digitalmars.D.bugs - Bug? Else clause in version statement

Andy Friesen <andy ikagames.com> Jul 20 2004

Sean Kelly <sean f4.ca> Jul 20 2004
Cabal <cabalN05P4M myrealbox.com> Jul 21 2004

"Carlos Santander B." <carlos8294 msn.com> Jul 21 2004

Cabal <cabalN05P4M myrealbox.com> Jul 21 2004

Stewart Gordon <smjg_1998 yahoo.com> Jul 21 2004

J C Calvarese <jcc7 cox.net> Jul 21 2004

Andy Friesen <andy ikagames.com> Jul 21 2004

Derek Parnell <derek psych.ward> Jul 21 2004

Regan Heath <regan netwin.co.nz> Jul 21 2004

Derek Parnell <derek psych.ward> Jul 21 2004

Andy Friesen <andy ikagames.com> writes:

This bug could exist in the compiler, the spec, or my brain, depending 
on how you look at it. :)

Should this be legal?

     int main() {
         if (true) {
             printf("tautology is neat");
         }
         version (None) {
             else { // line 6
                 printf("But paradox makes for a better screenplay");
             }
         }
         return 0; // line 10
     }

The error is

     test.d(6): found 'else' instead of statement
     test.d(10): Declaration expected, not 'return'

     test.d(11): unrecognized declaration

  -- andy

Jul 20 2004

Sean Kelly <sean f4.ca> writes:

In article <cdjsdn$1r1o$1 digitaldaemon.com>, Andy Friesen says...
This bug could exist in the compiler, the spec, or my brain, depending 
on how you look at it. :)

Should this be legal?

     int main() {
         if (true) {
             printf("tautology is neat");
         }
         version (None) {
             else { // line 6
                 printf("But paradox makes for a better screenplay");
             }
         }
         return 0; // line 10
     }


I would say no.  Whether or not "None" is defined, the code is not syntactically
correct.  This is a good example of why language features such as version are
much better than preprocessor macros :)

The error is

     test.d(6): found 'else' instead of statement
     test.d(10): Declaration expected, not 'return'
     test.d(11): unrecognized declaration


Seems reasonable.  The misplaced "else" clause is confusing the compiler.  I'd
ignore all errors after the first.


Sean

Jul 20 2004

Cabal <cabalN05P4M myrealbox.com> writes:

'else' is also allowed in the context of 'version'.

  version(Win32) {
    // Windows code
  }
  else {
    // code for real OS's
  }


Andy Friesen wrote:

 This bug could exist in the compiler, the spec, or my brain, depending
 on how you look at it. :)
 
 Should this be legal?
 
      int main() {
          if (true) {
              printf("tautology is neat");
          }
          version (None) {
              else { // line 6
                  printf("But paradox makes for a better screenplay");
              }
          }
          return 0; // line 10
      }
 
 The error is
 
      test.d(6): found 'else' instead of statement
      test.d(10): Declaration expected, not 'return'
 
      test.d(11): unrecognized declaration
 
   -- andy

Jul 21 2004

"Carlos Santander B." <carlos8294 msn.com> writes:

"Cabal" <cabalN05P4M myrealbox.com> escribi� en el mensaje
news:cdl5hf$2cl3$1 digitaldaemon.com
| 'else' is also allowed in the context of 'version'.
|
|   version(Win32) {
|     // Windows code
|   }
|   else {
|     // code for real OS's
|   }
|

I think that's completely different to what Andy wanted to do.



|
| Andy Friesen wrote:
|
|| This bug could exist in the compiler, the spec, or my brain, depending
|| on how you look at it. :)
||
|| Should this be legal?
||
||      int main() {
||          if (true) {
||              printf("tautology is neat");
||          }
||          version (None) {
||              else { // line 6
||                  printf("But paradox makes for a better screenplay");
||              }
||          }
||          return 0; // line 10
||      }
||
|| The error is
||
||      test.d(6): found 'else' instead of statement
||      test.d(10): Declaration expected, not 'return'
||
||      test.d(11): unrecognized declaration
||
||   -- andy


-----------------------
Carlos Santander Bernal

Jul 21 2004

Cabal <cabalN05P4M myrealbox.com> writes:

Carlos Santander B. wrote:

 think that's completely different to what Andy wanted



I wasn't trying to second guess him. I was just pointing out why what he had
done wasn't going to work...

Jul 21 2004

Stewart Gordon <smjg_1998 yahoo.com> writes:

Andy Friesen wrote:

<snip>
 Should this be legal?
 
     int main() {
         if (true) {
             printf("tautology is neat");
         }
         version (None) {
             else { // line 6
                 printf("But paradox makes for a better screenplay");
             }
         }
         return 0; // line 10
     }



No.  But this should:

     int main() {
         if (true) {
             printf("tautology is neat");
         }
         else version (None) {
             printf("But paradox makes for a better screenplay");
         }
         return 0;
     }

I've noticed in the spec that a literal if(0) is supposed to lead to 
'conditional' _compilation_, but is it the same with if(true)?

Stewart.

-- 
My e-mail is valid but not my primary mailbox, aside from its being the 
unfortunate victim of intensive mail-bombing at the moment.  Please keep 
replies on the 'group where everyone may benefit.

