为什么指定初始化以g没有实现++ [英] Why are designated initializers not implemented in g++

问题描述

有没有为什么的指定初始化的支持没有被添加至G任何具体的原因++？是C99的标准来晚和g ++开发的原因较早和较晚的人不关心这个问题，或者出现在C的语法实现指定初始化++的一些固有的困难？

Is there any specific reason why has support for designated initializers not been added to g++? Is the reason that C99 standards came late and g++ was developed earlier and later people didn't care about this issue, or there is some inherent difficulty in implementing designated initializers in the grammar of C++?

推荐答案

正如我在评论指出，G ++不支持C99标准指定initialisers，但它支持GNU扩展到C90，它允许指定initialisers。所以这不起作用：

As I noted in a comment, G++ doesn't support C99 standard designated initialisers, but it does support the GNU extension to C90 which allows designated initialisers. So this doesn't work:

union value_t {
    char * v_cp;
    float v_f;
};
union value_t my_val = { .v_f = 3.5f };

但这：

union value_t my_val = { v_f: 3.5f };

这似乎是C和C ++标准委员会之间的协调不好的交互（有没有特别好的理由C ++不支持C99的语法，他们只是还没有考虑过它），GCC政治（ C ++不应该支持C99语法，只是因为它是在C99，但它应该支持实现了完全一样的东西GNU扩展语法，因为这是一个可以应用到任何语言GNU扩展）。

This seems to be a bad interaction of co-ordination between the C and C++ standards committees (there is no particularly good reason why C++ doesn't support the C99 syntax, they just haven't considered it) and GCC politics (C++ shouldn't support C99 syntax just because it's in C99, but it should support GNU extension syntax that achieves exactly the same thing because that's a GNU extension that can be applied to either language).

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