Emit an error message when looking for String#offset.

Debugging two different apps relying on it and swallowing
the getDeclaredField exception took too much of my lifetime.
Adding a LOG(ERROR) can help diagnose quicker.

Also remove unused method getDeclaredFieldInternal.

Change-Id: I0923556a4fdbad2b06c1811ed741d23dbd4aa0a0
diff --git a/runtime/native/java_lang_Class.cc b/runtime/native/java_lang_Class.cc
index 1977481..e89c74d 100644
--- a/runtime/native/java_lang_Class.cc
+++ b/runtime/native/java_lang_Class.cc
@@ -288,13 +288,6 @@
       GetPublicFieldRecursive(soa.Self(), DecodeClass(soa, javaThis), name_string));
 }
 
-static jobject Class_getDeclaredFieldInternal(JNIEnv* env, jobject javaThis, jstring name) {
-  ScopedFastNativeObjectAccess soa(env);
-  auto* name_string = soa.Decode<mirror::String*>(name);
-  return soa.AddLocalReference<jobject>(
-      GetDeclaredField(soa.Self(), DecodeClass(soa, javaThis), name_string));
-}
-
 static jobject Class_getDeclaredField(JNIEnv* env, jobject javaThis, jstring name) {
   ScopedFastNativeObjectAccess soa(env);
   auto* name_string = soa.Decode<mirror::String*>(name);
@@ -306,6 +299,12 @@
   mirror::Field* result = GetDeclaredField(soa.Self(), klass, name_string);
   if (result == nullptr) {
     std::string name_str = name_string->ToModifiedUtf8();
+    if (name_str == "value" && klass->IsStringClass()) {
+      // We log the error for this specific case, as the user might just swallow the exception.
+      // This helps diagnose crashes when applications rely on the String#value field being
+      // there.
+      LOG(ERROR) << "The String#value field is not present on Android versions >= 6.0";
+    }
     // We may have a pending exception if we failed to resolve.
     if (!soa.Self()->IsExceptionPending()) {
       ThrowNoSuchFieldException(DecodeClass(soa, javaThis), name_str.c_str());
@@ -723,7 +722,6 @@
   NATIVE_METHOD(Class, getDeclaredConstructorsInternal, "!(Z)[Ljava/lang/reflect/Constructor;"),
   NATIVE_METHOD(Class, getDeclaredField, "!(Ljava/lang/String;)Ljava/lang/reflect/Field;"),
   NATIVE_METHOD(Class, getPublicFieldRecursive, "!(Ljava/lang/String;)Ljava/lang/reflect/Field;"),
-  NATIVE_METHOD(Class, getDeclaredFieldInternal, "!(Ljava/lang/String;)Ljava/lang/reflect/Field;"),
   NATIVE_METHOD(Class, getDeclaredFields, "!()[Ljava/lang/reflect/Field;"),
   NATIVE_METHOD(Class, getDeclaredFieldsUnchecked, "!(Z)[Ljava/lang/reflect/Field;"),
   NATIVE_METHOD(Class, getDeclaredMethodInternal,
diff --git a/test/143-string-value/check b/test/143-string-value/check
new file mode 100755
index 0000000..8659500
--- /dev/null
+++ b/test/143-string-value/check
@@ -0,0 +1,20 @@
+#!/bin/bash
+#
+# Copyright (C) 2015 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Strip run-specific numbers (pid and line number)
+sed -e 's/^art E [0-9]\+ [0-9]\+ art\/runtime\/native\/java_lang_Class.cc:[0-9]\+\] //' "$2" > "$2.tmp"
+
+diff --strip-trailing-cr -q "$1" "$2.tmp" >/dev/null
diff --git a/test/143-string-value/expected.txt b/test/143-string-value/expected.txt
new file mode 100644
index 0000000..06cdb89
--- /dev/null
+++ b/test/143-string-value/expected.txt
@@ -0,0 +1 @@
+The String#value field is not present on Android versions >= 6.0
diff --git a/test/143-string-value/info.txt b/test/143-string-value/info.txt
new file mode 100644
index 0000000..61ec816
--- /dev/null
+++ b/test/143-string-value/info.txt
@@ -0,0 +1,2 @@
+Test to ensure we emit an error message when being asked
+for String#value.
diff --git a/test/143-string-value/src/Main.java b/test/143-string-value/src/Main.java
new file mode 100644
index 0000000..e970692
--- /dev/null
+++ b/test/143-string-value/src/Main.java
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public class Main {
+  public static void main(String[] args) {
+    try {
+      String.class.getDeclaredField("value");
+      throw new Error("Expected to fail");
+    } catch (ReflectiveOperationException e) {
+      // Ignore...
+    }
+  }
+}