diff --git a/crates/ra_hir/src/code_model_api.rs b/crates/ra_hir/src/code_model_api.rs
index 9ae620efd4c..21ca36265d1 100644
--- a/crates/ra_hir/src/code_model_api.rs
+++ b/crates/ra_hir/src/code_model_api.rs
@@ -366,6 +366,28 @@ impl Function {
             Some(comments)
         }
     }
+
+    pub fn label(&self, db: &impl HirDatabase) -> Option<String> {
+        let def_loc = self.def_id.loc(db);
+        let syntax = db.file_item(def_loc.source_item_id);
+        let node = ast::FnDef::cast(&syntax).expect("fn def should point to FnDef node");
+
+        let label: String = if let Some(body) = node.body() {
+            let body_range = body.syntax().range();
+            let label: String = node
+                .syntax()
+                .children()
+                .filter(|child| !child.range().is_subrange(&body_range)) // Filter out body
+                .filter(|child| ast::Comment::cast(child).is_none()) // Filter out comments
+                .map(|node| node.text().to_string())
+                .collect();
+            label
+        } else {
+            node.syntax().text().to_string()
+        };
+
+        Some(label.trim().to_owned())
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/crates/ra_ide_api/src/completion/completion_item.rs b/crates/ra_ide_api/src/completion/completion_item.rs
index d70c3688988..b720a138210 100644
--- a/crates/ra_ide_api/src/completion/completion_item.rs
+++ b/crates/ra_ide_api/src/completion/completion_item.rs
@@ -263,6 +263,10 @@ impl Builder {
             self.documentation = Some(docs);
         }
 
+        if let Some(label) = function.label(ctx.db) {
+            self.detail = Some(label);
+        }
+
         self.kind = Some(CompletionItemKind::Function);
         self
     }
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_for.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_for.snap
index 3d8d5af78a0..eb806ad6228 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_for.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_for.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.858540400+00:00"
+created: "2019-01-22T15:38:19.841148300+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -25,7 +25,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn quux()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_if_let.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_if_let.snap
index 7ed1d5ccb5b..4bb28c7e893 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_if_let.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_if_let.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.860535200+00:00"
+created: "2019-01-22T15:38:19.863089100+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -39,7 +39,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn quux()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_let.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_let.snap
index 95581122d35..0579d00ec49 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_let.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__bindings_from_let.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.871506600+00:00"
+created: "2019-01-22T15:38:19.881041600+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -39,7 +39,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn quux(x: i32)"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_if_already_call.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_if_already_call.snap
index 18d8b3fb3c3..091bf581e36 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_if_already_call.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_if_already_call.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.797704900+00:00"
+created: "2019-01-22T15:38:19.788294+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -11,7 +11,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn main()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: None,
@@ -25,7 +27,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn frobnicate()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: None,
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_in_use_item.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_in_use_item.snap
index 8bf7bf06ce1..3bc3f5f38aa 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_in_use_item.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_in_use_item.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.801693300+00:00"
+created: "2019-01-22T15:38:19.815217100+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -11,7 +11,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "pub fn foo()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: None,
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_show_both_completions_for_shadowing.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_show_both_completions_for_shadowing.snap
index 5844254e14c..3e88d8c8e0b 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_show_both_completions_for_shadowing.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__dont_show_both_completions_for_shadowing.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.912397100+00:00"
+created: "2019-01-22T15:38:19.914951100+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -25,7 +25,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn foo() ->"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__inserts_parens_for_function_calls1.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__inserts_parens_for_function_calls1.snap
index 732a873824f..b30a4c9e96b 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__inserts_parens_for_function_calls1.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__inserts_parens_for_function_calls1.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.932343200+00:00"
+created: "2019-01-22T15:38:19.919937+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -11,7 +11,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn no_args()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
@@ -27,7 +29,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn main()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__inserts_parens_for_function_calls2.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__inserts_parens_for_function_calls2.snap
index 2431b3276b2..c524f3587c9 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__inserts_parens_for_function_calls2.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__inserts_parens_for_function_calls2.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.995180+00:00"
+created: "2019-01-22T15:38:19.996733+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -11,7 +11,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn main()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
@@ -27,7 +29,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn with_args(x: i32, y: String)"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__method_completion.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__method_completion.snap
index c294de5cbf2..ffeac0bf430 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__method_completion.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__method_completion.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.546394900+00:00"
+created: "2019-01-22T15:38:19.541947400+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -11,7 +11,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Method
         ),
-        detail: None,
+        detail: Some(
+            "fn the_method(&self)"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__module_items.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__module_items.snap
index 032516ab402..df9677ba3d4 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__module_items.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__module_items.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.874497400+00:00"
+created: "2019-01-22T15:38:19.896999400+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -11,7 +11,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn quux()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__module_items_in_nested_modules.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__module_items_in_nested_modules.snap
index b33babaf09f..f4b38feb061 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__module_items_in_nested_modules.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__module_items_in_nested_modules.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.875495300+00:00"
+created: "2019-01-22T15:38:19.896002200+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -11,7 +11,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn quux()"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__return_type.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__return_type.snap
index 24dbe6bb015..e6819f231cc 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__return_type.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__return_type.snap
@@ -25,7 +25,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Function
         ),
-        detail: None,
+        detail: Some(
+            "fn x() ->"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_autoderef.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_autoderef.snap
index 9ee668b3598..5ef140b2812 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_autoderef.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_autoderef.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.552379600+00:00"
+created: "2019-01-22T15:38:19.541947400+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -27,7 +27,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Method
         ),
-        detail: None,
+        detail: Some(
+            "fn foo(&self)"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_self.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_self.snap
index b9d70ea3f25..b7903c5bcb4 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_self.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__struct_field_completion_self.snap
@@ -1,5 +1,5 @@
 ---
-created: "2019-01-22T14:45:00.552379600+00:00"
+created: "2019-01-22T15:38:19.541947400+00:00"
 creator: insta@0.4.0
 expression: kind_completions
 source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
@@ -27,7 +27,9 @@ source: "crates\\ra_ide_api\\src\\completion\\completion_item.rs"
         kind: Some(
             Method
         ),
-        detail: None,
+        detail: Some(
+            "fn foo(self)"
+        ),
         documentation: None,
         lookup: None,
         insert_text: Some(