The debug info for a nested function has an entry for a "this" variable which points to the variables in the parent function that the nested function can use. The type of that variable is void*. If it were a kind of struct, then we could see those dependent variables. This is particularly useful for closures where the user can't look at the enclosing function's frame directly.
Is this an enhancement request?
I guess it would be an enhancement. I updated the bug.
added struct debug info to closure pointers in dmd 2.084