Tested with DMD 2.053.
Took me some time to reduce this:

A.d:
import B;
void main(){foo();}

B.d
int bar(){switch(0){};} // any switch statement that does not compile will do.
auto foo(){static if(__traits(compiles,{enum x=bar();})){}}


This code provokes an internal compiler error:
$ dmd A B
dmd: statement.c:2758: virtual Statement* SwitchStatement::semantic(Scope*): Assertion `!cases' failed.
Aborted