On Friday, 19 April 2013 at 19:06:39 UTC, Walter Bright wrote:
> On 4/19/2013 6:55 AM, deadalnix wrote:
>> As of for 2 I'd rather have a standard way to have attribute binding to the
>> return type or the declaration. This is a recurring problem, and auto is simply
>> one instance of it.
>
> I'm not understanding it being a recurring problem. There is a recurring misunderstanding that attributes are applying to a type when they are defined as applying to the declaration.
>

What is type of an impure function that return a pure, extern(C) function n D ?

On 04/19/2013 09:34 PM, deadalnix wrote:
> On Friday, 19 April 2013 at 19:06:39 UTC, Walter Bright wrote:
>> On 4/19/2013 6:55 AM, deadalnix wrote:
>>> As of for 2 I'd rather have a standard way to have attribute binding
>>> to the
>>> return type or the declaration. This is a recurring problem, and auto
>>> is simply
>>> one instance of it.
>>
>> I'm not understanding it being a recurring problem. There is a
>> recurring misunderstanding that attributes are applying to a type when
>> they are defined as applying to the declaration.
>>
>
> What is type of an impure function that return a pure, extern(C)
> function n D ?

Currently, it exists, yet cannot be named, and the formatted output of the compiler is wrong.

alias extern(C) int function()pure P;
P foo(){ return null; }

pragma(msg, typeof(&foo));

=> "extern (C) int function() pure function()"

On 4/19/2013 12:34 PM, deadalnix wrote:
> On Friday, 19 April 2013 at 19:06:39 UTC, Walter Bright wrote:
>> On 4/19/2013 6:55 AM, deadalnix wrote:
>>> As of for 2 I'd rather have a standard way to have attribute binding to the
>>> return type or the declaration. This is a recurring problem, and auto is simply
>>> one instance of it.
>>
>> I'm not understanding it being a recurring problem. There is a recurring
>> misunderstanding that attributes are applying to a type when they are defined
>> as applying to the declaration.
>>
>
> What is type of an impure function that return a pure, extern(C) function n D ?

A function foo:

extern(C) int function()pure foo() { return null; }

A type fp:

alias extern(C) int function()pure function() fp;

On Saturday, 20 April 2013 at 00:03:36 UTC, Walter Bright wrote:
> A function foo:
>
> extern(C) int function()pure foo() { return null; }
>

That is not it as foo is extern(C).

> A type fp:
>
> alias extern(C) int function()pure function() fp;

Same here.

In general we lack a mechanism to choose what an attribute bind to.

On Friday, 19 April 2013 at 22:16:43 UTC, Timon Gehr wrote:
> Currently, it exists, yet cannot be named, and the formatted output of the compiler is wrong.
>
> alias extern(C) int function()pure P;
> P foo(){ return null; }
>
> pragma(msg, typeof(&foo));
>
> => "extern (C) int function() pure function()"

Yes you have to use a alias to do this kind of thing. But some time, you can't alias (in case of inference for instance) and so can't choose what attribute bind to.

On 4/19/2013 11:08 PM, deadalnix wrote:
> On Saturday, 20 April 2013 at 00:03:36 UTC, Walter Bright wrote:
>> A function foo:
>>
>> extern(C) int function()pure foo() { return null; }
>>
>
> That is not it as foo is extern(C).

That is correct. I was thinking about the pure. The extern(C) can be done in a two step process, as Timon showed.


> In general we lack a mechanism to choose what an attribute bind to.

No, we don't. The attribute binds to the declaration.

BTW, in C++ also you gotta do the extern "C" as a two step process to attach it to a function type.

On 4/19/2013 11:12 PM, deadalnix wrote:
> But some time, you can't
> alias (in case of inference for instance) and so can't choose what attribute
> bind to.

Example, please.

On Saturday, 20 April 2013 at 06:24:36 UTC, Walter Bright wrote:
>> In general we lack a mechanism to choose what an attribute bind to.
>
> No, we don't. The attribute binds to the declaration.
>

In general we lack a mechanism to choose what direction we turn to.
No, we don't. We always turn to the right.

On Saturday, 20 April 2013 at 06:32:50 UTC, deadalnix wrote:
> On Saturday, 20 April 2013 at 06:24:36 UTC, Walter Bright wrote:
>>> In general we lack a mechanism to choose what an attribute bind to.
>>
>> No, we don't. The attribute binds to the declaration.
>>
>
> In general we lack a mechanism to choose what direction we turn to.
> No, we don't. We always turn to the right.

I am quite sure Walter has meant that linkage attribute was not supposed to be tied to a type by design. If you want to use it, you need a symbol (==declaration) and there can be only one at a time.

On Saturday, 20 April 2013 at 07:03:55 UTC, Dicebot wrote:
> On Saturday, 20 April 2013 at 06:32:50 UTC, deadalnix wrote:
>> On Saturday, 20 April 2013 at 06:24:36 UTC, Walter Bright wrote:
>>>> In general we lack a mechanism to choose what an attribute bind to.
>>>
>>> No, we don't. The attribute binds to the declaration.
>>>
>>
>> In general we lack a mechanism to choose what direction we turn to.
>> No, we don't. We always turn to the right.
>
> I am quite sure Walter has meant that linkage attribute was not supposed to be tied to a type by design. If you want to use it, you need a symbol (==declaration) and there can be only one at a time.

You don't need a symbol. They also control the ABI, and this isn't always related to a specific symbol.