1 files changed, 71 insertions, 0 deletions
diff --git a/src/test/ui/lint/unnecessary-extern-crate.rs b/src/test/ui/lint/unnecessary-extern-crate.rs
new file mode 100644
index 000000000..af2bd84bd
--- /dev/null
+++ b/src/test/ui/lint/unnecessary-extern-crate.rs
@@ -0,0 +1,71 @@
+// edition:2018
+
+#![deny(unused_extern_crates)]
+#![feature(test, rustc_private)]
+
+extern crate libc;
+//~^ ERROR unused extern crate
+//~| HELP remove
+extern crate libc as x;
+//~^ ERROR unused extern crate
+//~| HELP remove
+
+extern crate proc_macro;
+
+#[macro_use]
+extern crate test;
+
+pub extern crate test as y;
+
+pub extern crate alloc;
+
+pub(crate) extern crate alloc as a;
+
+pub(crate) extern crate alloc as b;
+
+mod foo {
+    pub(in crate::foo) extern crate alloc as c;
+
+    pub(super) extern crate alloc as d;
+
+    extern crate libc;
+    //~^ ERROR unused extern crate
+    //~| HELP remove
+
+    extern crate libc as x;
+    //~^ ERROR unused extern crate
+    //~| HELP remove
+
+    pub extern crate test;
+
+    pub extern crate test as y;
+
+    mod bar {
+        extern crate libc;
+        //~^ ERROR unused extern crate
+        //~| HELP remove
+
+        extern crate libc as x;
+        //~^ ERROR unused extern crate
+        //~| HELP remove
+
+        pub(in crate::foo::bar) extern crate alloc as e;
+
+        fn dummy() {
+            e::string::String::new();
+        }
+    }
+
+    fn dummy() {
+        c::string::String::new();
+        d::string::String::new();
+    }
+}
+
+
+fn main() {
+    a::string::String::new();
+    b::string::String::new();
+
+    proc_macro::TokenStream::new();
+}