From 398da593a53161c1ef9ca7dabbc5e9edf67deac6 Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Sun, 14 Apr 2024 15:15:03 +0000
Subject: [PATCH] Merge `WithNumNodes` into DirectedGraph

---
 .../rustc_borrowck/src/constraints/graph.rs   |  2 --
 .../src/graph/iterate/mod.rs                  | 24 +++++++++----------
 .../rustc_data_structures/src/graph/mod.rs    | 13 ++++------
 .../src/graph/reference.rs                    |  2 --
 .../src/graph/scc/mod.rs                      | 14 +++++------
 .../rustc_data_structures/src/graph/tests.rs  | 10 ++++----
 .../src/graph/vec_graph/mod.rs                |  4 +---
 compiler/rustc_middle/src/mir/basic_blocks.rs |  2 --
 .../rustc_middle/src/mir/generic_graphviz.rs  |  4 ++--
 .../src/coverage/counters.rs                  |  2 +-
 .../rustc_mir_transform/src/coverage/graph.rs |  4 +---
 .../rustc_mir_transform/src/coverage/spans.rs |  2 +-
 .../rustc_mir_transform/src/coverage/tests.rs |  2 +-
 13 files changed, 33 insertions(+), 52 deletions(-)

diff --git a/compiler/rustc_borrowck/src/constraints/graph.rs b/compiler/rustc_borrowck/src/constraints/graph.rs
index 8b7d9ec2cd6..470da9cbae6 100644
--- a/compiler/rustc_borrowck/src/constraints/graph.rs
+++ b/compiler/rustc_borrowck/src/constraints/graph.rs
@@ -216,9 +216,7 @@ fn next(&mut self) -> Option<Self::Item> {
 
 impl<'s, 'tcx, D: ConstraintGraphDirection> graph::DirectedGraph for RegionGraph<'s, 'tcx, D> {
     type Node = RegionVid;
-}
 
-impl<'s, 'tcx, D: ConstraintGraphDirection> graph::WithNumNodes for RegionGraph<'s, 'tcx, D> {
     fn num_nodes(&self) -> usize {
         self.constraint_graph.first_constraints.len()
     }
diff --git a/compiler/rustc_data_structures/src/graph/iterate/mod.rs b/compiler/rustc_data_structures/src/graph/iterate/mod.rs
index 9eb4b5278c0..c46fdb4e4f7 100644
--- a/compiler/rustc_data_structures/src/graph/iterate/mod.rs
+++ b/compiler/rustc_data_structures/src/graph/iterate/mod.rs
@@ -1,4 +1,4 @@
-use super::{DirectedGraph, WithNumNodes, WithStartNode, WithSuccessors};
+use super::{DirectedGraph, WithStartNode, WithSuccessors};
 use rustc_index::bit_set::BitSet;
 use rustc_index::{IndexSlice, IndexVec};
 use std::ops::ControlFlow;
@@ -6,14 +6,14 @@
 #[cfg(test)]
 mod tests;
 
-pub fn post_order_from<G: DirectedGraph + WithSuccessors + WithNumNodes>(
+pub fn post_order_from<G: DirectedGraph + WithSuccessors>(
     graph: &G,
     start_node: G::Node,
 ) -> Vec<G::Node> {
     post_order_from_to(graph, start_node, None)
 }
 
-pub fn post_order_from_to<G: DirectedGraph + WithSuccessors + WithNumNodes>(
+pub fn post_order_from_to<G: DirectedGraph + WithSuccessors>(
     graph: &G,
     start_node: G::Node,
     end_node: Option<G::Node>,
@@ -27,7 +27,7 @@ pub fn post_order_from_to<G: DirectedGraph + WithSuccessors + WithNumNodes>(
     result
 }
 
-fn post_order_walk<G: DirectedGraph + WithSuccessors + WithNumNodes>(
+fn post_order_walk<G: DirectedGraph + WithSuccessors>(
     graph: &G,
     node: G::Node,
     result: &mut Vec<G::Node>,
@@ -60,7 +60,7 @@ struct PostOrderFrame<Node, Iter> {
     }
 }
 
