考虑以下示例:
#include <array>
template <typename T>
struct A {
A() {}
};
typedef A<int> B;
struct S {
std::array<B, 1> b;
S() : b{{B()}} {}
};
int main() {
S s;
}
尝试用G 4.6.3和-std=c++0x
编译时,我会得到此错误:
test.cc: In constructor ‘S::S()’:
test.cc:13:16: error: no matching function for call to ‘std::array<A<int>, 1ul>::array(<brace-enclosed initializer list>)’
test.cc:13:16: note: candidates are:
/usr/include/c++/4.6/array:60:12: note: std::array<A<int>, 1ul>::array()
/usr/include/c++/4.6/array:60:12: note: candidate expects 0 arguments, 1 provided
/usr/include/c++/4.6/array:60:12: note: constexpr std::array<A<int>, 1ul>::array(const std::array<A<int>, 1ul>&)
/usr/include/c++/4.6/array:60:12: note: no known conversion for argument 1 from ‘<brace-enclosed initializer list>’ to ‘const std::array<A<int>, 1ul>&’
/usr/include/c++/4.6/array:60:12: note: constexpr std::array<A<int>, 1ul>::array(std::array<A<int>, 1ul>&&)
/usr/include/c++/4.6/array:60:12: note: no known conversion for argument 1 from ‘<brace-enclosed initializer list>’ to ‘std::array<A<int>, 1ul>&&’
但是,定义变量时相同的支撑初始化可行:
std::array<B, 1> b{{B()}};
是因为GCC的特定版本没有完全实现C 11,或者我缺少某些内容,而第一个示例不正确?
是因为GCC的此特定版本未完全实现C 11
很可能是。GCC 4.6非常过时。
或我缺少一些东西,第一个示例不正确?
关于C 11语法,您的示例很好。它在Colliru上编译而没有错误或警告。