re PR c++/55189 (enable -Wreturn-type by default)

re PR c++/55189 (enable -Wreturn-type by default)

	PR c++/55189
	* cp-tree.h (struct language_function): Add infinite_loop and
	infinite_loops.
	(current_function_infinite_loop): New.
	* semantics.c (begin_maybe_infinite_loop, end_maybe_infinite_loop)
	(break_maybe_infinite_loop): New.
	(finish_while_stmt_cond, finish_while_stmt, begin_do_stmt)
	(finish_do_stmt, finish_for_cond, finish_for_stmt)
	(begin_range_for_stmt): Use them.
	* decl.c (finish_function): Don't warn about missing return
	if current_function_infinite_loop.
	* pt.c (instantiate_decl): Copy current_function_infinite_loop.
	* parser.c (cp_parser_jump_statement): Call break_maybe_infinite_loop.

From-SVN: r207001