From 10364243dc4925a7fcf7f9e950d4c893570b7cc1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adolfo=20Ochagav=C3=ADa?= <github@adolfo.ochagavia.nl>
Date: Wed, 31 Jan 2024 13:33:52 +0100
Subject: [PATCH] fix: merge nodes more aggressively when unsat

---
 src/problem.rs                                  |  9 ---------
 tests/snapshots/solver__merge_installable.snap  | 10 ++++++++++
 tests/snapshots/solver__unsat_constrains_2.snap | 13 +------------
 tests/solver.rs                                 | 11 +++++++++++
 4 files changed, 22 insertions(+), 21 deletions(-)
 create mode 100644 tests/snapshots/solver__merge_installable.snap

diff --git a/src/problem.rs b/src/problem.rs
index a01c06d..060e61a 100644
--- a/src/problem.rs
+++ b/src/problem.rs
@@ -248,7 +248,6 @@ pub enum ConflictCause {
 /// - They all have the same name
 /// - They all have the same predecessor nodes
 /// - They all have the same successor nodes
-/// - None of them have incoming conflicting edges
 pub(crate) struct MergedProblemNode {
     pub ids: Vec<SolvableId>,
 }
@@ -370,14 +369,6 @@ impl ProblemGraph {
                 }
             };
 
-            if graph
-                .edges_directed(node_id, Direction::Incoming)
-                .any(|e| matches!(e.weight(), ProblemEdge::Conflict(..)))
-            {
-                // Nodes that are the target of a conflict should never be merged
-                continue;
-            }
-
             let predecessors: Vec<_> = graph
                 .edges_directed(node_id, Direction::Incoming)
                 .map(|e| e.source())
diff --git a/tests/snapshots/solver__merge_installable.snap b/tests/snapshots/solver__merge_installable.snap
new file mode 100644
index 0000000..116a4c7
--- /dev/null
+++ b/tests/snapshots/solver__merge_installable.snap
@@ -0,0 +1,10 @@
+---
+source: tests/solver.rs
+expression: "solve_snapshot(provider, &[\"a 0..3\", \"a 3..5\"])"
+---
+The following packages are incompatible
+|-- a >=3, <5 can be installed with any of the following options:
+    |-- a 3 | 4
+|-- a >=0, <3 cannot be installed because there are no viable options:
+    |-- a 1 | 2, which conflicts with the versions reported above.
+
diff --git a/tests/snapshots/solver__unsat_constrains_2.snap b/tests/snapshots/solver__unsat_constrains_2.snap
index ac86396..05bc545 100644
--- a/tests/snapshots/solver__unsat_constrains_2.snap
+++ b/tests/snapshots/solver__unsat_constrains_2.snap
@@ -1,21 +1,10 @@
 ---
 source: tests/solver.rs
-assertion_line: 703
 expression: error
 ---
 The following packages are incompatible
 |-- a * cannot be installed because there are no viable options:
-    |-- a 2 would require
-        |-- b *, which cannot be installed because there are no viable options:
-            |-- b 2 would require
-                |-- c >=2, <3, which cannot be installed because there are no viable options:
-                    |-- c 2 would constrain
-                        |-- a >=3, <4 , which conflicts with any installable versions previously reported
-            |-- b 1 would require
-                |-- c >=1, <2, which cannot be installed because there are no viable options:
-                    |-- c 1 would constrain
-                        |-- a >=3, <4 , which conflicts with any installable versions previously reported
-    |-- a 1 would require
+    |-- a 1 | 2 would require
         |-- b *, which cannot be installed because there are no viable options:
             |-- b 2 would require
                 |-- c >=2, <3, which cannot be installed because there are no viable options:
diff --git a/tests/solver.rs b/tests/solver.rs
index e9fc230..42b9ebc 100644
--- a/tests/solver.rs
+++ b/tests/solver.rs
@@ -912,6 +912,17 @@ fn test_merge_excluded() {
     insta::assert_snapshot!(solve_snapshot(provider, &["a"]));
 }
 
+#[test]
+fn test_merge_installable() {
+    let provider = BundleBoxProvider::from_packages(&[
+        ("a", 1, vec![]),
+        ("a", 2, vec![]),
+        ("a", 3, vec![]),
+        ("a", 4, vec![]),
+    ]);
+    insta::assert_snapshot!(solve_snapshot(provider, &["a 0..3", "a 3..5"]));
+}
+
 #[test]
 fn test_root_excluded() {
     let mut provider = BundleBoxProvider::from_packages(&[("a", 1, vec![])]);