A few bugs connected to structs

[kenji hara]

The definition of postblit generates an non-templated built-in
opAssign implicitly.
And it conflicts with your templated opAssign.

It is already filed in bugzilla.

Issue 4424 - Copy constructor and templated opAssign cannot coexist
http://d.puremagic.com/issues/show_bug.cgi?id=4424

Kenji Hara

2012/1/12 Benjamin Thaut <code at benjamin-thaut.de>:
> Am 11.01.2012 20:05, schrieb Timon Gehr:
>>
>> On 01/11/2012 05:58 PM, Benjamin Thaut wrote:
>>
>>> 1. It's currently not possible to overload opAssign for structs with a
>>> template because opAssign(T)(T rh) if(is(T == typeof(this)))
>>>
>>> is not allowed (stated in the documentation). And templates can not
>>> overload non template functions (already a known bug).
>>>
>>> 2. It's not possible to use auto ref with opAssign because
>>> opAssign(T)(auto ref T rh) if(is(T == typeof(this))) is not allowed
>>> (partly the same issue as 1).
>>>
>>> Why is this not allowed? (The documentation does not state any reason)
>>
>>
>> There is no reason, and DMD accepts it. Maybe file a bug against the
>> documentation?
>>
>> struct S{
>> auto opAssign(T)(auto ref T rhs) if(is(T==typeof(this))){return rhs;}
>> }
>>
>> void main(){
>> S a, b;
>> a=b;
>> }
>>
>>>
>>> 3. Calling a method that is overloaded with shared / const / immutable
>>> from within a function has to be done with this.method()
>>> otherwise the compiler complains about ambugiosity. Is method() not the
>>> same as this.method() ??
>>>
>>
>> Yes it is. Has this been filed already?
>
>
> I have a repro case for issue 1+2. It seems to be connected to the bostplit
> constructor. Does the postblit constructor infer with opAssign overloading?
>
> struct Array(T){
>  T[] data;
>
>  alias typeof(this) this_t;
>
>  this(this)
>  {
>    data = data.dup;
>  }
>
>  this_t opAssign(U)(auto ref U rh) if(is(U == this_t))
>  {
>    data = rh.data;
>    return rh;
>  }
>
>  auto opAssign(U)(U rh) if(is(U == T[]))
>  {
>    data = rh;
>    return rh;
>  }
> }
>
> int main(string[] argv)
> {
>   Array!int bla;
>   bla = [1,2,3];
>   return 0;
> }
>
> main.d(15): Error: function main.Array!(int).Array.opAssign conflicts with
> template main.Array!(int).Array.opAssign(U) if (is(U == this_t)) at
> main.d(25)
> main.d(40): Error: template instance main.Array!(int) error instantiating
>
>
> --
> Kind Regards
> Benjamin Thaut