I don't think this is really about GCC extensions (or obsolete language modes) rather than using the flexibility of the syntax to write things in a confusing way.

The first is simply K&R definitions + strange formatting.

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nneonneo 2 days ago | parent | next [-]

Only the first one is fully standards-compliant C; the others all invoke some non-standard (but widely-accepted) features. (I believe empty unions - and their interpretation as being 0-sized - are non-standard in C, but I am not 100% sure.)

	▲	uecker a day ago \| parent [-]
		My point was not that those are standards-compliant, but that the use of the GCC extensions is not the primary cause of those examples being unreadable. (which seemed to be the point the person I replied to was making - and I disagree with GCC extensions being bad).

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icedchai 2 days ago | parent | prev [-]

I always forget K&R syntax is still in there. I taught myself C in 1988, during the K&R -> ANSI transition. All my early Amiga C programs were K&R style.