Why do struct literals count as lvalues?

[Timon Gehr]

On 08/19/2011 03:46 PM, kennytm wrote:
> Timon Gehr<timon.gehr at gmx.ch>  wrote:
>
>> auto ref currently treats struct literals as lvalues too. (therefore, as
>> ref). And passing by value would be considerably less efficient for large structs.
>>
>> As I understand it, the only issue with allowing literals and function
>> results as lvalues is that generic code cannot detect if it is working
>> with a temporary or not. I don't know if this would be useful in D though.
>>
>> each code segment of the form:
>>
>> void foo(ref S);
>> ...
>> foo(S(...));
>>
>> is equivalent to one explicitly declaring the temporary:
>>
>> {auto __temp=S(...); foo(__temp);}
>>
>> The difference is that the first is more pleasant to write. If
>> temporaries would become rvalues everyone would always have to write the
>> second form manually. So imho it is just a syntax sugar issue.
>>
>> I'd actually argue that ref-passing should work for arbitrary function results too.
>
> Here I propose that we go a step further and abolish the notion of rvalue
> and lvalue entirely, and let the compiler insert necessary temporary
> variable when needed, so that we can finally write things like
>
>      uint w;
>      memcpy(w,&5.0f, w.sizeof);
>      13u = w;
>
> </joking>

And then of course you could do:

5=6;
assert(5==6);

It hasn't been working since the good ol' days of fortran =(.