re PR c++/21764 (visibility attributes on namespace scope)

re PR c++/21764 (visibility attributes on namespace scope)

        PR c++/21764
        * c-pragma.c (visstack): Move out of handle_pragma_visibility.
        (push_visibility, pop_visibility): Likewise.
        * c-pragma.h: Declare them.
        * cp/name-lookup.h (struct cp_binding_level): Add has_visibility
        bitfield.
        * cp/name-lookup.c: Include c-pragma.h.
        (push_namespace_with_attribs): Split out from push_namespace.
        Push visibility if appropriate.  Set TREE_PUBLIC on namespaces.
        (leave_scope): Pop visibility if appropriate.
        * cp/parser.c (cp_parser_declaration, cp_parser_namespace_name): Allow
        attributes on namespace declarations.

        PR c++/19238
        * cp/decl.c (cp_finish_decl): Call determine_visibility later.
        (start_preparsed_function): Likewise.
        * cp/cp-tree.h (CP_TYPE_CONTEXT, TYPE_NAMESPACE_SCOPE_P): New macros.
        (TYPE_CLASS_SCOPE_P, TYPE_FUNCTION_SCOPE_P): New macros.
        * cp/decl2.c (determine_visibility_from_class): Split out from...
        (determine_visibility): ...here.  Handle function scope and
        nested classes.
        (import_export_decl): Move visibility handling to
        determine_visibility_from_class.

From-SVN: r112239