Rollup merge of #123934 - WaffleLapkin:graph-mini-refactor, r=fmease

`rustc_data_structures::graph` mini refactor

Who doesn't love to breathe dust from the ancient times?

1 files changed, 5 insertions, 17 deletions

diff --git a/compiler/rustc_data_structures/src/graph/reference.rs b/compiler/rustc_data_structures/src/graph/reference.rs
index c259fe56c15..7a487552f53 100644
--- a/compiler/rustc_data_structures/src/graph/reference.rs
+++ b/compiler/rustc_data_structures/src/graph/reference.rs
@@ -2,38 +2,26 @@ use super::*;
 
 impl<'graph, G: DirectedGraph> DirectedGraph for &'graph G {
     type Node = G::Node;
-}
 
-impl<'graph, G: WithNumNodes> WithNumNodes for &'graph G {
     fn num_nodes(&self) -> usize {
         (**self).num_nodes()
     }
 }
 
-impl<'graph, G: WithStartNode> WithStartNode for &'graph G {
+impl<'graph, G: StartNode> StartNode for &'graph G {
     fn start_node(&self) -> Self::Node {
         (**self).start_node()
     }
 }
 
-impl<'graph, G: WithSuccessors> WithSuccessors for &'graph G {
-    fn successors(&self, node: Self::Node) -> <Self as GraphSuccessors<'_>>::Iter {
+impl<'graph, G: Successors> Successors for &'graph G {
+    fn successors(&self, node: Self::Node) -> impl Iterator<Item = Self::Node> {
         (**self).successors(node)
     }
 }
 
-impl<'graph, G: WithPredecessors> WithPredecessors for &'graph G {
-    fn predecessors(&self, node: Self::Node) -> <Self as GraphPredecessors<'_>>::Iter {
+impl<'graph, G: Predecessors> Predecessors for &'graph G {
+    fn predecessors(&self, node: Self::Node) -> impl Iterator<Item = Self::Node> {
         (**self).predecessors(node)
     }
 }
-
-impl<'iter, 'graph, G: WithPredecessors> GraphPredecessors<'iter> for &'graph G {
-    type Item = G::Node;
-    type Iter = <G as GraphPredecessors<'iter>>::Iter;
-}
-
-impl<'iter, 'graph, G: WithSuccessors> GraphSuccessors<'iter> for &'graph G {
-    type Item = G::Node;
-    type Iter = <G as GraphSuccessors<'iter>>::Iter;
-}