Merge "Flag forbidden super classes: AsyncTask and Activity"

src/main/java/com/android/tools/metalava/ApiLint.kt

@@ -71,6 +71,7 @@ import com.android.tools.metalava.doclava1.Errors.EXCEPTION_NAME
 import com.android.tools.metalava.doclava1.Errors.EXECUTOR_REGISTRATION
 import com.android.tools.metalava.doclava1.Errors.EXTENDS_ERROR
 import com.android.tools.metalava.doclava1.Errors.Error
+import com.android.tools.metalava.doclava1.Errors.FORBIDDEN_SUPER_CLASS
 import com.android.tools.metalava.doclava1.Errors.FRACTION_FLOAT
 import com.android.tools.metalava.doclava1.Errors.GENERIC_EXCEPTION
 import com.android.tools.metalava.doclava1.Errors.GETTER_SETTER_NAMES
@@ -309,6 +310,7 @@ class ApiLint(private val codebase: Codebase, private val oldCodebase: Codebase?
         checkUserHandle(cls, methods)
         checkParams(cls)
         checkSingleton(cls, methods, constructors)
+        checkExtends(cls)
 
         // TODO: Not yet working
         // checkOverloadArgs(cls, methods)
@@ -3232,6 +3234,23 @@ class ApiLint(private val codebase: Codebase, private val oldCodebase: Codebase?
         }
     }
 
+    private fun checkExtends(cls: ClassItem) {
+        // Call cls.superClass().extends() instead of cls.extends() since extends returns true for self
+        val superCls = cls.superClass() ?: return
+        if (superCls.extends("android.os.AsyncTask")) {
+            report(
+                FORBIDDEN_SUPER_CLASS, cls,
+                "${cls.simpleName()} should not extend `AsyncTask`. AsyncTask is an implementation detail. Expose a listener or, in androidx, a `ListenableFuture` API instead"
+            )
+        }
+        if (superCls.extends("android.app.Activity")) {
+            report(
+                FORBIDDEN_SUPER_CLASS, cls,
+                "${cls.simpleName()} should not extend `Activity`. Activity subclasses are impossible to compose. Expose a composable API instead."
+            )
+        }
+    }
+
     /**
      * Checks whether the given full package name is the same as the given root
      * package or a sub package (if we just did full.startsWith("java"), then

src/main/java/com/android/tools/metalava/doclava1/Errors.java

@@ -342,6 +342,7 @@ public class Errors {
     public static final Error MISSING_JVMSTATIC = new Error(381, WARNING, Category.API_LINT); // Formerly 143
     public static final Error DEFAULT_VALUE_CHANGE = new Error(382, ERROR, Category.API_LINT); // Formerly 144
     public static final Error DOCUMENT_EXCEPTIONS = new Error(383, ERROR, Category.API_LINT); // Formerly 145
+    public static final Error FORBIDDEN_SUPER_CLASS = new Error(384, ERROR, Category.API_LINT);
 
     static {
         // Attempt to initialize error names based on the field names

src/test/java/com/android/tools/metalava/ApiLintTest.kt

@@ -693,9 +693,11 @@ class ApiLintTest : DriverTest() {
                 src/android/pkg/MyClass1.java:3: error: Inconsistent class name; should be `<Foo>Activity`, was `MyClass1` [ContextNameSuffix] [Rule C4 in go/android-api-guidelines]
                 src/android/pkg/MyClass1.java:6: warning: Methods implemented by developers should follow the on<Something> style, was `badlyNamedAbstractMethod` [OnNameExpected]
                 src/android/pkg/MyClass1.java:7: warning: If implemented by developer, should follow the on<Something> style; otherwise consider marking final [OnNameExpected]
+                src/android/pkg/MyClass1.java:3: error: MyClass1 should not extend `Activity`. Activity subclasses are impossible to compose. Expose a composable API instead. [ForbiddenSuperClass]
                 src/android/pkg/MyClass2.java:3: error: Inconsistent class name; should be `<Foo>Provider`, was `MyClass2` [ContextNameSuffix] [Rule C4 in go/android-api-guidelines]
                 src/android/pkg/MyClass3.java:3: error: Inconsistent class name; should be `<Foo>Service`, was `MyClass3` [ContextNameSuffix] [Rule C4 in go/android-api-guidelines]
                 src/android/pkg/MyClass4.java:3: error: Inconsistent class name; should be `<Foo>Receiver`, was `MyClass4` [ContextNameSuffix] [Rule C4 in go/android-api-guidelines]
+                src/android/pkg/MyOkActivity.java:3: error: MyOkActivity should not extend `Activity`. Activity subclasses are impossible to compose. Expose a composable API instead. [ForbiddenSuperClass]
                 """,
             sourceFiles = *arrayOf(
                 java(
@@ -2030,4 +2032,43 @@ class ApiLintTest : DriverTest() {
             )
         )
     }
+
+    @Test
+    fun `Check forbidden super-classes`() {
+        check(
+            apiLint = "", // enabled
+            compatibilityMode = false,
+            warnings = """
+                src/android/pkg/FirstActivity.java:2: error: FirstActivity should not extend `Activity`. Activity subclasses are impossible to compose. Expose a composable API instead. [ForbiddenSuperClass]
+                src/android/pkg/IndirectActivity.java:2: error: IndirectActivity should not extend `Activity`. Activity subclasses are impossible to compose. Expose a composable API instead. [ForbiddenSuperClass]
+                src/android/pkg/MyTask.java:2: error: MyTask should not extend `AsyncTask`. AsyncTask is an implementation detail. Expose a listener or, in androidx, a `ListenableFuture` API instead [ForbiddenSuperClass]
+                """,
+            sourceFiles = *arrayOf(
+                java(
+                    """
+                    package android.pkg;
+                    public abstract class FirstActivity extends android.app.Activity {
+                        private FirstActivity() { }
+                    }
+                    """
+                ),
+                java(
+                    """
+                    package android.pkg;
+                    public abstract class IndirectActivity extends android.app.ListActivity {
+                        private IndirectActivity() { }
+                    }
+                    """
+                ),
+                java(
+                    """
+                    package android.pkg;
+                    public abstract class MyTask extends android.os.AsyncTask<String,String,String> {
+                        private MyTask() { }
+                    }
+                    """
+                )
+            )
+        )
+    }
 }