From ca1c7a306e29001714f697ed720589634affd32b Mon Sep 17 00:00:00 2001
From: Enrico Schaaf <54645197+enricoschaaf@users.noreply.github.com>
Date: Wed, 1 Jul 2026 19:40:55 +0000
Subject: [PATCH] fix(diag): bound transitive unused dependency traversal

---
 src/diagnostics/rules/unused_dependencies.rs | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/diagnostics/rules/unused_dependencies.rs b/src/diagnostics/rules/unused_dependencies.rs
index 312d8d09939..1016fce3c8b 100644
--- a/src/diagnostics/rules/unused_dependencies.rs
+++ b/src/diagnostics/rules/unused_dependencies.rs
@@ -1,6 +1,7 @@
+use std::collections::VecDeque;
 use std::path::Path;
 
-use crate::util::data_structures::IndexMap;
+use crate::util::data_structures::{HashSet, IndexMap};
 use cargo_util_schemas::manifest;
 use cargo_util_schemas::manifest::TomlPackageBuild;
 use cargo_util_terminal::report::AnnotationKind;
@@ -366,7 +367,8 @@ fn is_transitive_dep(
     seen_units: &Vec<Unit>,
     bcx: &BuildContext<'_, '_>,
 ) -> bool {
-    let mut queue = std::collections::VecDeque::new();
+    let mut queue = VecDeque::new();
+    let mut visited: HashSet<&Unit> = HashSet::default();
     for root_unit in seen_units {
         for unit_dep in &bcx.unit_graph[root_unit] {
             if root_unit.pkg.package_id() == unit_dep.unit.pkg.package_id() {
@@ -375,7 +377,9 @@ fn is_transitive_dep(
             if unit_dep.unit == *direct_dep_unit {
                 continue;
             }
-            queue.push_back(&unit_dep.unit);
+            if visited.insert(&unit_dep.unit) {
+                queue.push_back(&unit_dep.unit);
+            }
         }
     }
 
@@ -384,7 +388,9 @@ fn is_transitive_dep(
             if unit_dep.unit == *direct_dep_unit {
                 return true;
             }
-            queue.push_back(&unit_dep.unit);
+            if visited.insert(&unit_dep.unit) {
+                queue.push_back(&unit_dep.unit);
+            }
         }
     }