[C++ PATCH] Variadic templates, third revision (1/3)
Doug Gregor
doug.gregor@gmail.com
Wed Nov 1 16:17:00 GMT 2006
This patch addresses PR c++/20599 by introducing support for variadic
templates:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20599
This is the third revision of the variadic templates patch. It
addresses several small bugs, cleans up the terminology used in the
patch, tweaks the syntax slightly, and allows the use of variadic
templates in several more C++ contexts:
- Base specifier list
- Throw specifier list
- Initializer list
- Base class initializer list
This patch is dependent on the experimental C++0x mode patch, posted here:
http://gcc.gnu.org/ml/gcc-patches/2006-11/msg00024.html
More information about variadic templates is available here:
http://www.generic-programming.org/~dgregor/cpp/variadic-templates.html
This is part 1 of 3. It contains all of the C++ front end changes.
Tested on mainline with i686-pc-linux-gnu; no new regressions. All new
tests pass.
Okay for mainline?
Doug Gregor
Open Systems Lab @ Indiana University
2006-11-01 Douglas Gregor <doug.gregor@gmail.com>
PR c++/20599
* typeck.c (check_return_expr): Check for bare parameter packs.
(comptypes): Compare template parameter packs and
type pack expansions.
* decl.c (grokdeclarator): Deal with the declaration of function
parameter packs.
(grokparms): Verify that the (optional) function parameter pack is
at the end of the parameter list.
(xref_basetypes): Handle pack expansions in the base class.
* cp-tree.def (TYPE_ARGUMENT_PACK): New.
(NONTYPE_ARGUMENT_PACK): New.
(TYPE_PACK_EXPANSION): New.
(EXPR_PACK_EXPANSION): New.
* cp-objcp-common.c (cp_tree_size): Compute size of
(NON)TYPE_ARGUMENT_PACK and (TYPE|EXPR)_PACK_EXPANSION.
* error.c (dump_template_argument): Print template argument packs.
(dump_template_argument_list): Ditto.
(dump_template_parameter): Dump `...' for template type parameter
packs.
(dump_type): Dump TYPE_PACK_EXPANSION nodes.
(dump_parameters): Print function parameter packs.
(dump_template_parms): Print template argument packs.
(dump_expr): Dump EXPR_PACK_EXPANSION nodes.
(maybe_warn_variadic_templates): New.
* operators.def: Add ellipsis operator for EXPR_PACK_EXPANSION.
* mangle.c (write_type): Mangle TYPE_PACK_EXPANSION.
(write_template_arg): Write argument packs as separate arguments.
* cp-tree.h (struct template_parm_index_s): Add flag that
indicates that the template parameter is actually a parameter
pack.
(FUNCTION_PARAMETER_PACK_P): New.
(PACK_EXPANSION_P): New.
(PACK_EXPANSION_PATTERN): New.
(SET_PACK_EXPANSION_PATTERN): New.
(PACK_EXPANSION_PARAMETER_PACKS): New.
(ARGUMENT_PACK_P): New.
(ARGUMENT_PACK_ARGS): New.
(SET_ARGUMENT_PACK_ARGS): New.
(ARGUMENT_PACK_INCOMPLETE_P): New.
(ARGUMENT_PACK_EXPLICIT_ARGS): New.
(TEMPLATE_PARM_PARAMETER_PACK): New.
(TEMPLATE_TYPE_PARAMETER_PACK): New.
(struct cp_declarator): Add parameter_pack_p flag.
(maybe_warn_variadic_templates): Declare.
(process_template_parm): Add bool parameter.
(uses_parameter_packs): Declare.
(template_parms_variadic_p): Declare.
(make_pack_expansion): Declare.
(check_for_bare_parameter_packs): Declare.
* pt.c (comp_template_parms): Compare template parameter packs.
(template_parms_variadic_p): New.
(template_args_variadic_p): New.
(make_ith_pack_parameter_name): New.
(struct find_parameter_pack_data): New.
(find_parameter_packs_r): New.
(uses_parameter_packs): New.
(make_pack_expansion): New.
(check_for_bare_parameter_packs): New.
(expand_template_argument_pack): New.
(reduce_template_parm_level): Propagate parameter pack flag.
(process_template_parm): Add is_parameter_pack parameter to state
when the parameter is actually a parameter pack. Create template
parameter packs when is_parameter_pack is true.
(current_template_args): The argument for a template parameter
pack is an argument pack containing a single pack expansion.
(process_partial_specialization): When checking that non-type
argument expressions do not involve template parameters, loop over
the arguments in argument packs separately.
(push_template_decl_real): Check that the type of the declaration
does not have any bare parameter packs. Check that primary
templates have no more than one parameter pack, and that it comes
at the end of the template parameter list.
