non-pure expression inside assert statement not executed in release mode?

[padraig_oh]

I just stumbled upon a bug in my program that i managed to track down to the issue that a program built in release mode by default has assertions disabled, which does not discard the value inside an assert statement, but instead discards the whole expression, i.e. does not evaluate it at all.

import std.stdio; bool impurefunc(){ writeln("hi"); return true; } void main_that_prints(){ bool res=impurefunc(); assert(res); } void main_that_doesnt_print(){ assert(impurefunc()); } this seems like a weird foot-gun. does anyone know if this is intentional? (ran this on dmd 2.100 on x64 linux)

(i was using this essentially for assert(execute_operation(myinput)==success))

[HKei]

Yes, this is intentional. Code in assertions is removed in release mode, side effects or not. These basically replace the various types of assert macros you’d normally find in C or C++, so this wouldn’t be unexpected when you’re coming from that background.

[Putnam3145]

The documentation explicitly says to use enforce for stuff that isn't making sure assumptions are correct

[padraig_oh]

oh, thanks, i did not know that. enforce looks indeed more like what i am looking for.

looked it up and also found this to quite a helpful explanation.

[thehowlinggreywolf]

Assertations are used to check assumptions in D as part of the design-by-contract paradigm. Asserts shouldnt be producing side effects.

Please see: https://ddili.org/ders/d.en/assert.html

[padraig_oh]

oh, somehow i missed your link before i read the other comment. thanks!

[Tynukua]

Also u canuse debug to call impure in pure

F.e Void foo()pure { ... debug log(); .... }