2 files changed, 6 insertions, 12 deletions
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 414f17dfad4..29ba635a9b7 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -115,6 +115,7 @@
 
 #![deny(warnings)]
 #![feature(core_intrinsics)]
+#![feature(drain_filter)]
 
 #[macro_use]
 extern crate build_helper;
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index ec904eb2134..12b3d59e93d 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -186,27 +186,20 @@ impl Step for ToolBuild {
                       than in a previous build:\n");
             println!("the following dependencies are duplicated although they \
                       have the same features enabled:");
-            for (id, cur, prev) in &duplicates {
+            for (id, cur, prev) in duplicates.drain_filter(|(_, cur, prev)| cur.2 == prev.2) {
                 println!("  {}", id);
-                if cur.2 == prev.2 {
-                    // same features
-                    println!("    `{}` ({:?})\n    `{}` ({:?})", cur.0, cur.1, prev.0, prev.1);
-                }
+                // same features
+                println!("    `{}` ({:?})\n    `{}` ({:?})", cur.0, cur.1, prev.0, prev.1);
             }
             println!("the following dependencies have different features:");
             for (id, cur, prev) in duplicates {
                 println!("  {}", id);
-                if cur.2 == prev.2 {
-                    continue;
-                }
                 let cur_features: HashSet<_> = cur.2.into_iter().collect();
                 let prev_features: HashSet<_> = prev.2.into_iter().collect();
-                let cur_extra: Vec<_> = cur_features.difference(&prev_features).collect();
-                let prev_extra: Vec<_> = prev_features.difference(&cur_features).collect();
                 println!("    `{}` additionally enabled features {:?} at {:?}",
-                         cur.0, cur_extra, cur.1);
+                         cur.0, &cur_features - &prev_features, cur.1);
                 println!("    `{}` additionally enabled features {:?} at {:?}",
-                         prev.0, prev_extra, prev.1);
+                         prev.0, &prev_features - &cur_features, prev.1);
             }
             println!("");
             panic!("tools should not compile multiple copies of the same crate");