Merge macro examples from `ExamplePlugin` target into `MacroExamples` #2222

Matejkob · 2023-09-20T20:02:19Z

Resolves #2165

Matejkob

I've merged almost every macro example. I have some doubts about the quality of certain merged macros and whether they serve as good examples, but I'll leave that to your assessment.

Matejkob · 2023-09-20T20:04:40Z

Examples/Sources/ExamplePlugin/Macros.swift

-/// Add 'didSet' printing the new value.
-struct DidSetPrintMacro: AccessorMacro {
-  static func expansion(
-    of node: AttributeSyntax,
-    providingAccessorsOf declaration: some DeclSyntaxProtocol,
-    in context: some MacroExpansionContext
-  ) throws -> [AccessorDeclSyntax] {
-    guard
-      let identifier = declaration.as(VariableDeclSyntax.self)?.bindings.first?.pattern.as(IdentifierPatternSyntax.self)?.identifier
-    else {
-      return []
-    }
-
-    return ["didSet { print(\(identifier)) }"]
-  }
-}


Accessor macro cannot add an observable accessor so this example doesn't work so I removed it.

Matejkob · 2023-09-20T20:06:31Z

Examples/Sources/ExamplePlugin/Macros.swift

-/// 'print(<arg>)'.
-struct PrintAnyMacro: CodeItemMacro {
-  static func expansion(
-    of node: some FreestandingMacroExpansionSyntax,
-    in context: some MacroExpansionContext
-  ) throws -> [CodeBlockItemSyntax] {
-    guard let expr = node.arguments.first?.expression else {
-      return []
-    }
-    return ["print(\(expr))"]
-  }
-}


The code item macro is still behind a feature flag, so I've decided not to merge it into the official macro examples yet to avoid confusing users.

Matejkob · 2023-09-20T20:11:28Z

Examples/Sources/MacroExamples/Playground/PeerMacrosPlayground.swift

+
+  let counter = Counter()
+
+  //  print("Peer value with suffix name for \(Counter.self): \(String(describing: Counter_peer))")


Do you have any idea why Counter_peer con not be accessed here?

That appears to be a bug. @DougGregor is this a known issue that name lookup doesn’t work for peers of local types?

If I move the following to top-level it does work.

@PeerValueWithSuffixName actor Counter { var value = 0 }

OK, looks like it might be intentional that peer macro can’t introduce declarations on a local scope. If so, the error message should be improved. Filed swiftlang/swift#68661

Thanks Alex

ahoppen

I’m not sure if all of these examples are all that valuable. I think the ones that do provide additional value are:

FuncUniqueMacro since we don’t have any declaration macro examples right now
SendableExtensionMacro since we don’t have any extension macro examples right now
MemberDeprecatedMacro seems like a nice example and is a lot simpler than our existing MemberAttribute macro
PeerValueWithSuffixNameMacro also seems useful since it’s a very short example of a peer macro and all our current examples are a lot more complicated

I think the following aren’t really useful and I would just delete them:

EchoExpressionMacro since it doesn’t do anything and we have plenty expression macro examples already
EquatableConformanceMacro since conformance macros aren’t really a thing anymore
MetadataMacro: I think CaseDetectionMacro shows similar ideas and is a more realistic example

@rintaro @bnbarham Do you have opinions here as well?

Examples/Sources/MacroExamples/Implementation/Plugin.swift

ahoppen · 2023-09-20T23:54:09Z

Examples/Sources/MacroExamples/Playground/PeerMacrosPlayground.swift

+
+  let counter = Counter()
+
+  //  print("Peer value with suffix name for \(Counter.self): \(String(describing: Counter_peer))")


That appears to be a bug. @DougGregor is this a known issue that name lookup doesn’t work for peers of local types?

If I move the following to top-level it does work.

@PeerValueWithSuffixName actor Counter { var value = 0 }

bnbarham · 2023-09-21T18:51:34Z

I’m not sure if all of these examples are all that valuable. I think the ones that do provide additional value are:

FuncUniqueMacro since we don’t have any declaration macro examples right now

SendableExtensionMacro since we don’t have any extension macro examples right now

MemberDeprecatedMacro seems like a nice example and is a lot simpler than our existing MemberAttribute macro

PeerValueWithSuffixNameMacro also seems useful since it’s a very short example of a peer macro and all our current examples are a lot more complicated

I think the following aren’t really useful and I would just delete them:

EchoExpressionMacro since it doesn’t do anything and we have plenty expression macro examples already

EquatableConformanceMacro since conformance macros aren’t really a thing anymore

MetadataMacro: I think CaseDetectionMacro shows similar ideas and is a more realistic example

@rintaro @bnbarham Do you have opinions here as well?

