C++ 禁用单个警告错误
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Disable single warning error
提问by Cookie
Is there a way to disable just a single warning line in a cpp file with visual studio?
有没有办法使用visual studio禁用cpp文件中的单个警告行？
For example, if I catch an exception and don't handle it, I get error 4101 (unreferenced local variable). Is there a way to ignore this just in that function, but otherwise report it in the compilation unit? At the moment, I put #pragma warning (disable : 4101)at the top of the file, but that obviously just turns it off for the whole unit.
例如，如果我捕获一个异常并且不处理它，我会收到错误 4101（未引用的局部变量）。有没有办法在该函数中忽略它，但在编译单元中报告它？目前，我把它放在#pragma warning (disable : 4101)文件的顶部，但这显然只是关闭了整个单元。
回答by Andreas Brinck
#pragma warning( push )
#pragma warning( disable : 4101)
// Your function
#pragma warning( pop )
回答by Daniel Seither
If you only want to suppress a warning in a single line of code, you can use the suppresswarning specifier:
如果只想在一行代码中抑制警告，可以使用suppress警告说明符：
#pragma warning(suppress: 4101)
// here goes your single line of code where the warning occurs
For a single line of code, this works the same as writing the following:
对于单行代码，这与编写以下内容相同：
#pragma warning(push)
#pragma warning(disable: 4101)
// here goes your code where the warning occurs
#pragma warning(pop)
回答by Matteo Italia
#pragmapush/pop are often a solution for this kind of problems, but in this case why don't you just remove the unreferenced variable?
#pragmapush/pop 通常是此类问题的解决方案，但在这种情况下，为什么不删除未引用的变量呢？
try
{
// ...
}
catch(const your_exception_type &) // type specified but no variable declared
{
// ...
}
回答by sharptooth
Use #pragma warning ( push ), then #pragma warning ( disable ), then put your code, then use #pragma warning ( pop )as described here:
使用#pragma warning ( push ), then #pragma warning ( disable )，然后放置您的代码，然后#pragma warning ( pop )按照此处的说明使用：
#pragma warning( push )
#pragma warning( disable : WarningCode)
// code with warning
#pragma warning( pop )
回答by A876
Example:
例子：
#pragma warning(suppress:0000) // (suppress one error in the next line)
This pragma is valid for C++starting with Visual Studio 2005.
https://msdn.microsoft.com/en-us/library/2c8f766e(v=vs.80).aspx
此编译指示对从 Visual Studio 2005 开始的C++有效。https://msdn.microsoft.com/en-us/library/2c8f766e( v=vs.80)
.aspx
The pragma is NOT valid for C#through Visual Studio 2005 through Visual Studio 2015.
Error: "Expected disable or restore".
(I guess they never got around to implementing suppress...)
https://msdn.microsoft.com/en-us/library/441722ys(v=vs.140).aspx
该编译指示对C#到 Visual Studio 2005 到 Visual Studio 2015
无效。错误：“预期禁用或恢复”。
（我猜他们从来没有开始实施suppress......）https://msdn.microsoft.com/en-us/library/441722ys(v=vs.140)
.aspx
C# needs a different format. It would look like this (but not work):
C# 需要不同的格式。它看起来像这样（但不起作用）：
#pragma warning suppress 0642 // (suppress one error in the next line)
Instead of suppress, you have to disableand enable:
而不是suppress，你必须disable和enable：
if (condition)
#pragma warning disable 0642
; // Empty statement HERE provokes Warning: "Possible mistaken empty statement" (CS0642)
#pragma warning restore 0642
else
That is SO ugly, I think it is smarter to just re-style it:
这太丑了，我认为重新设计它更聪明：
if (condition)
{
// Do nothing (because blah blah blah).
}
else
回答by Christian.K
Instead of putting it on top of the file (or even a header file), just wrap the code in question with #pragma warning (push), #pragma warning (disable)and a matching #pragma warning (pop), as shown here.
相反，把它放在文件（甚至是头文件）之上的，只是包装与问题的代码#pragma warning (push)， #pragma warning (disable)以及匹配#pragma warning (pop)，如图所示这里。
Although there are some other options, including #pramga warning (once).
尽管还有其他一些选项，包括#pramga warning (once).
回答by Ajay
One may also use UNREFERENCED_PARAMETERdefined in WinNT.H. The definition is just:
也可以使用中UNREFERENCED_PARAMETER定义的WinNT.H。定义只是：
#define UNREFERENCED_PARAMETER(P) (P)
And use it like:
并像这样使用它：
void OnMessage(WPARAM wParam, LPARAM lParam)
{
UNREFERENCED_PARAMETER(wParam);
UNREFERENCED_PARAMETER(lParam);
}
Why would you use it, you might argue that you can just omit the variable name itself. Well, there are cases (different project configuration, Debug/Release builds) where the variable might actually be used. In another configuration that variable stands unused (and hence the warning).
为什么要使用它，您可能会争辩说您可以省略变量名称本身。好吧，在某些情况下（不同的项目配置、调试/发布版本）可能会实际使用该变量。在另一个配置中，该变量未使用（因此是警告）。
Some static code analysis may still give warning for this non-nonsensical statement (wParam;). In that case, you mayuse DBG_UNREFERENCED_PARAMETERwhich is same as UNREFERENCED_PARAMETERin debug builds, and does P=Pin release build.
某些静态代码分析可能仍会针对此无意义的语句 ( wParam;)发出警告。在这种情况下，您DBG_UNREFERENCED_PARAMETER可以使用与UNREFERENCED_PARAMETER调试版本相同的方法，并P=P在发布版本中使用。
#define DBG_UNREFERENCED_PARAMETER(P) (P) = (P)
回答by Adi Shavit
In certain situations you musthave a named parameter but you don't use it directly.
For example, I ran into it on VS2010, when 'e' is used only inside a decltypestatement, the compiler complains but you must have the named varible e.
在某些情况下，您必须有一个命名参数，但不直接使用它。
例如，我在 VS2010 上遇到了它，当 'e' 仅在decltype语句中使用时，编译器会抱怨，但您必须具有命名变量e。
All the above non-#pragmasuggestions all boil down to just adding a single statement:
以上所有非#pragma建议都归结为只添加一个语句：
bool f(int e)
{
// code not using e
return true;
e; // use without doing anything
}
回答by Alexey Malistov
If you want to disable unreferenced local variablewrite in some header
如果您想unreferenced local variable在某些标题中禁用写入
template<class T>
void ignore (const T & ) {}
and use
并使用
catch(const Except & excpt) {
ignore(excpt); // No warning
// ...
}
回答by orion elenzil
as @rampion mentioned, if you are in clang gcc, the warnings are by name, not number, and you'll need to do:
正如@rampion 所提到的，如果您在 clang gcc 中，警告是按名称而不是编号，您需要执行以下操作：
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-variable"
// ..your code..
#pragma clang diagnostic pop
this info comes from here
这个信息来自这里
