[Qemu-devel] [PATCH] w32: Always use standard instead of native format strings

[Qemu-devel] [PATCH] w32: Always use standard instead of native format strings

[Stefan Weil]

GLib 2.0 include files use __printf__ for the format attribute
which resolves to native format strings on w32 hosts.

QEMU wants standard format strings instead of native format
strings, so we simply change any declaration with __printf__
to use __gnu_printf__.

This works because all basic printf functions support both
kinds of format strings.

This fixes a compiler warning:

qapi/string-output-visitor.c: In function ‘print_type_int’:
qapi/string-output-visitor.c:34:5: warning: unknown conversion type character ‘l’ in format [-Wformat]
qapi/string-output-visitor.c:34:5: warning: too many arguments for format [-Wformat-extra-args]

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---
 compiler.h |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/compiler.h b/compiler.h
index 07ba1f8..c734a71 100644
--- a/compiler.h
+++ b/compiler.h
@@ -44,6 +44,11 @@
    /* Use gnu_printf when supported (qemu uses standard format strings). */
 #  define GCC_ATTR __attribute__((__unused__, format(gnu_printf, 1, 2)))
 #  define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
+#  if defined(_WIN32)
+    /* Map __printf__ to __gnu_printf__ because we want standard format strings
+     * even when MinGW or GLib include files use __printf__. */
+#   define __printf__ __gnu_printf__
+#  endif
 # endif
 #if defined(_WIN32)
 #define GCC_WEAK __attribute__((weak))
-- 
1.7.10

Re: [Qemu-devel] [PATCH] w32: Always use standard instead of native format strings

[Stefan Hajnoczi]

On Wed, Aug 22, 2012 at 09:42:32PM +0200, Stefan Weil wrote:
> GLib 2.0 include files use __printf__ for the format attribute
> which resolves to native format strings on w32 hosts.
> 
> QEMU wants standard format strings instead of native format
> strings, so we simply change any declaration with __printf__
> to use __gnu_printf__.
> 
> This works because all basic printf functions support both
> kinds of format strings.
> 
> This fixes a compiler warning:
> 
> qapi/string-output-visitor.c: In function ‘print_type_int’:
> qapi/string-output-visitor.c:34:5: warning: unknown conversion type character ‘l’ in format [-Wformat]
> qapi/string-output-visitor.c:34:5: warning: too many arguments for format [-Wformat-extra-args]
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
>  compiler.h |    5 +++++
>  1 file changed, 5 insertions(+)

Thanks, applied to the trivial patches tree:
https://github.com/stefanha/qemu/commits/trivial-patches

Stefan

Re: [Qemu-devel] [PATCH] w32: Always use standard instead of native format strings

[Eric Blake]

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On 08/22/2012 01:42 PM, Stefan Weil wrote:
> GLib 2.0 include files use __printf__ for the format attribute
> which resolves to native format strings on w32 hosts.
> 
> QEMU wants standard format strings instead of native format
> strings, so we simply change any declaration with __printf__
> to use __gnu_printf__.
> 
> This works because all basic printf functions support both
> kinds of format strings.
> 
> This fixes a compiler warning:
> 
> qapi/string-output-visitor.c: In function ‘print_type_int’:
> qapi/string-output-visitor.c:34:5: warning: unknown conversion type character ‘l’ in format [-Wformat]
> qapi/string-output-visitor.c:34:5: warning: too many arguments for format [-Wformat-extra-args]
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
>  compiler.h |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/compiler.h b/compiler.h
> index 07ba1f8..c734a71 100644
> --- a/compiler.h
> +++ b/compiler.h
> @@ -44,6 +44,11 @@
>     /* Use gnu_printf when supported (qemu uses standard format strings). */
>  #  define GCC_ATTR __attribute__((__unused__, format(gnu_printf, 1, 2)))
>  #  define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
> +#  if defined(_WIN32)
> +    /* Map __printf__ to __gnu_printf__ because we want standard format strings
> +     * even when MinGW or GLib include files use __printf__. */
> +#   define __printf__ __gnu_printf__
> +#  endif

Don't you need to make this conditional on the gcc version?  That is,
gcc 4.4 added __gnu_printf__, but gcc 4.3 understands only __printf__
and attempts to pass __gnu_printf__ will cause compilation failure.

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH] w32: Always use standard instead of native format strings

[Stefan Weil]

Am 24.09.2012 21:28, schrieb Eric Blake:
> On 08/22/2012 01:42 PM, Stefan Weil wrote:
>> GLib 2.0 include files use __printf__ for the format attribute
>> which resolves to native format strings on w32 hosts.
>>
>> QEMU wants standard format strings instead of native format
>> strings, so we simply change any declaration with __printf__
>> to use __gnu_printf__.
>>
>> This works because all basic printf functions support both
>> kinds of format strings.
>>
>> This fixes a compiler warning:
>>
>> qapi/string-output-visitor.c: In function ‘print_type_int’:
>> qapi/string-output-visitor.c:34:5: warning: unknown conversion type character ‘l’ in format [-Wformat]
>> qapi/string-output-visitor.c:34:5: warning: too many arguments for format [-Wformat-extra-args]
>>
>> Signed-off-by: Stefan Weil<sw@weilnetz.de>
>> ---
>>   compiler.h |    5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/compiler.h b/compiler.h
>> index 07ba1f8..c734a71 100644
>> --- a/compiler.h
>> +++ b/compiler.h
>> @@ -44,6 +44,11 @@
>>      /* Use gnu_printf when supported (qemu uses standard format strings). */
>>   #  define GCC_ATTR __attribute__((__unused__, format(gnu_printf, 1, 2)))
>>   #  define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
>> +#  if defined(_WIN32)
>> +    /* Map __printf__ to __gnu_printf__ because we want standard format strings
>> +     * even when MinGW or GLib include files use __printf__. */
>> +#   define __printf__ __gnu_printf__
>> +#  endif
>
> Don't you need to make this conditional on the gcc version?  That is,
> gcc 4.4 added __gnu_printf__, but gcc 4.3 understands only __printf__
> and attempts to pass __gnu_printf__ will cause compilation failure.
>

It is conditional. The complete code is here:

# if !QEMU_GNUC_PREREQ(4, 4)
    /* gcc versions before 4.4.x don't support gnu_printf, so use printf. */
#  define GCC_ATTR __attribute__((__unused__, format(printf, 1, 2)))
#  define GCC_FMT_ATTR(n, m) __attribute__((format(printf, n, m)))
# else
    /* Use gnu_printf when supported (qemu uses standard format strings). */
#  define GCC_ATTR __attribute__((__unused__, format(gnu_printf, 1, 2)))
#  define GCC_FMT_ATTR(n, m) __attribute__((format(gnu_printf, n, m)))
#  if defined(_WIN32)
     /* Map __printf__ to __gnu_printf__ because we want standard format 
strings
      * even when MinGW or GLib include files use __printf__. */
#   define __printf__ __gnu_printf__
#  endif
# endif

gcc 4.3 and older will still produce compiler warnings.