[Spice-devel] [spice-common v2 8/8] log: Let gcc know about the logging macros which abort

[Christophe Fergeau]

On Fri, Mar 29, 2019 at 07:18:35AM -0400, Frediano Ziglio wrote:
> > On Fri, Mar 29, 2019 at 06:57:59AM -0400, Frediano Ziglio wrote:
> > > > On Fri, Mar 29, 2019 at 11:30:46AM +0100, Christophe Fergeau wrote:
> > > > > Without the added abort(), it cannot know g_log(G_LOG_LEVEL_CRITICAL)
> > > > > will never return.
> > > > > 
> > > > > Signed-off-by: Christophe Fergeau <cfergeau at redhat.com>
> > > > > ---
> > > > >  common/log.h | 5 +++++
> > > > >  1 file changed, 5 insertions(+)
> > > > > 
> > > > > diff --git a/common/log.h b/common/log.h
> > > > > index 7c67e7a..1482358 100644
> > > > > --- a/common/log.h
> > > > > +++ b/common/log.h
> > > > > @@ -20,6 +20,7 @@
> > > > >  
> > > > >  #include <stdarg.h>
> > > > >  #include <stdio.h>
> > > > > +#include <stdlib.h>
> > > > >  #include <glib.h>
> > > > >  #include <spice/macros.h>
> > > > >  
> > > > > @@ -42,6 +43,7 @@ void spice_log(GLogLevelFlags log_level,
> > > > >  #define spice_return_if_fail(x) G_STMT_START {
> > > > >  \
> > > > >      if G_LIKELY(x) { } else {
> > > > >      \
> > > > >          spice_log(G_LOG_LEVEL_CRITICAL, SPICE_STRLOC, G_STRFUNC,
> > > > >          "condition `%s' failed", #x); \
> > > > > +        abort();
> > > > > \
> > > > >          return;
> > > > >          \
> > > > 
> > > > The 'return' statment is now unreachable code & can be removed -
> > > > surprised
> > > > the compiler didn't complain that its unreachable.
> > > > 
> > > 
> > > As OT I would also add that a "spice_return_if_fail" which don't return
> > > is confusing, basically it's a hidden assert.
> > 
> > Yeah it is a rather misleading name.  I see this code is importing glib.h
> > so I wonder why spice_return_if_fail needs to exist at all. Why not just
> > drop it and use g_return_if_fail from glib instead of reinventing the
> > wheel.  Or g_warn_if_fail if you want a log message, or g_assert if
> > you want a fatal error.
> > 
> > https://developer.gnome.org/glib/stable/glib-Warnings-and-Assertions.html#g-return-if-fail
> > 
> > Regards,
> > Daniel
> 
> Yes, this was discussed. The behaviour is different so it makes sense to keep
> them. For instance for use critical is fatal while in Glib not.
> Another difference is the informations they report.

Renaming spice_return_if_fail() to spice_assert_if_fail() or
something like this would make things much clearer. In the long run,
we should try to move away from these aborts when possible.

Christophe
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