Merge pull request #2785 from Azoy/integer-generics

Implement syntax and parsing for value generics

Author: Azoy

CodeGeneration/Sources/SyntaxSupport/GenericNodes.swift

@@ -93,10 +93,13 @@ public let GENERIC_NODES: [Node] = [
         kind: .collection(kind: .attributeList, collectionElementName: "Attribute", defaultsToEmpty: true)
       ),
       Child(
-        name: "eachKeyword",
-        deprecatedName: "each",
-        kind: .token(choices: [.keyword(.each)]),
-        nameForDiagnostics: "parameter pack specifier",
+        name: "specifier",
+        deprecatedName: "eachKeyword",
+        kind: .token(choices: [
+          .keyword(.each),
+          .keyword(.let),
+        ]),
+        nameForDiagnostics: "specifier",
         isOptional: true
       ),
       Child(

Release Notes/601.md

@@ -2,6 +2,10 @@
 
 ## New APIs
 
+- `GenericParameterSyntax` now has a new `specifier` property.
+  - Description: With the introduction of value generics, generic parameters can now be optionally preceded by either a `let` or an `each`. The `specifier` property captures the token representing which one was parsed.
+  - Pull Request: https://github.com/swiftlang/swift-syntax/pull/2785
+
 - `IntegerLiteralExprSyntax` and `FloatLiteralExprSyntax` now have a computed `representedLiteralValue` property.
   - Description: Allows retrieving the represented literal value when valid.
   - Issue: https://github.com/apple/swift-syntax/issues/405
@@ -27,6 +31,10 @@
 
 ## Deprecations
 
+- `GenericParameterSyntax` deprecated `eachKeyword` in favor of `specifier`
+  - Description: `specifier` is now used to grab either the `each` keyword for a generic parameter or the `let` keyword.
+  - Pull request: https://github.com/swiftlang/swift-syntax/pull/2785
+
 - `IncrementalEdit` deprecated in favor of `SourceEdit`
   - Description: `IncrementalEdit` is being dropped for `SourceEdit`. `SourceEdit` has deprecated compatibility layers to make it API-compatible with `IncrementalEdit`
   - Issue: https://github.com/apple/swift-syntax/issues/2532

Sources/SwiftParser/Declarations.swift

@@ -431,11 +431,12 @@ extension Parser {
       repeat {
         let attributes = self.parseAttributeList()
 
-        // Parse the 'each' keyword for a type parameter pack 'each T'.
-        var each = self.consume(if: .keyword(.each))
+        // Parse the 'each' keyword for a type parameter pack 'each T' or a
+        // 'let' keyword for a value parameter 'let N: Int'.
+        var specifier = self.consume(if: .keyword(.each), .keyword(.let))
 
-        let (unexpectedBetweenEachAndName, name) = self.expectIdentifier(allowSelfOrCapitalSelfAsIdentifier: true)
-        if attributes.isEmpty && each == nil && unexpectedBetweenEachAndName == nil && name.isMissing
+        let (unexpectedBetweenSpecifierAndName, name) = self.expectIdentifier(allowSelfOrCapitalSelfAsIdentifier: true)
+        if attributes.isEmpty && specifier == nil && unexpectedBetweenSpecifierAndName == nil && name.isMissing
           && elements.isEmpty && !self.at(prefix: ">")
         {
           break
@@ -445,8 +446,8 @@ extension Parser {
         let unexpectedBetweenNameAndColon: RawUnexpectedNodesSyntax?
         if let ellipsis = self.consume(ifPrefix: "...", as: .ellipsis) {
           unexpectedBetweenNameAndColon = RawUnexpectedNodesSyntax([ellipsis], arena: self.arena)
-          if each == nil {
-            each = missingToken(.each)
+          if specifier == nil {
+            specifier = missingToken(.each)
           }
         } else {
           unexpectedBetweenNameAndColon = nil
@@ -481,8 +482,8 @@ extension Parser {
         elements.append(
           RawGenericParameterSyntax(
             attributes: attributes,
-            eachKeyword: each,
-            unexpectedBetweenEachAndName,
+            specifier: specifier,
+            unexpectedBetweenSpecifierAndName,
             name: name,
             unexpectedBetweenNameAndColon,
             colon: colon,