(convert_template_argument): Handle coercions for pack expansion
expressions by coercing the pattern then rebuilding the expansion.
(coerce_template_parms): When coercing the arguments for a
variadic template, pack "extra" arguments into an argument pack.
(template_args_equal): Compare PACK_EXPANSION_P expressions.
(comp_template_args): Expand all template arguments packs before
comparing template argument lists.
(mangle_class_name_for_template): Make argument packs as separate
template arguments.
(for_each_template_parm_r): Visit all arguments in an argument
pack or visit the pattern of a pack expansion.
(instantiate_class_template): Handle pack expansions in the base
class list.
(tsubst_pack_expansion): New.
(tsubst_template_args): Handle substitutions of argument packs and
pack expansion into template argument lists.
(tsubst_decl): Expand function parameter packs into separate
function parameters.
(tsubst_arg_types): Unpack a type pack expansion into separate
argument types.
(tsubst_exception_specification): Handle pack expansions in
exception specifiers.
(tsubst): Handle substitutions into argument packs.
(tsubst_copy): sizeof(X...) returns the number of elements in
parameter pack X.
(tsubst_expr): Expression pack expansions and argument packs
cannot show up here; they will all be handled through function
calls, sizeof, and template argument lists.
(tsubst_copy_and_build): sizeof(X...) returns the number of
elements in parameter pack X. Handle pack expansions in TREE_LIST
and CONSTRUCTOR nodes.
(fn_type_unification): Handle "incomplete" explicit template
argument lists that specify some of the arguments for a template
parameter pack.
(type_unification_real): Unify arguments against pack expansions.
(template_parm_level_and_index): New, helper function.
(unify_pack_expansion): New.
(unify): Unify argument packs on an argument-by-argument basis,
handling variadic argument packs as well.
(more_specialized_fn): Handle unification of function parameter
packs. All things being equal, prefer non-variadic function
templates to variadic function templates.
(more_specialized_class): Prefer the variadic class template
partial specialization that binds fewer arguments to a parameter
pack.
(regenerate_decl_from_template): Expand function parameter packs
into separate parameters.
(instantiate_decl): Ditto.
(tsubst_initializer_list): Handle pack expansions for base-class
initializers.
(dependent_type_p_r): Determine dependent types in argument packs
and pack expansions.
(value_dependent_expression_p): Determine value-dependence of
non-type argument packs.
(dependent_template_arg_p): Handle argument packs.
* semantics.c (finish_cond): Check for bare parameter packs.
(finish_expr_stmt): Ditto.
(finish_for_expr): Ditto.
(finish_switch_cond): Ditto.
(finish_mem_initializers): Ditto.
* name-lookup.c (arg_assoc_type): Handle pack expansions and
argument packs.
* decl2.c (cp_build_parm_decl): Mark function parameter packs.
* parser.c (make_declarator): Declarator is not an expansion.
(make_pointer_declarator): Transfer parameter pack flag to outer
declarator.
(make_reference_declarator): Ditto.
(make_ptrmem_declarator): Ditto.
(make_call_declarator): Ditto.
(make_array_declarator): Ditto.
(cp_parser_postfix_expression): Allow pack expansion expressions
in the argument list for a call expression.
(cp_parser_parenthesized_expression_list): Add new parameter
ALLOW_EXPANSION_P. When true, parse the ellipsis to mean "expand
into separate arguments."
(cp_parser_new_placement): Allow pack expansion expressions.
(cp_parser_new_initializer): Ditto.
(cp_parser_mem_initializer_list): Allow ellipsis to create a
base-class initializer expansion.
(cp_parser_mem_initializer): Ditto.
(cp_parser_template_parameter_list): Keep track of whether the
template parameter is a template parameter pack.
(cp_parser_template_parameter): Parse the ellipsis to indicate a
template parameter pack.
(cp_parser_type_parameter): Ditto.
(cp_parser_template_argument_list): Parse the ellipsis to indicate
a pack expansion.
(cp_parser_direct_declarator): Parse the ellipsis to indicate that
this declarator is a parameter pack.
(cp_parser_parameter_declaration): The ellipsis does not end the
parameter declaration, because it might be a parameter pack. Parse
the ellipsis to indicate a parameter pack.
(cp_parser_initializer): Allow pack expansions.
(cp_parser_initializer_list): Allow ellipsis to create an
initializer expansion.
(cp_parser_base_clause): Allow ellipsis to create a base specifier
expansion.
(cp_parser_type_id_list): Allow ellipsis to create an exception
specifier expansion.
(cp_parser_attribute_list): Don't allow pack expansions.
(cp_parser_functional_cast): Allow pack expansions.
(cp_parser_sizeof_operand): Allow ellipsis following "sizeof" to
compute the length of a parameter pack.
(cp_parser_next_token_ends_template_argument_p): An ellipsis can
end a template argument.
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