我在使用 Sun 的 C++ 编译器时遇到问题。我读过 Oracle 的 Working with Pointers to Functions [from C++] 。这是一本很好的读物,我的印象是 SunCC 是该领域所有编译器中最合规的(尽管它给我带来了麻烦)。
测试代码如下,第24行为new_handler.sa_handler = (pfn ? pfn : &SignalHandler::NullHandler);
。展开三元运算符表明这就是问题所在: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
$
我不太清楚问题是什么。 Oracle 板上有一个类似的问题,但 OP 基本上是告诉 RTFM:Sun Studio 11 "Warning (Anachronism)" .
如何解决不合时宜的警告?
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;
}
最佳答案
您可以将 SignalHandler::NullHandler 更改为常规 C 函数(我们将其命名为 SignalHandler_NullHandler)。 然后将 SignalHandler_NullHandler 和 SignalHandlerFn 包装在 extern“C”中。
顺便说一句。我猜测如何“对齐”这两个函数,但您在评论中更好地解释了 C/C++ 转换存在问题。关于c++ - 警告(不合时宜): Assigning void(*)(int) to extern "C" void(*)(int),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39562034/