Remove Stat Node

It used to be a placeholder, and now it's obsoleted by DigestFile which actually has content

src/rust/engine/src/nodes.rs

@@ -788,31 +788,6 @@ impl From<DigestFile> for NodeKey {
   }
 }
 
-///
-/// A Node that represents consuming the stat for some path.
-///
-/// NB: Because the `Scandir` operation gets the stats for a parent directory in a single syscall,
-/// this operation results in no data, and is simply a placeholder for `Snapshot` Nodes to use to
-/// declare a dependency on the existence/content of a particular path. This makes them more error
-/// prone, unfortunately.
-///
-#[derive(Clone, Debug, Eq, Hash, PartialEq)]
-pub struct Stat(PathBuf);
-
-impl Node for Stat {
-  type Output = ();
-
-  fn run(self, _: Context) -> NodeFuture<()> {
-    future::ok(()).to_boxed()
-  }
-}
-
-impl From<Stat> for NodeKey {
-  fn from(n: Stat) -> Self {
-    NodeKey::Stat(n)
-  }
-}
-
 ///
 /// A Node that represents executing a directory listing that returns a Stat per directory
 /// entry (generally in one syscall). No symlinks are expanded.
@@ -1060,7 +1035,6 @@ pub enum NodeKey {
   DigestFile(DigestFile),
   ReadLink(ReadLink),
   Scandir(Scandir),
-  Stat(Stat),
   Select(Select),
   Snapshot(Snapshot),
   Task(Task),
@@ -1078,7 +1052,6 @@ impl NodeKey {
       &NodeKey::DigestFile(ref s) => format!("DigestFile({:?})", s.0),
       &NodeKey::ReadLink(ref s) => format!("ReadLink({:?})", s.0),
       &NodeKey::Scandir(ref s) => format!("Scandir({:?})", s.0),
-      &NodeKey::Stat(ref s) => format!("Stat({:?})", s.0),
       &NodeKey::Select(ref s) => {
         format!(
           "Select({}, {})",
@@ -1109,7 +1082,6 @@ impl NodeKey {
       &NodeKey::DigestFile(..) => "DigestFile".to_string(),
       &NodeKey::ReadLink(..) => "LinkDest".to_string(),
       &NodeKey::Scandir(..) => "DirectoryListing".to_string(),
-      &NodeKey::Stat(..) => "Stat".to_string(),
     }
   }
 
@@ -1121,7 +1093,6 @@ impl NodeKey {
       &NodeKey::DigestFile(ref s) => Some(s.0.path.as_path()),
       &NodeKey::ReadLink(ref s) => Some((s.0).0.as_path()),
       &NodeKey::Scandir(ref s) => Some((s.0).0.as_path()),
-      &NodeKey::Stat(ref s) => Some(s.0.as_path()),
 
       // Not FS operations:
       // Explicitly listed so that if people add new NodeKeys they need to consider whether their
@@ -1141,7 +1112,6 @@ impl Node for NodeKey {
     match self {
       NodeKey::DigestFile(n) => n.run(context).map(|v| v.into()).to_boxed(),
       NodeKey::ReadLink(n) => n.run(context).map(|v| v.into()).to_boxed(),
-      NodeKey::Stat(n) => n.run(context).map(|v| v.into()).to_boxed(),
       NodeKey::Scandir(n) => n.run(context).map(|v| v.into()).to_boxed(),
       NodeKey::Select(n) => n.run(context).map(|v| v.into()).to_boxed(),
       NodeKey::Snapshot(n) => n.run(context).map(|v| v.into()).to_boxed(),