这是一个Intellisense错误。 clang和gcc都接受此代码， webcompiler，在线Visual c ++编译器也接受此代码。

This is an Intellisense bug. Both clang and gcc accept this code, also webcompiler an online Visual c++ compiler accepts this code.

C ++ 14标准草案 12.1 [class.ctor] 表示默认的默认构造函数如果满足以下条件，则删除该类：

The draft C++14 standard section 12.1 [class.ctor] says a defaulted default constructor for a class is deleted if:

• X是类联合的类，其变体成员具有非-琐碎的默认构造函数，


• 没有大括号或相等初始化器的任何非静态数据成员都是引用类型，


• 任何非-没有大括号等于初始化器的const限定类型（或其数组）的变体非静态数据成员没有
  用户提供的默认构造函数，


• X是一个工会，其所有变体成员都是const限定类型（或其数组）。


• X是非工会类，任何匿名工会成员的所有成员都是const-限定类型（或其数组）


• 任何可能构造的子对象，除了具有大括号或等于初始化器的非静态数据成员外，其类类型为M（或其数组
  ），并且M没有默认构造函数或重载应用于M的默认构造函数的
  分辨率（13.3）导致
  的歧义性或导致从
  默认的默认构造函数或$ b中删除或无法访问的函数
• 任何可能构造的子对象都具有带有析构函数的类型，该析构函数已从默认的默认
  构造函数中删除或无法访问。

• X is a union-like class that has a variant member with a non-trivial default constructor,
• any non-static data member with no brace-or-equal-initializer is of reference type,
• any non-variant non-static data member of const-qualified type (or array thereof) with no brace-orequal- initializer does not have a user-provided default constructor,
• X is a union and all of its variant members are of const-qualified type (or array thereof),
• X is a non-union class and all members of any anonymous union member are of const-qualified type (or array thereof),
• any potentially constructed subobject, except for a non-static data member with a brace-or-equalinitializer, has class type M (or array thereof) and either M has no default constructor or overload resolution (13.3) as applied to M’s default constructor results in an ambiguity or in a function that is deleted or inaccessible from the defaulted default constructor, or
• any potentially constructed subobject has a type with a destructor that is deleted or inaccessible from the defaulted default constructor.

在此均不适用。

更新

在OP提交的错误报告中，响应为：

In the bug report filed by the OP the response was:

感谢您报告此问题。该修补程序应该在Visual Studio 2015的下一次更新中可用。

Thank you for reporting this issue. Fix should be available in the next update to Visual Studio 2015.