警告(Anachronism):将void(*)(int)赋给外部“C” void(*)(int) [英] Warning (Anachronism): Assigning void(*)(int) to extern "C" void(*)(int)
问题描述
我在使用Sun的C ++编译器时遇到问题。我已阅读了Oracle的使用指针到函数[从C ++] 。它的一个很好的阅读,我得到的印象SunCC是最符合这一领域的所有编译器(虽然它导致麻烦)。
测试代码如下,第24行是 new_handler.sa_handler =(pfn?pfn:& SignalHandler :: NullHandler);
。展开三元运算符显示这是问题: new_handler.sa_handler = pfn;
。
SunCC 5.11
$ /opt/solstudio12.2/bin/CC test.cxx
test.cxx,第24行:警告(Anachronism):将void(*)(int)赋给externCvoid(*)(int)。
test.cxx,line 58:其中:虽然实例化SignalHandler< 5,0>> :: SignalHandler(void(*)(int),int)。
test.cxx,第58行:其中:从非模板代码实例化。
SunCC 5.12 b
$ b
$ /opt/solarisstudio12.3/bin/CC test.cxx
test.cxx,第24行:警告(Anachronism) :将void(*)(int)赋给externCvoid(*)(int)。
test.cxx,line 58:其中:虽然实例化SignalHandler< 5,0>> :: SignalHandler(void(*)(int),int)。
test.cxx,第58行:其中:从非模板代码实例化。
SunCC 5.13 b
$ b$ /opt/solarisstudio12.4/bin/CC test.cxx
b
test.cxx,第24行:警告(Anachronism) :使用void(*)(int)初始化externCvoid(*)(int)。
test.cxx,line 58:其中:虽然实例化SignalHandler< 5,0>> :: SignalHandler(void(*)(int),int)。
test.cxx,第58行:其中:从非模板代码实例化。
$ b$ /opt/developerstudio12.5/bin/CC test.cxx
$
它不完全清楚我的问题是什么。这里是Oracle板上的类似问题,但OP基本上告诉RTFM: Sun Studio 11警告(Anachronism )。
如何解决不合时代的警告?
solaris:〜$ cat test.cxx
#include< signal.h>
externC{
typedef void(* SignalHandlerFn)(int);
};
template< int S,bool O = false>
struct SignalHandler
{
SignalHandler(SignalHandlerFn pfn = NULL,int flags = 0):m_installed(false)
{
struct sigaction new_handler;
do
{
int ret = 0;
ret = sigaction(S,0,&m_old);
if(ret!= 0)break; //失败
if(m_old.sa_handler!= 0&&!O)break;
new_handler.sa_handler =(pfn?pfn:& SignalHandler :: NullHandler);
new_handler.sa_flags =(pfn?flags:0);
ret = sigemptyset(& new_handler.sa_mask);
if(ret!= 0)break; // Failed
ret = sigaction(S,& new_handler,0);
if(ret!= 0)break; // Failed
m_installed = true;
} while(0);
}
〜SignalHandler()
{
if(m_installed)
sigaction(S,&m_old,0);
}
private:
struct sigaction m_old;
bool m_installed;
static void NullHandler(int / * unused * /){/ * continue * /}
private:
//不可复制
SignalHandler const SignalHandler&);
void operator =(const SignalHandler&);
};
int main(int argc,char * argv [])
{
SignalHandler< SIGTRAP,0>处理程序
return 0;
}
解决方案您可以更改SignalHandler :: NullHandler到一个常规的C函数(让我们把它命名为SignalHandler_NullHandler)。
然后在externC中包装SignalHandler_NullHandler和SignalHandlerFn。
BTW。这是我的猜测如何对齐这两个函数,但你已经解释了更好的在你的评论中,有一个C / C ++铸造的问题。
I'm having trouble with Sun's C++ compiler. I've read Oracle's Working with Pointers to Functions [from C++]. Its a good read, and I get the impression SunCC is most compliant among all the compilers in this area (though its causing me trouble).
The test code is below, and line 24 is
new_handler.sa_handler = (pfn ? pfn : &SignalHandler::NullHandler);
. Unrolling the ternary operator shows this is the issue:new_handler.sa_handler = pfn;
.SunCC 5.11
$ /opt/solstudio12.2/bin/CC test.cxx "test.cxx", line 24: Warning (Anachronism): Assigning void(*)(int) to extern "C" void(*)(int). "test.cxx", line 58: Where: While instantiating "SignalHandler<5, 0>::SignalHandler(void(*)(int), int)". "test.cxx", line 58: Where: Instantiated from non-template code.
SunCC 5.12
$ /opt/solarisstudio12.3/bin/CC test.cxx "test.cxx", line 24: Warning (Anachronism): Assigning void(*)(int) to extern "C" void(*)(int). "test.cxx", line 58: Where: While instantiating "SignalHandler<5, 0>::SignalHandler(void(*)(int), int)". "test.cxx", line 58: Where: Instantiated from non-template code.
SunCC 5.13
$ /opt/solarisstudio12.4/bin/CC test.cxx "test.cxx", line 24: Warning (Anachronism): Using void(*)(int) to initialize extern "C" void(*)(int). "test.cxx", line 58: Where: While instantiating "SignalHandler<5, 0>::SignalHandler(void(*)(int), int)". "test.cxx", line 58: Where: Instantiated from non-template code.
SunCC 5.14
$ /opt/developerstudio12.5/bin/CC test.cxx $
Its not exactly clear to me what the problem is. Here's a similar issue on the Oracle boards, but the OP is basically told to RTFM: Sun Studio 11 "Warning (Anachronism)".
How do I resolve the anachronistic warning?
solaris:~$ cat test.cxx #include <signal.h> extern "C" { typedef void (*SignalHandlerFn) (int); }; template <int S, bool O=false> struct SignalHandler { SignalHandler(SignalHandlerFn pfn = NULL, int flags = 0) : m_installed(false) { struct sigaction new_handler; do { int ret = 0; ret = sigaction (S, 0, &m_old); if (ret != 0) break; // Failed if (m_old.sa_handler != 0 && !O) break; new_handler.sa_handler = (pfn ? pfn : &SignalHandler::NullHandler); new_handler.sa_flags = (pfn ? flags : 0); ret = sigemptyset (&new_handler.sa_mask); if (ret != 0) break; // Failed ret = sigaction (S, &new_handler, 0); if (ret != 0) break; // Failed m_installed = true; } while(0); } ~SignalHandler() { if (m_installed) sigaction (S, &m_old, 0); } private: struct sigaction m_old; bool m_installed; static void NullHandler(int /*unused*/) { /* continue*/ } private: // Not copyable SignalHandler(const SignalHandler &); void operator=(const SignalHandler &); }; int main(int argc, char* argv[]) { SignalHandler<SIGTRAP, 0> handler; return 0; }
解决方案You may change SignalHandler::NullHandler to a regular C function (let's name it SignalHandler_NullHandler). Then wrap both SignalHandler_NullHandler and SignalHandlerFn in extern „C".
BTW. It was my guess how to „align" these two functions but you have explained it better in your comment that there is a problem with C/C++ casting.
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