Function prototype + definition in the same file

[Manu]

On 26 September 2012 13:09, deadalnix <deadalnix at gmail.com> wrote:

> Le 26/09/2012 10:14, Manu a écrit :
>
>> On 26 September 2012 02:35, Timon Gehr <timon.gehr at gmx.ch
>> <mailto:timon.gehr at gmx.ch>> wrote:
>>
>>     On 09/26/2012 01:29 AM, Timon Gehr wrote:
>>
>>         On 09/25/2012 01:53 PM, Manu wrote:
>>
>>             So I have this recurring pattern, it's really starting to
>>             annoy me.
>>             It stems from the fact that a function prototype and the
>>             definition can
>>             not appear in the same file in D (as it can in C/C++)
>>             Eg,
>>
>>             void func(int x); // <-- declaration of function, informs
>>             type and
>>             associated names, args, ...
>>
>>             //later
>>             void func(int x) // <-- may be generated with magic (and may
>>             use the
>>             prototype declaration for type information as declared by
>>             the prototype
>>             above)
>>             {
>>                 ... do stuff
>>             }
>>
>>             I really need this. Why is it illegal? Is there chance of
>>             having this
>>             supported? What are the problems?
>>             ...
>>
>>
>>         It is illegal because nobody has written code to support it. It
>>         should be possible to support it. I don't think there are any
>>         problems
>>         with the concept.
>>
>>
>>     (The implementation faces some challenges, the following is easy to
>>     get wrong:
>>
>>     module module_;
>>
>>     void foo();
>>
>>     alias foo alias1;
>>     static if(is(typeof(alias1))){
>>          void foo(){}
>>          alias foo alias2;
>>     }
>>
>>     static assert(__traits(isSame, alias1, alias2));
>>     static assert(__traits(allMembers, module_).length == 3); // 2
>>     alias, 1 function definition
>>     )
>>
>>
>> I'm not sure I understand the point being illustrated here. I don't see
>> how the aliases are relevant?
>>
>
> From a compiler perspective, the example above is hell. That was his point.
>
> In other terms, supporting such a feature add complexity to the compiler,
> and it should come with a sufficient benefice to make sense to implement.
>

I can't imagine why the example above is hell, but I know nothing about the
compiler.

I have no idea how the existing bug was implemented, but it needs to be
fixed one way or another.
It sounds fairly trivial to me to promote a prototype to a definition if a
definition is found later in the same module.
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