[英]Why does Clang 12 refuse to initialize aggregates in the C++20 way?
As far as I understand, the following program should work in C++20 mode:据我了解,以下程序应该在 C++20 模式下工作:
#include <vector>
struct B{ int a0, a1; };
int main()
{
std::vector<B> bs;
bs.emplace_back( 0, 0 );
}
And it really does in Visual Studio 2019 and gcc 11. But not in clang 12, which produces the error:它在 Visual Studio 2019 和 gcc 11 中确实如此。但不是在 clang 12 中,这会产生错误:
/opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/12.0.0/../../../../include/c++/12.0.0/bits/alloc_traits.h:514:4: error: no matching function for call to 'construct_at'
std::construct_at(__p, std::forward<_Args>(__args)...);
^~~~~~~~~~~~~~~~~
In online compiler: https://gcc.godbolt.org/z/GzccTWc5z在在线编译器中: https : //gcc.godbolt.org/z/GzccTWc5z
Is this because clang does not fully support C++20 yet?这是因为 clang 还没有完全支持 C++20 吗?
This is a C++20 feature that allows aggregate initialization through the standard constructor syntax, rather than the typical braced-list initialization syntax.这是一个 C++20 特性,允许通过标准构造函数语法进行聚合初始化,而不是典型的花括号列表初始化语法。 (Note that this only works if the parameters cannot be used in a valid call to a default or copy/move constructor. If they could, that would be called instead of performing aggregate initialization.)
(请注意,这仅适用于无法在对默认或复制/移动构造函数的有效调用中使用参数的情况。如果可以,则将调用该函数而不是执行聚合初始化。)
According to the official C++ Support in Clang page, Clang does not yet support parenthesized initialization of aggregates (which is P0960R3 and P1975R0 ).根据Clang 中的官方C++ 支持页面,Clang 尚不支持聚合的括号初始化(即P0960R3和P1975R0 )。 This is as of Clang version 13.
这是从 Clang 版本 13 开始的。
A support matrix for C++20 features is also maintained on cppreference.com . cppreference.com 上还维护了 C++20 特性的支持矩阵。 This shows that support for P0960R3 is as follows:
这表明对 P0960R3 的支持如下:
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