Re: Detecting superfluous "else"

[Daniel Letai <dani at letai dot org dot il>]

On 19/07/2018 18:56, Eric Gallager wrote:
> On 7/19/18, U.Mutlu <um@mutluit.com> wrote:
> > Hi,
> > it makes me 'crazy' when I see such if-else constructs:
> >     if (x)
> >       return 7;
> >     else
> >       return 4;
> >
> > (Of course in this case one better would use the shorthand "return x ? 7 :
> > 4;", but that's not the issue here)
> >
> > The 'else' is obviously superfluous/redundant, ie. unneeded at all:
> >     if (x)
> >       return 7;
> >     return 4;
> >
> > Is it possible to warn about such unneccessary occurances of "else"?
> > If not, then I suggest to add a new warning code -Wsuperfluous-else or
> > -Wredundant-else or so.
> >
> > Thx
> Semi-related: bug 81851: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81851
> (my disagreement with that request is similar to my disagreement with
> this request)
Your example might be worth a warning, to allow the developer to refactor

> int g (int i)
> {
>    if (i == 0)   // no warning
>      return 0;
> #if SOME_OTHER_PLATFORM
>    if (i == 2)
>      return 1;
> #endif
>    return 0;
> }
to
> int g (int i)
> {
> #if SOME_OTHER_PLATFORM
>    if (i == 2)
>      return 1;
> #endif
>    return 0;
> }
It is purely stylistic, but if one is worried about dup branch at all, than it's reasonable to assume one would want this warning too.
It would require distinguishing between multiple possible branches by the preprocessor, rather than the compiler. No idea who emits the dup branch warning.