[debug] Print strings using their description in the debugger

stdlib/public/core/DebuggerSupport.swift

@@ -238,7 +238,13 @@ public enum _DebuggerSupport {
       print("\(name) : ", terminator: "", to: &target)
     }
 
-    if let str = asStringRepresentation(value: value, mirror: mirror, count: count) {
+    if isRoot, let value = value as? String {
+      // We don't want to use string's debug desciprtion for 'po' because it
+      // escapes the string and prints it raw (e.g. prints "\n" instead of
+      // actually printing a newline), but only if its the root value. Otherwise,
+      // continue using the debug description.
+      print(value, terminator: "", to: &target)
+    } else if let str = asStringRepresentation(value: value, mirror: mirror, count: count) {
       print(str, terminator: "", to: &target)
     }
 

test/stdlib/BridgedObjectDebuggerSupport.swift

@@ -77,7 +77,12 @@ StringForPrintObjectTests.test("NSStringUTF8") {
   let debug = debugVal(&newNSUTF16)
   expectEqual("🏂☃❅❆❄︎⛄️❄️", String(reflecting: nsUTF16))
   expectEqual("\"🏂☃❅❆❄︎⛄️❄️\"", String(reflecting: newNSUTF16))
-  expectEqual("\"🏂☃❅❆❄︎⛄️❄️\"\n", printed)
+
+  if #available(SwiftStdlib 6.0, *) {
+    expectEqual("🏂☃❅❆❄︎⛄️❄️\n", printed)
+  } else {
+    expectEqual("\"🏂☃❅❆❄︎⛄️❄️\"\n", printed)
+  }
   expectEqual(printed, debug)
 }
 

test/stdlib/DebuggerSupport.swift

@@ -101,6 +101,13 @@ StringForPrintObjectTests.test("DontBridgeThisStruct") {
 }
 #endif
 
+if #available(SwiftStdlib 6.0, *) {
+  StringForPrintObjectTests.test("String") {
+    let printed = _stringForPrintObject("hello\nworld")
+    expectEqual(printed, "hello\nworld\n")
+  }
+}
+
 class RefCountedObj {
   var patatino : Int
   init(_ p : Int) {