[Bug c/16833] -fno-builtin prevents automatic format checks for standard functions

["pinskia at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-07-30 15:39 -------
The documentation changed:
-Wformat
Check calls to printf and scanf, etc., to make sure that the arguments supplied have types appropriate 
to the format string specified, and that the conversions specified in the format string make sense. This 
includes standard functions, and others specified by format  attributes (see Function Attributes), in the 
printf, scanf, strftime and strfmon (an X/Open extension, not in the C standard) families (or other 
target-specific families).
The formats are checked against the format features supported by GNU libc version 2.2. These include 
all ISO C90 and C99 features, as well  as features from the Single Unix Specification and some BSD and 
GNU extensions. Other library implementations may not support all these  features; GCC does not 
support warning about features that go beyond a particular library's limitations. However, if -pedantic  
is used with -Wformat, warnings will be given about format features not in the selected standard 
version (but not for strfmon formats, since those are not in any version of the C standard). See Options 
Controlling C Dialect .

Since -Wformat also checks for null format arguments for several functions, -Wformat also implies -
Wnonnull.

-Wformat is included in -Wall. For more control over some  aspects of format checking, the options -
Wformat-y2k, -Wno-format-extra-args, -Wno-format-zero-length, -Wformat-nonliteral, -Wformat-
security, and -Wformat=2 are available, but are not included in -Wall. 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16833