-pub fn reverse_post_order<G: DirectedGraph + WithSuccessors + WithNumNodes>(
+pub fn reverse_post_order<G: DirectedGraph + WithSuccessors>(
     graph: &G,
     start_node: G::Node,
 ) -> Vec<G::Node> {
@@ -72,7 +72,7 @@ pub fn reverse_post_order<G: DirectedGraph + WithSuccessors + WithNumNodes>(
 /// A "depth-first search" iterator for a directed graph.
 pub struct DepthFirstSearch<'graph, G>
 where
-    G: ?Sized + DirectedGraph + WithNumNodes + WithSuccessors,
+    G: ?Sized + DirectedGraph + WithSuccessors,
 {
     graph: &'graph G,
     stack: Vec<G::Node>,
@@ -81,7 +81,7 @@ pub struct DepthFirstSearch<'graph, G>
 
 impl<'graph, G> DepthFirstSearch<'graph, G>
 where
-    G: ?Sized + DirectedGraph + WithNumNodes + WithSuccessors,
+    G: ?Sized + DirectedGraph + WithSuccessors,
 {
     pub fn new(graph: &'graph G) -> Self {
         Self { graph, stack: vec![], visited: BitSet::new_empty(graph.num_nodes()) }
@@ -127,7 +127,7 @@ pub fn visited(&self, node: G::Node) -> bool {
 
 impl<G> std::fmt::Debug for DepthFirstSearch<'_, G>
 where
-    G: ?Sized + DirectedGraph + WithNumNodes + WithSuccessors,
+    G: ?Sized + DirectedGraph + WithSuccessors,
 {
     fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let mut f = fmt.debug_set();
@@ -140,7 +140,7 @@ fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 
 impl<G> Iterator for DepthFirstSearch<'_, G>
 where
-    G: ?Sized + DirectedGraph + WithNumNodes + WithSuccessors,
+    G: ?Sized + DirectedGraph + WithSuccessors,
 {
     type Item = G::Node;
 
@@ -201,7 +201,7 @@ struct Event<N> {
 /// [CLR]: https://en.wikipedia.org/wiki/Introduction_to_Algorithms
 pub struct TriColorDepthFirstSearch<'graph, G>
 where
-    G: ?Sized + DirectedGraph + WithNumNodes + WithSuccessors,
+    G: ?Sized + DirectedGraph + WithSuccessors,
 {
     graph: &'graph G,
     stack: Vec<Event<G::Node>>,
@@ -211,7 +211,7 @@ pub struct TriColorDepthFirstSearch<'graph, G>
 
 impl<'graph, G> TriColorDepthFirstSearch<'graph, G>
 where
-    G: ?Sized + DirectedGraph + WithNumNodes + WithSuccessors,
+    G: ?Sized + DirectedGraph + WithSuccessors,
 {
     pub fn new(graph: &'graph G) -> Self {
         TriColorDepthFirstSearch {
@@ -278,7 +278,7 @@ pub fn run_from<V>(mut self, root: G::Node, visitor: &mut V) -> Option<V::BreakV
 
 impl<G> TriColorDepthFirstSearch<'_, G>
 where
-    G: ?Sized + DirectedGraph + WithNumNodes + WithSuccessors + WithStartNode,
+    G: ?Sized + DirectedGraph + WithSuccessors + WithStartNode,
 {
     /// Performs a depth-first search, starting from `G::start_node()`.
     ///
diff --git a/compiler/rustc_data_structures/src/graph/mod.rs b/compiler/rustc_data_structures/src/graph/mod.rs
index e06ab2fe36b..853b8f1775e 100644
--- a/compiler/rustc_data_structures/src/graph/mod.rs
+++ b/compiler/rustc_data_structures/src/graph/mod.rs
@@ -12,9 +12,7 @@
 
 pub trait DirectedGraph {
     type Node: Idx;
-}
 
-pub trait WithNumNodes: DirectedGraph {
     fn num_nodes(&self) -> usize;
 }
 
@@ -28,10 +26,7 @@ pub trait WithSuccessors: DirectedGraph
 {
     fn successors(&self, node: Self::Node) -> <Self as GraphSuccessors<'_>>::Iter;
 
