Add support for a new archetype "printf0" for the "format" function

attribute.  It is like the existing "printf" archetype, except that
it doesn't complain if the format string is a null pointer.  See
the node "Function Attributes" in the GCC info pages if you don't
know what this is all about.

This change will allow us to add format string checking for the
err(3) family of functions.

1 files changed, 9 insertions, 7 deletions

diff --git a/contrib/gcc/extend.texi b/contrib/gcc/extend.texi
index e85799c..8eee030 100644
--- a/contrib/gcc/extend.texi
+++ b/contrib/gcc/extend.texi
@@ -1394,13 +1394,15 @@ for consistency with the @code{printf} style format string argument
 @code{my_format}.
 
 The parameter @var{archetype} determines how the format string is
-interpreted, and should be either @code{printf} or @code{scanf}.  The
-parameter @var{string-index} specifies which argument is the format
-string argument (starting from 1), while @var{first-to-check} is the
-number of the first argument to check against the format string.  For
-functions where the arguments are not available to be checked (such as
-@code{vprintf}), specify the third parameter as zero.  In this case the
-compiler only checks the format string for consistency.
+interpreted, and should be @code{printf}, @code{printf0}, or
+@code{scanf}.  @code{printf0} allows the format string to be a null
+pointer, while @code{printf} does not.  The parameter @var{string-index}
+specifies which argument is the format string argument (starting
+from 1), while @var{first-to-check} is the number of the first
+argument to check against the format string.  For functions where
+the arguments are not available to be checked (such as @code{vprintf}),
+specify the third parameter as zero.  In this case the compiler
+only checks the format string for consistency.
 
 In the example above, the format string (@code{my_format}) is the second
 argument of the function @code{my_print}, and the arguments to check