Problems with variadic parameters

[ericlippert]

There are numerous problems with variadic parameters.

In ordinary functions and methods, the grammar given is

  parameter-list:
    ...
    parameter-declaration-list  ,opt
    parameter-declaration-list  ,  ... 

But this isn't complete; the "..." is allowed to have an attribute, a type and a name, the same as any other parameter. The grammar should be

    variadic-parameter:
      ...
      attribute-specification-opt type-specifier ...  variable-name

Note that if it has a type then it must have a name, and if it has a name then it must have a type.

The grammar for constructor parameters is even more wrong:

  constructor-parameter-declaration-list:
    constructor-parameter-declaration
    constructor-parameter-declaration-list  ,  constructor-parameter-declaration

First of all, this does not allow a trailing comma when it should. Second, it makes no mention of variadic parameters, which are legal in a constructor.

Note that a variadic parameter with a name in a constructor is also allowed to have a visibility modifier, so that should be in the grammar as well.