c-format.c (FMT_FLAG_DOLLAR_GAP_POINTER_OK): New.

	* c-format.c (FMT_FLAG_DOLLAR_GAP_POINTER_OK): New.
	(format_types): Use it for scanf.
	(dollar_arguments_pointer_p): New.
	(init_dollar_format_checking): Store details of which arguments
	are pointers.
	(maybe_read_dollar_number): Reallocate dollar_arguments_pointer_p.
	(finish_dollar_format_checking): Take extra parameter
	pointer_gap_ok.  Treat unused arguments differently if
	pointer_gap_ok and the unused arguments are pointers.
	(check_format_info_main): Pass extra argument to
	finish_dollar_format_checking.
	* doc/invoke.texi (-Wno-format-extra-args): Document behavior when
	unused arguments are present between used arguments with operand
	numbers.

testsuite:
	* gcc.dg/format/strfmon-1.c: Update comments.  Adjust examples
	from Austin Group draft 7.
	* gcc.dg/format/xopen-1.c: Update comments.  Add tests for gaps in
	scanf format arguments.
	* gcc.dg/format/no-exargs-2.c: New test.

From-SVN: r47327

1 files changed, 8 insertions, 0 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index bf05c075bfd..21b785324ed 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -1849,6 +1849,14 @@ If @option{-Wformat} is specified, do not warn about excess arguments to a
 @code{printf} or @code{scanf} format function.  The C standard specifies
 that such arguments are ignored.
 
+Where the unused arguments lie between used arguments that are
+specified with @samp{$} operand number specifications, normally
+warnings are still given, since the implementation could not know what
+type to pass to @code{va_arg} to skip the unused arguments.  However,
+in the case of @code{scanf} formats, this option will suppress the
+warning if the unused arguments are all pointers, since the Single
+Unix Specification says that such unused arguments are allowed.
+
 @item -Wformat-nonliteral
 @opindex Wformat-nonliteral
 If @option{-Wformat} is specified, also warn if the format string is not a