I don't think it was actually written by Bjarne, I think it was K. Carroll and others from Lockheed Martin, but I expect the document is this one:

https://www.stroustrup.com/JSF-AV-rules.pdf

which is linked from the Applications page of Bjarne's website.

There are a couple others as well:

https://stroustrup.com/autonomics09.pdf

https://stroustrup.com/sec09.pdf

https://stroustrup.com/mbd09.pdf

Ah, thanks for the link; yes this is the one I was referring to. I had thought it was by Bjarne since it was on his site, but either way, it's an interesting read.

This one might also be interesting https://web.cecs.pdx.edu/~kimchris/cs201/handouts/The%20Powe...

It's basically just a quick list of 10 useful rules to follow for safety-critical code.

(I've seen a different format in the past, that wasn't quite as fancy, but this is the only version I can find at the moment)

Interesting. I wonder how compiler-dependent rule 10 is. Like, if I'm writing for a compiler that gives really bad and usually unhelpful warnings that make my code worse... but I suppose these are more very strict guidelines than rules.

That section explicitly addresses that question and says you should rewrite it in a way that avoids the warning, since "usually unhelpful" means "sometimes critical". It's certainly an uncompromising view but that's what you get when failure is disastrous.