fix: avoid panic when used pipelineRef or pipelineSpec in pipeline task

fix #7720

Currently, the `pipelineRef` and `pipelineSpec` are only in preview mode
and not yet supported. If a user has configured this field and enabled alpha
features, it might bypass validation and enter into controller logic. It is now
necessary to implement relevant checks within the controller logic to clearly
prompt the user, instead of causing the program to panic.

pkg/reconciler/pipelinerun/resources/pipelinerunresolution.go

@@ -630,7 +630,8 @@ func resolveTask(
 	pipelineTask v1.PipelineTask,
 ) (*resources.ResolvedTask, error) {
 	rt := &resources.ResolvedTask{}
-	if pipelineTask.TaskRef != nil {
+	switch {
+	case pipelineTask.TaskRef != nil:
 		// If the TaskRun has already a stored TaskSpec in its status, use it as source of truth
 		if taskRun != nil && taskRun.Status.TaskSpec != nil {
 			rt.TaskSpec = taskRun.Status.TaskSpec
@@ -655,8 +656,13 @@ func resolveTask(
 			}
 		}
 		rt.Kind = pipelineTask.TaskRef.Kind
-	} else {
+	case pipelineTask.TaskSpec != nil:
 		rt.TaskSpec = &pipelineTask.TaskSpec.TaskSpec
+	default:
+		// If the alpha feature is enabled, and the user has configured pipelineSpec or pipelineRef, it will enter here.
+		// Currently, the controller is not yet adapted, and to avoid a panic, an error message is provided here.
+		// TODO: Adjust the logic here once the feature is supported in the future.
+		return nil, fmt.Errorf("Currently, Task %q does not support PipelineRef or PipelineSpec, please use TaskRef or TaskSpec instead", pipelineTask.Name)
 	}
 	rt.TaskSpec.SetDefaults(ctx)
 	return rt, nil

pkg/reconciler/pipelinerun/resources/pipelinerunresolution_test.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"fmt"
 	"sort"
+	"strings"
 	"testing"
 	"time"
 
@@ -2434,6 +2435,31 @@ func TestResolvePipelineRun_PipelineTaskHasNoResources(t *testing.T) {
 	}
 }
 
+func TestResolvePipelineRun_PipelineTaskHasPipelineRef(t *testing.T) {
+	pt := v1.PipelineTask{
+		Name:        "pipeline-in-pipeline",
+		PipelineRef: &v1.PipelineRef{Name: "pipeline"},
+	}
+
+	getTask := func(ctx context.Context, name string) (*v1.Task, *v1.RefSource, *trustedresources.VerificationResult, error) {
+		return task, nil, nil, nil
+	}
+	getTaskRun := func(name string) (*v1.TaskRun, error) { return &trs[0], nil }
+	pr := v1.PipelineRun{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "pipelinerun",
+		},
+	}
+
+	_, err := ResolvePipelineTask(context.Background(), pr, getTask, getTaskRun, nopGetCustomRun, pt, nil)
+	if err == nil {
+		t.Errorf("Error getting tasks for fake pipeline %s, expected an error but got nil.", p.ObjectMeta.Name)
+	}
+	if !strings.Contains(err.Error(), "does not support PipelineRef or PipelineSpec") {
+		t.Errorf("Error getting tasks for fake pipeline %s: expected contains keyword but got %s", p.ObjectMeta.Name, err)
+	}
+}
+
 func TestResolvePipelineRun_TaskDoesntExist(t *testing.T) {
 	pts := []v1.PipelineTask{{
 		Name:    "mytask1",