奇怪的GCC数组初始化行为 [英] Weird GCC array initialization behavior

问题描述

当我看到另一个问题（原始代码使用 std :: thread 而不是 std :: vector ，但语法是一样的）：

  #include< iostream> 
 #include< vector> 
 #include< iterator> 
 #include< algorithm> 
 
 int main（）
 {
 std :: vector< double> vecs [10] = std :: vector&Double;（10,1）; 
 for（auto& vec：vecs）{
 std :: copy（vec.begin（），vec.end（），std :: ostream_iterator< double>（std :: cout， ）; 
 std :: cout<< std :: endl; 
} 
 return 0; 
} 
  

此代码不应编译; std :: vector< double> vecs [10] = std :: vector< double>（10,1）; 是无效的初始化语法，clang使用拒绝它error：array initializer必须是初始化器list 。但是，GCC 接受它，并显示为用指定临时文件的副本初始化列表中的每个向量。 p>

这是我从来没有听说过的某些GCC扩展（不知何故也设法生存 -pedantic-errors ）

解决方案

我认为这是一个错误。

  #include< vector> 
 
 int main（）
 {
 std :: vector< double> x = std :: vector&Double;（10,1）; 
 std :: vector< double> vecs [10] = x; 
 return 0; 
} 
  

工作（如您所见）。

While

  int main（）
 {
 int x = 10; 
 int is [10] = x; 
 return 0; 
} 
  

会产生（预期）错误。

I encountered a variant of this code when looking at another question (the original code used a std::thread instead of std::vector, but the syntax is the same):

#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>

int main()
{
    std::vector<double> vecs[10] = std::vector<double>(10, 1);
    for(auto& vec: vecs){
        std::copy(vec.begin(), vec.end(), std::ostream_iterator<double>(std::cout, " "));
        std::cout<<std::endl;
    }
    return 0;
}

This code shouldn't compile; std::vector<double> vecs[10] = std::vector<double>(10, 1); is not valid initialization syntax, and clang rejects it with error: array initializer must be an initializer list. However, GCC accepts it and appears to initialize every vector in the list with a copy of the specified temporary.

Is this some GCC extension I've never heard about (that somehow also managed to survive -pedantic-errors) or just a plain bug?

解决方案

I would consider this a bug.

#include <vector>

int main()
{
  std::vector<double> x = std::vector<double>(10, 1);
  std::vector<double> vecs[10] = x;
  return 0;
}

Works (as you have spotted).

While

int main()
{
  int x = 10;
  int is[10] = x;
  return 0;
}

yields the (expected) error.

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