It's not possible as long as your language has: - non-discriminated unions mixing pointers and non-pointers - linking with C or other languages (as you can't

It's not possible as long as your language has: - non-discriminated unions mixing pointers and non-pointers - linking with C or other languages (as you can't scan their stack frames precisely) - void*, memcpy, or other ways to move around memory which might have pointers. A language without all of the above would be of limited utility. However, it's possible to dramatically improve the situation using: - precise heap scanning - by knowing the type of each object allocated; - precise stack scanning - by knowing the stack layout of all functions at all points throughout their execution; - GC hooks for user-defined union types.