http://d.puremagic.com/issues/show_bug.cgi?id=7133

           Summary: [tdpl] There should be no empty statement
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Mac OS X
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: andrei@metalanguage.com


--- Comment #0 from Andrei Alexandrescu <andrei@metalanguage.com> 2011-12-18 18:17:17 PST ---
The statement ";" should not exist. It is never needed, never useful, and in most cases the compiler requires it to be replaced with '{}'.

Walter and I agreed on all of the above so ";" is not present in TDPL. It should be slowly deprecated and ultimately removed from D. It is just junk in the trunk.

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Jonathan M Davis <jmdavisProg@gmx.com> changed:

           What    |Removed                     |Added
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                 CC|                            |jmdavisProg@gmx.com


--- Comment #1 from Jonathan M Davis <jmdavisProg@gmx.com> 2011-12-18 18:25:35 PST ---
The one case that I'm aware of where some have argued for its value is labels. e.g.

LABEL:;

Since labels require a statement, ; makes it so that you can you can use a label without really having a statement. I'm not sure that that merits keeping it however, since in every other use case that I can think of, it has no value.

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--- Comment #3 from Jonathan M Davis <jmdavisProg@gmx.com> 2011-12-18 18:28:18 PST ---
I didn't think that that worked, since {} isn't a statement (at least, as far as I know, it isn't), but if it works, it's certainly better.

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--- Comment #4 from Andrei Alexandrescu <andrei@metalanguage.com> 2011-12-18 20:06:48 PST ---
{} is the empty statement in D.

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--- Comment #5 from Jonathan M Davis <jmdavisProg@gmx.com> 2011-12-18 20:11:40 PST ---
Is that different from C++? I thought that {} was just an empty scope without any statements in it at all in both C/C++ and D.

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Stewart Gordon <smjg@iname.com> changed:

           What    |Removed                     |Added
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                 CC|                            |smjg@iname.com
           Platform|Other                       |All
         OS/Version|Mac OS X                    |All
           Severity|normal                      |enhancement


--- Comment #6 from Stewart Gordon <smjg@iname.com> 2011-12-19 05:07:21 PST ---
(In reply to comment #5)
> Is that different from C++? I thought that {} was just an empty scope without any statements in it at all in both C/C++ and D.

It is, but in 100% of cases the compiler can optimise away that empty scope and so it's equivalent to an empty statement.

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jakobovrum@gmail.com changed:

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                 CC|                            |jakobovrum@gmail.com


--- Comment #7 from jakobovrum@gmail.com 2011-12-19 05:16:39 PST ---
(In reply to comment #3)
> I didn't think that that worked, since {} isn't a statement (at least, as far as I know, it isn't), but if it works, it's certainly better.

It is indeed a statement, it's called a block statement, also in D: http://dlang.org/statement.html#BlockStatement

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timon.gehr@gmx.ch changed:

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--- Comment #8 from timon.gehr@gmx.ch 2011-12-19 06:23:35 PST ---
(In reply to comment #0)
> The statement ";" should not exist. It is never needed, never useful, and in most cases the compiler requires it to be replaced with '{}'.
> 
> Walter and I agreed on all of the above so ";" is not present in TDPL. It should be slowly deprecated and ultimately removed from D. It is just junk in the trunk.

I think it is useful. This looks odd:

    int    i = 2;
    for({} i<2; i++){}

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--- Comment #9 from Stewart Gordon <smjg@iname.com> 2011-12-19 07:17:31 PST ---
(In reply to comment #8)
> I think it is useful. This looks odd:
> 
>     int    i = 2;
>     for({} i<2; i++){}

The ; you're replacing there isn't a statement - it's something explicitly allowed by the ForStatement syntax.

ForStatement:
    for (Initialize Testopt ; Incrementopt) ScopeStatement

Initialize:
    ;
    NoScopeNonEmptyStatement

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Don <clugdbug@yahoo.com.au> changed:

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                 CC|                            |clugdbug@yahoo.com.au


--- Comment #10 from Don <clugdbug@yahoo.com.au> 2011-12-24 04:41:20 PST ---
(In reply to comment #2)
> LABEL: {}
> 
> is as good and marginally nicer.
Bear in mind that it only ever happens at the end of a block, so the next character is always a }.

The existing label syntax needs to be retained for asm statements, though, since they don't have {}.

asm {
  jmp done;
done:
     ;
}
which is already ugly, and will look really silly when nude ; statements are
gone. I wish we could get rid of that silly semicolon.
In fact the oddity is that labels are considered to be statements, yet they
don't end with a semicolon.

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