LLMs remove the familiarity of “I wrote this and deeply understand this”. In other words, everything is “legacy code” now ;-)

For those who are less experienced with the constant surprises that legacy code bases can provide, LLMs are deeply unsettling.

This is the key point for me in all this.

I've never worked in web development, where it seems to me the majority of LLM coding assistants are deployed.

I work on safety critical and life sustaining software and hardware. That's the perspective I have on the world. One question that comes up is "why does it take so long to design and build these systems?" For me, the answer is: that's how long it takes humans to reach a sufficient level of understanding of what they're doing. That's when we ship: when we can provide objective evidence that the systems we've built are safe and effective. These systems we build, which are complex, have to interact with the real world, which is messy and far more complicated.

Writing more code means that's more complexity for humans (note the plurality) to understand. Hiring more people means that's more people who need to understand how the systems work. Want to pull in the schedule? That means humans have to understand in less time. Want to use Agile or this coding tool or that editor or this framework? Fine, these tools might make certain tasks a little easier, but none of that is going to remove the requirement that humans need to understand complex systems before they will work in the real world.

So then we come to LLMs. It's another episode of "finally, we can get these pesky engineers and their time wasting out of the loop". Maybe one day. But we are far from that today. What matters today is still how well do human engineers understand what they're doing. Are you using LLMs to help engineers better understand what they are building? Good. If that's the case you'll probably build more robust systems, and you _might_ even ship faster.

Are you trying to use LLMs to fool yourself into thinking this still isn't the game of humans needing to understand what's going on? "Let's offload some of the understanding of how these systems work onto the AI so we can save time and money". Then I think we're in trouble.

I suspect that we are going to have a wave of gurus who show up soon to teach us how to code with LLMs. There’s so much doom and gloom in these sorts of threads about the death of quality code that someone is going to make money telling people how to avoid that problem.

The scenario you describe is a legitimate concern if you’re checking in AI generated code with minimal oversight. In fact I’d say it’s inevitable if you don’t maintain strict quality control. But that’s always the case, which is why code review is a thing. Likewise you can use LLMs without just checking in garbage.

The way I’ve used LLMs for coding so far is to give instructions and then iterate on the result (manually or with further instructions) until it meets my quality standards. It’s definitely slower than just checking in the first working thing the LLM churns out, but it’s sill been faster than doing it myself, I understand it exactly as well because I have to in order to give instructions (design) and iterate.

My favorite definition of “legacy code” is “code that is not tested” because no matter who writes code, it turns into a minefield quickly if it doesn’t have tests.

I see where you're coming from, and I agree with the implication that this is more of an issue for inexperienced devs. Having said that, I'd push back a bit on the "legacy" characterization.

For me, if I check in LLM-generated code, it means I've signed off on the final revision and feel comfortable maintaining it to a similar degree as though it were fully hand-written. I may not know every character as intimately as that of code I'd finished writing by hand a day ago, but it shouldn't be any more "legacy" to me than code I wrote by hand a year ago.

It's a bit of a meme that AI code is somehow an incomprehensible black box, but if that is ever the case, it's a failure of the user, not the tool. At the end of the day, a human needs to take responsibility for any code that ends up in a product. You can't just ship something that people will depend on not to harm them without any human ever having had the slightest idea of what it does under the hood.

I think it was Cory Doctorow who compared AI-generated code to asbestos. Back in its day, asbestos was in everything, because of how useful it seemed. Fast forward decades and now asbestos abatement is a hugely expensive and time-consuming requirement for any remodeling or teardown project. Lead paint has some of the same history.