c++ - assert(true) 警告签名/未签名不匹配

Question

Visual Studio 2008，调试版本。这行C++

assert(true);

引起投诉

warning C4365: 'argument' : conversion from 'long' to 'unsigned int', signed/unsigned mismatch

当用任何(有用的) bool 表达式替换 true 时，警告仍然存在，即使是 1ul。

仅供引用，编译器的文件 assert.h 是:

#define assert(_Expression) (void)( (!!(_Expression)) || (_wassert(_CRT_WIDE(#_Expression), _CRT_WIDE(__FILE__), __LINE__), 0) )
extern "C" _CRTIMP void __cdecl _wassert(_In_z_ const wchar_t * _Message, _In_z_ const wchar_t *_File, _In_ unsigned _Line);

如何在不抑制所有 C4365 的情况下完全抑制此警告？是__LINE__的错吗？？

Answer 1

The bug report explains it very well :

This issue occurs because __LINE__ is of type long, and the assert macro passes __LINE__ as an argument to the _wassert function, which expects an unsigned int. When not compiling with /ZI, __LINE__ is a constant expression, so the compiler can statically determine that the conversion to unsigned int will result in the same value. When compiling with /ZI, __LINE__ is not a constant expression, so the compiler cannot statically determine that the conversion will result in the same value and it issues warning C4365.

它还提供了一个解决方法:

As a workaround for this issue, I would recommend #undefing assert in your source code, and re-#define-ing it, using the same definition as in <assert.h>, but with a cast to suppress the warning.

请注意，此错误似乎已从 MSVC2015 开始修复。