This code causes DMD 0.97 to segfault:

   struct A (T)
   {
      mixin B! (T, A! (T));
   }

   A! (int) x;

Its output before crashing is:

   parse     foo
   semantic  foo
   foo.d(3): template instance A!(int) A is not a template declaration
   foo.d(3):[crash here]