9 Declarations [dcl.dcl]

The type-specifiers are

The optional attribute-specifier-seq in a type-specifier-seq or a defining-type-specifier-seq appertains to the type denoted by the preceding type-specifiers or defining-type-specifiers ([dcl.meaning]).

The attribute-specifier-seq affects the type only for the declaration it appears in, not other declarations involving the same type.

As a general rule, at most one defining-type-specifier is allowed in the complete decl-specifier-seq of a declaration or in a defining-type-specifier-seq, and at most one type-specifier is allowed in a type-specifier-seq.

The only exceptions to this rule are the following:

• (2.1)
  const can be combined with any type specifier except itself.
• (2.2)
  volatile can be combined with any type specifier except itself.
• (2.3)
  signed or unsigned can be combined with char, long, short, or int.
• (2.4)
  short or long can be combined with int.
• (2.5)
  long can be combined with double.
• (2.6)
  long can be combined with long.

Except in a declaration of a constructor, destructor, or conversion function, at least one defining-type-specifier that is not a cv-qualifier shall appear in a complete type-specifier-seq or a complete decl-specifier-seq.75