Bug 3237 – Access Violation during reference counting

RcName is a struct that does reference counting. When I store an instance of RcName in an object, everything seems to go fine, except that I get an access violation during the final destruction.

Created attachment 439 test case for access violatin while reference counting

compile with -gc and run under windbg, the windows debugger. Shows that it crashes because _cnt is null in the first line of release().

Created attachment 440 simplified case with a write in the destructor of Counter

I simplified the example. It turns out that the destructor of a class object Counter is called. I have no idea what mechanism may call the destructor other than GC. A new file attached.

The cause of the crash is there is a dependency in the code on the order in which the gc runs the destructors on collected objects. Dependency on this order is not valid D code. Generally, one cannot refer to other objects on the GC heap when inside a destructor for a GC object.