Merge "libbinder: fix ToString() for smart pointers" am: 616ddc4f6f am: 06863efc21 am: da67104987

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1589291

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I30fc85023a60a111317bdba8cb0c104932a4b88a

1 files changed, 37 insertions, 11 deletions

diff --git a/libs/binder/ndk/include_cpp/android/binder_to_string.h b/libs/binder/ndk/include_cpp/android/binder_to_string.h
index bd51b1167f..584292551b 100644
--- a/libs/binder/ndk/include_cpp/android/binder_to_string.h
+++ b/libs/binder/ndk/include_cpp/android/binder_to_string.h
@@ -28,10 +28,22 @@
 
 #include <codecvt>
 #include <locale>
+#include <memory>
+#include <optional>
 #include <sstream>
 #include <string>
 #include <type_traits>
 
+#if __has_include(<utils/StrongPointer.h>)
+#include <utils/StrongPointer.h>
+#define HAS_STRONG_POINTER
+#endif
+
+#if __has_include(<utils/String16.h>)
+#include <utils/String16.h>
+#define HAS_STRING16
+#endif
+
 #if __has_include(<android/binder_ibinder.h>)
 #include <android/binder_auto_utils.h>
 #include <android/binder_interface_utils.h>
@@ -42,9 +54,6 @@
 #include <binder/IInterface.h>
 #include <binder/ParcelFileDescriptor.h>
 #include <binder/ParcelableHolder.h>
-#include <utils/String16.h>
-#include <utils/StrongPointer.h>
-#define HAS_CPP_INTERFACE
 #endif  //_has_include
 
 namespace android {
@@ -80,11 +89,28 @@ class HasToStringFunction {
     enum { value = decltype(_test<_T>(0))::value };
 };
 
-// Truthy if _T is like a pointer
+template <typename T, template <typename...> typename U>
+struct IsInstantiationOf : std::false_type {};
+
+template <template <typename...> typename U, typename... Args>
+struct IsInstantiationOf<U<Args...>, U> : std::true_type {};
+
+// Truthy if _T is like a pointer: one of sp/optional/shared_ptr
 template <typename _T>
 class IsPointerLike {
     template <typename _U>
-    static auto _test(int) -> decltype(!std::declval<_U>(), *std::declval<_U>(), std::true_type());
+    static std::enable_if_t<
+#ifdef HAS_STRONG_POINTER
+            IsInstantiationOf<_U, sp>::value ||  // for IBinder and interface types in the C++
+                                                 // backend
+#endif
+                    IsInstantiationOf<_U, std::optional>::value ||  // for @nullable types in the
+                                                                    // C++/NDK backends
+                    IsInstantiationOf<_U, std::shared_ptr>::value,  // for interface types in the
+                                                                    // NDK backends
+
+            std::true_type>
+    _test(int);
     template <typename _U>
     static std::false_type _test(...);
 
@@ -142,12 +168,17 @@ std::string ToString(const _T& t) {
         return std::to_string(t);
     } else if constexpr (std::is_same_v<std::string, _T>) {
         return t;
-#ifdef HAS_CPP_INTERFACE
+#ifdef HAS_STRING16
     } else if constexpr (std::is_same_v<String16, _T>) {
         std::stringstream out;
         out << t;
         return out.str();
 #endif
+    } else if constexpr (details::IsPointerLike<_T>::value) {
+        if (!t) return "(null)";
+        std::stringstream out;
+        out << ToString(*t);
+        return out.str();
     } else if constexpr (details::HasToStringMethod<_T>::value) {
         return t.toString();
     } else if constexpr (details::HasToStringFunction<_T>::value) {
@@ -168,11 +199,6 @@ std::string ToString(const _T& t) {
         }
         out << "]";
         return out.str();
-    } else if constexpr (details::IsPointerLike<_T>::value) {
-        if (!t) return "(null)";
-        std::stringstream out;
-        out << ToString(*t);
-        return out.str();
     } else {
         return "{no toString() implemented}";
     }