[Bug c/37768] bogus warnings on x86_64-mingw32 due to attribute((format(printf))) breakage

[joseph at codesourcery dot com]

------- Comment #1 from joseph at codesourcery dot com  2008-10-08 16:15 -------
Subject: Re:   New: bogus warnings on x86_64-mingw32 due to
 attribute((format(printf))) breakage

On Wed, 8 Oct 2008, mikpe at it dot uu dot se wrote:

> When gcc is configured to generate code for x86_64-pc-mingw32, that is MinGW
> for 64-bit Windows, attribute((format(printf))) is redefined by the backend to
> be compatible with MSVC's runtime library, which differs significantly from
> C99.

Correct.  This is the conclusion we eventually reached, that "printf" 
would be for the system formats (e.g. for a function wrapping a call to a 
system function), that "gnu_printf" would be for the formats accepted by 
the GNU C Library (including GNU extensions) on all platforms and that 
"ms_printf" would be for the MSVC formats, on Windows platforms only.

> The program below illustrates the issue. It declares a private C99-compliant
> snprintf() implementation and invokes it with "%zu" and "%llx" formats. This
> triggers the following bogus warnings on x86_64-pc-mingw32:

Use gnu_printf for such an implementation.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37768