Sources/SwiftParser/generated/Parser+TokenSpecSet.swift

@@ -1852,6 +1852,58 @@ extension FunctionParameterSyntax {
   }
 }
 
+extension GenericParameterSyntax {
+  @_spi(Diagnostics)
+  public enum SpecifierOptions: TokenSpecSet {
+    case each
+    case `let`
+    
+    init?(lexeme: Lexer.Lexeme, experimentalFeatures: Parser.ExperimentalFeatures) {
+      switch PrepareForKeywordMatch(lexeme) {
+      case TokenSpec(.each):
+        self = .each
+      case TokenSpec(.let):
+        self = .let
+      default:
+        return nil
+      }
+    }
+    
+    public init?(token: TokenSyntax) {
+      switch token {
+      case TokenSpec(.each):
+        self = .each
+      case TokenSpec(.let):
+        self = .let
+      default:
+        return nil
+      }
+    }
+    
+    var spec: TokenSpec {
+      switch self {
+      case .each:
+        return .keyword(.each)
+      case .let:
+        return .keyword(.let)
+      }
+    }
+    
+    /// Returns a token that satisfies the `TokenSpec` of this case.
+    ///
+    /// If the token kind of this spec has variable text, e.g. for an identifier, this returns a token with empty text.
+    @_spi(Diagnostics)
+    public var tokenSyntax: TokenSyntax {
+      switch self {
+      case .each:
+        return .keyword(.each)
+      case .let:
+        return .keyword(.let)
+      }
+    }
+  }
+}
+
 extension IdentifierPatternSyntax {
   @_spi(Diagnostics)
   public enum IdentifierOptions: TokenSpecSet {

Sources/SwiftParserDiagnostics/ParseDiagnosticsGenerator.swift

@@ -1022,15 +1022,16 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
       return .skipChildren
     }
     // Emit a custom diagnostic for an unexpected '...' after the type name.
-    if node.eachKeyword?.isPresent ?? false {
+    if node.specifier?.isPresent ?? false {
       removeToken(
         node.unexpectedBetweenNameAndColon,
         where: { $0.tokenKind == .ellipsis },
         message: { _ in .typeParameterPackEllipsis }
       )
     } else if let unexpected = node.unexpectedBetweenNameAndColon,
       let unexpectedEllipsis = unexpected.onlyPresentToken(where: { $0.tokenKind == .ellipsis }),
-      let each = node.eachKeyword
+      let specifier = node.specifier,
+      specifier.tokenKind == .keyword(.each)
     {
       addDiagnostic(
         unexpected,
@@ -1040,11 +1041,11 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
             message: ReplaceTokensFixIt(replaceTokens: [unexpectedEllipsis], replacements: [.keyword(.each)]),
             changes: [
               .makeMissing(unexpected),
-              .makePresent(each, trailingTrivia: .space),
+              .makePresent(specifier, trailingTrivia: .space),
             ]
           )
         ],
-        handledNodes: [unexpected.id, each.id]
+        handledNodes: [unexpected.id, specifier.id]
       )
     }
     if let inheritedTypeName = node.inheritedType?.as(IdentifierTypeSyntax.self)?.name {

Sources/SwiftParserDiagnostics/generated/ChildNameForDiagnostics.swift

@@ -168,8 +168,8 @@ private func childNameForDiagnostics(_ keyPath: AnyKeyPath) -> String? {
     return "type"
   case \FunctionParameterSyntax.defaultValue:
     return "default value"
-  case \GenericParameterSyntax.eachKeyword:
-    return "parameter pack specifier"
+  case \GenericParameterSyntax.specifier:
+    return "specifier"
   case \GenericParameterSyntax.name:
     return "name"
   case \GenericParameterSyntax.inheritedType:

Sources/SwiftRefactor/OpaqueParameterToGeneric.swift

@@ -60,7 +60,7 @@ fileprivate class SomeParameterRewriter: SyntaxRewriter {
 
     let genericParam = GenericParameterSyntax(
       attributes: [],
-      eachKeyword: nil,
+      specifier: nil,
       name: paramNameSyntax,
       colon: colon,
       inheritedType: inheritedType,

