1 files changed, 39 insertions, 0 deletions
diff --git a/src/test/ui/rust-2018/remove-extern-crate.rs b/src/test/ui/rust-2018/remove-extern-crate.rs
new file mode 100644
index 000000000..bbb84cd46
--- /dev/null
+++ b/src/test/ui/rust-2018/remove-extern-crate.rs
@@ -0,0 +1,39 @@
+// run-rustfix
+// edition:2018
+// check-pass
+// aux-build:remove-extern-crate.rs
+// compile-flags:--extern remove_extern_crate
+
+#![warn(rust_2018_idioms)]
+
+extern crate core; //~ WARNING unused extern crate
+// Shouldn't suggest changing to `use`, as `another_name`
+// would no longer be added to the prelude which could cause
+// compilation errors for imports that use `another_name` in other
+// modules. See #57672.
+extern crate core as another_name;
+use remove_extern_crate;
+#[macro_use]
+extern crate remove_extern_crate as something_else;
+
+// Shouldn't suggest changing to `use`, as the `alloc`
+// crate is not in the extern prelude - see #54381.
+extern crate alloc;
+
+fn main() {
+    another_name::mem::drop(3);
+    another::foo();
+    remove_extern_crate::foo!();
+    bar!();
+    alloc::vec![5];
+}
+
+mod another {
+    extern crate core; //~ WARNING `extern crate` is not idiomatic
+    use remove_extern_crate;
+
+    pub fn foo() {
+        core::mem::drop(4);
+        remove_extern_crate::foo!();
+    }
+}