That list sounds mostly reasonable to me, though the reasoning for not including EquatableConformanceMacro is more because SendableExtensionMacro is basically the exact same but with a better implementation.

Matejkob · 2023-09-21T20:36:15Z

Speak of SendableExtensionMacro:

Do you know what is goin' on?

…mples` target

…target

ahoppen · 2023-09-21T21:11:50Z

Do you know what is goin' on?

Oh, the macro expansion is considered a different source file in the compiler. Could you file a bug at https://github.com/apple/swift/issues?

I would suggest we just remove that example as well. We should add an example for an extension macro but I we could do that in a follow-up PR.

bnbarham · 2023-09-21T21:14:53Z

I would suggest we just remove that example as well. We should add an example for an extension macro but I we could do that in a follow-up PR.

Could just rename to to Equatable 😅

Matejkob · 2023-09-21T21:17:37Z

I would suggest we just remove that example as well. We should add an example for an extension macro but I we could do that in a follow-up PR.

Could just rename to to Equatable 😅

That could work! 😅

Examples/Sources/MacroExamples/Implementation/Extension/SendableExtensionMacro.swift

…` target

bnbarham · 2023-09-22T18:03:20Z

@swift-ci please test

ahoppen · 2023-09-23T01:07:21Z

@swift-ci Please test Windows

Fixes up several broken links in the documentation: - ExamplePlugin was rolled in to the MacroExamples in swiftlang#2222 but the link was not updated. - A link the changelog pointed to sourcekit-lsp when it should have been swift-syntax. - The Parsing Basics document has moved.

Matejkob requested review from ahoppen and bnbarham as code owners September 20, 2023 20:02

Matejkob commented Sep 20, 2023

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ahoppen reviewed Sep 21, 2023

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Matejkob added 3 commits September 21, 2023 22:47

Move FuncUniqueMacro from ExamplePlugin to MacroExamples target

ab93681

Move PeerValueWithSuffixNameMacro from ExamplePlugin to `MacroExa…

69b68ca

…mples` target

Move MemberDeprecatedMacro from ExamplePlugin to MacroExamples …

cb105c1

…target

Matejkob force-pushed the merge-example-plung-target-into-macro-examples branch from 80dddfa to 067236d Compare September 21, 2023 20:47

bnbarham reviewed Sep 21, 2023

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Examples/Sources/MacroExamples/Implementation/Extension/SendableExtensionMacro.swift Outdated Show resolved Hide resolved

Matejkob added 3 commits September 22, 2023 19:55

Move EquatableExtensionMacro from ExamplePlugin to `MacroExamples…

2ae060c

…` target

Remove ExamplePlugin target

18fe285

Sort providing macros collection alphabetically

0c044f7

Matejkob force-pushed the merge-example-plung-target-into-macro-examples branch from 067236d to 0c044f7 Compare September 22, 2023 17:58

ahoppen approved these changes Sep 23, 2023

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ahoppen enabled auto-merge September 23, 2023 01:08

ahoppen merged commit fee7838 into swiftlang:main Sep 23, 2023
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ahoppen added a commit to ahoppen/swift-syntax that referenced this pull request Sep 25, 2023

Applying PR swiftlang#2222

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plemarquand mentioned this pull request Oct 7, 2024

Fix three broken links #2875

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Merge macro examples from `ExamplePlugin` target into `MacroExamples` #2222

Merge macro examples from `ExamplePlugin` target into `MacroExamples` #2222

Matejkob commented Sep 20, 2023 •

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		let counter = Counter()

		// print("Peer value with suffix name for \(Counter.self): \(String(describing: Counter_peer))")

Merge macro examples from ExamplePlugin target into MacroExamples #2222

Merge macro examples from ExamplePlugin target into MacroExamples #2222

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Merge macro examples from `ExamplePlugin` target into `MacroExamples` #2222

Merge macro examples from `ExamplePlugin` target into `MacroExamples` #2222

Matejkob commented Sep 20, 2023 •

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