1 files changed, 32 insertions, 0 deletions
diff --git a/tests/ui/proc-macro/auxiliary/duplicate.rs b/tests/ui/proc-macro/auxiliary/duplicate.rs
new file mode 100644
index 00000000000..b8f82b46f09
--- /dev/null
+++ b/tests/ui/proc-macro/auxiliary/duplicate.rs
@@ -0,0 +1,32 @@
+// force-host
+// no-prefer-dynamic
+
+#![deny(unused)]
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::*;
+
+#[proc_macro_attribute]
+pub fn duplicate(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let mut new_name = Some(attr.into_iter().nth(0).unwrap());
+    let mut encountered_idents = 0;
+    let input = item.to_string();
+    let ret = item
+        .into_iter()
+        .map(move |token| match token {
+            TokenTree::Ident(_) if encountered_idents == 1 => {
+                encountered_idents += 1;
+                new_name.take().unwrap()
+            }
+            TokenTree::Ident(_) => {
+                encountered_idents += 1;
+                token
+            }
+            _ => token,
+        })
+        .collect::<TokenStream>();
+    let mut input_again = input.parse::<TokenStream>().unwrap();
+    input_again.extend(ret);
+    input_again
+}