blocks|key|371353|text|使用-Wno-unused-variable应该可以。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|371354|entityMap^0|2|K|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Use <code>-Wno-unused-variable</code> should work.

blocks|key|153236|text|编译器已经告诉你，它不是value，而是variable。您正在寻找-Wno-unused-variable。另外，尝试使用g%2B%2B+--help=warnings查看可用选项列表。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|153237|entityMap^0|C|5|K|8|Y|K|1Q|J|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|G|$]]

The compiler is already telling you, it's not <code>value</code> but <code>variable</code>. You are looking for <code>-Wno-unused-variable</code>. Also, try <code>g++ --help=warnings</code> to see a list of available options.

blocks|key|153284|text|-Wno-unused-variable交换机通常可以完成此任务。但是，如果您关心项目中的这些事情，这确实是一个非常有用的警告。但是，当GCC开始警告您代码中没有的内容时，它会变得很烦人。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|153285|我建议您保留警告，但是对于包含第三方项目的目录，请使用-isystem而不是-I。那面旗子告诉GCC不要警告你你无法控制的东西。|153286|例如，不使用-IC:\\boost_1_52_0，而使用-isystem+C:\\boost_1_52_0。|153287|希望能有所帮助。祝好运!|153288|entityMap^0|0|K|0|R|8|12|2|0|6|I|S|P|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|10|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|M|$]]

The <code>-Wno-unused-variable</code> switch usually does the trick. However, that is a very useful warning indeed if you care about these things in your project. It becomes annoying when GCC starts to warn you about things not in your code though.

I would recommend you keeping the warning on, but use <code>-isystem</code> instead of <code>-I</code> for include directories of third-party projects. That flag tells GCC not to warn you about the stuff you have no control over.

For example, instead of <code>-IC:\\boost_1_52_0</code>, say <code>-isystem C:\\boost_1_52_0</code>.

Hope it helps. Good Luck!

blocks|key|371449|text|export+IGNORE_WARNINGS=1|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|371450|它确实会显示警告，但会继续构建|unstyled|371451|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>export IGNORE_WARNINGS=1
</code></pre>

It does display warnings, but continues with the build

blocks|key|371510|text|如果您使用的是gcc，并且想要禁用所选代码的警告，则可以使用#杂注编译器指令：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|371511|#pragma+GCC+diagnostic+push
#pragma+GCC+diagnostic+ignored+"-Wunused-variable"
(+your+problematic+library+includes+)
#pragma+GCC+diagnostic+pop|code-block|syntax|javascript|371512|对于您控制的代码，您还可以使用__attribute__((unused))来指示编译器不使用特定变量。|offset|length|style|CODE|371513|entityMap^0|0|0|F|N|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

If you're using gcc and want to disable the warning for selected code, you can use the #pragma compiler directive:

<pre><code>#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-variable"
( your problematic library includes )
#pragma GCC diagnostic pop
</code></pre>

For code you control, you may also use <code>__attribute__((unused))</code> to instruct the compiler that specific variables are not used.

blocks|key|371585|text|-Wall和-Wextra为GCC搭台，后续-Wno-unused-variable可能不会生效例如，如果您有：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|371586|CFLAGS+%2B=+-std=c99+-pedantic+-pedantic-errors+-Werror+-g0+-Os+\+++++-fno-strict-overflow+-fno-strict-aliasing+\+++++-Wall+-Wextra+\+++++-pthread+\+++++-Wno-unused-label+\+++++-Wno-unused-function+\+++++-Wno-unused-parameter+\+++++-Wno-unused-variable+\+++++$(INC)|371587|然后，GCC看到了-Wall+-Wextra指令，似乎忽略了-Wno-unused-variable|371588|相反，这可以看起来像下面这样，你可以得到在编译中不会停止对未使用的变量的预期效果：|371589|CFLAGS+%2B=+-std=c99+-pedantic+-pedantic-errors+-Werror+-g0+-Os+\+++++-fno-strict-overflow+-fno-strict-aliasing+\+++++-pthread+\+++++-Wno-unused-label+\+++++-Wno-unused-function+\+++++$(INC)|371590|它被称为“警告”而不是“错误”是有充分理由的。仅仅因为你的代码不完整而导致编译失败(比方说你正在破坏算法)可能是失败的。|371591|entityMap^0|0|5|6|7|M|K|0|0|7B|0|9|D|U|K|0|0|0|58|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|16|8|@]|D|@]|E|$]]|$1|L|3|M|5|6|7|17|8|@$9|18|A|19|B|C]]|D|@]|E|$]]|$1|N|3|O|5|6|7|1A|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|Q|$]]

