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我正在尝试使用 Xcode 9.2 (9C40b) 和 CMake 3.11.0-rc3 为 iOS 10+构建Ceres 1.13.0 。似乎 CMake 无法识别 Xcode 9 提供的 clang 版本。这是怎么回事？看起来不像，因为以前版本的 Ceres 构建得很好。

这个问题似乎表明 CMake 不支持 AppleClang，这对我来说似乎很可笑。这里的另一个团队在 macOS 上使用 CMake 构建了我们的大量代码，仅使用 Xcode 提供的 clang。

我还尝试修改 Ceres iOS.cmake 文件以按照该 SO 答案的建议设置 CMP0025 策略，但这没有任何区别。

更新

我注意到了一些事情。当 CMake 适用于其他构建时，它会将编译器正确标识为AppleClang 9.0.0.9000039. 当它失败时，您可以看到下面的消息（它称之为“Clang”）。在这两种情况下，它都将 CXX 编译器标识为/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++. 下面的输出显示了无法识别编译器的情况

$ cmake $CERES_DIR -DCMAKE_TOOLCHAIN_FILE=$CERES_DIR/cmake/iOS.cmake -DCXX11=ON -DLAPACK=OFF -DEIGEN_INCLUDE_DIR=$EIGEN_INCLUDE_DIR -DIOS_PLATFORM=OS -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=../
-- Building with Xcode version: 9.2
-- Configuring iOS build for platform: OS, architecture(s): arm64
-- Using C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang
-- Using CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++
-- Using libtool: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/libtool
-- Building for minimum iOS version: 11.2 (SDK version: 11.2)
-- Detected Ceres version: 1.13.0 from /Users/me/Projects/Clients/MyCompany/repo/thirdparty/ceres-solver-1.13.0/include/ceres/version.h
-- Building Ceres for iOS platform: OS
-- Building for iOS: Forcing use of miniglog instead of glog.
-- Building for iOS: SuiteSparse, CXSparse, LAPACK, gflags, and OpenMP are not available.
-- Building for iOS: Will not build examples.
-- No preference for use of exported Eigen CMake configuration set, and no hints for include directory provided. Defaulting to preferring an installed/exported Eigen CMake configuration if available.
-- Found installed version of Eigen: /usr/local/share/eigen3/cmake
-- Found Eigen version 3.3.4: /usr/local/include/eigen3

   ===============================================================
   Disabling the use of Eigen as a sparse linear algebra library.
   This does not affect the covariance estimation algorithm 
   which can still use the EIGEN_SPARSE_QR algorithm.
   ===============================================================

-- Building without LAPACK.
-- Building without SuiteSparse.
-- Building without CXSparse.
   ===============================================================
   Compiling without any sparse library: SuiteSparse, CXSparse 
   & Eigen (Sparse) are all disabled or unavailable.  No sparse 
   linear solvers (SPARSE_NORMAL_CHOLESKY & SPARSE_SCHUR)
   will be available when Ceres is used.
   ===============================================================
-- Google Flags disabled; no tests or tools will be built!
-- Compiling minimal glog substitute into Ceres.
-- Using minimal glog substitute (include): internal/ceres/miniglog
-- Max log level for minimal glog substitute: 2
-- Building without OpenMP (disabling multithreading).
-- Looking for C++ include unordered_map
-- Looking for C++ include unordered_map - found
-- Performing Test HAVE_UNORDERED_MAP_IN_STD_NAMESPACE
-- Performing Test HAVE_UNORDERED_MAP_IN_STD_NAMESPACE - Success
-- Found unordered_map/set in std namespace.
-- Looking for C++ include memory
-- Looking for C++ include memory - found
-- Performing Test HAVE_SHARED_PTR_IN_STD_NAMESPACE
-- Performing Test HAVE_SHARED_PTR_IN_STD_NAMESPACE - Success
-- Found shared_ptr in std namespace using <memory> header.
   ==============================================================
   Compiling Ceres using C++11.  This will result in a version 
   of Ceres that will require the use of C++11 in client code.
   ==============================================================
-- Building Ceres as a static library.
-- Enabling CERES_NO_LAPACK in Ceres config.h
-- Enabling CERES_NO_SUITESPARSE in Ceres config.h
-- Enabling CERES_NO_CXSPARSE in Ceres config.h
-- Enabling CERES_USE_CXX11 in Ceres config.h
-- Enabling CERES_NO_THREADS in Ceres config.h
-- Enabling CERES_STD_UNORDERED_MAP in Ceres config.h
CMake Error at cmake/AddCeresCXX11RequirementsToTarget.cmake:70 (target_compile_features):
  target_compile_features no known features for CXX compiler

  "Clang"

  version 9.0.0.9000039.
Call Stack (most recent call first):
  internal/ceres/CMakeLists.txt:223 (add_ceres_cxx11_requirements_to_target)


-- Do not build any example.
-- Configuring incomplete, errors occurred!
See also "/Users/me/Projects/Clients/MyCompany/repo/iOS/lib/ceres/build/CMakeFiles/CMakeOutput.log".

Xcode 版本：

$ /usr/bin/clang --version
Apple LLVM version 9.0.0 (clang-900.0.39.2)
Target: x86_64-apple-darwin17.4.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

非常感谢您的指导。

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1 回答 1

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啊，看来我需要删除中间的 CMake 文件。弄糊涂了。这样做使问题消失了（还必须在 iOS 11 之前指定最小部署目标，或者找到一种方法告诉 Ceres 除了 arm64 之外不要构建任何东西）。

于 2018-03-22T00:32:31.810 回答