[asveikau]

> your assertion that Some compilers will set that for you in an optimized build strikes me as unlikely

Uhh, I didn't make it up. I remember now what I was thinking of: the defaults for Visual Studio (not the compiler, the IDE) are to have -DNDEBUG in release mode. So lots of Windows projects end up having it without the authors explicitly asking.

(I thought I also once used a machine, maybe some obscure Unix, where cc would add it if you specified -O. I don't remember the details of that, or if I might be confusing it with what VS did.)

FWIW I don't think it's weird that assert has this quirk, I think some people in this discussion just disagree about what an assert is. If you think of it as an extra debug check that might not be evaluated and should not have side effects, and are fine with that conceptually, no problems.