Template specification conflict

[simendsjo]

On 02.08.2011 15:25, Dmitry Olshansky wrote:
> On 02.08.2011 16:30, simendsjo wrote:
>> On 02.08.2011 14:22, Dmitry Olshansky wrote:
>>> On 02.08.2011 16:18, simendsjo wrote:
>>>> On 02.08.2011 14:13, Dmitry Olshansky wrote:
>>>>> On 02.08.2011 16:06, simendsjo wrote:
>>>>>> On 02.08.2011 13:55, Dmitry Olshansky wrote:
>>>>>>> On 02.08.2011 15:06, simendsjo wrote:
>>>>>>>> The following program gives me
>>>>>>>> "Error: template t.S.__ctor(C) if(isSomeChar!(C)) conflicts with
>>>>>>>> constructor t.S.this at t.d(4)"
>>>>>>>>
>>>>>>>> Is this because char etc can be converted to uint? Shouldn't the
>>>>>>>> template specification make this unambiguous?
>>>>>>>>
>>>>>>>> import std.traits;
>>>>>>>>
>>>>>>>> struct S {
>>>>>>>> this(uint i) {}
>>>>>>>> this(C)(C c) if(isSomeChar!C) {}
>>>>>>>> }
>>>>>>>>
>>>>>>>> void main() {}
>>>>>>>
>>>>>>> struct S {
>>>>>>> this()(uint i) {}
>>>>>>> this(C)(C c) if(isSomeChar!C) {}
>>>>>>> }
>>>>>>>
>>>>>>> should do it, though it (and workaround) looks like a bug to me.
>>>>>>>
>>>>>>
>>>>>> With the empty templated this, I get other errors though:
>>>>>> "t.d(5): Error: constructor t.S.this conflicts with template
>>>>>> t.S.__ctor() at t.d(4)"
>>>>>>
>>>>>> struct S {
>>>>>> this()(int a) {} // 4
>>>>>> this(int a, int b) {} // 5
>>>>>> }
>>>>>>
>>>>> Same logic here once you have template constructor, all others need to
>>>>> be template, empty spec is a trick to get anything to be a
>>>>> template. And
>>>>> in this example you really do not need empty spec () in 4.
>>>>>
>>>>
>>>> So my first example is a bug, and the second is a wrong error message?
>>>> Wondering what I should post in a potential bug report, and if it's
>>>> one or two bugs.
>>> I think there is only one bug: template constructor (and functions IIRC)
>>> can't be overloaded with non-template.
>>> Both your examples show this bug, since this()(int a){} and this(C)(C c)
>>> if(isSomeChar!C) {} are template constructors, while others are not.
>>> I think the bug was there for quite some time and likely to be filed
>>> already, so check Bugzilla first.
>>>
>>
>> While changing ctors to templates, I came across another issue (bug?)
>> regarding assignment to immutable (and probably const) members from
>> templated ctors:
>> Error: can only initialize const member v inside constructor
>> Error: template instance t.S2.__ctor!() error instantiating
>>
>> struct S {
>> immutable int v;
>> this(int v) {
>> this.v = v;
>> }
>> }
>>
>> struct S2 {
>> immutable int v;
>> this()(int v) {
>> this.v = v;
>> }
>> }
>>
>> void main() {
>> auto s = S(1); // ok
>> auto s2 = S2(1); // fails
>> }
>>
>
> Most definitely a bug, you seem to hit a lot of 'em recently :)
>

http://d.puremagic.com/issues/show_bug.cgi?id=6427