Sources/SwiftSyntax/generated/ChildNameForKeyPath.swift

@@ -1551,12 +1551,12 @@ public func childName(_ keyPath: AnyKeyPath) -> String? {
     return "unexpectedBeforeAttributes"
   case \GenericParameterSyntax.attributes:
     return "attributes"
-  case \GenericParameterSyntax.unexpectedBetweenAttributesAndEachKeyword:
-    return "unexpectedBetweenAttributesAndEachKeyword"
-  case \GenericParameterSyntax.eachKeyword:
-    return "eachKeyword"
-  case \GenericParameterSyntax.unexpectedBetweenEachKeywordAndName:
-    return "unexpectedBetweenEachKeywordAndName"
+  case \GenericParameterSyntax.unexpectedBetweenAttributesAndSpecifier:
+    return "unexpectedBetweenAttributesAndSpecifier"
+  case \GenericParameterSyntax.specifier:
+    return "specifier"
+  case \GenericParameterSyntax.unexpectedBetweenSpecifierAndName:
+    return "unexpectedBetweenSpecifierAndName"
   case \GenericParameterSyntax.name:
     return "name"
   case \GenericParameterSyntax.unexpectedBetweenNameAndColon:

Sources/SwiftSyntax/generated/RenamedChildrenCompatibility.swift

@@ -3610,45 +3610,45 @@ extension GenericParameterClauseSyntax {
 }
 
 extension GenericParameterSyntax {
-  @available(*, deprecated, renamed: "unexpectedBetweenAttributesAndEachKeyword")
-  public var unexpectedBetweenAttributesAndEach: UnexpectedNodesSyntax? {
+  @available(*, deprecated, renamed: "unexpectedBetweenAttributesAndSpecifier")
+  public var unexpectedBetweenAttributesAndEachKeyword: UnexpectedNodesSyntax? {
     get {
-      return unexpectedBetweenAttributesAndEachKeyword
+      return unexpectedBetweenAttributesAndSpecifier
     }
     set {
-      unexpectedBetweenAttributesAndEachKeyword = newValue
+      unexpectedBetweenAttributesAndSpecifier = newValue
     }
   }
 
-  @available(*, deprecated, renamed: "eachKeyword")
-  public var each: TokenSyntax? {
+  @available(*, deprecated, renamed: "specifier")
+  public var eachKeyword: TokenSyntax? {
     get {
-      return eachKeyword
+      return specifier
     }
     set {
-      eachKeyword = newValue
+      specifier = newValue
     }
   }
 
-  @available(*, deprecated, renamed: "unexpectedBetweenEachKeywordAndName")
-  public var unexpectedBetweenEachAndName: UnexpectedNodesSyntax? {
+  @available(*, deprecated, renamed: "unexpectedBetweenSpecifierAndName")
+  public var unexpectedBetweenEachKeywordAndName: UnexpectedNodesSyntax? {
     get {
-      return unexpectedBetweenEachKeywordAndName
+      return unexpectedBetweenSpecifierAndName
     }
     set {
-      unexpectedBetweenEachKeywordAndName = newValue
+      unexpectedBetweenSpecifierAndName = newValue
     }
   }
 
-  @available(*, deprecated, renamed: "GenericParameterSyntax(leadingTrivia:_:attributes:_:eachKeyword:_:name:_:colon:_:inheritedType:_:trailingComma:_:trailingTrivia:)")
+  @available(*, deprecated, renamed: "GenericParameterSyntax(leadingTrivia:_:attributes:_:specifier:_:name:_:colon:_:inheritedType:_:trailingComma:_:trailingTrivia:)")
   @_disfavoredOverload
   public init(
       leadingTrivia: Trivia? = nil,
       _ unexpectedBeforeAttributes: UnexpectedNodesSyntax? = nil,
       attributes: AttributeListSyntax = [],
-      _ unexpectedBetweenAttributesAndEach: UnexpectedNodesSyntax? = nil,
-      each: TokenSyntax? = nil,
-      _ unexpectedBetweenEachAndName: UnexpectedNodesSyntax? = nil,
+      _ unexpectedBetweenAttributesAndEachKeyword: UnexpectedNodesSyntax? = nil,
+      eachKeyword: TokenSyntax? = nil,
+      _ unexpectedBetweenEachKeywordAndName: UnexpectedNodesSyntax? = nil,
       name: TokenSyntax,
       _ unexpectedBetweenNameAndColon: UnexpectedNodesSyntax? = nil,
       colon: TokenSyntax? = nil,
@@ -3663,9 +3663,9 @@ extension GenericParameterSyntax {
         leadingTrivia: leadingTrivia, 
         unexpectedBeforeAttributes, 
         attributes: attributes, 
-        unexpectedBetweenAttributesAndEach, 
-        eachKeyword: each, 
-        unexpectedBetweenEachAndName, 
+        unexpectedBetweenAttributesAndEachKeyword, 
+        specifier: eachKeyword, 
+        unexpectedBetweenEachKeywordAndName, 
         name: name, 
         unexpectedBetweenNameAndColon, 
         colon: colon, 

