I don't think I've ever seen a C function that uses unions for this purpose though?
replyI can think of two common patterns that I've seen frequently:
* Return NULL for errors (sometimes with a global errorno() function).
* Return an integer error with any return values as out parameters.
So if it is possible to improve, why doesn't anyone do it?
Yet the authors of crypt did not use them. The C language is not designed in a way to encourage people to write code that correctly uses tagged unions (or nullable pointers for that matter).
replyWhere are you going with those goal posts?
replyGoalposts are fine. If crypt did return union type, C still allows cowboy programmers to straight extract the char* without any check whether it's valid. So we'd end up in exactly the same situation.
replyNowhere. It's the same argument as upthread. A language that forces downstream consumers of an API to correctly deal with all possible outcomes would have prevented this.
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