void * 。请参阅标准中的[temp.param] / 4，该摘要也总结在 http： //en.cppreference.com/w/cpp/language/template_parameters#Non-type_template_parameter

Template parameters of type void* are not allowed. See [temp.param]/4 in the standard, also summarized at http://en.cppreference.com/w/cpp/language/template_parameters#Non-type_template_parameter

非类型 template-parameter 必须具有以下类型之一（可选的 cv限定）类型：

A non-type template-parameter shall have one of the following (optionally cv-qualified) types:

• 整数或枚举类型，


• 指向对象或函数的指针，


• 对对象的左值引用或对函数的左值引用，


• 指向成员的指针，


• std :: nullptr_t 。

• integral or enumeration type,
• pointer to object or pointer to function,
• lvalue reference to object or lvalue reference to function,
• pointer to member,
• std::nullptr_t.

由于 void 不是对象或函数类型，因此 void * 不在允许的类型中。

Since void is not an object or function type, void* is not among the permitted types.

附录： A void *在编译时知道的值不是很有用。由于常量表达式不允许 reinterpret_cast ，因此无法在编译时检查其值；在编译时，对于某些对象类型 T ，也无法将其转换为 T * 。

Addendum: A void* value known at compile time wouldn't be very useful. It's not possible to examine its value at compile time since reinterpret_cast is not allowed in constant expressions; nor is it possible to convert it to T* for some object type T at compile time.