• Eric (19/19) May 12 2016 is(T : A!T) tells if T can automatically be converted to A!T. The
• Daniel N (7/14) May 12 2016 Yes, it's a bug. Please file an issue.
• Eric (2/8) May 12 2016 Bug report filed, and thanks for the workaround.

Eric <eric x.com> writes:

is(T : A!T) tells if T can automatically be converted to A!T.  The
last line below is doing just that, yet the template constraint 
does not work.

class A(T) if (is(T : A!T))
{
}

// if (is(T : A!T)) gives this error:
// Error: template instance x.A!(B) does not match
//        template declaration A(T) if (is(T : A!T))
//        while looking for match for A!(B)

class B : A!(B)
{
}

void main(string[] args)
{
     B b = new B();
     A!B a = b; // compiles fine
}

-Eric

Daniel N <ufo orbiting.us> writes:

On Thursday, 12 May 2016 at 15:33:24 UTC, Eric wrote:
 is(T : A!T) tells if T can automatically be converted to A!T.  
 The
 last line below is doing just that, yet the template constraint 
 does not work.

 class A(T) if (is(T : A!T))
 {
 }

Yes, it's a bug. Please file an issue.

Meanwhile try this workaround:
class A(T)
{
   static assert(is(T : A!T), "...");
}

Eric <eric x.com> writes:

 Yes, it's a bug. Please file an issue.

 Meanwhile try this workaround:
 class A(T)
 {
   static assert(is(T : A!T), "...");
 }

Bug report filed, and thanks for the workaround.

-Eric