Re: [Qemu-trivial] [Qemu-devel] [PATCH 5/6] Remove warning in printf due to type mismatch

[Stefan Weil <weil@mail.berlios.de>]

Am 27.05.2011 21:11, schrieb Markus Armbruster:
> Stefan Weil <weil@mail.berlios.de> writes:
>
>> Am 27.05.2011 19:22, schrieb Alexandre Raymond:
>>> ----8<----
>>> qemu/target-lm32/translate.c: In function
>>> ‘gen_intermediate_code_internal’:
>>> qemu/target-lm32/translate.c:1135: warning: format ‘%zd’ expects
>>> type ‘signed size_t’, but argument 4 has type ‘int’
>>> ----8<----
>>>
>>> Both gen_opc_ptr and gen_opc_buf are "uint16_t *", so a simple '%d' 
>>> should
>>> be able to describe their relative difference.
>>>
>>> Signed-off-by: Alexandre Raymond <cerbere@gmail.com>
>>> ---
>>> target-lm32/translate.c | 2 +-
>>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/target-lm32/translate.c b/target-lm32/translate.c
>>> index eb21158..0f69f27 100644
>>> --- a/target-lm32/translate.c
>>> +++ b/target-lm32/translate.c
>>> @@ -1132,7 +1132,7 @@ static void
>>> gen_intermediate_code_internal(CPUState *env,
>>> if (qemu_loglevel_mask(CPU_LOG_TB_IN_ASM)) {
>>> qemu_log("\n");
>>> log_target_disas(pc_start, dc->pc - pc_start, 0);
>>> - qemu_log("\nisize=%d osize=%zd\n",
>>> + qemu_log("\nisize=%d osize=%d\n",
>>> dc->pc - pc_start, gen_opc_ptr - gen_opc_buf);
>>> }
>>> #endif
>>
>> Nack.
>>
>> The original code is correct, because the difference of two pointers
>> is always of type ssize_t (well, obviously not with your compiler,
>> but then I assume that your compiler is broken).
>
> ISO/IEC 9899:1999 §6.5.6 on pointer subtraction:
>
> The size of the result is implementation-defined, and its type (a
> signed integer type) is ptrdiff_t defined in the <stddef.h> header.
>
> The pedantically correct way to print a pointer difference is the 't'
> type modifier. Ibid. §7.19.6.1 on fprintf():
>
> t Specifies that a following d, i, o, u, x, or X conversion
> specifier applies to a ptrdiff_t or the corresponding unsigned
> integer type argument; or that a following n conversion
> specifier applies to a pointer to a ptrdiff_t argument.
>
> ssize_t is POSIX, not ISO C. It can differ from ptrdiff_t only if
> ptrdiff_t has a different size than size_t, which would be kind of sick.
> ISO C permits all kinds of sickness. Whether tolerating a particular
> sickness is worth our while is another question.
>
> [...]

That's correct. And ptrdiff_t needs %td.

Alexandre, could you please try %td instead of %zd?

Cheers,
Stefan W.