Movatterモバイル変換

Proposed resolution (10/00):

Change the grammar in 9.2.9.5 [dcl.type.elab] to read

elaborated-type-specifier:
class-key::_optnested-name-specifier_opt identifier
class-key::_optnested-name-specifier_opttemplate_opttemplate-id
enum ::_optnested-name-specifier_opt identifier
typename ::_optnested-name-specifieridentifier
typename ::_optnested-name-specifiertemplate_opttemplate-id

class-key identifier;
friendclass-key::_optidentifier;
friendclass-key::_opttemplate-id;
friendclass-key::_optnested-name-specifier identifier;
friendclass-key::_optnested-name-specifiertemplate_opttemplate-id;

I can't find the answer to the following in the standard. Doesanybody have a reference?

The syntax for elaborated type specifier is

elaborated-type-specifier:
class-key::_optnested-name-specifier_optidentifier
enum::_opt nested-name-specifier_optidentifier
typename::_opt nested-name-specifieridentifier
typename::_opt nested-name-specifiertemplate_opt template-id

If anelaborated-type-specifier is the sole constituent of a declaration,the declaration is ill-formed unless it is an explicit specialization(13.9.4 [temp.expl.spec]),an explicit instantiation(13.9.3 [temp.explicit]) or it has one of the followingforms:


class-keyidentifier;
friendclass-keyidentifier;
friendclass-key::identifier;
friendclass-keynested-name-specifier identifier ;

    class foo<int> // foo is a template

Anelaborated-type-specifier shall be used in afriend declaration for a class.*

[Footnote: Theclass-key of theelaborated-type-specifier is required.—end footnote]

[Example:

    template<class T> class task;    template<class T> task<T>* preempt(task<T>*);    template<class T> class task {        // ...        friend void next_time();        friend void process(task<T>*);        friend task<T>* preempt<T>(task<T>*);        template<class C> friend int func(C);        friend class task<int>;        template<class P> friend class frd;        // ...    };

An additional problem was reported viacomp.std.c++: thegrammar does not allow the following example:

    namespace A{      class B{};    };    namespace B{      class A{};      class C{friend class ::A::B;      };    };