Partial implementation of namespaces.

Partial implementation of namespaces.
	* decl.c (push_namespace): Handle redeclaration error.
	* cp-tree.h (IDENTIFIER_NAMESPACE_VALUE): New macro.
	(IDENTIFIER_NAMESPACE_BINDINGS): New macro.
	(NAMESPACE_BINDING): New macro.
	(IDENTIFIER_GLOBAL_VALUE): Use NAMESPACE_BINDING.
	* *.c: Use them.
	* pt.c (push_template_decl): Use innermost_args.
	* decl.c (get_unique_name): Tweak from earlier in the name.
	* cp-tree.def: Add CPLUS_BINDING node.
	* cp-tree.h (tree_binding): new struct
	(BINDING_SCOPE, BINDING_VALUE): new macros
	(current_namespace, global_namespace): declare extern
	(struct lang_decl_flags): new field in_namespace
	(DECL_NAMESPACE_USING, DECL_NAMESPACE_USERS): new macros
	(DECL_NAMESPACE, SET_DECL_NAMESPACE): new macros
	(TREE_INDIRECT_USING): new macro
	* decl2.c (current_namespace, global_namespace): Declare.  The
	value is a NAMESPACE_DECL now, not a TREE_LIST.
	(is_namespace_ancestor, namespace_ancestor):new static functions.
	(add_using_namespace, ambiguous_decl): likewise.
	(lookup_using_namespace): new support function for lookup_name.
	(qualified_lookup_using_namespace): new support function for
	do_scoped_id and lookup_namespace_name
	(get_namespace_id): mark as obsolete.
	(current_namespace_id): Likewise.
	(do_namespace_alias): Implement.
	(do_using_directive): Implement as call to add_using_namespace.
	* decl.c (binding_for_name): new function.
	(push_namespace, pop_namespace): implement.
	(push_decl): don't install a FUNCTION_DECL in the global branch.
	(lookup_namespace_name): implement using qualified lookup.
	(lookup_name_real): For global scoping, lookup in
	global_namespace. For namespace scoping, lookup in given
	namespace. For unscoped lookup, iterate over namespace,
	considering using directives.
	(init_decl_processing): initialize global_namespace.
	(grokvardecl): Build assembler name as static name for globals.
	(grokdeclarator): Remove old namespace mangling.
	(xref_tag): When installing a global binding for the
	tag, make sure we have an identifier.
	* method.c (build_overload_nested_name): mangle namespaces.
	(build_qualified_name): Likewise.
	(build_decl_overload_real): Likewise.
	* lex.c (build_lang_decl): set namespace for new declaration to
	current_namespace.
	(do_scoped_id): find global names in global or current
	namespace, or using qualified namespace lookup, depending on
	context.
	* init.c (build_member_call): When scope is namespace, use
	build_x_function_call instead.
	(build_offset_ref): When scope is namespace, collapse processing
	to lookup_namespace_name instead.
	* error.c (dump_decl): Support NAMESPACE_DECL.
	* decl.c (pushdecl): Bind globals to current namespace.
	(push_overloaded_decl): Likewise.
	(lookup_tag): Likewise.
	(lookup_name_current_level): Likewise.
	(xref_tag): Likewise.
	(start_function): Likewise.
	* lex.c (do_identifier): Likewise.
	(identifier_typedecl_value): Likewise.
	(real_yylex): Likewise.
	* method.c (do_inline_function_hair): Likewise.
	* parse.y (unscoped): Likewise.
	* pt.c (check_explicit_specialization): Likewise.
	(lookup_template_class): Likewise.
	* rtti.c (call_void_fn): Likewise.
	* sig.c (build_sigtable): Likewise.
	* ptree.c (lang_print_xnode): New function.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@18227 138bc75d-0d04-0410-961f-82ee72b054a4