[libcamera-devel] [PATCH 02/11] libcamera: log: Add an ASSERT macro

[Laurent Pinchart]

Hi Jacopo,

On Monday, 7 January 2019 12:25:13 EET Jacopo Mondi wrote:
> On Sun, Jan 06, 2019 at 04:33:19AM +0200, Laurent Pinchart wrote:
> > The ASSERT() macro is similar to the assert() macro defined by the C
> > standard, but uses the libcamera logging infrastructure.
> 
> ../src/libcamera/include/log.h:42:45: error: expected primary-expression
> before ‘{’ token #define ASSERT(condition) static_cast<void>({    \
>                                              ^
> ../src/libcamera/media_device.cpp:267:2: note: in expansion of macro
> ‘ASSERT’ ASSERT(valid_);
>   ^~~~~~
> 
> Am I the only one?

No, after fixing the #if(n)def NDEBUG issue Niklas pointed out, I received the 
same error. I've fixed it by adding an extra () around the {} statement.

> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> > 
> >  src/libcamera/include/log.h |  9 +++++++++
> >  src/libcamera/log.cpp       | 16 ++++++++++++++++
> >  2 files changed, 25 insertions(+)
> > 
> > diff --git a/src/libcamera/include/log.h b/src/libcamera/include/log.h
> > index 03842be02d0e..774916f04274 100644
> > --- a/src/libcamera/include/log.h
> > +++ b/src/libcamera/include/log.h
> > 
> > @@ -36,6 +36,15 @@ private:
> >  #define LOG(severity) LogMessage(__FILE__, __LINE__,
> >  Log##severity).stream()> 
> > +#ifdef NDEBUG
> > +#define ASSERT(condition) static_cast<void>({				\
> 
> Why do you use a cast to void? Isn't this better wrapped in a
> canonical "do { } while(0)" ?

I don't know what the pros and cons of each option are, they're both used 
widely.

> > +	if (condition)							\
> 
> I feel we should trigger this if the condition is not satisfied, not
> the other way around, am I wrong?
> http://www.cplusplus.com/reference/cassert/assert/

I must have been really tired when I wrote this... Will fix.

> > +		LOG(Fatal) << "assertion \"" #condition "\" failed";	\
> > +})
> > +#else
> > +#define ASSERT(condition) static_cast<void>(false && (condition))
> > +#endif
> > +
> >  } /* namespace libcamera */
> >  
> >  #endif /* __LIBCAMERA_LOG_H__ */
> > diff --git a/src/libcamera/log.cpp b/src/libcamera/log.cpp
> > index a5823c64eaa6..4165cbd654fc 100644
> > --- a/src/libcamera/log.cpp
> > +++ b/src/libcamera/log.cpp
> > @@ -48,6 +48,22 @@ namespace libcamera {
> > 
> >   * terminates immediately after printing the message.
> >   */
> > 
> > +/**
> > + * \def ASSERT(condition)
> > + * \brief Abort program execution if assertion is failed
> 
> s/is failed/fails ?

Fixed.

> > + *
> > + * If \a condition is false, ASSERT() logs an error message with the
> > Fatal log + * level and aborts program execution.
> 
> Ah, ok, seems like it should then be "if (!(condition))" according to
> documentation too.

At least the documentation is right :-)

> > + *
> > + * If the macro NDEBUG is defined before including log.h, ASSERT()
> > generates no + * code.
> > + *
> > + * Using conditions that have side effects with ASSERT() is not
> > recommended, as + * these effects would depend on whether NDEBUG is
> > defined or not. Similarly, + * ASSERT() should not be used to check for
> > errors that can occur under normal + * conditions as those checks would
> > then be removed when compiling with NDEBUG.
> > + */
> > +
> >  static const char *log_severity_name(LogSeverity severity)
> >  {
> >  	static const char * const names[] = {

-- 
Regards,

Laurent Pinchart