Detecting superfluous "else"

Detecting superfluous "else"

[U.Mutlu]

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

Re: Detecting superfluous "else"

[Paul Koning]

> On Jul 19, 2018, at 4:49 AM, 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.

I don't see any reason to warn about that code.  It's perfectly valid, and in my view is clearer than the alternative.  I've written both but I most often write the "else" variant for the reason that it expresses the semantics explicitly.

Warnings are appropriate for code that is known to be a source of bugs, or where there is a reasonable chance that the intent of the programmer doesn't match what was actually written.  That's not the case here.

	paul

Re: Detecting superfluous "else"

[Jonathan Wakely]

On Thu, 19 Jul 2018 at 14:01, Paul Koning wrote:
> Warnings are appropriate for code that is known to be a source of bugs, or where there is a reasonable chance that the intent of the programmer doesn't match what was actually written.  That's not the case here.

Agreed. This seems to be a purely stylistic preference.

Re: Detecting superfluous "else"

[Eric Gallager]

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)

Re: Detecting superfluous "else"

[Daniel Letai]

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.

Re: Detecting superfluous "else"

[Didier Kryn]

Le 19/07/2018 à 10:49, U.Mutlu a écrit :
> 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

     Let me express the point of view of an old C programmer (and also 
programmer in other languages).

     From a semantic point of view  (if I can dare to use this word) the 
two forms are different.

     The first one, which you dislike, is appropriate in the general 
situation of an alternative in which the two cases have the same order 
of probability to happen. The form you propose is more appropriate to 
catch exceptions while leaving straightforward the "normal" execution 
thread.

     Although the C language is very loose about semantics, leaving it 
to the appreciation of the programmer, a well written program is one in 
which the author takes care of semantics. Some programmers find it 
stylish to minimize the character count of expressions and the size of 
the source file. My opinion is that size doesn't matter; the important 
is to favour the readibility, which includes making as clear as possible 
what the intent of the author is. Often, this is better achieved by the 
way the instructions are written than by adding comments.

     Thanks.

                     Didier