Destructors are inherently difficult to design and I'm well aware they are currently **unusable**. :)
There are mostly 2 different ways to design them: C++ style which assumes the compiler cannot do any lifetime analysis but then allows for certain assignment optimizations in the spec (and more recently it requires them iirc) and Rust style which bases it on top of its superb lifetime analysis. The beginnings of a lifetime analysis for Nim is in `compiler/writetracking.nim`. This computes "deep immutability" and whether the memory coming from a parameter is escaping. Without more source annotations. So ... first we need to get this into production ready shape before tackling destructors...
