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

[Daniel Dunbar]

As just a user of the language, as much as I hate churn I personally wouldn't mind seeing this fixed. In this case, I think the laxness can make it harder for developers to form the right mental model of the language; I know I have personally stumbled over this in the past.

 - Daniel

> On Jun 2, 2016, at 2:00 PM, Jordan Rose via swift-dev <swift-dev at swift.org> wrote:
> 
> 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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