Re: [Libreoffice] [PATCH] Simple fix for fontconfig.cxx to review (from cppcheck report)

Hi Mat,

15.01.2012 03:29, Mat M пишет:
> Hello
>
> Le Sat, 14 Jan 2012 16:00:31 +0100, julien2412 <serval2412@yahoo.fr> a
> écrit:
>
> > Hello,
> >
> > cppcheck reported this :
> > core/vcl/generic/fontmanager/fontconfig.cxx
> > 196 duplicateExpression style Same expression on both sides of '-'
> >
> > class SortFont : public ::std::binary_function< const FcPattern*, const
> > FcPattern*, bool >
> > {
> > public:
> > bool operator()(const FcPattern *a, const FcPattern *b)
> > {
> > int comp = compareFontNames(a, b);
> > if (comp != 0)
> > return comp < 0;
> >
> > int nVersionA=0, nVersionB=0;
> >
> > bool bHaveA = FcPatternGetInteger(a, FC_FONTVERSION, 0,
> > &nVersionA) == FcResultMatch;
> > bool bHaveB = FcPatternGetInteger(b, FC_FONTVERSION, 0,
> > &nVersionB) == FcResultMatch;
> >
> > if (bHaveA && bHaveB)
> > return nVersionA > nVersionB;
> >
> > 196: return bHaveA - bHaveA;<--- Same expression on both sides of
> > '-'.
> > }
> > };
> >
> > If we follow the same logic as the function compareFontNames defined some
> > lines above in the same file :
> > int compareFontNames(const FcPattern *a, const FcPattern *b)
> > {
> > FcChar8 *pNameA=NULL, *pNameB=NULL;
> >
> > bool bHaveA = FcPatternGetString(a, FC_FAMILY, 0, &pNameA) ==
> > FcResultMatch;
> > bool bHaveB = FcPatternGetString(b, FC_FAMILY, 0, &pNameB) ==
> > FcResultMatch;
> >
> > if (bHaveA && bHaveB)
> > return strcmp((const char*)pNameA, (const char*)pNameB);
> >
> > return bHaveA - bHaveB;
> > }
> >
> > it seems it should be :
> > return bHaveA - bHaveB;
> >
> > Any idea ?
> Subtracting booleans ??? Is there some magic here ?
> Moreover, if we state that boolean difference returns a boolean, is
> there an automatic cast, as the function should return an int ?

AFAIK in arithmetic bools are concerted to int so that true->1 and false->0.
Then, the result is converted back to bool (because the function returns 
bool) so that 0->false and 'any other value'->true.

So "return bool1 - bool2" can be replaced with not-so-magic "return 
bool1 != bool2", right?

By the way, the author of the code is Caolan, let's ask him. :)

Ivan