The problem is that the value associated with the magic literals are not available in the type checker (they're emitted in SILGen), which means we can't do a uniqueness check. I suppose we could make it work by only allowing only one magic literal of each kind to be associated with an enum case (i.e. you can't have two cases of #line) but I am not sure if that's a better rule than not allowing magic literals in the first place.

Regardless, the compiler shouldn't be crashing here, which is a bug.

EDIT: Upon thinking a bit more, I think it's possible to support these literals by moving some of the code from SILGen into AST/Sema. I'll give it a try soon.

Comment by Jonathan Pappas (JIRA)

@theblixguy Thank you,

I also found that using ExpressibleByNilLiteral and setting one of the raw values to nil also causes the same issue.

Thanks. I don’t think nil can be supported as it’s not a unique literal. I think the only ones that can potentially be supported is #file, #function, #line and #column.

The crash is now fixed by #32364. I'll create a new SR to track adding support for #file, #filePath, #function, #line and #column.