A bug quite hard to summarize understandably. The code may help:

--
module aliasesType;

alias int myAlias;
--
module definesType;
import aliasesType;
import usesType; // creates the import cycle

typedef myAlias myTypedef;
--
module usesType;
import definesType;

template T(x) {}

// just use T with myTypedef somehow, doesn't matter what this is
mixin T!(myTypedef);
--

Compiling the definesType module results in the error "definesType.d(5): Error: identifier 'myAlias' is not defined". Using the fully qualified name "aliasesType.myAlias" instead fixes this error.