我正尝试将clang与gcc标准库头一起使用，如下所示：
/opt/rh/llvm-toolset-11.0/root/usr/bin/clang -MD -MF bazel-out/k8-fastbuild/bin/external/com_google_googletest/_objs/gtest/gtest-typed-test.d '-frandom-seed=bazel-out/k8-fastbuild/bin/external/com_google_googletest/_objs/gtest/gtest-typed-test.o' -iquote external/com_google_googletest -iquote bazel-out/k8-fastbuild/bin/external/com_google_googletest -isystem external/com_google_googletest/googlemock -isystem bazel-out/k8-fastbuild/bin/external/com_google_googletest/googlemock -isystem external/com_google_googletest/googlemock/include -isystem bazel-out/k8-fastbuild/bin/external/com_google_googletest/googlemock/include -isystem external/com_google_googletest/googletest -isystem bazel-out/k8-fastbuild/bin/external/com_google_googletest/googletest -isystem external/com_google_googletest/googletest/include -isystem bazel-out/k8-fastbuild/bin/external/com_google_googletest/googletest/include -isystem /opt/rh/devtoolset-11/root/usr/include/c++/11 -isystem /opt/rh/devtoolset-11/root/usr/include/c++/11/bits -isystem /opt/rh/devtoolset-11/root/include/c++/11/x86_64-redhat-linux/bits -fdiagnostics-color -Wfatal-errors '-std=c++2a' -Wall -Wno-sign-compare '--gcc-toolchain=/opt/rh/devtoolset-11/root' -Wheader-guard -pthread -c external/com_google_googletest/googletest/src/gtest-typed-test.cc -o bazel-out/k8-fastbuild/bin/external/com_google_googletest/_objs/gtest/gtest-typed-test.o
然后我得到这个错误：
In file included from external/com_google_googletest/googletest/include/gtest/gtest.h:62:
In file included from external/com_google_googletest/googletest/include/gtest/internal/gtest-internal.h:40:
In file included from external/com_google_googletest/googletest/include/gtest/internal/gtest-port.h:395:
/opt/rh/devtoolset-11/root/usr/include/c++/11/bits/regex.h:56:9: fatal error: use of undeclared identifier 'regex_constants'
regex_constants::match_flag_type __flags);
出现错误的原因可能是什么？gcc和clang之间是否不兼容？我应该安装clang-headers和libc++吗？这是通过安装llvm-dev包实现的吗？
gtest-port.h文件包括一个带有#include <regex.h>的文件(请参阅此处获取代码(。它希望该文件是POSIXregex.h，它通常直接安装在前缀/usr/include下。正如您在错误消息中看到的，编译器会尝试包含/usr/include/c++/11/bits/regex.h，这是错误的文件。
.../bits/中的头文件并不意味着用户代码将直接包括在内。是标准库实现的内部。因此，直接包含它失败并不奇怪(丢失的符号可能在另一个内部头文件中定义(。
为了解决您的问题，我建议您尝试在编译命令中省略.../bits目录*。我不知道是谁告诉你要包括它们，但它们并不意味着要添加到编译器搜索路径中。
*从编译器命令行中删除以下两个标志：
-isystem /opt/rh/devtoolset-11/root/usr/include/c++/11/bits
-isystem /opt/rh/devtoolset-11/root/include/c++/11/x86_64-redhat-linux/bits