-    fn depth_first_search(&self, from: Self::Node) -> iterate::DepthFirstSearch<'_, Self>
-    where
-        Self: WithNumNodes,
-    {
+    fn depth_first_search(&self, from: Self::Node) -> iterate::DepthFirstSearch<'_, Self> {
         iterate::DepthFirstSearch::new(self).with_start_node(from)
     }
 }
@@ -60,20 +55,20 @@ pub trait WithStartNode: DirectedGraph {
 }
 
 pub trait ControlFlowGraph:
-    DirectedGraph + WithStartNode + WithPredecessors + WithSuccessors + WithNumNodes
+    DirectedGraph + WithStartNode + WithPredecessors + WithSuccessors
 {
     // convenient trait
 }
 
 impl<T> ControlFlowGraph for T where
-    T: DirectedGraph + WithStartNode + WithPredecessors + WithSuccessors + WithNumNodes
+    T: DirectedGraph + WithStartNode + WithPredecessors + WithSuccessors
 {
 }
 
 /// Returns `true` if the graph has a cycle that is reachable from the start node.
 pub fn is_cyclic<G>(graph: &G) -> bool
 where
-    G: ?Sized + DirectedGraph + WithStartNode + WithSuccessors + WithNumNodes,
+    G: ?Sized + DirectedGraph + WithStartNode + WithSuccessors,
 {
     iterate::TriColorDepthFirstSearch::new(graph)
         .run_from_start(&mut iterate::CycleDetector)
diff --git a/compiler/rustc_data_structures/src/graph/reference.rs b/compiler/rustc_data_structures/src/graph/reference.rs
index c259fe56c15..d15513c95db 100644
--- a/compiler/rustc_data_structures/src/graph/reference.rs
+++ b/compiler/rustc_data_structures/src/graph/reference.rs
@@ -2,9 +2,7 @@
 
 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()
     }
diff --git a/compiler/rustc_data_structures/src/graph/scc/mod.rs b/compiler/rustc_data_structures/src/graph/scc/mod.rs
index b54d75f7ed7..a9967c2ecbb 100644
--- a/compiler/rustc_data_structures/src/graph/scc/mod.rs
+++ b/compiler/rustc_data_structures/src/graph/scc/mod.rs
@@ -7,7 +7,7 @@
 
 use crate::fx::FxHashSet;
 use crate::graph::vec_graph::VecGraph;
-use crate::graph::{DirectedGraph, GraphSuccessors, WithNumEdges, WithNumNodes, WithSuccessors};
+use crate::graph::{DirectedGraph, GraphSuccessors, WithNumEdges, WithSuccessors};
 use rustc_index::{Idx, IndexSlice, IndexVec};
 use std::ops::Range;
 
@@ -39,7 +39,7 @@ pub struct SccData<S: Idx> {
 }
 
 impl<N: Idx, S: Idx + Ord> Sccs<N, S> {
-    pub fn new(graph: &(impl DirectedGraph<Node = N> + WithNumNodes + WithSuccessors)) -> Self {
+    pub fn new(graph: &(impl DirectedGraph<Node = N> + WithSuccessors)) -> Self {
         SccsConstruction::construct(graph)
     }
 
@@ -89,17 +89,15 @@ pub fn reverse(&self) -> VecGraph<S> {
     }
 }
 
-impl<N: Idx, S: Idx> DirectedGraph for Sccs<N, S> {
+impl<N: Idx, S: Idx + Ord> DirectedGraph for Sccs<N, S> {
     type Node = S;
-}
 
-impl<N: Idx, S: Idx + Ord> WithNumNodes for Sccs<N, S> {
     fn num_nodes(&self) -> usize {
         self.num_sccs()
     }
 }
 
-impl<N: Idx, S: Idx> WithNumEdges for Sccs<N, S> {
+impl<N: Idx, S: Idx + Ord> WithNumEdges for Sccs<N, S> {
     fn num_edges(&self) -> usize {
         self.scc_data.all_successors.len()
     }
@@ -158,7 +156,7 @@ fn create_scc(&mut self, successors: impl IntoIterator<Item = S>) -> S {
     }
 }
 
