I suppose you can even ship the test/logging allocator with your production build, and instruct your users to run your program with some option / env var set to

I suppose you can even ship the test/logging allocator with your production build, and instruct your users to run your program with some option / env var set to activate it. This would allow to repro a problem right where it happens, hopefully with some info helpful for debugging attached. Not a great approach for critical software, but may be much better than what C++ normally offers for e.g. game software, where the development speed definitely trumps correctness.