> It's just that generational/incremental collection is hard to impossible without having support for write barriers/read barriers/snapshotting on the compiler or hardware side, which makes that a practical no-go for a language that was never designed to have GC support.

It was demonstrated in the mid 80s that the MMU could be used to implement the write barrier (when I saw that I knew lisp machines were a dead end, though I kept using them for as long as was feasible). You can use this and other compiler support to implement it in a language not designed for GC support, no problem.

The issue I think you meant is that you can’t have a transporting collector (which also compacts your working set, even allowing you to return memory to the system). A language like C++ doesn’t anticipate an object’s address ever changing, so that’s a no go.

I suppose you could write special shared_ptr / unique_ptr that supported address mutation but you’d need a compiler flag to check for an object’s address being taken… but to some degree the destructor paradigm renders a lot of this moot.