mixin template M(T)
{
}
struct S
{
mixin M!((typeof(this)) => 0);
mixin M!(() => undefined);
}
With v2.066.0-b6 running on Windows this leads to:
main.d(8): Error: undefined identifier undefined
Unhandled exception at 0x00439BF1 in dmd.exe: 0xC0000005: Access violation reading location 0x00000029.
Removing one of the mixins or replacing "undefined" with a literal works.