gcc/c-family/ChangeLog:
	PR c/52952
	* c-format.c: Include "diagnostic.h".
	(location_column_from_byte_offset): Delete.
	(location_from_offset): Delete.
	(format_warning_va): New function.
	(format_warning_at_substring): New function.
	(format_warning_at_char): New function.
	(check_format_arg): Capture location of format_tree and pass to
	check_format_info_main.
	(argument_parser): Add fields "start_of_this_format" and
	"format_string_cst".
	(flag_chars_t::validate): Add param "format_string_cst".  Convert
	warning_at call using location_from_offset to call to
	format_warning_at_char.
	(argument_parser::argument_parser): Add param "format_string_cst_"
	and use use it to initialize field "format_string_cst".
	Initialize new field "start_of_this_format".
	(argument_parser::read_format_flags): Convert warning_at call
	using location_from_offset to a call to format_warning_at_char.
	(argument_parser::read_any_format_left_precision): Likewise.
	(argument_parser::read_any_format_precision): Likewise.
	(argument_parser::read_any_other_modifier): Likewise.
	(argument_parser::find_format_char_info): Likewise, in three places.
	(argument_parser::parse_any_scan_set): Likewise, in one place.
	(argument_parser::handle_conversions): Likewise, in two places.
	(argument_parser::check_argument_type): Add param "fmt_param_loc"
	and use it to make a substring_loc.  Pass the latter to
	check_format_types.
	(check_format_info_main): Add params "fmt_param_loc" and
	"format_string_cst".  Convert warning_at calls using
	location_from_offset to calls to format_warning_at_char.  Pass the
	new params to the arg_parser ctor.  Pass "format_string_cst" to
	flag_chars.validate.  Pass "fmt_param_loc" to
	arg_parser.check_argument_type.
	(check_format_types): Convert first param from a location_t
	to a const substring_loc & and rename to "fmt_loc".  Attempt
	to extract the range of the relevant parameter and pass it
	to format_type_warning.
	(format_type_warning): Convert first param from a location_t
	to a const substring_loc & and rename to "fmt_loc".  Add
	params "param_range" and "type".  Replace calls to warning_at
	with calls to format_warning_at_substring.

gcc/testsuite/ChangeLog:
	PR c/52952
	* gcc.dg/cpp/pr66415-1.c: Likewise.
	* gcc.dg/format/asm_fprintf-1.c: Update column numbers.
	* gcc.dg/format/c90-printf-1.c: Likewise.
	* gcc.dg/format/diagnostic-ranges.c: New test case.

From-SVN: r239253