Can you provide a reference to both of those affecting _ABI_? "VLAs as [...] function arguments" sounds like it would just be normal passing of arrays. It's no

Can you provide a reference to both of those affecting _ABI_? "VLAs as [...] function arguments" sounds like it would just be normal passing of arrays. It's not clear that VLAs have any effect here. "VLAs as struct members [...]" is still not clearly an ABI issue: if they existed, the types would still be confined to the function they are declared in, and thus would not affect ABI.