c – 标准中的覆盖和noexcept的顺序

是否需要覆盖和noexcept的顺序？

class Base
{
public:
  virtual void foo() {}
};

class Derived : public Base
{
public:
  // virtual void foo() override {} // Ok
  // virtual void foo() noexcept {} // Ok
  // virtual void foo() noexcept override {} // Ok
  virtual void foo() override noexcept {} // Error
};

int main() {}

我正在使用gcc 4.7.2.

解决方法

实际上,是的,它很难找到,因为它有点分散.附件A(语法摘要)在这方面有所帮助.让我们试着找到具体的位：

declarator:
    ptr-declarator
    noptr-declarator parameters-and-qualifiers trailing-return-type

parameters-and-qualifiers:
    ( parameter-declaration-clause ) attribute-specifier-seqopt cv-qualifier-seqopt
    ref-qualifieropt exception-specificationot

exception-specification:
    dynamic-exception-specification
    noexcept-specification

noexcept-specification:
    noexcept ( constant-expression )
    noexcept

然后是覆盖

member-declarator:
    declarator virt-specifier-seqopt pure-specifieropt
    declarator brace-or-equal-initializeropt
    identifieropt attribute-specifier-seqopt: constant-expression

virt-specifier-seq:
    virt-specifier
    virt-specifier-seq virt-specifier

virt-specifier:
    override
    final

所以声明符是包含noexcept关键字的东西,但是在member-declarator中,virt-specifier出现在声明符之后.