Presence of struct destructor makes lvalue?

[kenji hara]

This is definitely a bug.

http://d.puremagic.com/issues/show_bug.cgi?id=9907

Kenji Hara

2013/4/9 Ali Çehreli <acehreli at yahoo.com>

> On 04/08/2013 12:24 PM, Maxim Fomin wrote:
>
> > DMD often inserts temporaries when they are unexpected (or users do not
> > expect when they should).
> >
> > D main function in destructor case is rewritten as:
> >
> >     S s = S(1);
> >     s.opAssign(foo(2));
> >     s.opAssign((S __sl1779 = S(3); , __sl1779))
>
> Have you manually typed those lines or is there a tool that outputs that
> "preprocessor" ;) output?
>
>
> >
> > Hence, ref version is taken in account because '__sl1779' is a good
> lvalue.
> >
> > Troubles seems to come from
> > https://github.com/D-**Programming-Language/dmd/blob/**
> master/src/expression.c#L4203<https://github.com/D-Programming-Language/dmd/blob/master/src/expression.c#L4203>
> >
>
> Thank you very much for finding the related line. :) Quoting:
>
> Expression *StructLiteralExp::semantic(**Scope *sc)
> { Expression *e;
>
> // ...
>
>     /* If struct requires a destructor, rewrite as:
>      * (S tmp = S()),tmp
>      * so that the destructor can be hung on tmp.
>      */
>     if (sd->dtor && sc->func)
>     {
>         Identifier *idtmp = Lexer::uniqueId("__sl");
>         VarDeclaration *tmp = new VarDeclaration(loc, type, idtmp, new
> ExpInitializer(0, this));
>         tmp->storage_class |= STCctfe;
>         Expression *ae = new DeclarationExp(loc, tmp);
>         Expression *e = new CommaExp(loc, ae, new VarExp(loc, tmp));
>         e = e->semantic(sc);
>         return e;
>     }
>
>     return this;
> }
>
> Is it because destructors cannot be "hung" on literals?
>
> It is inconsistent that function-returned rvalues do not behave the same
> as literal-rvalues.
>
> Ali
>
>
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