To play along....

Go does have build tags, so one could have 2 files for the assert function, each with opposite build tag logic. It does allow for an effective NOP (it would be a stub function and I believe the compiler would eliminate that).

I tested this and it does indeed eliminate that code.

I'm wondering if it inlines it (and thus eliminates it).

But this would come with a performance penalty: it makes the function you assert() in no longer a leaf function (it calls assert()) and AFAIK, Go only inlines leaf functions. (So, any function in which you call assert() is no longer eligible for inlining.)

chrchang523 is correct. In my test the caller function can still get inlined.

deathanatos: Go 1.12 can inline non-leaf functions, and I’d be surprised if it still fails to do the right thing here.

It would still evaluate the condition in both cases, unless it can guarantee that the condition is a pure function with no observable side effects.