diff -durN gcc-4.4.5.orig/gcc/c-common.c gcc-4.4.5/gcc/c-common.c

 --- gcc-4.4.5.orig/gcc/c-common.c	2010-07-27 15:07:28.000000000 +0200

 +++ gcc-4.4.5/gcc/c-common.c	2010-10-09 22:59:03.000000000 +0200

 @@ -301,7 +301,7 @@

  /* Warn about format/argument anomalies in calls to formatted I/O functions

     (*printf, *scanf, strftime, strfmon, etc.).  */

 -int warn_format;

 +int warn_format = 1;

  /* Warn about using __null (as NULL in C++) as sentinel.  For code compiled

     with GCC this doesn't matter as __null is guaranteed to have the right

 diff -durN gcc-4.4.5.orig/gcc/c.opt gcc-4.4.5/gcc/c.opt

 --- gcc-4.4.5.orig/gcc/c.opt	2009-09-18 23:53:23.000000000 +0200

 +++ gcc-4.4.5/gcc/c.opt	2010-10-09 22:59:03.000000000 +0200

 @@ -236,7 +236,7 @@

  Warn about format strings that contain NUL bytes

  Wformat-security

 -C ObjC C++ ObjC++ Var(warn_format_security) Warning

 +C ObjC C++ ObjC++ Var(warn_format_security) Init(1) Warning

  Warn about possible security problems with format functions

  Wformat-y2k

 diff -durN gcc-4.4.5.orig/gcc/doc/invoke.texi gcc-4.4.5/gcc/doc/invoke.texi

 --- gcc-4.4.5.orig/gcc/doc/invoke.texi	2010-09-08 20:13:03.000000000 +0200

 +++ gcc-4.4.5/gcc/doc/invoke.texi	2010-10-09 22:59:03.000000000 +0200

 @@ -2888,6 +2888,9 @@

  @option{-Wformat-nonliteral}, @option{-Wformat-security}, and

  @option{-Wformat=2} are available, but are not included in @option{-Wall}.

 +NOTE: In Gentoo, this option is enabled by default for C, C++, ObjC, ObjC++.

 +To disable, use @option{-Wformat=0}.

 +

  @item -Wformat-y2k

  @opindex Wformat-y2k

  @opindex Wno-format-y2k

 @@ -2941,6 +2944,11 @@

  in future warnings may be added to @option{-Wformat-security} that are not

  included in @option{-Wformat-nonliteral}.)

 +NOTE: In Gentoo, this option is enabled by default for C, C++, ObjC, ObjC++.

 +To disable, use @option{-Wno-format-security}, or disable all format warnings

 +with @option{-Wformat=0}.  To make format security warnings fatal, specify

 +@option{-Werror=format-security}.

 +

  @item -Wformat=2

  @opindex Wformat=2

  @opindex Wno-format=2