Parcelable: Allow custom describeContents() implementation

Author: yanex

plugins/android-extensions/android-extensions-compiler/src/org/jetbrains/kotlin/android/parcel/ParcelableResolveExtension.kt

@@ -18,6 +18,7 @@ package org.jetbrains.kotlin.android.parcel
 
 import kotlinx.android.parcel.MagicParcel
 import org.jetbrains.kotlin.android.parcel.ParcelableSyntheticComponent.ComponentKind.*
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.descriptors.impl.SimpleFunctionDescriptorImpl
@@ -78,14 +79,18 @@ class ParcelableResolveExtension : SyntheticResolveExtension {
             fromSupertypes: List<SimpleFunctionDescriptor>,
             result: MutableCollection<SimpleFunctionDescriptor>
     ) {
-        if (name.asString() == DESCRIBE_CONTENTS.methodName && clazz.isMagicParcelable) {
+        if (name.asString() == DESCRIBE_CONTENTS.methodName && clazz.isMagicParcelable && result.none { it.isDescribeContents() }) {
             result += createMethod(clazz, DESCRIBE_CONTENTS, clazz.builtIns.intType)
         } else if (name.asString() == WRITE_TO_PARCEL.methodName && clazz.isMagicParcelable) {
             val builtIns = clazz.builtIns
             val parcelClassType = resolveParcelClassType(clazz.module)
             result += createMethod(clazz, WRITE_TO_PARCEL, builtIns.unitType, "parcel" to parcelClassType, "flags" to builtIns.intType)
         }
     }
+
+    private fun SimpleFunctionDescriptor.isDescribeContents(): Boolean {
+        return typeParameters.isEmpty() && valueParameters.isEmpty() && returnType?.let { type -> KotlinBuiltIns.isInt(type) } == true
+    }
 }
 
 interface ParcelableSyntheticComponent {

plugins/android-extensions/android-extensions-compiler/testData/parcel/codegen/customDescribeContents.kt

@@ -0,0 +1,9 @@
+// CURIOUS_ABOUT describeContents
+
+import kotlinx.android.parcel.*
+import android.os.Parcelable
+
+@MagicParcel
+class User(val firstName: String, val lastName: String, val age: Int, val isProUser: Boolean) : Parcelable {
+    override fun describeContents() = 100
+}

plugins/android-extensions/android-extensions-compiler/testData/parcel/codegen/customDescribeContents.txt

@@ -0,0 +1,41 @@
+public static class User$CREATOR : java/lang/Object, android/os/Parcelable$Creator {
+    public void <init>()
+
+    public final User createFromParcel(android.os.Parcel p0)
+
+    public final User[] newArray(int p0)
+}
+
+public final class User : java/lang/Object, android/os/Parcelable {
+    public final static User$CREATOR CREATOR
+
+    private final int age
+
+    private final java.lang.String firstName
+
+    private final boolean isProUser
+
+    private final java.lang.String lastName
+
+    static void <clinit>()
+
+    public void <init>(java.lang.String p0, java.lang.String p1, int p2, boolean p3)
+
+    public int describeContents() {
+        LABEL (L0)
+        LINENUMBER (8)
+          BIPUSH (100)
+          IRETURN
+        LABEL (L1)
+    }
+
+    public final int getAge()
+
+    public final java.lang.String getFirstName()
+
+    public final java.lang.String getLastName()
+
+    public final boolean isProUser()
+
+    public final void writeToParcel(android.os.Parcel p0, int p1)
+}

plugins/android-extensions/android-extensions-compiler/testData/parcel/codegen/simple.kt

@@ -1,4 +1,4 @@
-// CURIOUS_ABOUT writeToParcel, createFromParcel, <clinit>
+// CURIOUS_ABOUT writeToParcel, createFromParcel, <clinit>, describeContents
 
 import kotlinx.android.parcel.*
 import android.os.Parcelable

plugins/android-extensions/android-extensions-compiler/testData/parcel/codegen/simple.txt

@@ -45,7 +45,12 @@ public final class User : java/lang/Object, android/os/Parcelable {
 
     public void <init>(java.lang.String p0, java.lang.String p1, int p2, boolean p3)
 
-    public final int describeContents()
+    public final int describeContents() {
+        LABEL (L0)
+          LDC (0)
+          IRETURN
+        LABEL (L1)
+    }
 
     public final int getAge()
 

plugins/plugins-tests/tests/org/jetbrains/kotlin/android/parcel/ParcelBytecodeListingTestGenerated.java

@@ -36,6 +36,12 @@ public void testAllFilesPresentInCodegen() throws Exception {
         KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("plugins/android-extensions/android-extensions-compiler/testData/parcel/codegen"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
     }
 
+    @TestMetadata("customDescribeContents.kt")
+    public void testCustomDescribeContents() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("plugins/android-extensions/android-extensions-compiler/testData/parcel/codegen/customDescribeContents.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("listInsideList.kt")
     public void testListInsideList() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("plugins/android-extensions/android-extensions-compiler/testData/parcel/codegen/listInsideList.kt");