Add support for @preconcurrency type attribute

Part of the `@preconcurrency` conformances feature. Swift Forums discussion - https://forums.swift.org/t/pitch-dynamic-actor-isolation-enforcement/68354

Author: xedin

CodeGeneration/Sources/SyntaxSupport/KeywordSpec.swift

@@ -232,6 +232,7 @@ public enum Keyword: CaseIterable {
  case package
  case postfix
  case `precedencegroup`
+ case preconcurrency
  case prefix
  case `private`
  case `Protocol`
@@ -684,6 +685,8 @@ public enum Keyword: CaseIterable {
  return KeywordSpec("unavailable")
  case .unchecked:
  return KeywordSpec("unchecked")
+ case .preconcurrency:
+ return KeywordSpec("preconcurrency")
  case .unowned:
  return KeywordSpec("unowned")
  case .unsafe:

Sources/SwiftParser/TokenPrecedence.swift

@@ -247,6 +247,7 @@ enum TokenPrecedence: Comparable {
  .escaping,
  .noDerivative,
  .noescape,
+ .preconcurrency,
  .Sendable,
  .retroactive,
  .unchecked:

Sources/SwiftParser/TokenSpecSet.swift

@@ -636,6 +636,7 @@ enum TypeAttribute: TokenSpecSet {
  case escaping
  case noDerivative
  case noescape
+ case preconcurrency
  case retroactive
  case Sendable
  case unchecked
@@ -652,6 +653,7 @@ enum TypeAttribute: TokenSpecSet {
  case TokenSpec(.escaping): self = .escaping
  case TokenSpec(.noDerivative): self = .noDerivative
  case TokenSpec(.noescape): self = .noescape
+ case TokenSpec(.preconcurrency): self = .preconcurrency
  case TokenSpec(.Sendable): self = .Sendable
  case TokenSpec(.retroactive): self = .retroactive
  case TokenSpec(.unchecked): self = .unchecked
@@ -671,6 +673,7 @@ enum TypeAttribute: TokenSpecSet {
  case .escaping: return .keyword(.escaping)
  case .noDerivative: return .keyword(.noDerivative)
  case .noescape: return .keyword(.noescape)
+ case .preconcurrency: return .keyword(.preconcurrency)
  case .retroactive: return .keyword(.retroactive)
  case .Sendable: return .keyword(.Sendable)
  case .unchecked: return .keyword(.unchecked)

Sources/SwiftParser/Types.swift

@@ -924,7 +924,7 @@ extension Parser {
  mutating func parseTypeAttribute() -> RawAttributeListSyntax.Element {
  switch peek(isAtAnyIn: TypeAttribute.self) {
  case ._local, ._noMetadata, .async, .escaping, .noDerivative, .noescape,
- .retroactive, .Sendable, .unchecked, .autoclosure:
+ .preconcurrency, .retroactive, .Sendable, .unchecked, .autoclosure:
  // Known type attribute that doesn't take any arguments
  return parseAttributeWithoutArguments()
  case .differentiable:

Sources/SwiftSyntax/generated/Keyword.swift

@@ -174,6 +174,7 @@ public enum Keyword: UInt8, Hashable {
  case package
  case postfix
  case `precedencegroup`
+ case preconcurrency
  case prefix
  case `private`
  case `Protocol`
@@ -676,6 +677,8 @@ public enum Keyword: UInt8, Hashable {
  self = .associatedtype
  case "differentiable":
  self = .differentiable
+ case "preconcurrency":
+ self = .preconcurrency
  case "witness_method":
  self = .witness_method
  default:
@@ -949,6 +952,7 @@ public enum Keyword: UInt8, Hashable {
  "package", 
  "postfix", 
  "precedencegroup", 
+ "preconcurrency", 
  "prefix", 
  "private", 
  "Protocol", 

Tests/SwiftParserTest/DeclarationTests.swift

@@ -742,6 +742,20 @@ final class DeclarationTests: ParserTestCase {
  )
  }
 
+ func testParsePreconcurrency() {
+ assertParse(
+ """
+ struct MyValue: @preconcurrency P {}
+ """
+ )
+
+ assertParse(
+ """
+ extension MyValue: @preconcurrency P {}
+ """
+ )
+ }
+
  func testParseDynamicReplacement() {
  assertParse(
  """