Allow deduction guides to look into primary template.
* cp-tree.h (struct saved_scope): Add deduction_guide_type.
(struct cp_decl_specifier_seq): Add constructor_p.
* parser.c (cp_parser_decl_specifier_seq): Set constructor_p.
(cp_parser_init_declarator): Check it. Set ctor_dtor_or_conv_p.
Clear deduction_guide_type. Don't handle deduction guide names.
(cp_parser_declarator): Don't clear ctor_dtor_or_conv_p.
(cp_parser_direct_declarator): Likewise. Handle deduction guides.
(cp_parser_member_declaration, cp_parser_cache_defarg)
(cp_parser_objc_class_ivars): Set ctor_dtor_or_conv_p.
* pt.c (tsubst_copy, tsubst_copy_and_build): Revert last change.
(build_deduction_guide): Set deduction_guide_type.
(dependent_scope_p): Check deduction_guide_type.
* search.c (lookup_member): Likewise.
From-SVN: r245858