``` typedef a = b; typedef b = a; ``` currently hangs the interpreter until it has a stack overflow. Ideally it should be detected, and give a nicer error message.
Other types too: enums, arrays, structs, etc. (I don't know how they could be circular, but we should prove that it isn't possible using any type)
*** Bug 189024 has been marked as a duplicate of this bug. ***
Migrated to https://github.com/gpuweb/WHLSL/issues/116