create http_client to send the request.
        http_client client(U("http://www.dictionaryapi.com/api/v1/references/"));

        // Build request URI and start the request.
        uri_builder builder(U("thesaurus/xml/"));
        builder.append_path(U("ranking"),true);
        builder.append_query(U("?key"), U("--------------------"));
        return client.request(methods::GET, builder.to_string());
  })

  // Handle response headers arriving.
  .then( [=](http_response response ) {
    printf("Received response status code:%u\n", response.status_code());

    // Write response body into the file.
    return response.body().read_to_end(fileStream->streambuf());
  })

  // Close the file stream.
  .then( [=](size_t ) {
    return fileStream->close();
  });

  // Wait for all the outstanding I/O to complete and handle any exceptions
  try {
    requestTask.wait();
  } catch (const std::exception &e) {
    printf("Error exception:%s\n", e.what());
  }//try-catch BLOCK

  return 0;
}//Main

为了节省一些空间，只打印一些相同的错误，它们都找不到:

    [vscode] Executing cmake command: cmake --build /Users/gumpy/git-repos/webapi/build --target all --config Debug -- -j 10
[ 50%] Building CXX object CMakeFiles/anyExecutable.dir/webclient.cpp.o
Apple LLVM version 8.0.0 (clang-800.0.38)
Target: x86_64-apple-darwin15.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" -cc1 -triple x86_64-apple-macosx10.11.0 -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -emit-obj -disable-free -disable-llvm-verifier -discard-value-names -main-file-name webclient.cpp -mrelocation-model pic -pic-level 2 -mthread-model posix -mdisable-fp-elim -masm-verbose -munwind-tables -target-cpu core2 -target-linker-version 274.1 -v -dwarf-column-info -debug-info-kind=standalone -dwarf-version=2 -debugger-tuning=lldb -coverage-file /Users/gumpy/git-repos/webapi/build/CMakeFiles/anyExecutable.dir/webclient.cpp.o -resource-dir /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/8.0.0 -I /usr/local/include -I /usr/local/opt/openssl/include -I /usr/local/opt/libiconv/include -stdlib=libc++ -O3 -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /Users/gumpy/git-repos/webapi/build -ferror-limit 19 -fmessage-length 0 -stack-protector 1 -fblocks -fobjc-runtime=macosx-10.11.0 -fencode-extended-block-signature -fcxx-exceptions -fexceptions -fmax-type-align=16 -fno-common -fdiagnostics-show-option -vectorize-loops -vectorize-slp -o CMakeFiles/anyExecutable.dir/webclient.cpp.o -x c++ /Users/gumpy/git-repos/webapi/webclient.cpp
clang -cc1 version 8.0.0 (clang-800.0.38) default target x86_64-apple-darwin15.6.0
ignoring nonexistent directory "/usr/include/c++/v1"
ignoring duplicate directory "/usr/local/include"
  as it is a non-system directory that duplicates a system directory
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/opt/openssl/include
 /usr/local/opt/libiconv/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1
 /usr/local/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/8.0.0/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
 /usr/include
 /System/Library/Frameworks (framework directory)
 /Library/Frameworks (framework directory)
End of search list.
[100%] Linking CXX executable anyExecutable
Apple LLVM version 8.0.0 (clang-800.0.38)
Target: x86_64-apple-darwin15.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld" -demangle -dynamic -arch x86_64 -macosx_version_min 10.11.0 -o anyExecutable -L/usr/local/opt/openssl/lib -L/usr/local/opt/libiconv/lib -search_paths_first -headerpad_max_install_names -lcpprest -lboost_system -lcrypto -lssl CMakeFiles/anyExecutable.dir/webclient.cpp.o /usr/local/lib/libboost_program_options-mt.dylib -lc++ -lSystem /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/8.0.0/lib/darwin/libclang_rt.osx.a
Undefined symbols for architecture x86_64:
  "boost::this_thread::interruption_point()", referenced from:
      boost::condition_variable::wait(boost::unique_lock<boost::mutex>&) in webclient.cpp.o
      boost::condition_variable::do_wait_until(boost::unique_lock<boost::mutex>&, timespec const&) in webclient.cpp.o
  "boost::chrono::steady_clock::now()", referenced from:
      pplx::details::event_impl::wait(unsigned int) in webclient.cpp.o
  "boost::chrono::system_clock::now()", referenced from:
      pplx::details::event_impl::wait(unsigned int) in webclient.cpp.o
  "boost::detail::get_current_thread_data()", referenced from:
      boost::detail::interruption_checker::interruption_checker(_opaque_pthread_mutex_t*, _opaque_pthread_cond_t*) in webclient.cpp.o
ld: symbol(s) not found for architecture x86_64

Answer 1

缺少符号名称是由于缺少库。必要的 CPPFLAGS 和 LDFLAGS 是:

CPPFLAGS = -stdlib=libc++
LDFLAGS = -lcpprest -lboost_system -lboost_thread-mt -lboost_chrono-mt -lssl -lcrypto

非常感谢大家的帮助。