clang：错误：：错误在Mac OSX El Capitan构建XGBoost上不支持的选项'-fopenmp'

Question

我正在尝试按照以下说明为Python构建XGBoost软件包：

这是使用支持OpenMP的编译器安装XGBoost的完整解决方案。通过获得openmp支持的gcc-5.xx brew install gcc --without-multilib。（brew是OS X上apt-get的事实上的标准。因此，不建议单独安装HPC，但应该可以。）：

git clone --recursive https://github.com/dmlc/xgboost
cd xgboost; cp make/config.mk ./config.mk; make -j4

该错误恰好在make -j4命令中发生。

事前搜索，我尝试了这两种解决方案，但无济于事，除了担心担心会弄乱一切而安装另一个gcc的部分。

以下是make配置文件。它没有任何怀疑。

#-----------------------------------------------------
#  xgboost: the configuration compile script
#
#  If you want to change the configuration, please use the following
#  steps. Assume you are on the root directory of xgboost.
#  First copy the this file so that any local changes will be ignored by git
#
#  $ cp make/config.mk .
#
#  Next modify the according entries, and then compile by
#
#  $ make
#
#  or build in parallel with 8 threads
#
#  $ make -j8
#----------------------------------------------------

# choice of compiler, by default use system preference.
# export CC = gcc
# export CXX = g++
# export MPICXX = mpicxx

# the additional link flags you want to add
ADD_LDFLAGS =

# the additional compile flags you want to add
ADD_CFLAGS =

# Whether enable openmp support, needed for multi-threading.
USE_OPENMP = 1

# whether use HDFS support during compile
USE_HDFS = 0

# whether use AWS S3 support during compile
USE_S3 = 0

# whether use Azure blob support during compile
USE_AZURE = 0

# Rabit library version,
# - librabit.a Normal distributed version.
# - librabit_empty.a Non distributed mock version,
LIB_RABIT = librabit.a

# path to libjvm.so
LIBJVM=$(JAVA_HOME)/jre/lib/amd64/server

# List of additional plugins, checkout plugin folder.
# uncomment the following lines to include these plugins
# you can also add your own plugin like this
#
# XGB_PLUGINS += plugin/example/plugin.mk

Answer 1

您安装gcc了Homebrew，但错误来自clang。这仅表示您的默认编译器仍指向clang而不是新安装的gcc。如果您在Makefile中阅读了注释，则会看到以下几行：

# choice of compiler, by default use system preference.
# export CC = gcc
# export CXX = g++
# export MPICXX = mpicxx

在您的情况下，您不需要系统之一。
注意：gcc系统指向clang：

$ which gcc
/usr/bin/gcc
$ gcc --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.3.0 (clang-703.0.29)
Target: x86_64-apple-darwin15.4.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

而是将这些变量指向中的某个内容/usr/local/bin，例如：

$ export CC=/usr/local/bin/gcc

和类似的其他两个变量，CXX和MPICXX，如：

$ export CC=/usr/local/bin/gcc;CXX=/usr/local/bin/g++;MPICXX=/usr/local/bin/mpicxx