使用初始化列表声明动态分配数组的数组大小
Declaring array size for dynamically allocated array with initializer list
我正在尝试使用初始化程序列表来初始化动态声明的数组，但我注意到我必须使用 GCC 提供数组大小，否则会出现错误。如果忽略数组大小，使用 MSVC 尝试相同操作不会导致任何错误。使用带有动态数组的初始化列表时是否强制提供数组大小？这是实现定义的东西吗，这就是为什么两个编译器都不同的原因？
int *array { new int [3] {0, 1, 2} }; // Works with both MSVC and GCC.
int *array { new int [] {0, 1, 2} }; // Works only with MSVC, not GCC.
这是 P1009R2：新表达式中的数组大小推导，它是为 C++20 实现的。
Bjarne Stroustrup pointed out the following inconsistency in the C++ language:
double a[]{1,2,3}; // this declaration is OK, ...
double* p = new double[]{1,2,3}; // ...but this one is ill-formed!
Jens Maurer provided the explanation why it doesn’t work: For a new-expression, the expression
inside the square brackets is currently mandatory according to the C++ grammar. When uniform
initialization was introduced for C++11, the rule about deducing the size of the array from the
number of initializers was never extended to the new-expression case. Presumably this was simply
overlooked. There is no fundamental reason why we cannot make this work [...]
Proposed wording
The reported issue is intended as a defect report with the proposed resolution as follows. The effect
of the wording changes should be applied in implementations of all previous versions of C++ where
they apply. [...]
从 GCC's C++ Standards Support pages 我们可能会注意到 GCC 列出了从 GCC 11 开始实施的 P1009R2，并且我们可能会验证 GCC 11 已经向后移植了实施以接受 OP 的例子，因为早在很久以前作为 C++11.
DEMO（海湾合作委员会 11/-std=c++11）。
我正在尝试使用初始化程序列表来初始化动态声明的数组，但我注意到我必须使用 GCC 提供数组大小，否则会出现错误。如果忽略数组大小，使用 MSVC 尝试相同操作不会导致任何错误。使用带有动态数组的初始化列表时是否强制提供数组大小？这是实现定义的东西吗，这就是为什么两个编译器都不同的原因？
int *array { new int [3] {0, 1, 2} }; // Works with both MSVC and GCC.
int *array { new int [] {0, 1, 2} }; // Works only with MSVC, not GCC.
这是 P1009R2：新表达式中的数组大小推导，它是为 C++20 实现的。
Bjarne Stroustrup pointed out the following inconsistency in the C++ language:
double a[]{1,2,3}; // this declaration is OK, ... double* p = new double[]{1,2,3}; // ...but this one is ill-formed!Jens Maurer provided the explanation why it doesn’t work: For a new-expression, the expression inside the square brackets is currently mandatory according to the C++ grammar. When uniform initialization was introduced for C++11, the rule about deducing the size of the array from the number of initializers was never extended to the new-expression case. Presumably this was simply overlooked. There is no fundamental reason why we cannot make this work [...]
Proposed wording
The reported issue is intended as a defect report with the proposed resolution as follows. The effect of the wording changes should be applied in implementations of all previous versions of C++ where they apply. [...]
从 GCC's C++ Standards Support pages 我们可能会注意到 GCC 列出了从 GCC 11 开始实施的 P1009R2，并且我们可能会验证 GCC 11 已经向后移植了实施以接受 OP 的例子，因为早在很久以前作为 C++11.
DEMO（海湾合作委员会 11/-std=c++11）。