MacOS下编译C++ gRPC项目报错：全局命名空间无signbit等cmath成员

长话短说： 编译时引入#include <cmath>头文件触发报错no member named 'signbit' in the global space
目标： 编译纯C++实现的gRPC客户端-服务端应用

报错信息 #

g++ -std=c++17 client.cpp mathtest.pb.cc mathtest.grpc.pb.cc -o  client `pkg-config --libs --cflags protobuf grpc++`
In file included from client.cpp:3:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpc++/grpc++.h:26:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/grpcpp.h:52:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/channel.h:28:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/impl/codegen/completion_queue.h:45:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/impl/codegen/sync.h:32:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/synchronization/mutex.h:72:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/synchronization/internal/kernel_timeout.h:34:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/time/clock.h:26:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/time/time.h:78:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:321:9: error: no member named 'signbit' in the global namespace
using ::signbit;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:322:9: error: no member named 'fpclassify' in the global namespace
using ::fpclassify;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:323:9: error: no member named 'isfinite' in the global namespace
using ::isfinite;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:324:9: error: no member named 'isinf' in the global namespace
using ::isinf;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:325:9: error: no member named 'isnan' in the global namespace
using ::isnan;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:326:9: error: no member named 'isnormal' in the global namespace
using ::isnormal;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:327:7: error: no member named 'isgreater' in the global namespace; did you mean '::std::greater'?
using ::isgreater;
      ^~
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/functional:742:29: note: '::std::greater' declared here
struct _LIBCPP_TEMPLATE_VIS greater : binary_function<_Tp, _Tp, bool>
                            ^
In file included from client.cpp:3:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpc++/grpc++.h:26:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/grpcpp.h:52:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/channel.h:28:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/impl/codegen/completion_queue.h:45:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/impl/codegen/sync.h:32:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/synchronization/mutex.h:72:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/synchronization/internal/kernel_timeout.h:34:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/time/clock.h:26:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/time/time.h:78:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:328:7: error: no member named 'isgreaterequal' in the global namespace; did you mean '::std::greater_equal'?
using ::isgreaterequal;
      ^~
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/functional:771:29: note: '::std::greater_equal' declared here
struct _LIBCPP_TEMPLATE_VIS greater_equal : binary_function<_Tp, _Tp, bool>
                            ^
In file included from client.cpp:3:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpc++/grpc++.h:26:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/grpcpp.h:52:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/channel.h:28:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/impl/codegen/completion_queue.h:45:
In file included from /opt/homebrew/Cellar/grpc/1.41.1/include/grpcpp/impl/codegen/sync.h:32:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/synchronization/mutex.h:72:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/synchronization/internal/kernel_timeout.h:34:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/time/clock.h:26:
In file included from /opt/homebrew/Cellar/abseil/20210324.2_1/include/absl/time/time.h:78:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:329:9: error: no member named 'isless' in the global namespace
using ::isless;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:330:9: error: no member named 'islessequal' in the global namespace
using ::islessequal;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:331:9: error: no member named 'islessgreater' in the global namespace
using ::islessgreater;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:332:9: error: no member named 'isunordered' in the global namespace
using ::isunordered;
      ~~^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cmath:333:9: error: no member named 'isunordered' in the global namespace
using ::isunordered;
      ~~^

以上仅为截取的部分报错内容，还有更多cmath相关错误，推测找到正确解决方案后可全部消除。

已尝试的解决方法 #

• 切换不同SDK路径

# 查看当前SDK路径
xcrun --show-sdk-path

# 切换SDK
sudo xcode-select -s /Library/Developer/CommandLineTools          # 使用CommandLineTools SDK
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer   # 使用XCode.app SDK

• 修改cmath文件中的#include <math.h>引用

修复方案：

1. 调整#include<...>的搜索顺序，优先搜索/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1路径即可解决。
2. 修改/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/cmath文件中的<math.h>引用，替换为#include</Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/math.h>

• 在编译命令中添加-isysroot /sdk/path参数，完整命令如下：
  g++ -std=c++17 client.cpp mathtest.pb.cc mathtest.grpc.pb.cc -o client -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk 'pkg-config --libs --cflags protobuf grpc++'
• 卸载、重装并更新Xcode命令行工具
• 重装gcc

设备配置 #

,xNMM.          ---------------------------------
               .OMMMMo           OS: macOS 12.0.1 21A559 arm64
               OMMM0,            Host: MacBookPro18,3
     .;loddo:' loolloddol;.      Kernel: 21.1.0
   cKMMMMMMMMMMNWMMMMMMMMMM0:    Uptime: 12 days, 22 hours, 41 mins
 .KMMMMMMMMMMMMMMMMMMMMMMMWd.    Packages: 53 (brew)
 XMMMMMMMMMMMMMMMMMMMMMMMX.      Shell: zsh 5.8
;MMMMMMMMMMMMMMMMMMMMMMMM:       Resolution: 1512x982
:MMMMMMMMMMMMMMMMMMMMMMMM:       DE: Aqua
.MMMMMMMMMMMMMMMMMMMMMMMMX.      WM: Quartz Compositor
 kMMMMMMMMMMMMMMMMMMMMMMMMWd.    WM Theme: Blue (Dark)
 .XMMMMMMMMMMMMMMMMMMMMMMMMMMk   Terminal: iTerm2
  .XMMMMMMMMMMMMMMMMMMMMMMMMK.   Terminal Font: Monaco 12
    kMMMMMMMMMMMMMMMMMMMMMMd     CPU: Apple M1 Pro
     ;KMMMMMMMWXXWMMMMMMMk.      GPU: Apple M1 Pro
       .cooc,.    .,coo:.        Memory: 3551MiB / 32768MiB

目前暂未找到其他可行排查方向，经过数小时调研，推测该问题为MacOS系统层面问题而非项目配置问题，恳请各位提供协助，非常感谢。

内容的提问来源于stack exchange，提问作者zebra14