Can anyone tell me why this doesn't compile? Dmd 2.062 says that it cannot deduce the template function from arguments types.

import std.stdio;

void main()
{
	test!(dchar, int)('b', 6, 'a', 54);
}

template test(Types...)
{
    void test(T...)(const Types v, const T values...)
    {
        writefln("%s,%s", v);
        foreach (s; values)
            writefln("%s,%s", s);
    }
}

Thank you,
Jonathan

On Wed, 22 May 2013 21:16:44 -0400, Jonathan Crapuchettes <jcrapuchettes@gmail.com> wrote:

> Can anyone tell me why this doesn't compile? Dmd 2.062 says that it
> cannot deduce the template function from arguments types.
>
> import std.stdio;
>
> void main()
> {
> 	test!(dchar, int)('b', 6, 'a', 54);
> }
>
> template test(Types...)
> {
>     void test(T...)(const Types v, const T values...)

Do you need that last elipsis?  I thought you didn't, but not sure.

-Steve

On Wednesday, May 22, 2013 21:31:53 Steven Schveighoffer wrote:
> On Wed, 22 May 2013 21:16:44 -0400, Jonathan Crapuchettes
> 
> <jcrapuchettes@gmail.com> wrote:
> > Can anyone tell me why this doesn't compile? Dmd 2.062 says that it cannot deduce the template function from arguments types.
> > 
> > import std.stdio;
> > 
> > void main()
> > {
> > 
> > test!(dchar, int)('b', 6, 'a', 54);
> > 
> > }
> > 
> > template test(Types...)
> > {
> > 
> > void test(T...)(const Types v, const T values...)
> 
> Do you need that last elipsis? I thought you didn't, but not sure.

You don't, and I'm surprised that it compiles, since I don't think that the elipsis is actually legal there. AFAIK, the only time that an elipsis is legal in the function arguments is with array variadics; e.g.

auto foo(int[] bar...) {...}

- Jonathan M Davis

On Wed, 22 May 2013 23:28:21 -0400, Jonathan M Davis wrote:

> On Wednesday, May 22, 2013 21:31:53 Steven Schveighoffer wrote:
>> On Wed, 22 May 2013 21:16:44 -0400, Jonathan Crapuchettes
>> 
>> <jcrapuchettes@gmail.com> wrote:
>> > Can anyone tell me why this doesn't compile? Dmd 2.062 says that it cannot deduce the template function from arguments types.
>> > 
>> > import std.stdio;
>> > 
>> > void main()
>> > {
>> > 
>> > test!(dchar, int)('b', 6, 'a', 54);
>> > 
>> > }
>> > 
>> > template test(Types...)
>> > {
>> > 
>> > void test(T...)(const Types v, const T values...)
>> 
>> Do you need that last elipsis? I thought you didn't, but not sure.
> 
> You don't, and I'm surprised that it compiles, since I don't think that the elipsis is actually legal there. AFAIK, the only time that an elipsis is legal in the function arguments is with array variadics; e.g.
> 
> auto foo(int[] bar...) {...}
> 
> - Jonathan M Davis

The last ellipsis was a remnant of testing. Thank you for pointing that out. Removing it still doesn't help the compiler deduce the argument types. It appears that the issue has to do with the usage of the "Types" TypeTuple. If the

const Types v

is swapped out for

const dchar v1, const int v2

the code compiles just fine. This makes me wonder if dmd is not interpreting the Types TypeTuple correctly in the inner-function.

Jonathan

On 05/23/2013 07:21 PM, Jonathan Crapuchettes wrote:
> On Wed, 22 May 2013 23:28:21 -0400, Jonathan M Davis wrote:
>
>> On Wednesday, May 22, 2013 21:31:53 Steven Schveighoffer wrote:
>>> On Wed, 22 May 2013 21:16:44 -0400, Jonathan Crapuchettes
>>>
>>> <jcrapuchettes@gmail.com> wrote:
>>>> Can anyone tell me why this doesn't compile? Dmd 2.062 says that it
>>>> cannot deduce the template function from arguments types.
>>>>
>>>> import std.stdio;
>>>>
>>>> void main()
>>>> {
>>>>
>>>> test!(dchar, int)('b', 6, 'a', 54);
>>>>
>>>> }
>>>>
>>>> template test(Types...)
>>>> {
>>>>
>>>> void test(T...)(const Types v, const T values...)
>>>
>>> Do you need that last elipsis? I thought you didn't, but not sure.
>>
>> You don't, and I'm surprised that it compiles, since I don't think that
>> the elipsis is actually legal there. AFAIK, the only time that an
>> elipsis is legal in the function arguments is with array variadics; e.g.
>>
>> auto foo(int[] bar...) {...}
>>
>> - Jonathan M Davis
>
> The last ellipsis was a remnant of testing. Thank you for pointing that
> out. Removing it still doesn't help the compiler deduce the argument
> types. It appears that the issue has to do with the usage of the "Types"
> TypeTuple. If the
>
> const Types v
>
> is swapped out for
>
> const dchar v1, const int v2
>
> the code compiles just fine. This makes me wonder if dmd is not
> interpreting the Types TypeTuple correctly in the inner-function.
>
> Jonathan
>

Yes, this is indeed a compiler bug.

http://d.puremagic.com/issues/

Thank you for the help. Bug report at http://d.puremagic.com/issues/ show_bug.cgi?id=10156