<code>-Wall</code> and <code>-Wextra</code> sets the stage in GCC and the subsequent <code>-Wno-unused-variable</code> may not take effect. For example, if you have:

<code>CFLAGS += -std=c99 -pedantic -pedantic-errors -Werror -g0 -Os \
 -fno-strict-overflow -fno-strict-aliasing \
 -Wall -Wextra \
 -pthread \
 -Wno-unused-label \
 -Wno-unused-function \
 -Wno-unused-parameter \
 -Wno-unused-variable \
 $(INC)</code>

then GCC sees the instruction <code>-Wall -Wextra</code> and seems to ignore <code>-Wno-unused-variable</code>

This can instead look like this below and you get the desired effect of not being stopped in your compile on the unused variable:

<code>CFLAGS += -std=c99 -pedantic -pedantic-errors -Werror -g0 -Os \
 -fno-strict-overflow -fno-strict-aliasing \
 -pthread \
 -Wno-unused-label \
 -Wno-unused-function \
 $(INC)</code>

There is a good reason it is called a "warning" vs an "error". Failing the compile just because you code is not complete (say you are stubbing the algorithm out) can be defeating.

blocks|key|153543|text|可以在变量前加上'(void)‘前缀。如果您没有访问构建框架的权限，或者您只想影响行为的本地更改，这将非常有用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|153544|即：|153545|int+main()
{
++int+unused1;+++++++//This+will+print+warning
++int+unused2;+++++++//This+will+not+print+warning+-
+++++++++++++++++++++//+++++++++++++++++++++++++++++%7C
++(void)+unused2;++++//+<----------------------------
}|code-block|syntax|javascript|153546|输出：|153547|$+g%2B%2B+-Wall+test.cc
test.cc:+In+function+‘int+main()’:
test.cc:4:7:+warning:+unused+variable+‘unused1’+[-Wunused-variable]
++++4+%7C+++int+unused1;
++++++%7C+++++++%5E~~~~~~|153548|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You can prefix the variables with '(void)'.
This can be useful if you don't have access to the build framework or you only want to affect a local change in behavior.
IE:
<pre><code>int main()
{
 int unused1; //This will print warning
 int unused2; //This will not print warning -
 // |
 (void) unused2; // &lt;----------------------------
}
</code></pre>
Output:
<pre><code>$ g++ -Wall test.cc
test.cc: In function ‘int main()’:
test.cc:4:7: warning: unused variable ‘unused1’ [-Wunused-variable]
 4 | int unused1;
 | ^~~~~~~
</code></pre>

I'd like to know what switch you pass to the gcc compiler to turn off unused variable warnings? I'm getting errors out of boost on windows and I do not want to touch the boost code:

<pre><code>C:\boost_1_52_0/boost/system/error_code.hpp: At global scope:
C:\boost_1_52_0/boost/system/error_code.hpp:214:36: error: 'boost::system::posix_category' defined but not used [-Werror=unused-variable]
C:\boost_1_52_0/boost/system/error_code.hpp:215:36: error: 'boost::system::errno_ecat' defined but not used [-Werror=unused-variable]
C:\boost_1_52_0/boost/system/error_code.hpp:216:36: error: 'boost::system::native_ecat' defined but not used [-Werror=unused-variable]
</code></pre>

I tried using both <code>-Wunused-value</code> and <code>-Wno-unused-value</code> but neither suppressed the messages above.

What is the right command, here is my compile line:

<pre><code>g++ -g -fno-inline -Wall -Werror -Wextra -Wfloat-equal -Wshadow
-Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wno-conversion 
-Wdisabled-optimization -Wredundant-decls -Wunused-value -Wno-deprecated 
-IC:\\boost_1_52_0 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 
-c -o op.o op.cpp
</code></pre>

Perhaps the <code>-Wall</code> overrides my goal?

How do you disable the unused variable warnings coming out of gcc in 3rd party code I do not wish to edit?

编译器

我想知道你给gcc编译器传递了什么开关来关闭未使用的变量警告？我在windows上的boost中遇到错误，我不想接触boost代码：C:\boost_1_52_0/boost/system/error_code.hpp: At global scope:C:\boost_1_52_0/boost/system/erro...

问在我不想编辑的第三方代码中，如何禁用来自gcc的未使用变量警告？
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问在我不想编辑的第三方代码中，如何禁用来自gcc的未使用变量警告？
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