Frankly, the problem is that (generally, across languages various compiler hints) @inline sometimes fails to inline. At this point I’ve given up on ever having an @inline that reliably inlines, and I would very happily settle for an @assert_inline that doesn’t change the generated assembly at all but reliably crashes out if the function isn’t inline.

Julia is by far the worst language about this. It would be vastly more usable with the addition of @assert_type_stable, @assert_doesn’t_allocate, and @assert_doesn’t_error macros.