This combination would be an interesting point in the design space:
• Manual memory management
• A hardened allocator that unquarantines memory only after a tracing GC has run to make sure no dangling pointers
• Type-After-Type for pointers to stack.
I think this is safe.
Conversation
Replying to
Android has a tracing GC integrated with the system malloc implementations for memory leak detection. Same approach could theoretically be used for this (android.googlesource.com/platform/syste). It would likely be a major latency issue because it can't really use a smart GC implementation.