I don't understand this sentence. That is the purpose of the runtime check, to make sure the code generated by a buggy compiler, on a specific architecture, doesn't try to run. Bug reports can then be filed, as they should be.
If you're writing a Linux kernel module (known compiler) for a known architecture, which is where this is often used, then you have a known environment, so there's little risk, except the rare compiler bug, which is a risk that extends far beyond packed structs.
This is something that I've used, and I've seen used, often in the hardware world. I'm having difficulty sympathizing with all the fear in this comment section. Don't use it if its use can't be made rational, for you. But please don't tell me that I'm failing to get something that I am familiar with.