Jul 21 2004

J C Calvarese <jcc7 cox.net> writes:

In article <cdlfl4$2hu7$1 digitaldaemon.com>, Stewart Gordon says...
Andy Friesen wrote:

<snip>
 Should this be legal?
 
     int main() {
         if (true) {
             printf("tautology is neat");
         }
         version (None) {
             else { // line 6
                 printf("But paradox makes for a better screenplay");
             }
         }
         return 0; // line 10
     }



No.  But this should:

     int main() {
         if (true) {
             printf("tautology is neat");
         }
         else version (None) {
             printf("But paradox makes for a better screenplay");
         }
         return 0;
     }


I don't know if the other versions should work, but this version does:

#int main() {
#    if (true) {
#        printf("tautology is neat");
#    }
#    else {
#        version (None) {
#            printf("But paradox makes for a better screenplay");
#        }    
#    }
#    return 0;
#}


Hope that helps some.

I've noticed in the spec that a literal if(0) is supposed to lead to 
'conditional' _compilation_, but is it the same with if(true)?

Stewart.

-- 
My e-mail is valid but not my primary mailbox, aside from its being the 
unfortunate victim of intensive mail-bombing at the moment.  Please keep 
replies on the 'group where everyone may benefit.


jcc7

Jul 21 2004

Andy Friesen <andy ikagames.com> writes:

J C Calvarese wrote:

 I don't know if the other versions should work, but this version does:
 
 #int main() {
 #    if (true) {
 #        printf("tautology is neat");
 #    }
 #    else {
 #        version (None) {
 #            printf("But paradox makes for a better screenplay");
 #        }    
 #    }
 #    return 0;
 #}
 
 
 Hope that helps some.


Sort of, but not really.  I came across the 'bug' as a result of a 
little source code preprocessing app.  (converting DMD to D)

Apparently, DMD sets higher standards than the ones it follows. ;)

  -- andy

Jul 21 2004

Derek Parnell <derek psych.ward> writes:

On Tue, 20 Jul 2004 12:43:48 -0700, Andy Friesen wrote:

 This bug could exist in the compiler, the spec, or my brain, depending 
 on how you look at it. :)
 
 Should this be legal?
 
      int main() {
          if (true) {
              printf("tautology is neat");
          }
          version (None) {
              else { // line 6
                  printf("But paradox makes for a better screenplay");
              }
          }
          return 0; // line 10
      }
 
 The error is
 
      test.d(6): found 'else' instead of statement
      test.d(10): Declaration expected, not 'return'
 
      test.d(11): unrecognized declaration
 
   -- andy


I suspect this is how it is supposed to be written ...
<code>

int main() {
    version (None) {
        if (true) {
            printf("tautology is neat");
        }
        else { // line 6
            printf("But paradox makes for a better screenplay");
        }
    }
    else
    {
        if (true) {
            printf("tautology is neat");
        };
    }
    return 0; // line 10
}

</code>
-- 
Derek
Melbourne, Australia
22/Jul/04 2:43:52 PM

Jul 21 2004

Regan Heath <regan netwin.co.nz> writes:

On Thu, 22 Jul 2004 14:44:32 +1000, Derek Parnell <derek psych.ward> wrote:
 On Tue, 20 Jul 2004 12:43:48 -0700, Andy Friesen wrote:

 This bug could exist in the compiler, the spec, or my brain, depending
 on how you look at it. :)

 Should this be legal?

      int main() {
          if (true) {
              printf("tautology is neat");
          }
          version (None) {
              else { // line 6
                  printf("But paradox makes for a better screenplay");
              }
          }
          return 0; // line 10
      }

 The error is

      test.d(6): found 'else' instead of statement
      test.d(10): Declaration expected, not 'return'

      test.d(11): unrecognized declaration

   -- andy


 I suspect this is how it is supposed to be written ..
 <code>

 int main() {
     version (None) {
         if (true) {
             printf("tautology is neat");
         }
         else { // line 6
             printf("But paradox makes for a better screenplay");
         }
     }
     else
     {
         if (true) {
             printf("tautology is neat");
         };
     }
     return 0; // line 10
 }

 </code>


Yeah.. but that is somewhat more verbose than the original.
Is this equivalent to the original?

void main() {
   if (true) {
     printf("tautology is neat");
   }
   else {
     version (None) {
       printf("But paradox makes for a better screenplay");
     }
   }
}

Regan.

-- 
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

Jul 21 2004

Derek Parnell <derek psych.ward> writes:

On Thu, 22 Jul 2004 17:12:02 +1200, Regan Heath wrote:

 On Thu, 22 Jul 2004 14:44:32 +1000, Derek Parnell <derek psych.ward> wrote:
 On Tue, 20 Jul 2004 12:43:48 -0700, Andy Friesen wrote:

 This bug could exist in the compiler, the spec, or my brain, depending
 on how you look at it. :)

 Should this be legal?

      int main() {
          if (true) {
              printf("tautology is neat");
          }
          version (None) {
              else { // line 6
                  printf("But paradox makes for a better screenplay");
              }
          }
          return 0; // line 10
      }

 The error is

      test.d(6): found 'else' instead of statement
      test.d(10): Declaration expected, not 'return'

      test.d(11): unrecognized declaration

   -- andy


 I suspect this is how it is supposed to be written ..
 <code>

 int main() {
     version (None) {
         if (true) {
             printf("tautology is neat");
         }
         else { // line 6
             printf("But paradox makes for a better screenplay");
         }
     }
     else
     {
         if (true) {
             printf("tautology is neat");
         };
     }
     return 0; // line 10
 }

 </code>


 Yeah.. but that is somewhat more verbose than the original.
 Is this equivalent to the original?
 
 void main() {
    if (true) {
      printf("tautology is neat");
    }
    else {
      version (None) {
        printf("But paradox makes for a better screenplay");
      }
    }
 }
 
 Regan.


Oh your code is much neater. I forgot that "else{}" is a useful construct. 
-- 
Derek
Melbourne, Australia
22/Jul/04 3:37:47 PM

Jul 21 2004

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digitalmars.D.bugs - Bug? Else clause in version statement