mac10.15编译swoole失败，出现“no member named 'signbit' in the global namespace”错误信息的解决方案 作者: 灯小笼 时间: 2020-08-03 分类: 默认分类 在mac 10.15.16系统上，编译swoole 4.4.18的时候，在执行`make`命令时，出现错误提示：`no member named 'signbit' in the global namespace using ::signbit;`，使得编译总是失败。 对于想在mac使用swoole的开发者而言，多少算是一种挫败。本来兴致冲冲想在mac身上研究一下swoole，却在编译swoole的php插件时栽了这么一个跟头。为了解决这个拦路虎，和朋友问了一圈，无解，又在在网上搜了很多文章，始终未找到解答。 不过，只要真心想解决问题，并且为之努力，机遇还是会到来的。 <!--more--> 具体出错信息如下： ```bash In file included from /usr/local/Cellar/php/7.4.7/include/php/main/php.h:33: In file included from /usr/local/Cellar/php/7.4.7/include/php/Zend/zend.h:27: In file included from /usr/local/Cellar/php/7.4.7/include/php/Zend/zend_types.h:25: In file included from /usr/local/Cellar/php/7.4.7/include/php/Zend/zend_portability.h:43: In file included from /usr/local/Cellar/php/7.4.7/include/php/Zend/zend_config.h:1: In file included from /usr/local/Cellar/php/7.4.7/include/php/main/../main/php_config.h:2336: /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/cmath:317:9: error: no member named 'signbit' in the global namespace using ::signbit; ~~^ /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/cmath:318:9: error: no member named 'fpclassify' in the global namespace using ::fpclassify; ~~^ /Library/Developer/CommandLineTools/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) ^ ... /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/cmath:649:25: error: no template named 'numeric_limits' return _FloatBigger ? numeric_limits<_IntT>::max() : (numeric_limits<_IntT>::max() >> _Bits << _Bits); ^ fatal error: too many errors emitted, stopping now [-ferror-limit=] 177 warnings and 20 errors generated. make: *** [php_swoole_cxx.lo] Error 1 ``` 在网上还找到一篇文章，描述的现象而言，和我遇到的问题是一致的：《[Mac 安装 Swoole 报错： error: no member named 'isless' in the global namespace using ::isless;](https://www.v2ex.com/t/665718)》 最终对我起到帮助的一篇文章是：[Catalina C++: Using <cmath> headers yield error: no member named 'signbit' in the global namespace](https://stackoverflow.com/questions/58628377/catalina-c-using-cmath-headers-yield-error-no-member-named-signbit-in-th)，其中[Niloy Datta](https://stackoverflow.com/users/5052841/niloy-datta)的回答帮我解决了难题。 下面引用一下他的发言内容： > Using the command:（使用命令查看include的路径） > ``` > gcc -Wp,-v -E - > ``` > my #include <...> search sequence:（我的#include查询顺序是） > ```bash > /usr/local/include > /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/10.0.1/include > /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include > /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include > /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/System/Library/Frameworks (framework directory) > ``` > The reason of #include error is described below:(#include出现错误原因如下) > - \#include<cmath> resides in /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1 > - It includes < math.h \>. > - It searches /usr/local/include directory as this is the first directory to search. There is a math.h in "/usr/local/include/c++/9.3.0/" directory > - It tries to use this. > - But expectation was to use the math.h of the same directory /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1 > - The math.h of /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1 include math.h of /usr/local/include using #include_next<math.h> > - As wrong math.h is included/linked with /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/cmath, the compilation error happens > > The fix:(解决方案) > > 1. If we can alter the search order of #include<...> to search /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1 at first, it can be fixed. > 2. Using \#include</Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/math.h> instead of <math.h> in /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/cmath ### 再用中文说明一下 归根结底，其实就是和`#include`的检索顺序有关系。首先可以通过命令找到自己系统的`#include`的顺序。在我的系统里边按照` gcc -Wp,-v -E -`，结果如下： ```bash clang -cc1 version 11.0.3 (clang-1103.0.32.62) default target x86_64-apple-darwin19.6.0 ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/local/include" ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/Library/Frameworks" #include "..." search starts here: #include <...> search starts here: /usr/local/include /Library/Developer/CommandLineTools/usr/lib/clang/11.0.3/include /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include /Library/Developer/CommandLineTools/usr/include /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks (framework directory) End of search list. ``` 而能找到math.h的第一个路径，则是`/usr/local/include/math.h`这个文件，这和预期是不一致的，预期要使用的math.h是其同目录的math.h。因此，我们可以对原来的cmath代码进行调整，将`<math.h>`改成`"math.h"`即可。 **修改“/Library/Developer/CommandLineTools/usr/include/c++/v1/cmath”中的`#include <math.h>`为`#include "math.h"`**。 这就是最终的解决方案，按此方法修改后，`make`命令可以正常进行，`swoole`可以正常在mac下编译通过了。 标签: none
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