Make EnumTypeAdapter friendly with obfuscation

gson/pom.xml

@@ -16,6 +16,12 @@
       <artifactId>junit</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.github.wvengen</groupId>
+      <artifactId>proguard-maven-plugin</artifactId>
+      <version>2.3.1</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>
@@ -69,6 +75,87 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>com.coderplus.maven.plugins</groupId>
+        <artifactId>copy-rename-maven-plugin</artifactId>
+        <version>1.0</version>
+        <executions>
+          <execution>
+            <id>pre-obfuscate-class</id>
+            <phase>process-test-classes</phase>
+            <goals>
+              <goal>rename</goal>
+            </goals>
+            <configuration>
+              <fileSets>
+                <fileSet>
+                  <sourceFile>${project.build.directory}/test-classes/com/google/gson/functional/EnumWithObfuscatedTest.class</sourceFile>
+                  <destinationFile>${project.build.directory}/test-classes-obfuscated-injar/com/google/gson/functional/EnumWithObfuscatedTest.class</destinationFile>
+                </fileSet>
+                <fileSet>
+                  <sourceFile>${project.build.directory}/test-classes/com/google/gson/functional/EnumWithObfuscatedTest$Gender.class</sourceFile>
+                  <destinationFile>${project.build.directory}/test-classes-obfuscated-injar/com/google/gson/functional/EnumWithObfuscatedTest$Gender.class</destinationFile>
+                </fileSet>
+              </fileSets>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>com.github.wvengen</groupId>
+        <artifactId>proguard-maven-plugin</artifactId>
+        <executions>
+          <execution>
+            <phase>process-test-classes</phase>
+            <goals><goal>proguard</goal></goals>
+          </execution>
+        </executions>
+        <configuration>
+          <proguardVersion>6.2.2</proguardVersion>
+          <obfuscate>true</obfuscate>
+          <injar>test-classes-obfuscated-injar</injar>
+          <outjar>test-classes-obfuscated-outjar</outjar>
+          <inFilter>**/*.class</inFilter>
+          <proguardInclude>${basedir}/src/test/resources/testcases-proguard.conf</proguardInclude>
+          <libs>
+            <lib>${project.build.directory}/classes</lib>
+            <lib>${java.home}/jmods/java.base.jmod</lib>
+          </libs>
+        </configuration>
+        <dependencies>
+          <dependency>
+            <groupId>net.sf.proguard</groupId>
+            <artifactId>proguard-base</artifactId>
+            <version>6.2.2</version>
+            <scope>runtime</scope>
+          </dependency>
+        </dependencies>
+      </plugin>
+      <plugin>
+        <artifactId>maven-resources-plugin</artifactId>
+        <version>2.7</version>
+        <executions>
+          <execution>
+            <id>post-obfuscate-class</id>
+            <phase>process-test-classes</phase>
+            <goals>
+              <goal>copy-resources</goal>
+            </goals>
+            <configuration>
+              <outputDirectory>${project.build.directory}/test-classes/com/google/gson/functional</outputDirectory>
+              <resources>
+                <resource>
+                  <directory>${project.build.directory}/test-classes-obfuscated-outjar/com/google/gson/functional</directory>
+                  <includes>
+                    <include>EnumWithObfuscatedTest.class</include>
+                    <include>EnumWithObfuscatedTest$Gender.class</include>
+                  </includes>
+                </resource>
+              </resources>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
 </project>

gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java

@@ -17,12 +17,15 @@
 package com.google.gson.internal.bind;
 
 import java.io.IOException;
+import java.lang.reflect.Field;
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.net.InetAddress;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
 import java.sql.Timestamp;
 import java.util.ArrayList;
 import java.util.BitSet;
@@ -776,9 +779,20 @@ private static final class EnumTypeAdapter<T extends Enum<T>> extends TypeAdapte
 
     public EnumTypeAdapter(Class<T> classOfT) {
       try {
-        for (T constant : classOfT.getEnumConstants()) {
+        for (final Field field : classOfT.getDeclaredFields()) {
+          if (!field.isEnumConstant()) {
+            continue;
+          }
+          AccessController.doPrivileged(new PrivilegedAction<Void>() {
+            @Override public Void run() {
+              field.setAccessible(true);
+              return null;
+            }
+          });
+          @SuppressWarnings("unchecked")
+          T constant = (T)(field.get(null));
           String name = constant.name();
-          SerializedName annotation = classOfT.getField(name).getAnnotation(SerializedName.class);
+          SerializedName annotation = field.getAnnotation(SerializedName.class);
           if (annotation != null) {
             name = annotation.value();
             for (String alternate : annotation.alternate()) {
@@ -788,7 +802,7 @@ public EnumTypeAdapter(Class<T> classOfT) {
           nameToConstant.put(name, constant);
           constantToName.put(constant, name);
         }
-      } catch (NoSuchFieldException e) {
+      } catch (IllegalAccessException e) {
         throw new AssertionError(e);
       }
     }

gson/src/test/java/com/google/gson/functional/EnumWithObfuscatedTest.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2008 Google Inc.
+ *
+ * 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.
+ */
+
+package com.google.gson.functional;
+
+import com.google.gson.Gson;
+import com.google.gson.annotations.SerializedName;
+
+import junit.framework.TestCase;
+
+/**
+ * Functional tests for enums with Proguard.
+ *
+ * @author Young Cha
+ */
+public class EnumWithObfuscatedTest extends TestCase {
+  private Gson gson;
+
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    gson = new Gson();
+  }
+
+  public enum Gender {
+    @SerializedName("MAIL")
+    MALE,
+
+    @SerializedName("FEMAIL")
+    FEMALE
+  }
+
+  public void testEnumClassWithObfuscated() {
+    for (Gender enumConstant: Gender.class.getEnumConstants()) {
+      try {
+        Gender.class.getField(enumConstant.name());
+        fail("Enum is not obfuscated");
+      } catch (NoSuchFieldException ignore) {
+      }
+    }
+
+    assertEquals(Gender.MALE, gson.fromJson("\"MAIL\"", Gender.class));
+    assertEquals("\"MAIL\"", gson.toJson(Gender.MALE, Gender.class));
+  }
+}

gson/src/test/resources/testcases-proguard.conf

@@ -0,0 +1,20 @@
+# Options from Android Gradle Plugins
+# https://android.googlesource.com/platform/tools/base/+/refs/heads/studio-master-dev/build-system/gradle-core/src/main/resources/com/android/build/gradle
+-optimizations !code/simplification/arithmetic,!code/simplification/cast,!field/*,!class/merging/*
+-optimizationpasses 5
+-allowaccessmodification
+-keepattributes *Annotation*,Signature,InnerClasses,EnclosingMethod
+-keepclassmembers enum * {
+  public static **[] values();
+  public static ** valueOf(java.lang.String);
+}
+
+-keep enum com.google.gson.functional.EnumWithObfuscatedTest$Gender
+-keep class com.google.gson.functional.EnumWithObfuscatedTest {
+  public void test*();
+  protected void setUp();
+}
+
+-dontwarn com.google.gson.functional.EnumWithObfuscatedTest
+-dontwarn junit.framework.TestCase
+