Sources/SwiftSyntax/generated/raw/RawSyntaxNodesGHI.swift

@@ -390,9 +390,9 @@ public struct RawGenericParameterSyntax: RawSyntaxNodeProtocol {
   public init(
       _ unexpectedBeforeAttributes: RawUnexpectedNodesSyntax? = nil, 
       attributes: RawAttributeListSyntax, 
-      _ unexpectedBetweenAttributesAndEachKeyword: RawUnexpectedNodesSyntax? = nil, 
-      eachKeyword: RawTokenSyntax?, 
-      _ unexpectedBetweenEachKeywordAndName: RawUnexpectedNodesSyntax? = nil, 
+      _ unexpectedBetweenAttributesAndSpecifier: RawUnexpectedNodesSyntax? = nil, 
+      specifier: RawTokenSyntax?, 
+      _ unexpectedBetweenSpecifierAndName: RawUnexpectedNodesSyntax? = nil, 
       name: RawTokenSyntax, 
       _ unexpectedBetweenNameAndColon: RawUnexpectedNodesSyntax? = nil, 
       colon: RawTokenSyntax?, 
@@ -408,9 +408,9 @@ public struct RawGenericParameterSyntax: RawSyntaxNodeProtocol {
       layout.initialize(repeating: nil)
       layout[0] = unexpectedBeforeAttributes?.raw
       layout[1] = attributes.raw
-      layout[2] = unexpectedBetweenAttributesAndEachKeyword?.raw
-      layout[3] = eachKeyword?.raw
-      layout[4] = unexpectedBetweenEachKeywordAndName?.raw
+      layout[2] = unexpectedBetweenAttributesAndSpecifier?.raw
+      layout[3] = specifier?.raw
+      layout[4] = unexpectedBetweenSpecifierAndName?.raw
       layout[5] = name.raw
       layout[6] = unexpectedBetweenNameAndColon?.raw
       layout[7] = colon?.raw
@@ -431,15 +431,15 @@ public struct RawGenericParameterSyntax: RawSyntaxNodeProtocol {
     layoutView.children[1].map(RawAttributeListSyntax.init(raw:))!
   }
 
-  public var unexpectedBetweenAttributesAndEachKeyword: RawUnexpectedNodesSyntax? {
+  public var unexpectedBetweenAttributesAndSpecifier: RawUnexpectedNodesSyntax? {
     layoutView.children[2].map(RawUnexpectedNodesSyntax.init(raw:))
   }
 
-  public var eachKeyword: RawTokenSyntax? {
+  public var specifier: RawTokenSyntax? {
     layoutView.children[3].map(RawTokenSyntax.init(raw:))
   }
 
-  public var unexpectedBetweenEachKeywordAndName: RawUnexpectedNodesSyntax? {
+  public var unexpectedBetweenSpecifierAndName: RawUnexpectedNodesSyntax? {
     layoutView.children[4].map(RawUnexpectedNodesSyntax.init(raw:))
   }
 

Sources/SwiftSyntax/generated/raw/RawSyntaxValidation.swift

@@ -1357,7 +1357,7 @@ func validateLayout(layout: RawSyntaxBuffer, as kind: SyntaxKind) {
     assertNoError(kind, 0, verify(layout[0], as: RawUnexpectedNodesSyntax?.self))
     assertNoError(kind, 1, verify(layout[1], as: RawAttributeListSyntax.self))
     assertNoError(kind, 2, verify(layout[2], as: RawUnexpectedNodesSyntax?.self))
-    assertNoError(kind, 3, verify(layout[3], as: RawTokenSyntax?.self, tokenChoices: [.keyword("each")]))
+    assertNoError(kind, 3, verify(layout[3], as: RawTokenSyntax?.self, tokenChoices: [.keyword("each"), .keyword("let")]))
     assertNoError(kind, 4, verify(layout[4], as: RawUnexpectedNodesSyntax?.self))
     assertNoError(kind, 5, verify(layout[5], as: RawTokenSyntax.self, tokenChoices: [.tokenKind(.identifier)]))
     assertNoError(kind, 6, verify(layout[6], as: RawUnexpectedNodesSyntax?.self))