proptest, do we have more then one conflict that matches?

Yes, apparently we do. So I can't do optimizations based on that being unique.

Author: Eh2406

src/cargo/core/resolver/conflict_cache.rs

@@ -37,6 +37,7 @@ impl ConflictStoreTrie {
                 }
             }
             ConflictStoreTrie::Node(m) => {
+                let mut out = None;
                 for (&pid, store) in must_contain
                     .map(|f| m.range(..=f))
                     .unwrap_or_else(|| m.range(..))
@@ -46,13 +47,13 @@ impl ConflictStoreTrie {
                         if let Some(o) =
                             store.find_conflicting(cx, must_contain.filter(|&f| f != pid))
                         {
-                            return Some(o);
+                            assert!(out.replace(o).is_none());
                         }
                     }
                     // Else, if it is not active then there is no way any of the corresponding
                     // subtrie will be conflicting.
                 }
-                None
+                out
             }
         }
     }

tests/testsuite/resolve.rs

@@ -1407,3 +1407,31 @@ fn conflict_store_bug() {
     let reg = registry(input);
     let _ = resolve_and_validated(pkg_id("root"), vec![dep("j")], &reg);
 }
+
+#[test]
+fn conflict_store_more_then_one_match() {
+    let input = vec![
+        pkg!(("A", "0.0.0")),
+        pkg!(("A", "0.0.1")),
+        pkg!(("A-sys", "0.0.0")),
+        pkg!(("A-sys", "0.0.1")),
+        pkg!(("A-sys", "0.0.2")),
+        pkg!(("A-sys", "0.0.3")),
+        pkg!(("A-sys", "0.0.12")),
+        pkg!(("A-sys", "0.0.16")),
+        pkg!(("B-sys", "0.0.0")),
+        pkg!(("B-sys", "0.0.1")),
+        pkg!(("B-sys", "0.0.2") => [dep_req("A-sys", "= 0.0.12"),]),
+        pkg!(("BA-sys", "0.0.0") => [dep_req("A-sys","= 0.0.16"),]),
+        pkg!(("BA-sys", "0.0.1") => [dep("bad"),]),
+        pkg!(("BA-sys", "0.0.2") => [dep("bad"),]),
+        pkg!("nA" => [
+            dep("A"),
+            dep_req("A-sys", "<= 0.0.3"),
+            dep("B-sys"),
+            dep("BA-sys"),
+        ]),
+    ];
+    let reg = registry(input);
+    let _ = resolve_and_validated(pkg_id("root"), vec![dep("nA")], &reg);
+}