MSVC -Wall标准头中成千上万的警告是怎么回事？
MSVC -Wall标准头中成千上万的警告是怎么回事？
提问于 2010-10-23 07:55:41
有些人似乎建议你使用-Wall，但是当我在一个小的测试项目上这样做时，我得到了5800个警告，其中大多数是在标准标题或windows标题中。
这是故意的行为吗？我如何让我的编译警告免费？
这里只是一些阅读乐趣的例子：
1>c:\program files\microsoft visual studio 10.0\vc\include\stdint.h(105): warning C4668: '_INTPTR' is not defined as a preprocessor macro, replacing with '0' for '#if/#elif'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(109): warning C4820: '_wfinddata64i32_t' : '4' bytes padding added after data member '_wfinddata64i32_t::attrib'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(114): warning C4820: '_wfinddata64i32_t' : '4' bytes padding added after data member '_wfinddata64i32_t::name'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(118): warning C4820: '_wfinddata64_t' : '4' bytes padding added after data member '_wfinddata64_t::attrib'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(488): warning C4820: '_stat32' : '2' bytes padding added after data member '_stat32::st_gid'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(504): warning C4820: 'stat' : '2' bytes padding added after data member 'stat::st_gid'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(520): warning C4820: '_stat32i64' : '2' bytes padding added after data member '_stat32i64::st_gid'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(521): warning C4820: '_stat32i64' : '4' bytes padding added after data member '_stat32i64::st_rdev'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(525): warning C4820: '_stat32i64' : '4' bytes padding added after data member '_stat32i64::st_ctime'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(534): warning C4820: '_stat64i32' : '2' bytes padding added after data member '_stat64i32::st_gid'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(548): warning C4820: '_stat64' : '2' bytes padding added after data member '_stat64::st_gid'
1>c:\program files\microsoft visual studio 10.0\vc\include\wchar.h(549): warning C4820: '_stat64' : '4' bytes padding added after data member '_stat64::st_rdev'
1>c:\program files\microsoft visual studio 10.0\vc\include\crtdbg.h(1078): warning C4986: 'operator new[]': exception specification does not match previous declaration
1> c:\program files\microsoft visual studio 10.0\vc\include\new(79) : see declaration of 'operator new[]'
1>c:\program files\microsoft visual studio 10.0\vc\include\crtdbg.h(1095): warning C4986: 'operator delete[]': exception specification does not match previous declaration
1> c:\program files\microsoft visual studio 10.0\vc\include\new(77) : see declaration of 'operator delete[]'
1>c:\program files\microsoft visual studio 10.0\vc\include\typeinfo(76): warning C4820: 'type_info' : '3' bytes padding added after data member 'type_info::_M_d_name'
1>c:\program files\microsoft sdks\windows\v7.0a\include\basetsd.h(114): warning C4668: '__midl' is not defined as a preprocessor macro, replacing with '0' for '#if/#elif'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(8154): warning C4820: '_SECURITY_QUALITY_OF_SERVICE' : '2' bytes padding added after data member '_SECURITY_QUALITY_OF_SERVICE::EffectiveOnly'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(8165): warning C4820: '_SE_IMPERSONATION_STATE' : '2' bytes padding added after data member '_SE_IMPERSONATION_STATE::EffectiveOnly'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(8334): warning C4820: '_QUOTA_LIMITS' : '4' bytes padding added after data member '_QUOTA_LIMITS::PagefileLimit'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(8357): warning C4820: '_QUOTA_LIMITS_EX' : '4' bytes padding added after data member '_QUOTA_LIMITS_EX::PagefileLimit'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(8405): warning C4820: '_JOBOBJECT_BASIC_LIMIT_INFORMATION' : '4' bytes padding added after data member '_JOBOBJECT_BASIC_LIMIT_INFORMATION::SchedulingClass'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(8984): warning C4820: '_FILE_NOTIFY_INFORMATION' : '2' bytes padding added after data member '_FILE_NOTIFY_INFORMATION::FileName'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(9012): warning C4820: '_REPARSE_GUID_DATA_BUFFER' : '3' bytes padding added after data member '_REPARSE_GUID_DATA_BUFFER::GenericReparseBuffer'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(10131): warning C4820: '<unnamed-tag>' : '3' bytes padding added after data member '<unnamed-tag>::Data'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(10241): warning C4820: '<unnamed-tag>' : '4' bytes padding added after data member '<unnamed-tag>::DecreaseTime'
1>c:\program files\microsoft sdks\windows\v7.0a\include\winnt.h(10262): warning C4820: '<unnamed-tag>' : '4' bytes padding added after data member '<unnamed-tag>::TimerInterval'
1>c:\program files\microsoft sdks\windows\v7.0a\include\wincrypt.h(1440): warning C4668: 'NTDDI_WINLH' is not defined as a preprocessor macro, replacing with '0' for '#if/回答 4
Stack Overflow用户
回答已采纳
发布于 2010-10-23 08:02:29
Visual C++ /Wall启用在/W4中默认为禁用的所有警告。正如您已经发现的，有一个很好的理由来解释为什么这些警告在默认情况下是被禁用的(感谢编译器告诉我您已经添加了填充；我真的很感激！)在Visual C++上使用/W4可能是最好的。
英特尔C++也是这样的(我不知道其他使用EDG前端的编译器)。如果你将它设置为/W5，它会喷出大量的信息性消息。我个人最喜欢的是，如果存储类说明符不在声明的开头，它会发出警告(所以，const static int是不可行的，但static const int是可以的)。
Stack Overflow用户
发布于 2013-05-19 03:20:30
要禁用来自您无法控制的系统标头的警告，只需使用以下结构：
#pragma warning(push, 0)
//Some includes with unfixable warnings
#pragma warning(pop)或者更有选择性地用于特定的警告：
#pragma warning( push )
#pragma warning( disable : 4081)
#pragma warning( disable : 4706 )
// system header includes
#pragma warning( pop )这个答案是从另一个堆栈溢出线程中盗取的：(https://stackoverflow.com/questions/2541984/how-to-suppress-warnings-in-external-headers-in-visual-c)。
我完全同意"edA-qa mort-ora-y“的评论。我想在我的代码中看到所有的警告，包括像C4265这样的重要东西(DTOR不是虚拟的)。虽然C4265处于警告级别3，但微软在他们的智慧中已经默认关闭了它，你需要/Wall来获得它。有关隐藏哪些警告的详细信息，请参阅此页面：
http://msdn.microsoft.com/en-GB/library/23k5d385(v=vs.80).aspx
为了看到这些并抑制来自外部标题的噪音，这个页面给出了很好的建议，我认为完全回答了开始这个主题的原始问题：
http://blogs.msdn.com/b/vcblog/archive/2010/12/14/off-by-default-compiler-warnings-in-visual-c.aspx
基本上，它建议使用适当的#编译指示创建一个‘全局’包含文件，以抑制您不关心的警告(可能是填充警告)，以上述方式防止外部头文件，然后使用/Wall编译。这是一项工作，但值得一试。在GCC的领导下，这只是一个使用-isystem的问题。Microsoft开发:请注意！VS是一个聪明的产品，但它有时真的很愚蠢，使用简单的东西。
Stack Overflow用户
发布于 2010-10-23 07:57:59
对于MSVC，请使用/W4。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/4001736
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