From 798f43da502e4b8d52e9b907420708d956faa054 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Fri, 17 Jul 2020 15:44:37 +0200
Subject: [PATCH] Fix out of bounds panic in active parameter

---
 crates/ra_ide/src/call_info.rs               |  4 ++++
 crates/ra_ide/src/completion/presentation.rs | 16 ++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/crates/ra_ide/src/call_info.rs b/crates/ra_ide/src/call_info.rs
index 14980afdd0..ff602202f2 100644
--- a/crates/ra_ide/src/call_info.rs
+++ b/crates/ra_ide/src/call_info.rs
@@ -161,6 +161,10 @@ impl ActiveParameter {
 
         let idx = active_parameter?;
         let mut params = signature.params(sema.db);
+        if !(idx < params.len()) {
+            mark::hit!(too_many_arguments);
+            return None;
+        }
         let (pat, ty) = params.swap_remove(idx);
         let name = pat?.to_string();
         Some(ActiveParameter { ty, name })
diff --git a/crates/ra_ide/src/completion/presentation.rs b/crates/ra_ide/src/completion/presentation.rs
index c7b74e6355..9a94ff4767 100644
--- a/crates/ra_ide/src/completion/presentation.rs
+++ b/crates/ra_ide/src/completion/presentation.rs
@@ -1159,6 +1159,22 @@ fn go(world: &WorldSnapshot) { go(w<|>) }
         );
     }
 
+    #[test]
+    fn too_many_arguments() {
+        mark::check!(too_many_arguments);
+        check_scores(
+            r#"
+struct Foo;
+fn f(foo: &Foo) { f(foo, w<|>) }
+"#,
+            expect![[r#"
+                st Foo []
+                fn f(…) []
+                bn foo []
+            "#]],
+        );
+    }
+
     #[test]
     fn guesses_macro_braces() {
         check_edit(