[SE-0163] Migrate from deprecated Unicode APIs #32920

benrimmington · 2020-07-16T07:23:52Z

UnicodeCodec, UnicodeDecodingResult, and some typealiases were deprecated by the SE-0163 proposal.

benrimmington

See also: #33167, #33175

benrimmington · 2020-07-28T01:47:05Z

@swift-ci Please smoke test

stdlib/public/core/MigrationSupport.swift

benrimmington · 2020-07-28T07:12:40Z

stdlib/public/core/Unicode.swift

-  @inlinable
-  public static func == (
-    lhs: UnicodeDecodingResult,
-    rhs: UnicodeDecodingResult
-  ) -> Bool {
-    switch (lhs, rhs) {
-    case (.scalarValue(let lhsScalar), .scalarValue(let rhsScalar)):
-      return lhsScalar == rhsScalar
-    case (.emptyInput, .emptyInput):
-      return true
-    case (.error, .error):
-      return true
-    default:
-      return false
-    }
-  }


This can be synthesized by the compiler.

This is not exactly the same, because the synthesized definition isn’t inlinable. How that will affect performance/code size of code using these APIs is difficult to predict.

benrimmington · 2020-07-28T07:13:50Z

stdlib/public/core/Unicode.swift

+}
+
+extension Unicode.UTF8 {


The non-deprecated APIs could be moved into UTF8.swift:

Unicode.UTF8.isContinuation(_:)

Unicode.UTF8._nullCodeUnitOffset(in:)

Unicode.UTF8._decodeOne(_:) (used in UnicodeLongTest.swift)

The deprecated APIs could be moved into MigrationSupport.swift:

UnicodeDecodingResult enum,

UnicodeCodec protocol and conformances.

The unused APIs could be moved into LegacyABI.swift:

Unicode.UTF16._decodeOne(_:)

transcode(_:_:_:_:stopOnError:) (unavailable since Swift 3).

benrimmington · 2020-07-28T19:48:46Z

@CodaFi Please could you review, and merge if possible?

I've added some comments above, for anything which requires more attention or follow-up PRs.

CodaFi

Benchmarks and test changes LGTM. But @milseman or @airspeedswift should sign off on the stdlib changes

CodaFi · 2020-07-28T19:56:30Z

@swift-ci benchmark

milseman · 2020-07-28T23:50:36Z

I realize this went through SE quite a while ago, but I think it's a bad idea to formally remove the Unicode aliases, especially for UTF8/UTF16.

benrimmington · 2020-07-29T00:04:43Z

@milseman Can we keep the typealiases at deprecated: 100000 indefinitely?

I've copied the simple renames into #33167, in case they can be merged sooner; and to make it easier to review this PR (after rebasing).

lorentey · 2020-07-28T23:58:48Z

stdlib/public/core/MigrationSupport.swift

-//===--- Slicing Support --------------------------------------------------===//
-
-// @available(swift,deprecated: 5.0, renamed: "Unicode.UTF8")
+@available(swift, deprecated: 100000, /*obsoleted: TODO,*/ renamed: "Unicode.UTF8")


Even if these deprecations were part of SE-0163, and even if we tie them into a new language mode, implementing them at this point would be wildly disruptive. Swift 4.0 with SE-0163 was released three years ago; a huge amount of Swift code has been written since then that uses these names. Thus, I believe these changes would deserve a standalone proposal.

Also, that batch of SEs were part of a larger attempt to reformulate strings that didn't pan out in practice. They have several portions that weren't fully thought through, much less implemented, so I don't think we want to blindly apply them without some reevaluation.

lorentey · 2020-07-29T01:52:19Z

Can we keep the typealiases at deprecated: 100000 indefinitely?

Why? The version number 100000 has no special meaning, and it should not appear in any compiler diagnostics or generated documentation. If the reason why SE-0163 intended to deprecate these names still stands, then I think we should reconfirm this through swift-evolution and set the deprecation to a valid version number.

benrimmington · 2020-07-29T02:13:20Z

@lorentey Version number 100000 is from the API_TO_BE_DEPRECATED macro in the <os/availability.h> header.

It seems to affect only the documentation, at least when applied to an OS availability attribute.

For example, in SwiftUI the colorScheme(_:) method has the generated interface:

@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
extension View {

    /// Sets this view's color scheme.
    ///
    /// Use `colorScheme(_:)` to set the color scheme for the view to which you
    /// apply it and any subviews. If you want to set the color scheme for all
    /// views in the presentation, use ``View/preferredColorScheme(_:)``
    /// instead.
    ///
    /// - Parameter colorScheme: The color scheme for this view.
    ///
    /// - Returns: A view that sets this view's color scheme.
    @available(iOS, introduced: 13.0, deprecated: 100000.0, renamed: "preferredColorScheme(_:)")
    @available(OSX, introduced: 10.15, deprecated: 100000.0, renamed: "preferredColorScheme(_:)")
    @available(tvOS, introduced: 13.0, deprecated: 100000.0, renamed: "preferredColorScheme(_:)")
    @available(watchOS, introduced: 6.0, deprecated: 100000.0, renamed: "preferredColorScheme(_:)")
    @inlinable public func colorScheme(_ colorScheme: ColorScheme) -> some View
}

benrimmington · 2020-07-29T03:56:04Z

@swift-ci Please smoke test

lorentey · 2020-07-29T03:59:25Z

Version number 100000 is from the API_TO_BE_DEPRECATED macro in the <os/availability.h> header.

~~Unfortunately AFAIK that only applies to C. :-( We could adopt it in Swift, but without the macro name the number seems opaque.~~ Oh, the fact that it shows up in generated interfaces is rather terrible. 😱

The 9999s we use elsewhere set an unfortunate precedent for doing such things; I guess it's time to replace them too with a better system.

benrimmington commented Jul 16, 2020

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benrimmington mentioned this pull request Jul 16, 2020

[SE-0163] Add Latin1 to Unicode codecs #32782

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benrimmington force-pushed the se-0163-migration branch from 6477ba7 to 3cc0ad1 Compare July 20, 2020 07:26

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[SE-0163] Migrate from deprecated Unicode APIs (part 2) #33167

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milseman requested a review from lorentey July 28, 2020 23:49

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[SE-0163] Migrate from deprecated Unicode APIs (part 3) #33175

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benrimmington force-pushed the se-0163-migration branch from 3cc0ad1 to 90c4e4b Compare July 29, 2020 03:14

[SE-0163] Migrate from deprecated Unicode APIs

f5421bd

benrimmington force-pushed the se-0163-migration branch from 90c4e4b to f5421bd Compare July 29, 2020 03:29

benrimmington closed this Aug 7, 2020

benrimmington deleted the se-0163-migration branch August 7, 2020 09:18

[SE-0163] Migrate from deprecated Unicode APIs #32920

[SE-0163] Migrate from deprecated Unicode APIs #32920

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