assert() is meant to be compiled away if NDEBUG is defined, otherwise it shouldn't be called assert(). Given that assert() may be compiled away, it makes sense not to give it anything that has side effects.
Abseil has the convention where instead of assert(), users call "CHECK" for checks that are guaranteed to happen at run time, or "DCHECK" for checks that will be compiled away when NDEBUG is defined.
https://github.com/abseil/abseil-cpp/blob/0093ac6cac892086a6...
https://github.com/abseil/abseil-cpp/blob/0093ac6cac892086a6...
If your assert compiles down to `if (condition) {}` in production then the compiler will optimize away the condition while keeping any side effects.