[libvirt] [PATCH] fix failure when building with --disable-debug

[Daniel P. Berrange]

On Wed, Jul 11, 2012 at 05:05:24PM +0800, Hu Tao wrote:
> When building with --disable-debug, VIR_DEBUG expands to a nop.
> But parameters to VIR_DEBUG can be variables that are passed only
> to VIR_DEBUG. In the case the building system complains about unused
> variables.
> ---
>  src/libvirt_private.syms |    1 +
>  src/util/logging.c       |   15 +++++++++++++++
>  src/util/logging.h       |    3 ++-
>  3 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index b173590..48c4df7 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -739,6 +739,7 @@ virLockManagerRelease;
>  
>  
>  # logging.h
> +virEatParam;
>  virLogDefineFilter;
>  virLogDefineOutput;
>  virLogEmergencyDumpAll;
> diff --git a/src/util/logging.c b/src/util/logging.c
> index f8233cd..999dd01 100644
> --- a/src/util/logging.c
> +++ b/src/util/logging.c
> @@ -1262,3 +1262,18 @@ void virLogSetFromEnv(void) {
>      if (debugEnv && *debugEnv)
>          virLogParseOutputs(debugEnv);
>  }
> +
> +/**
> + * virEatParam:
> + *
> + * Do nothing but eat parameters. See VIR_DEBUG_INT.
> + *
> + * Currently only VIR_DEBUG_INT uses this function, which could
> + * have been defined right before VIR_DEBUG_INT, but it makes
> + * `make syntax-check' unhappy about ATTRIBUTE_UNUSED appearing
> + * in .h file.
> + */
> +void virEatParam(void *unused ATTRIBUTE_UNUSED, ...)
> +{
> +    /* do nothing */
> +}

Could you in fact put this in logging.h and mark it 'inline' so
the compiler does away with it entirely, but still thinks the
params are used ?


> diff --git a/src/util/logging.h b/src/util/logging.h
> index 70318d0..b96a115 100644
> --- a/src/util/logging.h
> +++ b/src/util/logging.h
> @@ -35,7 +35,7 @@
>      virLogMessage(category, VIR_LOG_DEBUG, f, l, 0, __VA_ARGS__)
>  # else
>  #  define VIR_DEBUG_INT(category, f, l, ...)    \
> -    do { } while (0)
> +    virEatParam((void*)category, f, l, __VA_ARGS__)
>  # endif /* !ENABLE_DEBUG */
>  
>  # define VIR_INFO_INT(category, f, l, ...)                              \
> @@ -142,4 +142,5 @@ extern void virLogVMessage(const char *category, int priority,
>                             va_list vargs) ATTRIBUTE_FMT_PRINTF(6, 0);
>  extern int virLogSetBufferSize(int size);
>  extern void virLogEmergencyDumpAll(int signum);
> +void virEatParam(void *unused, ...);

Oh and rename it to:

  s/virEatParam/virLogEatParam/


Regards,
Daniel
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