[swift-dev] Simple question about ParameterTypeFlags

[Slava Pestov]

It is one of the user-facing features from John McCall’s ownership manifesto.

Slava

> On Dec 11, 2017, at 3:33 PM, David Zarzycki <dave at znu.io> wrote:
> 
> This is a tangent from the original question, but is __shared a planned feature? Or just experimental work?
> 
> Dave
> 
>> On Dec 11, 2017, at 17:12, Slava Pestov <spestov at apple.com> wrote:
>> 
>> Sorry, what I meant is that they make sense with our language model, but it’s not surprising that it doesn’t work today. In any case, __shared is not yet completely implemented or even designed, so it doesn’t matter.
>> 
>> Slava
>> 
>>> On Dec 11, 2017, at 2:05 PM, David Zarzycki <dave at znu.io> wrote:
>>> 
>>> Hi Slava,
>>> 
>>> Interesting. Did I make a mistake in my test then? Both __shared @escaping and __shared @autoclosure are failing below.
>>> 
>>> Dave
>>> 
>>>> On Dec 11, 2017, at 16:58, Slava Pestov via swift-dev <swift-dev at swift.org> wrote:
>>>> 
>>>> I think perhaps __shared @escaping and __shared @autoclosure should be OK. You’re just passing the context as a +0 value instead of +1. Also __shared varargs make sense for the same reason. But it’s not important to get that working right now.
>>>> 
>>>> The others look OK.
>>>> 
>>>> Slava
>>>> 
>>>>> On Dec 11, 2017, at 1:15 PM, David Zarzycki via swift-dev <swift-dev at swift.org> wrote:
>>>>> 
>>>>> Hello! I’m trying to test which ParameterTypeFlags flag combinations are valid. I wrote the following test case. Are the results “as expected”, or are some of the failures incorrect?
>>>>> 
>>>>> // RUN: %target-typecheck-verify-swift
>>>>> 
>>>>> 
>>>>> //
>>>>> // isVariadic is NOT compatible with any flag combinations
>>>>> //
>>>>> // expected-error at +1 {{@autoclosure must not be used on variadic parameters}}
>>>>> func v_and_autoclosure(arg : @autoclosure ()->()...) {}
>>>>> // expected-error at +1 {{@escaping attribute may only be used in function parameter position}}
>>>>> func v_and_escaping(arg : @escaping ()->()...) {}
>>>>> // expected-error at +1 {{'inout' must not be used on variadic parameters}}
>>>>> func v_and_inout(arg : inout Int...) {}
>>>>> // expected-error at +1 {{'__shared' must not be used on variadic parameters}}
>>>>> func v_and_shared(arg : __shared Int...) {}
>>>>> 
>>>>> //
>>>>> // 'inout' is NOT compatible with remaining parameter flag combinations
>>>>> //
>>>>> // expected-error at +1 {{parameter must not have multiple '__owned', 'inout', '__shared', 'var', or 'let' specifiers}}
>>>>> func inout_and_shared(arg : inout __shared Int) {}
>>>>> // expected-error at +1 {{'inout' may only be used on parameters}}
>>>>> func inout_and_escaping(arg : @escaping inout ()->()) {}
>>>>> // expected-error at +1 {{@escaping attribute may only be used in function parameter position}}
>>>>> func escaping_and_inout(arg : inout @escaping ()->()) {}
>>>>> // expected-error at +1 {{@autoclosure may only be used on parameters}}
>>>>> func inout_and_autoclosure(arg : inout @autoclosure ()->()) {}
>>>>> // expected-error at +1 {{'inout' may only be used on parameters}}
>>>>> func autoclosure_and_inout(arg : @autoclosure inout ()->()) {}
>>>>> 
>>>>> //
>>>>> // '__shared' is NOT compatible with remaining parameter flag combinations
>>>>> //
>>>>> // expected-error at +1 {{'__shared' may only be used on parameters}}
>>>>> func autoclosure_and_shared(arg : @autoclosure __shared ()->()) {}
>>>>> // expected-error at +1 {{@autoclosure may only be used on parameters}}
>>>>> func shared_and_autoclosure(arg : __shared @autoclosure ()->()) {}
>>>>> // expected-error at +1 {{'__shared' may only be used on parameters}}
>>>>> func escaping_and_shared(arg : @escaping __shared ()->()) {}
>>>>> // expected-error at +1 {{@escaping attribute may only be used in function parameter position}}
>>>>> func shared_and_escaping(arg : __shared @escaping ()->()) {}
>>>>> 
>>>>> //
>>>>> // @autoclosure and @escaping are the only valid parameter flag combinations
>>>>> //
>>>>> func autoclosure_and_escaping(arg : @autoclosure @escaping ()->()) {}
>>>>> func escaping_and_autoclosure(arg : @escaping @autoclosure ()->()) {}
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>>>> 
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>> 
>