Fix for PR debug/41266

ChangeLog:

	* include/dwarf2.h (enum dwarf_tag): Add
	DW_TAG_template_parameter_pack and DW_TAG_formal_parameter_pack.

gcc/ChangeLog:

	* dwarf2out.c (template_parameter_pack_die,
	gen_formal_parameter_pack_die ): New functions.
	(make_ith_pack_parameter_name): Remove this function.
	(dwarf_tag_name): Support printing DW_TAG_template_parameter_pack and
	DW_TAG_formal_parameter_pack.
	(gen_generic_params_dies): Represent each template parameter pack
	by a DW_TAG_template_parameter_pack DIE. Argument pack elements are
	represented by usual DW_TAG_template_*_parameter DIEs that are
	children of the DW_TAG_template_parameter_pack element DIE.
	(generic_parameter_die): This doesn't deal with parameter pack
	names anymore. Don't generate DW_AT_name for some DIEs, e.g. children of
	parameter pack DIEs.
	(gen_formal_parameter_die): Add a flag to not emit DW_AT_name
	in certain cases, e.g. for pack elements.
	(gen_formal_types_die, gen_decl_die): Adjust usage of
	gen_formal_parameter_die.
	(gen_subprogram_die): Represent each function parameter pack by a
	DW_TAG_formal_parameter_pack DIE. Arguments of of the pack are
	represented by usual DW_TAG_formal_parameter DIEs that are children
	of the DW_TAG_formal_parameter_pack DIE. Remove references to
	____builtin_va_alist decls as no part of the compiler uses those
	anymore.
	* langhooks.h (struct lang_hooks_for_decls): Add
	function_parm_expanded_from_pack_p, get_generic_function_decl
	and function_parameter_pack_p hooks.  Fix comment for
	get_innermost_generic_parms hook.
	* langhooks-def.h (LANG_HOOKS_FUNCTION_PARAMETER_PACK_P,
	LANG_HOOKS_FUNCTION_PARM_EXPANDED_FROM_PACK_P ): Declare new hook
	macros and use them to initialize lang_hook.

gcc/cp/ChangeLog:

	* cp-lang.c (LANG_HOOKS_FUNCTION_PARAMETER_PACK_P,
	LANG_HOOKS_FUNCTION_PARM_EXPANDED_FROM_PACK_P,
	LANG_HOOKS_GET_GENERIC_FUNCTION_DECL): Initialize these
	hooks for the c++ FE.
	* cp-tree.h (function_parameter_pack_p, get_function_template_decl,
	function_parameter_expanded_from_pack_p): Declare ...
	* pt.c (function_parameter_pack_p, get_function_template_decl,
	function_parameter_expanded_from_pack_p): ... new hooks.
	(get_template_info): Make this more robust.
	(template_args_variadic_p, make_ith_pack_parameter_name): Add a new
	line between comment and function.
	(get_template_argument_pack_elems): Fix comment.
	(tsubst_decl): Arguments of function parameter packs are not
	parameter packs themselves.

gcc/testsuite/ChangeLog:
	* g++.dg/debug/dwarf2/template-func-params-4.C: Adjust.
	* g++.dg/debug/dwarf2/template-func-params-7.C: Likewise.
	* g++.dg/debug/dwarf2/template-params-4.C: Likewise.

From-SVN: r152043