From 66241589690bff9488b64101b281a7a2b3a2393f Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonasschievink@gmail.com>
Date: Tue, 20 Apr 2021 16:25:24 +0200
Subject: [PATCH] Fix panic in `replace_derive_with_manual_impl`

---
 .../handlers/replace_derive_with_manual_impl.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs b/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
index 870a8d4ffba..47d8b9c9161 100644
--- a/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
+++ b/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
@@ -47,6 +47,11 @@ pub(crate) fn replace_derive_with_manual_impl(
         return None;
     }
 
+    if !args.syntax().text_range().contains(ctx.offset()) {
+        cov_mark::hit!(outside_of_attr_args);
+        return None;
+    }
+
     let trait_token = args.syntax().token_at_offset(ctx.offset()).find(|t| t.kind() == IDENT)?;
     let trait_name = trait_token.text();
 
@@ -396,4 +401,16 @@ struct Foo {}
             ",
         )
     }
+
+    #[test]
+    fn works_at_start_of_file() {
+        cov_mark::check!(outside_of_attr_args);
+        check_assist_not_applicable(
+            replace_derive_with_manual_impl,
+            r#"
+$0#[derive(Debug)]
+struct S;
+            "#,
+        );
+    }
 }