tools/flow: ignore faulty tasks outside the root

This may only occur with InferTasks, the use of which
is highly discouraged.

Fixes #608

Change-Id: I840534a913e03630caabf3eb58a10a93d51b5a18
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/7943
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

cmd/cue/cmd/testdata/script/cmd_issue596.txt → cmd/cue/cmd/testdata/script/cmd_inferred.txt

@@ -3,8 +3,25 @@ cmp stdout expect-stdout
 -- f1.cue --
 package kube
 
+pkg: {
+	#Def: {
+		a: int
+		b: #Role
+	}
+	#Role: {
+		kind: string
+		name: string
+	}
+
+}
+
+test: pkg.#Def
 test: {
     a: 1
+	b: {
+		kind: "foo"
+		name: "bar"
+	}
 }
 
 // A kind at the top-level should not be allowed.
@@ -26,4 +43,7 @@ command: dump: {
 
 -- expect-stdout --
 a: 1
+b:
+  kind: foo
+  name: bar
 

tools/flow/flow_test.go

@@ -101,6 +101,9 @@ func taskFunc(v cue.Value) (flow.Runner, error) {
 				return nil
 			}), nil
 		}
+		if err != nil && v.Lookup("$id").Exists() {
+			return nil, err
+		}
 
 	case "valToOut":
 		return flow.RunnerFunc(func(t *flow.Task) error {

tools/flow/tasks.go

@@ -99,8 +99,13 @@ func (c *Controller) getTask(scope *Task, v cue.Value) *Task {
 
 		var errs errors.Error
 		if err != nil {
-			c.addErr(err, "invalid task")
-			errs = errors.Promote(err, "create task")
+			if !c.inRoot(w) {
+				// Must be in InferTask mode. In this case we ignore the error.
+				r = nil
+			} else {
+				c.addErr(err, "invalid task")
+				errs = errors.Promote(err, "create task")
+			}
 		}
 
 		if r != nil {
@@ -224,4 +229,18 @@ func (c *Controller) markTaskDependencies(t *Task, n *adt.Vertex) {
 	})
 }
 
+func (c *Controller) inRoot(n *adt.Vertex) bool {
+	path := cue.MakeValue(c.opCtx, n).Path().Selectors()
+	root := c.cfg.Root.Selectors()
+	if len(path) < len(root) {
+		return false
+	}
+	for i, sel := range root {
+		if path[i] != sel {
+			return false
+		}
+	}
+	return true
+}
+
 var cycleMarker = &Task{}

tools/flow/testdata/infer.txtar

@@ -8,10 +8,14 @@ top1: {
     $after: top0
 }
 
+top3: {
+    $id: string // not a task
+}
+
 root: {
     t1: {
         $id: "valToOut"
-        $after: top1
+        $after: [top1, top3]
     }
 }
 -- out/run/errors --
@@ -61,10 +65,12 @@ graph TD
 -- out/run/t3/value --
 {
 	$id: "valToOut"
-	$after: {
+	$after: [{
 		$id: "valToOut"
 		$after: {
 			$id: "valToOut"
 		}
-	}
+	}, {
+		$id: string
+	}]
 }