From 220bf74a9e689f078a80eb00ff0b5726010197a1 Mon Sep 17 00:00:00 2001
From: Pete Davison <pd93.uk@outlook.com>
Date: Wed, 6 Sep 2023 00:00:36 +0000
Subject: [PATCH] feat: better taskfile cycle error handling

---
 errors/errors.go          |  1 +
 errors/errors_taskfile.go | 18 ++++++++++++++++++
 taskfile/reader.go        |  6 ++++++
 3 files changed, 25 insertions(+)

diff --git a/errors/errors.go b/errors/errors.go
index 46ad328b..400c0f16 100644
--- a/errors/errors.go
+++ b/errors/errors.go
@@ -20,6 +20,7 @@ const (
 	CodeTaskfileVersionCheckError
 	CodeTaskfileNetworkTimeout
 	CodeTaskfileDuplicateInclude
+	CodeTaskfileCycle
 )
 
 // Task related exit codes
diff --git a/errors/errors_taskfile.go b/errors/errors_taskfile.go
index 2951bf90..ba5579c2 100644
--- a/errors/errors_taskfile.go
+++ b/errors/errors_taskfile.go
@@ -191,3 +191,21 @@ func (err *TaskfileDuplicateIncludeError) Error() string {
 func (err *TaskfileDuplicateIncludeError) Code() int {
 	return CodeTaskfileDuplicateInclude
 }
+
+// TaskfileCycleError is returned when we detect that a Taskfile includes a
+// set of Taskfiles that include each other in a cycle.
+type TaskfileCycleError struct {
+	Source      string
+	Destination string
+}
+
+func (err TaskfileCycleError) Error() string {
+	return fmt.Sprintf("task: include cycle detected between %s <--> %s",
+		err.Source,
+		err.Destination,
+	)
+}
+
+func (err TaskfileCycleError) Code() int {
+	return CodeTaskfileCycle
+}
diff --git a/taskfile/reader.go b/taskfile/reader.go
index 790c991a..707c6562 100644
--- a/taskfile/reader.go
+++ b/taskfile/reader.go
@@ -153,6 +153,12 @@ func (r *Reader) include(node Node) error {
 					Namespaces:  []string{namespace, edge.Properties.Data.(*ast.Include).Namespace},
 				}
 			}
+			if errors.Is(err, graph.ErrEdgeCreatesCycle) {
+				return errors.TaskfileCycleError{
+					Source:      node.Location(),
+					Destination: includeNode.Location(),
+				}
+			}
 			return err
 		})
 		return nil