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[Bug c/37768] bogus warnings on x86_64-mingw32 due to attribute((format(printf))) breakage
- From: "joseph at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 8 Oct 2008 16:15:08 -0000
- Subject: [Bug c/37768] bogus warnings on x86_64-mingw32 due to attribute((format(printf))) breakage
- References: <bug-37768-7665@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- 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.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37768