Update Signature attribute in ClassFile when an @androidentrypoint ha…

…s parameterized types.

When an Android entry point has a superclass that uses parameterized types then the Class file will contain a Signature attribute that also has to be updated since the super_class is changed via Hilt's transform. The attribute is not checked by the JVM during linking, which is why it had not caused any issues before, but it does affected certain reflective APIs. See: https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.9

Fixes: #3094
RELNOTES=Fix an issue where Hilt transform was not correctly updating the Signature attribute of an @androidentrypoint whose superclass contained a type variable.
PiperOrigin-RevId: 414441547

java/dagger/hilt/android/plugin/src/main/kotlin/dagger/hilt/android/plugin/AndroidEntryPointClassVisitor.kt

@@ -70,7 +70,8 @@ class AndroidEntryPointClassVisitor(
     newSuperclassName =
       packageName + "/Hilt_" + className.replace("$", "_")
     oldSuperclassName = superName ?: error { "Superclass of $name is null!" }
-    super.visit(version, access, name, signature, newSuperclassName, interfaces)
+    val newSignature = signature?.replace(oldSuperclassName, newSuperclassName)
+    super.visit(version, access, name, newSignature, newSuperclassName, interfaces)
   }
 
   override fun visitMethod(

java/dagger/hilt/android/plugin/src/test/kotlin/TransformTest.kt

@@ -19,6 +19,7 @@ import java.io.DataInputStream
 import java.io.FileInputStream
 import javassist.bytecode.ByteArray
 import javassist.bytecode.ClassFile
+import javassist.bytecode.SignatureAttribute
 import org.gradle.testkit.runner.TaskOutcome
 import org.junit.Assert
 import org.junit.Before
@@ -306,6 +307,59 @@ class TransformTest {
     assertThat(assembleTask.outcome).isEqualTo(TaskOutcome.SUCCESS)
   }
 
+  // Verifies the Signature attribute in the ClassFile is updated when the superclass uses type
+  // variables or parameterized types.
+  // See: https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.9
+  @Test
+  fun testTransform_genericSuperclass() {
+    gradleRunner.addDependencies(
+      "implementation 'androidx.appcompat:appcompat:1.1.0'",
+      "implementation 'com.google.dagger:hilt-android:LOCAL-SNAPSHOT'",
+      "annotationProcessor 'com.google.dagger:hilt-compiler:LOCAL-SNAPSHOT'"
+    )
+
+    gradleRunner.addSrc(
+      srcPath = "minimal/BaseActivity.java",
+      srcContent =
+      """
+        package minimal;
+
+        import androidx.appcompat.app.AppCompatActivity;
+
+        public abstract class BaseActivity<T> extends AppCompatActivity {
+        }
+        """.trimIndent()
+    )
+
+    gradleRunner.addSrc(
+      srcPath = "minimal/SimpleActivity.java",
+      srcContent =
+      """
+        package minimal;
+
+        @dagger.hilt.android.AndroidEntryPoint
+        public class SimpleActivity extends BaseActivity<String> {
+        }
+        """.trimIndent()
+    )
+
+    val result = gradleRunner.build()
+    val assembleTask = result.getTask(":assembleDebug")
+    Assert.assertEquals(TaskOutcome.SUCCESS, assembleTask.outcome)
+
+    val transformedClass = result.getTransformedFile("minimal/SimpleActivity.class")
+    FileInputStream(transformedClass).use { fileInput ->
+      ClassFile(DataInputStream(fileInput)).let { classFile ->
+        Assert.assertEquals("minimal.Hilt_SimpleActivity", classFile.superclass)
+        val signatureAttr = classFile.getAttribute(SignatureAttribute.tag) as SignatureAttribute
+        Assert.assertEquals(
+          "Lminimal/Hilt_SimpleActivity<Ljava/lang/String;>;",
+          signatureAttr.signature
+        )
+      }
+    }
+  }
+
   companion object {
     const val TRANSFORM_TASK_NAME =
       ":transformDebugClassesWithAsm"