PR c++/43912
	Generate proxy VAR_DECLs for better lambda debug info.
	* cp-tree.h (FUNCTION_NEEDS_BODY_BLOCK): Add lambda operator().
	(LAMBDA_EXPR_PENDING_PROXIES): New.
	(struct tree_lambda_expr): Add pending_proxies.
	* name-lookup.c (pushdecl_maybe_friend_1): Handle capture shadowing.
	(qualify_lookup): Use is_lambda_ignored_entity.
	* parser.c (cp_parser_lambda_expression): Don't adjust field names.
	Call insert_pending_capture_proxies.
	(cp_parser_lambda_introducer): Use this_identifier.
	(cp_parser_lambda_declarator_opt): Call the object parameter
	of the op() "__closure" instead of "this".
	(cp_parser_lambda_body): Call build_capture_proxy.
	* semantics.c (build_capture_proxy, is_lambda_ignored_entity): New.
	(insert_pending_capture_proxies, insert_capture_proxy): New.
	(is_normal_capture_proxy, is_capture_proxy): New.
	(add_capture): Add __ to field names here, return capture proxy.
	(add_default_capture): Use this_identifier, adjust to expect
	add_capture to return a capture proxy.
	(outer_lambda_capture_p, thisify_lambda_field): Remove.
	(finish_id_expression, lambda_expr_this_capture): Adjust.
	(build_lambda_expr): Initialize LAMBDA_EXPR_PENDING_PROXIES.
	* pt.c (tsubst_copy_and_build): Check that LAMBDA_EXPR_PENDING_PROXIES
	is null.

From-SVN: r175158