Disable assign-only property analysis with Swift 6.1, #901 (#905)

Author: ileitch

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ##### Breaking
 
-- None.
+- Assign-only property analysis is disabled with Swift 6.1 due to a Swift bug: https://github.com/swiftlang/swift/issues/80394.
 
 ##### Enhancements
 

Sources/Frontend/Commands/ScanCommand.swift

@@ -202,6 +202,11 @@ struct ScanCommand: FrontendCommand {
         logger.debug(swiftVersion.fullVersion)
         try swiftVersion.validateVersion()
 
+        if swiftVersion.version.isVersion(equalTo: "6.1"), !retainAssignOnlyProperties {
+            logger.warn("Assign-only property analysis is disabled with Swift 6.1 due to a Swift bug: https://github.com/swiftlang/swift/issues/80394.")
+            configuration.retainAssignOnlyProperties = true
+        }
+
         let project: Project = if configuration.guidedSetup {
             try GuidedSetup(configuration: configuration, shell: shell, logger: logger).perform()
         } else {