While this construct looks pretty weird if you decompose it element by element using the rules of the language it becomes rather clear IMO. The most arcane feature here is probably the bitfield syntax that you might not encounter very often in the wild.
The problem with C IMO is that the compilers are very permissive by default and it's easy to trigger an undefined behaviour with seemingly harmless code if you're not careful. Things like promotion rules make it difficult to guess at a glance how the code is going to behave if you don't have a very good understanding of these (rather quircky) rules. There's also the whole mess of the pointer vs. array distinction which sometimes matter and sometimes doesn't etc...
By comparison these BUILD_BUG_ON macros are relatively straightforward IMO. The naming is a bit misleading unfortunately but at least it's in full CAPS so you know it's a macro...
The problem with C IMO is that the compilers are very permissive by default and it's easy to trigger an undefined behaviour with seemingly harmless code if you're not careful. Things like promotion rules make it difficult to guess at a glance how the code is going to behave if you don't have a very good understanding of these (rather quircky) rules. There's also the whole mess of the pointer vs. array distinction which sometimes matter and sometimes doesn't etc...
By comparison these BUILD_BUG_ON macros are relatively straightforward IMO. The naming is a bit misleading unfortunately but at least it's in full CAPS so you know it's a macro...