Tests: Add a regression test for module interface printing of conditionally available property wrappers.

Author: tshortli

test/ModuleInterface/property_wrapper_availability.swift

@@ -0,0 +1,28 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-emit-module-interface(%t/Library.swiftinterface) %s -module-name Library -target %target-swift-abi-5.3-triple
+// RUN: %target-swift-typecheck-module-from-interface(%t/Library.swiftinterface) -module-name Library
+// RUN: %FileCheck %s < %t/Library.swiftinterface
+
+@available(SwiftStdlib 5.2, *)
+@propertyWrapper
+public struct ConditionallyAvailableWrapper<T> {
+  public var wrappedValue: T
+
+  public init(wrappedValue: T) {
+    self.wrappedValue = wrappedValue
+  }
+}
+
+// CHECK: public struct HasWrappers {
+public struct HasWrappers {
+  // CHECK: @available(macOS 10.15.4, iOS 13.4, watchOS 6.2, tvOS 13.4, *)
+  // CHECK-NEXT: @Library.ConditionallyAvailableWrapper public var x: Swift.Int {
+  // CHECK-NEXT:   get
+  // CHECK-NEXT:   @available(iOS 13.4, tvOS 13.4, watchOS 6.2, macOS 10.15.4, *)
+  // CHECK-NEXT:   set
+  // CHECK-NEXT:   @available(iOS 13.4, tvOS 13.4, watchOS 6.2, macOS 10.15.4, *)
+  // CHECK-NEXT:   _modify
+  // CHECK-NEXT: }
+  @available(SwiftStdlib 5.2, *)
+  @ConditionallyAvailableWrapper public var x: Int
+}