异常规范在声明和函数实现中不兼容 [英] Exception specifications are not compatible in declaration and in realisation of function

问题描述

我们有以下代码

int main()
{
  void f() throw(int);
  f();
  return 0;
}

void f() { }

GCC clang编译好。但是，在标准中有这样的段落：

GCC and clang compiles it well. But, in standard there is such paragraph:

n3376 15.4 / 4

如果任何函数具有异常规范，它不是noexcept规范，允许
所有异常，该函数的所有声明，包括定义和任何显式特化，应具有兼容的异常规范。

n3376 15.4/4

If any declaration of a function has an exception-specification that is not a noexcept-specification allowing all exceptions, all declarations, including the definition and any explicit specialization, of that function shall have a compatible exception-specification.

并且对于以下示例：gcc - error，clang - warning

And for following example: gcc - error, clang - warning

void f() throw(int);

int main()
{
  f();
  return 0;
}

void f() { }

是这些片段的区别？谢谢。

Why there is difference in these snippets? Thanks.

推荐答案

从std规范的n3376 15.4 / 4，函数的所有dereclices和定义必须具有相同的投掷类型。这里：

The n3376 15.4/4 from the std specifie that all déclarations and definitions of a function must have the same throwing type. Here :

void f() throw(int);
int main()
{
  f();
  return 0;
}

void f() { }

void f（）throw（int）; 和定义 void f（）{} 所以他们是冲突，因为声明是为一个函数，它抛出int，而定义是一个没有throw规范的函数。

the declaration void f() throw(int); and the definition void f() { } are in global scop. So they are in conflict because the declaration is for a function which throw int while the definition is for a function without a throw specification.

现在，当你把声明主要scop，定义不在同一个scop，在这个scop的定义是不知道所以你可以编译。

Now, when you put the declaration in the main scop, the definition isn't in the same scop, during this scop the definition isn't known so you can compile.

我希望你能理解我的英语，对不起。

I hope you understood my english, sorry about it.

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