AST: support availability on Windows

[compnerd]

Enable Windows specific availability annotations in Swift.

Replace this paragraph with a description of your changes and rationale. Provide links to external references/discussions if appropriate.

Resolves SR-NNNN.

[compnerd]

@swift-ci please test

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CC: @benrimmington

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@swift-ci please test Windows platform

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 2214d7f54e365daabf3c48ff95eed9b8c02b2a2d

[compnerd]

@swift-ci please test

[compnerd]

@swift-ci please test

[benrimmington]

What happens when a version number is used?

The parser/runtime might allow:

• #available(Windows 10, *) is always false on Windows.
• @available(Windows 10, *)
• @available(Windows, introduced: 10, deprecated: 11, obsoleted: 12)

[compnerd]

I can add the additional test cases, however, I'm not sure that the versions make too much sense. Microsoft has announced that Windows 10 is the last version. Do we really want to have build version numbers here? I think that can get confusing and unwieldy. You would be looking at something like:

@available(Windows, introduced: 10.0.107763.1, deprecated: 10.0.19140.2)

[benrimmington]

I was just wondering what happens when someone tries using version numbers on Windows. Does the compiler crash? Or is there an error or warning? Or are version numbers allowed at compile-time, but ignored at run-time?

• Parser::parseNewDeclAttribute

• Parser::parseAvailabilitySpecList

• Parser::parseExtendedAvailabilitySpecList

https://github.com/apple/swift/blob/c10064a698d2b6424353a83b216514855d668f41/stdlib/public/core/Availability.swift#L39-L42

[compnerd]

Ah, okay. I'll certainly add those test cases. It shouldn't crash the compiler, merely fail (warning/error). The version numbers aren't supported.

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@swift-ci please test

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This seems to cause some problems for SK-LSP. I want to get the reviews taken care of for the change, but leave the merging to until after the SourceKit-LSP issues have been worked out.

[compnerd]

@swift-ci please test

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@swift-ci please test Windows platform

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@swift-ci please test

[compnerd]

@swift-ci please test Windows platform

[compnerd]

The additional tests have been added, I think that all the review comments have been addressed and SK-LSP has been updated, so optimistically merging this for now.