Re-enable the ComposeRendering sample.

samples/src/main/java/com/squareup/sample/hellocomposerendering/HelloRenderingWorkflow.kt

@@ -15,35 +15,46 @@
  */
 package com.squareup.sample.hellocomposerendering
 
-// There is a bug in Compose dev12 that crashes the compiler when processing this code.
-// See https://github.com/square/workflow-kotlin-compose/issues/42.
-// /**
-//  * A [ComposeWorkflow] that is used by [HelloWorkflow] to render the screen.
-//  *
-//  * This workflow has type `Workflow<String, Toggle, ComposeRendering>`.
-//  */
-// object HelloRenderingWorkflow : ComposeWorkflow<String, Toggle>() {
-//
-//   object Toggle
-//
-//   @Composable override fun render(
-//     props: String,
-//     outputSink: Sink<Toggle>,
-//     viewEnvironment: ViewEnvironment
-//   ) {
-//     MaterialTheme {
-//       Text(
-//           props,
-//           modifier = Modifier
-//               .ripple()
-//               .clickable(onClick = { outputSink.send(Toggle) })
-//               .wrapContentSize(Alignment.Center)
-//       )
-//     }
-//   }
-// }
-//
-// @Preview(showBackground = true)
-// @Composable fun HelloRenderingWorkflowPreview() {
-//   HelloRenderingWorkflow.preview(props = "hello")
-// }
+import androidx.compose.foundation.Text
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.wrapContentSize
+import androidx.compose.material.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.ui.tooling.preview.Preview
+import com.squareup.sample.hellocomposerendering.HelloRenderingWorkflow.Toggle
+import com.squareup.workflow.Sink
+import com.squareup.workflow.ui.ViewEnvironment
+import com.squareup.workflow.ui.compose.ComposeWorkflow
+import com.squareup.workflow.ui.compose.tooling.preview
+
+/**
+ * A [ComposeWorkflow] that is used by [HelloWorkflow] to render the screen.
+ *
+ * This workflow has type `Workflow<String, Toggle, ComposeRendering>`.
+ */
+object HelloRenderingWorkflow : ComposeWorkflow<String, Toggle>() {
+
+  object Toggle
+
+  @Composable override fun render(
+    props: String,
+    outputSink: Sink<Toggle>,
+    viewEnvironment: ViewEnvironment
+  ) {
+    MaterialTheme {
+      Text(
+          props,
+          modifier = Modifier
+              .clickable(onClick = { outputSink.send(Toggle) })
+              .wrapContentSize(Alignment.Center)
+      )
+    }
+  }
+}
+
+@Preview(showBackground = true)
+@Composable fun HelloRenderingWorkflowPreview() {
+  HelloRenderingWorkflow.preview(props = "hello")
+}

samples/src/main/java/com/squareup/sample/hellocomposerendering/HelloWorkflow.kt

@@ -50,9 +50,8 @@ object HelloWorkflow : StatefulWorkflow<Unit, State, Nothing, ComposeRendering>(
     props: Unit,
     state: State,
     context: RenderContext<State, Nothing>
-  ): ComposeRendering = ComposeRendering.NoopRendering
-  // See https://github.com/square/workflow-kotlin-compose/issues/42.
-  //context.renderChild(HelloRenderingWorkflow, state.name) { helloAction }
+  ): ComposeRendering =
+    context.renderChild(HelloRenderingWorkflow, state.name) { helloAction }
 
   override fun snapshotState(state: State): Snapshot = Snapshot.of(if (state == Hello) 1 else 0)
 }

samples/src/main/java/com/squareup/sample/launcher/Samples.kt

@@ -23,6 +23,8 @@ import com.squareup.sample.hellocompose.App
 import com.squareup.sample.hellocompose.HelloComposeActivity
 import com.squareup.sample.hellocomposebinding.DrawHelloRenderingPreview
 import com.squareup.sample.hellocomposebinding.HelloBindingActivity
+import com.squareup.sample.hellocomposerendering.HelloComposeRenderingActivity
+import com.squareup.sample.hellocomposerendering.HelloRenderingWorkflowPreview
 import com.squareup.sample.nestedrenderings.NestedRenderingsActivity
 import com.squareup.sample.nestedrenderings.RecursiveViewFactoryPreview
 import kotlin.reflect.KClass
@@ -32,11 +34,10 @@ val samples = listOf(
         "Hello Compose Binding", HelloBindingActivity::class,
         "Creates a ViewFactory using bindCompose."
     ) { DrawHelloRenderingPreview() },
-    // Broken in dev12, see https://github.com/square/workflow-kotlin-compose/issues/42.
-    // Sample(
-    //     "Hello Compose Rendering", HelloComposeRenderingActivity::class,
-    //     "Uses ComposeWorkflow to create a workflow that draws itself."
-    // ) { HelloRenderingWorkflowPreview() },
+    Sample(
+        "Hello Compose Rendering", HelloComposeRenderingActivity::class,
+        "Uses ComposeWorkflow to create a workflow that draws itself."
+    ) { HelloRenderingWorkflowPreview() },
     Sample(
         "Hello Compose", HelloComposeActivity::class,
         "A pure Compose app that launches its root Workflow from inside Compose."