With https://github.com/dlang/phobos/pull/4826 I've added a small improvement to sort() and also a simple watermark-based way to avoid performance regressions: count the number of comparisons done on some predefined data patterns and make sure it stays at a specific watermark.

Whenever new changes are made, an assertion fails that either prompts the user to update the watermark (yay) or verify why the number of comparisons has increased. (There may be legitimate reasons for that.)

Currently we don't count swaps, but we should. Does anyone want to take up on that?


Andrei