Question

我有以下代码，它可以很好地编译GCC 4.8.4，GCC 5.2.0和clang 3.8.0 trunk（带-std = c ++ 11）

#include <utility>
#include <thread>

struct Callable {
    static void run() {}
};

void start(Callable && c)
{
    std::thread t(&c.run); // construct thread
}

int main()
{
    Callable c;
    start(std::move(c));
}

（在左值上使用std :: move不是犹太洁食，但这不是重点）。

但是，如果我将线程构造函数调用更改为

std::thread t(c.run);

clang仍在编译它，但GCC 5.2.0抱怨：

/home/bulletmagnet/workspace/zarquon/prog/msyncd/src/new_thread_test.cc: In function ‘void start(Callable&&)’:
/home/bulletmagnet/workspace/zarquon/prog/msyncd/src/new_thread_test.cc:10:24: error: no matching function for call to ‘std::thread::thread(void())’
     std::thread t(c.run);
                        ^
In file included from /home/bulletmagnet/workspace/zarquon/prog/msyncd/src/new_thread_test.cc:2:0:
/usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/include/c++/thread:133:7: note: candidate: std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void(); _Args = {}]
       thread(_Callable&& __f, _Args&&... __args)
       ^
/usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/include/c++/thread:133:7: note:   no known conversion for argument 1 from ‘void()’ to ‘void (&&)()’
/usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/include/c++/thread:128:5: note: candidate: std::thread::thread(std::thread&&)
     thread(thread&& __t) noexcept
     ^
/usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/include/c++/thread:128:5: note:   no known conversion for argument 1 from ‘void()’ to ‘std::thread&&’
/usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/include/c++/thread:122:5: note: candidate: std::thread::thread()
     thread() noexcept = default;
     ^
/usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/include/c++/thread:122:5: note:   candidate expects 0 arguments, 1 provided

（GCC 4.8.4也抱怨）。

那么，哪个编译器是对的？

Answer 1

我认为 Clang是对的，EDG也接受了代码，所以我打开了https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68386

明显的解决方法是不要使用这种奇怪的语法来引用静态成员函数，而是将其称为Callable::run，它可以使用或不使用&运算符。

将成员函数传递给没有address-of的std :: thread

1 个答案: