Internal Error

[Neil Vice]

I've encountered the following error in DMD 2.012:

    Internal error: ..\ztc\cod1.c 1662

I would submit a bug report except that I can't seem to determine a simple 
case that produces the bug, so I guess I'm looking for some assistance in 
narrowing down the problem.

I have two structs, one representing a time-stamp and another representing a 
time-period. They both implement opSub. Nested within a method in a class 
within a class in a seperate package I have some code along the lines of:

    auto result = a - (b - c);

where a is a TimePeriod and b & c are TimeStamps.

If I replace this line with:

    auto _result = b - c;
    auto result = a - _result;

the Internal error goes away.

I have attempted to construct a simple case with two similar structs with 
opSub methods and a main() containing the problem expression, however I 
cannot reproduce the error.

Any suggestions on where to go from here?