Hi folks,

I've been working on resolving memory leaks detected by ASan in our unit tests and identified a significant issue with our current approach to test instance generation.

Current Problem: Our generate_test_instance() function returns std::list<T*> for types that support encoding/decoding. While this works functionally, it creates memory management issues because:

- The lifecycle of generated test instances is inconsistently managed
- Callers don't always properly clean up allocated memory
- This results in numerous ASan memory leak reports in both unit tests and ceph-dencoder

Proposed Solution: I propose we modify the function to return std::list<std::shared_ptr<T>> instead of raw pointers. This change would:

- Automatically handle memory cleanup through RAII
- Work correctly with types that lack move constructors
- Eliminate the memory leaks we're currently seeing when testing with ASan enabled
- Require updates to calling code, but provide cleaner memory semantics

I considered adding suppression rules for the affected tests and ceph-dencoder, but that would only mask the underlying issue rather than properly addressing the memory management problem.

Next Steps:
If this approach sounds reasonable, I can prepare a patch that implements this change along with the necessary caller updates.

What are your thoughts on this approach? Are there any concerns or alternative solutions you'd like to consider?

Regards
Kefu Chai