"I told you so": noreturn sucks a leech and has virtually no utility

Paul Backus snarwin at gmail.com
Sat Oct 16 13:40:23 UTC 2021

On Saturday, 16 October 2021 at 05:27:42 UTC, Ola Fosheim Grøstad 
> On Friday, 15 October 2021 at 19:10:42 UTC, Stefan Koch wrote:
>> Seconded. The point of noreturn is precisely to reject less.
>> The no-return type has no values which means reading or 
>> writing that type is merely undefined behavior. It doesn't 
>> have to be rejected.
> If we ignore the DIP, couldn't you just as well claim that you 
> should be able to assume anything about a type that is never 
> instantiated as long as the assumption does not lead to a 
> contradiction?

Even if you, the programmer, could make such assumptions, the 
compiler cannot, because proving that a type is never 
instantiated is halting-equivalent.

`noreturn`, on the other hand, is defined in the language spec to 
be impossible to instantiate, so the compiler does not need to 
prove anything.

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