swiftlang
diff --git a/‎Sources/SwiftParser/ExperimentalFeatures.swift
Lines changed: 3 additions & 0 deletions b/‎Sources/SwiftParser/ExperimentalFeatures.swift
Lines changed: 3 additions & 0 deletions
diff --git a/‎Sources/SwiftParser/Modifiers.swift
Lines changed: 21 additions & 5 deletions b/‎Sources/SwiftParser/Modifiers.swift
Lines changed: 21 additions & 5 deletions
diff --git a/‎Tests/SwiftParserTest/DeclarationTests.swift
Lines changed: 18 additions & 1 deletion b/‎Tests/SwiftParserTest/DeclarationTests.swift
Lines changed: 18 additions & 1 deletion
@@ -26,4 +26,7 @@ extension Parser.ExperimentalFeatures {
 
   /// Whether to enable the parsing of 'then' statements.
   public static let thenStatements = Self(rawValue: 1 << 1)
+
+  /// Whether to enable the parsing of strict concurrency for globals.
+  public static let globalConcurrency = Self(rawValue: 1 << 2)
 }
@@ -61,7 +61,12 @@ extension Parser {
       case (.declarationModifier(.unowned), let handle)?:
         elements.append(self.parseUnownedModifier(handle))
       case (.declarationModifier(.nonisolated), let handle)?:
-        elements.append(parseNonisolatedModifier(handle))
+        if experimentalFeatures.contains(.globalConcurrency) {
+          elements.append(parseNonisolatedModifier(handle))
+        } else {
+          let (unexpectedBeforeKeyword, keyword) = self.eat(handle)
+          elements.append(RawDeclModifierSyntax(unexpectedBeforeKeyword, name: keyword, detail: nil, arena: self.arena))
+        }
       case (.declarationModifier(.final), let handle)?,
         (.declarationModifier(.required), let handle)?,
         (.declarationModifier(.optional), let handle)?,
@@ -99,9 +104,9 @@ extension Parser {
 }
 
 extension Parser {
-  mutating func parseModifierDetail(_ keyword: Keyword) -> RawDeclModifierDetailSyntax {
+  mutating func parseModifierDetail() -> RawDeclModifierDetailSyntax {
     let (unexpectedBeforeLeftParen, leftParen) = self.expect(.leftParen)
-    let (unexpectedBeforeDetailToken, detailToken) = self.expect(.identifier, TokenSpec(keyword, remapping: .identifier), default: .identifier)
+    let (unexpectedBeforeDetailToken, detailToken) = self.expect(.identifier, TokenSpec(.set, remapping: .identifier), default: .identifier)
     let (unexpectedBeforeRightParen, rightParen) = self.expect(.rightParen)
     return RawDeclModifierDetailSyntax(
       unexpectedBeforeLeftParen,
@@ -119,7 +124,7 @@ extension Parser {
 
     let detail: RawDeclModifierDetailSyntax?
     if self.at(.leftParen) {
-      detail = self.parseModifierDetail(.set)
+      detail = self.parseModifierDetail()
     } else {
       detail = nil
     }
@@ -224,7 +229,18 @@ extension Parser {
 
     let detail: RawDeclModifierDetailSyntax?
     if self.at(.leftParen) {
-      detail = self.parseModifierDetail(.unsafe)
+      let (unexpectedBeforeLeftParen, leftParen) = self.expect(.leftParen)
+      let (unexpectedBeforeDetailToken, detailToken) = self.expect(TokenSpec(.unsafe, remapping: .identifier))
+      let (unexpectedBeforeRightParen, rightParen) = self.expect(.rightParen)
+      detail = RawDeclModifierDetailSyntax(
+        unexpectedBeforeLeftParen,
+        leftParen: leftParen,
+        unexpectedBeforeDetailToken,
+        detail: detailToken,
+        unexpectedBeforeRightParen,
+        rightParen: rightParen,
+        arena: self.arena
+      )
     } else {
       detail = nil
     }
 
@@ -193,8 +193,25 @@ final class DeclarationTests: ParserTestCase {
       struct A {
         nonisolated(unsafe) let b = 0
         nonisolated(unsafe) var c: Int { 0 }
+        nonisolated(1️⃣safe) let d = 0
       }
-      """
+      """,
+      diagnostics: [
+        DiagnosticSpec(
+          message: "expected 'unsafe' in modifier",
+          fixIts: ["replace 'safe' with 'unsafe'"]
+        )
+      ],
+      fixedSource: """
+        nonisolated(unsafe) let a = 0
+
+        struct A {
+          nonisolated(unsafe) let b = 0
+          nonisolated(unsafe) var c: Int { 0 }
+          nonisolated(unsafe) let d = 0
+        }
+        """,
+      experimentalFeatures: [.globalConcurrency]
     )
   }
Original file line number	Diff line number	Diff line change
`@@ -26,4 +26,7 @@ extension Parser.ExperimentalFeatures {`
`26`	`26`
`27`	`27`	`/// Whether to enable the parsing of 'then' statements.`
`28`	`28`	`public static let thenStatements = Self(rawValue: 1 << 1)`
	`29`	`+`
	`30`	`+ /// Whether to enable the parsing of strict concurrency for globals.`
	`31`	`+ public static let globalConcurrency = Self(rawValue: 1 << 2)`
`29`	`32`	`}`