resolve: record task list of dependency cycles

1 files changed, 29 insertions, 6 deletions

diff --git a/src/resolve.rs b/src/resolve.rs
index 0758016..ab2eef3 100644
--- a/src/resolve.rs
+++ b/src/resolve.rs
@@ -6,14 +6,20 @@ use crate::types::*;
 #[derive(Debug)]
 pub enum Error {
 	TaskNotFound(TaskRef),
-	DependencyCycle(TaskRef),
+	DependencyCycle { tasks: Vec<TaskRef>, complete: bool },
 }
 
 impl fmt::Display for Error {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		match self {
-			Error::TaskNotFound(id) => write!(f, "Task not found: {}", id),
-			Error::DependencyCycle(id) => write!(f, "DependencyCycle: {}", id),
+			Error::TaskNotFound(id) => write!(f, "Task not found: {:?}", id),
+			Error::DependencyCycle { tasks, complete } => {
+				write!(f, "Dependency Cycle: {:?}", tasks)?;
+				if !complete {
+					write!(f, " (incomplete)")?;
+				}
+				Ok(())
+			}
 		}
 	}
 }
@@ -43,7 +49,12 @@ impl<'a> Resolver<'a> {
 
 	pub fn add_goal(&mut self, task: &TaskRef) -> Result<()> {
 		match self.resolve_state.get(task) {
-			Some(ResolveState::Resolving) => return Err(Error::DependencyCycle(task.clone())),
+			Some(ResolveState::Resolving) => {
+				return Err(Error::DependencyCycle {
+					tasks: vec![task.clone()],
+					complete: false,
+				})
+			}
 			Some(ResolveState::Resolved) => return Ok(()),
 			None => (),
 		}
@@ -57,9 +68,21 @@ impl<'a> Resolver<'a> {
 			.insert(task.clone(), ResolveState::Resolving);
 
 		for dep in &task_def.depends {
-			let res = self.add_goal(dep);
-			if res.is_err() {
+			let mut res = self.add_goal(dep);
+			if let Err(ref mut error) = res {
 				self.resolve_state.remove(task);
+
+				if let Error::DependencyCycle {
+					ref mut tasks,
+					complete: ref mut complete @ false,
+				} = error
+				{
+					tasks.push(task.clone());
+					if tasks[0] == task.as_str() {
+						*complete = true
+					}
+				}
+
 				return res;
 			}
 		}