diff --git a/.travis.yml b/.travis.yml
index 905c0748f45..f54d4d55cd9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,7 +19,6 @@ matrix:
     - env: CFG_RELEASE_CHANNEL=beta
     - os: osx
     - env: INTEGRATION=bitflags
-    - env: INTEGRATION=cargo
     - env: INTEGRATION=chalk
     - env: INTEGRATION=crater
     - env: INTEGRATION=error-chain
@@ -41,6 +40,8 @@ matrix:
     - env: INTEGRATION=rust-semverver
     # can be moved back to include section after https://github.com/rust-lang-nursery/failure/pull/298 is merged
     - env: INTEGRATION=failure
+    # `cargo test` doesn't finish - disabling for now.
+    # - env: INTEGRATION=cargo
 
 script:
   - |
diff --git a/src/imports.rs b/src/imports.rs
index f6b41deaef9..08647dee490 100644
--- a/src/imports.rs
+++ b/src/imports.rs
@@ -242,30 +242,31 @@ impl UseTree {
                     format!("{}use {};", vis, s)
                 }
             })?;
-        if let Some(ref attrs) = self.attrs {
-            let attr_str = attrs.rewrite(context, shape)?;
-            let lo = attrs.last().as_ref()?.span().hi();
-            let hi = self.span.lo();
-            let span = mk_sp(lo, hi);
-
-            let allow_extend = if attrs.len() == 1 {
-                let line_len = attr_str.len() + 1 + use_str.len();
-                !attrs.first().unwrap().is_sugared_doc
-                    && context.config.inline_attribute_width() >= line_len
-            } else {
-                false
-            };
+        match self.attrs {
+            Some(ref attrs) if !attrs.is_empty() => {
+                let attr_str = attrs.rewrite(context, shape)?;
+                let lo = attrs.last().as_ref()?.span().hi();
+                let hi = self.span.lo();
+                let span = mk_sp(lo, hi);
+
+                let allow_extend = if attrs.len() == 1 {
+                    let line_len = attr_str.len() + 1 + use_str.len();
+                    !attrs.first().unwrap().is_sugared_doc
+                        && context.config.inline_attribute_width() >= line_len
+                } else {
+                    false
+                };
 
-            combine_strs_with_missing_comments(
-                context,
-                &attr_str,
-                &use_str,
-                span,
-                shape,
-                allow_extend,
-            )
-        } else {
-            Some(use_str)
+                combine_strs_with_missing_comments(
+                    context,
+                    &attr_str,
+                    &use_str,
+                    span,
+                    shape,
+                    allow_extend,
+                )
+            }
+            _ => Some(use_str),
         }
     }
 
diff --git a/tests/source/issue-3515.rs b/tests/source/issue-3515.rs
new file mode 100644
index 00000000000..9f760cb94e8
--- /dev/null
+++ b/tests/source/issue-3515.rs
@@ -0,0 +1,6 @@
+// rustfmt-reorder_imports: false
+
+use std :: fmt :: { self , Display } ;
+use std :: collections :: HashMap ;
+
+fn main() {}
diff --git a/tests/target/issue-3515.rs b/tests/target/issue-3515.rs
new file mode 100644
index 00000000000..b59d03c6c82
--- /dev/null
+++ b/tests/target/issue-3515.rs
@@ -0,0 +1,6 @@
+// rustfmt-reorder_imports: false
+
+use std::fmt::{self, Display};
+use std::collections::HashMap;
+
+fn main() {}
diff --git a/tests/target/long-use-statement-issue-3154.rs b/tests/target/long-use-statement-issue-3154.rs
index 339382b5bbf..877241e3b6f 100644
--- a/tests/target/long-use-statement-issue-3154.rs
+++ b/tests/target/long-use-statement-issue-3154.rs
@@ -1,3 +1,3 @@
 // rustfmt-reorder_imports: false
 
-pub use self :: super :: super :: super :: root::mozilla::detail::StringClassFlags as nsTStringRepr_ClassFlags ;
+pub use self::super::super::super::root::mozilla::detail::StringClassFlags as nsTStringRepr_ClassFlags;