-struct SccsConstruction<'c, G: DirectedGraph + WithNumNodes + WithSuccessors, S: Idx> {
+struct SccsConstruction<'c, G: DirectedGraph + WithSuccessors, S: Idx> {
     graph: &'c G,
 
     /// The state of each node; used during walk to record the stack
@@ -218,7 +216,7 @@ enum WalkReturn<S> {
 
 impl<'c, G, S> SccsConstruction<'c, G, S>
 where
-    G: DirectedGraph + WithNumNodes + WithSuccessors,
+    G: DirectedGraph + WithSuccessors,
     S: Idx,
 {
     /// Identifies SCCs in the graph `G` and computes the resulting
diff --git a/compiler/rustc_data_structures/src/graph/tests.rs b/compiler/rustc_data_structures/src/graph/tests.rs
index 7f4ef906b36..df58b965ccf 100644
--- a/compiler/rustc_data_structures/src/graph/tests.rs
+++ b/compiler/rustc_data_structures/src/graph/tests.rs
@@ -36,6 +36,10 @@ pub fn new(start_node: usize, edges: &[(usize, usize)]) -> Self {
 
 impl DirectedGraph for TestGraph {
     type Node = usize;
+
+    fn num_nodes(&self) -> usize {
+        self.num_nodes
+    }
 }
 
 impl WithStartNode for TestGraph {
@@ -44,12 +48,6 @@ fn start_node(&self) -> usize {
     }
 }
 
-impl WithNumNodes for TestGraph {
-    fn num_nodes(&self) -> usize {
-        self.num_nodes
-    }
-}
-
 impl WithPredecessors for TestGraph {
     fn predecessors(&self, node: usize) -> <Self as GraphPredecessors<'_>>::Iter {
         self.predecessors[&node].iter().cloned()
diff --git a/compiler/rustc_data_structures/src/graph/vec_graph/mod.rs b/compiler/rustc_data_structures/src/graph/vec_graph/mod.rs
index 00f6266ce1d..79efe3fb8e0 100644
--- a/compiler/rustc_data_structures/src/graph/vec_graph/mod.rs
+++ b/compiler/rustc_data_structures/src/graph/vec_graph/mod.rs
@@ -1,4 +1,4 @@
-use crate::graph::{DirectedGraph, GraphSuccessors, WithNumEdges, WithNumNodes, WithSuccessors};
+use crate::graph::{DirectedGraph, GraphSuccessors, WithNumEdges, WithSuccessors};
 use rustc_index::{Idx, IndexVec};
 
 #[cfg(test)]
@@ -80,9 +80,7 @@ pub fn successors(&self, source: N) -> &[N] {
 
 impl<N: Idx> DirectedGraph for VecGraph<N> {
     type Node = N;
-}
 
-impl<N: Idx> WithNumNodes for VecGraph<N> {
     fn num_nodes(&self) -> usize {
         self.node_starts.len() - 1
     }
diff --git a/compiler/rustc_middle/src/mir/basic_blocks.rs b/compiler/rustc_middle/src/mir/basic_blocks.rs
index 3ecd5b9cd34..80a9b460f35 100644
--- a/compiler/rustc_middle/src/mir/basic_blocks.rs
+++ b/compiler/rustc_middle/src/mir/basic_blocks.rs
@@ -141,9 +141,7 @@ fn deref(&self) -> &IndexSlice<BasicBlock, BasicBlockData<'tcx>> {
 
 impl<'tcx> graph::DirectedGraph for BasicBlocks<'tcx> {
     type Node = BasicBlock;
-}
 
