Bug > Swift > Enum > String Protocol

I was attempting to create an enumeration in which all its elements were file names, and I stumbled across something interesting. Like so:

enum FileNames: String {
     case main = #file

This resulted in an internal error. (Segmentation Fault: 11)

I was able to figure how to get an actual error message:

enum Foo: String {
    case one = "\(1)"

Error: Raw value for enum case must be a literal

Related Questions:
• Is #file considered a String literal?
• Why does #file break the enum? Should this be reported on
• I noticed that replacing String to Int and #file to #line causes the same issue. Is this a hint?

Color Literals Don’t Work

I thought they did, but I made a mistake. It also causes the same internal error.

import UIKit

enum ColorEnum: UIColor {
    case foo = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0)

The Swift Programming Language (Swift 5.2)

According to Apple, #file is considered a literal:

#file is described as a literal according to Apple

What about nil Literals?

These also crash the compiler.

enum Foo: String? {
    case breaks = nil

23 Characters of Mass Destruction

enum I:Int?{case a=nil}

Bug Fixed

The crash has now been fixed, it has been merged officially into Swift here: Merged on GitHub Here’s the bug report: SR-12998

Adding Support!
The use of magic literals as raw values for enum cases is being supported here: SR-13022