[swift-dev] Delaying the enforcement of ".self" out of Swift 3?

Jordan Rose jordan_rose at apple.com
Thu Jun 2 16:00:53 CDT 2016


We have a bug for this, https://bugs.swift.org/browse/SR-899. I had pretty much the same reaction you did, which is that it's definitely a bug but it's probably not worth changing right now.

Jordan


> On Jun 2, 2016, at 13:21, Douglas Gregor via swift-dev <swift-dev at swift.org> wrote:
> 
> Hi all,
> 
> While working on some unrelated refactoring, I stumbled across a minor fix that would make use properly enforce “.self” when we want to get the metatype of a named type. For example, the Swift compiler currently (incorrectly) allows
> 
> 	sizeof(UInt)
> 
> which should be
> 
> 	sizeof(UInt.self)
> 
> The fix for this is actually pretty simple (patch attached), but the question is… do we want to fix the problem, if we think that we’ll get SE-0090 that makes “.self” go away?
> 
> 	https://github.com/apple/swift-evolution/blob/master/proposals/0090-remove-dot-self.md
> 
> On the one hand, I want to fix the problem:
> 
> 	* This came out of a desire to make the AST more sane. Essentially, the folding of expressions into TypeExprs—which will go away entirely if/when SE-0090 is implemented—is pulling in the parentheses describing call arguments. Without the fix, we still have weird AST.
> 	* SE-0090 is labeled as “deferred out of Swift 3”, so having the compiler not implement the stated language for an entire release cycle seems really unfortunate.
> 
> OTOH, I don’t want to jerk people’s code around, forcing them to add “.self” now only to remove it a year from now (or whenever).
> 
> Thoughts?
> 
> 	- Doug
> 
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