clang++ 无法在 macOS Catalina 中编译 cmath

Question

我有一个导入 cmath 的简单 C++ 程序。

#include <cmath>

int main() {
    return 0;
}

我正在尝试使用以下命令对其进行编译。

clang++ -o test main.cpp -std=c++14

但是，我收到以下错误

In file included from main.cpp:2:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:317:9: error: 
      no member named 'signbit' in the global namespace
using ::signbit;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:318:9: error: 
      no member named 'fpclassify' in the global namespace
using ::fpclassify;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:319:9: error: 
      no member named 'isfinite' in the global namespace; did you mean 'finite'?
using ::isfinite;
      ~~^
/usr/local/include/math.h:749:12: note: 'finite' declared here
extern int finite(double)
           ^
In file included from main.cpp:2:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:320:9: error: 
      no member named 'isinf' in the global namespace
using ::isinf;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:321:9: error: 
      no member named 'isnan' in the global namespace
using ::isnan;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:322:9: error: 
      no member named 'isnormal' in the global namespace
using ::isnormal;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:323:9: error: 
      no member named 'isgreater' in the global namespace
using ::isgreater;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:324:9: error: 
      no member named 'isgreaterequal' in the global namespace
using ::isgreaterequal;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:325:9: error: 
      no member named 'isless' in the global namespace
using ::isless;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:326:9: error: 
      no member named 'islessequal' in the global namespace
using ::islessequal;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:327:9: error: 
      no member named 'islessgreater' in the global namespace
using ::islessgreater;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:328:9: error: 
      no member named 'isunordered' in the global namespace
using ::isunordered;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:329:9: error: 
      no member named 'isunordered' in the global namespace
using ::isunordered;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:335:9: error: 
      no member named 'abs' in the global namespace; did you mean 'fabs'?
using ::abs;
      ~~^
/usr/local/include/math.h:417:15: note: 'fabs' declared here
extern double fabs(double);
              ^
In file included from main.cpp:2:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:640:26: error: 
      no template named 'numeric_limits'
    bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits),
                         ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:640:60: error: 
      no template named 'numeric_limits'
    bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits),
                                                           ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:641:18: error: 
      no template named 'numeric_limits'
    int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)>
                 ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:641:50: error: 
      no template named 'numeric_limits'
    int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)>
                                                 ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:646:17: error: 
      no template named 'numeric_limits'
  static_assert(numeric_limits<_FloatT>::radix == 2, "FloatT has incorrect radix");
                ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

这是我的系统规格。

macOS Catalina 版本 10.15.2

Apple clang 版本 11.0.3 (clang-1103.0.32.29)

Xcode 版本 11.4 (11E146)（不确定这是否重要）

感谢您的帮助！

编辑：更新到 macOS 10.15.4 和 Xcode 11.4.1 仍然有同样的问题

Answer 1

我相信这是Catalina C++: Using <cmath> headers yield error: no member named 'signbit' in the global namespace的回答

最简单的解决方案似乎是卸载适用于 Catalina 的命令行工具，但我在 High Sierra 上遇到了这个问题，我求助于编辑 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/cmath

注释掉#include <math.h> 并替换为：

#include</Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/math.h>

我必须这样做才能让自制软件的 Rust (rustc-1.53​​.0) 在 High Sierra 上编译。可能更好的方法是告诉 cmake：

set(CMAKE_OSX_SYSROOT /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk)

因为弄乱系统提供的标头通常不是一个好主意。