-impl<'tcx> graph::WithNumNodes for BasicBlocks<'tcx> {
     #[inline]
     fn num_nodes(&self) -> usize {
         self.basic_blocks.len()
diff --git a/compiler/rustc_middle/src/mir/generic_graphviz.rs b/compiler/rustc_middle/src/mir/generic_graphviz.rs
index 299b50525cb..f22f113e493 100644
--- a/compiler/rustc_middle/src/mir/generic_graphviz.rs
+++ b/compiler/rustc_middle/src/mir/generic_graphviz.rs
@@ -5,7 +5,7 @@
 
 pub struct GraphvizWriter<
     'a,
-    G: graph::DirectedGraph + graph::WithSuccessors + graph::WithStartNode + graph::WithNumNodes,
+    G: graph::DirectedGraph + graph::WithSuccessors + graph::WithStartNode,
     NodeContentFn: Fn(<G as graph::DirectedGraph>::Node) -> Vec<String>,
     EdgeLabelsFn: Fn(<G as graph::DirectedGraph>::Node) -> Vec<String>,
 > {
@@ -19,7 +19,7 @@ pub struct GraphvizWriter<
 
 impl<
     'a,
-    G: graph::DirectedGraph + graph::WithSuccessors + graph::WithStartNode + graph::WithNumNodes,
+    G: graph::DirectedGraph + graph::WithSuccessors + graph::WithStartNode,
     NodeContentFn: Fn(<G as graph::DirectedGraph>::Node) -> Vec<String>,
     EdgeLabelsFn: Fn(<G as graph::DirectedGraph>::Node) -> Vec<String>,
 > GraphvizWriter<'a, G, NodeContentFn, EdgeLabelsFn>
diff --git a/compiler/rustc_mir_transform/src/coverage/counters.rs b/compiler/rustc_mir_transform/src/coverage/counters.rs
index 69dc4f2ddea..6e73a476421 100644
--- a/compiler/rustc_mir_transform/src/coverage/counters.rs
+++ b/compiler/rustc_mir_transform/src/coverage/counters.rs
@@ -2,7 +2,7 @@
 
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::graph::WithNumNodes;
+use rustc_data_structures::graph::DirectedGraph;
 use rustc_index::IndexVec;
 use rustc_middle::mir::coverage::{CounterId, CovTerm, Expression, ExpressionId, Op};
 
diff --git a/compiler/rustc_mir_transform/src/coverage/graph.rs b/compiler/rustc_mir_transform/src/coverage/graph.rs
index ed8c4d8283d..4cbad47cdc8 100644
--- a/compiler/rustc_mir_transform/src/coverage/graph.rs
+++ b/compiler/rustc_mir_transform/src/coverage/graph.rs
@@ -1,7 +1,7 @@
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::graph::dominators::{self, Dominators};
-use rustc_data_structures::graph::{self, GraphSuccessors, WithNumNodes, WithStartNode};
+use rustc_data_structures::graph::{self, DirectedGraph, GraphSuccessors, WithStartNode};
 use rustc_index::bit_set::BitSet;
 use rustc_index::IndexVec;
 use rustc_middle::mir::{self, BasicBlock, Terminator, TerminatorKind};
@@ -193,9 +193,7 @@ fn index_mut(&mut self, index: BasicCoverageBlock) -> &mut BasicCoverageBlockDat
 
 impl graph::DirectedGraph for CoverageGraph {
     type Node = BasicCoverageBlock;
-}
 
-impl graph::WithNumNodes for CoverageGraph {
     #[inline]
     fn num_nodes(&self) -> usize {
         self.bcbs.len()
diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs
index 672de1fbe60..03ede886688 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans.rs
@@ -1,4 +1,4 @@
-use rustc_data_structures::graph::WithNumNodes;
+use rustc_data_structures::graph::DirectedGraph;
 use rustc_index::bit_set::BitSet;
 use rustc_middle::mir;
 use rustc_span::{BytePos, Span};
diff --git a/compiler/rustc_mir_transform/src/coverage/tests.rs b/compiler/rustc_mir_transform/src/coverage/tests.rs
index 569998de35e..631cc3c6f05 100644
--- a/compiler/rustc_mir_transform/src/coverage/tests.rs
+++ b/compiler/rustc_mir_transform/src/coverage/tests.rs
@@ -28,8 +28,8 @@
 use super::graph::{self, BasicCoverageBlock};
 
 use itertools::Itertools;
-use rustc_data_structures::graph::WithNumNodes;
 use rustc_data_structures::graph::WithSuccessors;
+use rustc_data_structures::graph::DirectedGraph;
 use rustc_index::{Idx, IndexVec};
 use rustc_middle::mir::*;
 use rustc_middle::ty;