我认为这是C ++ 11标准中的（次要）缺陷

Question

I believe this to be a (minor) defect in the C++11 Standard. In [dcl.dcl] we have:

simple-declaration :

decl-specifier-seq _opt init-declarator-list _opt ;

The decl-specifier-seq can't be optional.

For instance the snippet below doesn't compile:

x;

If I'm correct here, then the beginning of paragraph §8.3/1 should also be altered:

From:

A list of declarators appears after an optional (Clause 7) decl-specifier-seq (7.1).

To:

A list of declarators appears after a decl-specifier-seq (7.1).

Answer 1

Too long for a comment

In clause 7, paragraph 3:

In a simple-declaration , the optional init-declarator-list can be omitted only when declaring a class (Clause 9) or enumeration (7.2), that is, when the decl-specifier-seq contains either a class-specifier , an elaborated-type-specifier with a class-key (9.1), or an enum-specifier . In these cases and whenever a class-specifier or enum-specifier is present in the decl-specifier-seq , the identifiers in these specifiers are among the names being declared by the declaration (as class-names , enum-names , or enumerators , depending on the syntax). In such cases, and except for the declaration of an unnamed bit-field (9.6), the decl-specifier-seq shall introduce one or more names into the program, or shall redeclare a name introduced by a previous declaration.

And in clause 7, paragraph 9

Only in function declarations for constructors, destructors, and type conversions can the decl-specifier-seq be omitted.