Exclude properties of class with type Self

[johnno1962]

Hi Apple,

as a followup to #22863, prevent people from declaring properties of type Self which seems to not work particularly well as mentioned in the Jira below and the previous PR. This isn't really a solution but prevents compiler crashes and erratic diagnostics. cc @slavapestov. It now gives the error below when a user tries to declare a property with type Self in a class:

h.swift:155:15: error: 'Self' is only available in a protocol or as the result of a method in a class; did you mean 'A1'?
  var copied: Self {
              ^~~~
              A1

Resolves #52537.

[xwu]

Is there a reason to exclude this for concrete value types?

[johnno1962]

Value types work so I've pushed another commit. @xwu, are you able to run tests for me please?

[johnno1962]

I've re-synced to apple/master and tests now pass so this change should be ready to merge.

[xwu]

@swift-ci Please test

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - c317fda

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - c317fda

[johnno1962]

👍, thanks @xwu, LGTM.

[johnno1962]

@swift-ci Please test

[johnno1962]

@xwu, when you have a spare moment could you @swift-ci Please test again for me?

[xwu]

@swift-ci Please test

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 40016d5

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 40016d5

[johnno1962]

Thanks @xwu, over to you @slavapestov

[slavapestov]

If you want, you can try to lift the restriction on get-only properties returning Self in a subsequent PR. It shouldn't be difficult!

[johnno1962]

Thanks @slavapestov, another time perhaps. Would you be able to cherry pick it to 5.1 for me please? I've exhausted my git skills with the fork I have which doesn't have a swift-5.1-branch.

[slavapestov]

Sure.

[slavapestov]

Here you go: #23613

[johnno1962]

ta!