[Test] Add a regression test for property wrapper backing initializers that

involve inout closure parameters and were previously type checked twice.

Author: hborla

test/Sema/property_wrappers.swift

@@ -0,0 +1,28 @@
+// RUN: %target-swift-frontend -typecheck -disable-availability-checking -dump-ast %s | %FileCheck %s
+
+struct Transaction {
+  var state: Int?
+}
+
+@propertyWrapper
+struct Wrapper<Value> {
+  var wrappedValue: Value
+
+  init(wrappedValue: Value,
+       reset: @escaping (Value, inout Transaction) -> Void) {
+    self.wrappedValue = wrappedValue
+  }
+}
+
+// rdar://problem/59685601
+// CHECK-LABEL: R_59685601
+struct R_59685601 {
+  // CHECK: tuple_expr implicit type='(wrappedValue: String, reset: (String, inout Transaction) -> Void)'
+  // CHECK-NEXT: opaque_value_expr implicit type='String'
+  // CHECK-NEXT: string_literal_expr type='String'
+  @Wrapper(reset: { value, transaction in
+    transaction.state = 10
+  })
+  private var value = "hello"
+}
+