Add validation test for issue #46000

Author: Greg Titus

validation-test/Sema/issue-46000.swift

@@ -0,0 +1,23 @@
+// RUN: %target-typecheck-verify-swift
+
+// https://github.com/apple/swift/issues/46000
+
+import Dispatch
+import Foundation
+
+extension DispatchData {
+
+  func asFoundationData<T>(execute: (Data) throws -> T) rethrows -> T {
+
+    //FIXME: SWIFT(SR-3097) - DispatchData.withUnsafeBytes crashes when empty.
+    guard isEmpty == false else {
+      return try execute(Data())
+    }
+
+    return try withUnsafeBytes { (ptr: UnsafePointer<Int8>) -> Void in
+      // expected-error@-1 {{cannot convert return expression of type 'Void' to return type 'T'}}
+      let foundationData = Data(bytesNoCopy: UnsafeMutableRawPointer(mutating: ptr), count: count, deallocator: .none)
+      return try execute(foundationData) // expected-error {{cannot convert value of type 'T' to closure result type 'Void'}}
+    }
+  }
+}