diff --git a/crates/completion/src/completions/dot.rs b/crates/completion/src/completions/dot.rs
index d04eef65a79..0880a38304e 100644
--- a/crates/completion/src/completions/dot.rs
+++ b/crates/completion/src/completions/dot.rs
@@ -83,7 +83,7 @@ fn foo(s: S) { s.$0 }
 "#,
             expect![[r#"
                 fd foo   u32
-                me bar() fn bar(&self)
+                me bar() -> ()
             "#]],
         );
     }
@@ -99,7 +99,7 @@ impl S {
 "#,
             expect![[r#"
                 fd the_field (u32,)
-                me foo()     fn foo(self)
+                me foo()     -> ()
             "#]],
         )
     }
@@ -115,7 +115,7 @@ impl A {
 "#,
             expect![[r#"
                 fd the_field (u32, i32)
-                me foo()     fn foo(&self)
+                me foo()     -> ()
             "#]],
         )
     }
@@ -165,7 +165,7 @@ mod m {
 fn foo(a: A) { a.$0 }
 "#,
             expect![[r#"
-                me the_method() pub(crate) fn the_method(&self)
+                me the_method() -> ()
             "#]],
         );
     }
@@ -198,7 +198,7 @@ impl A<i32> {
 fn foo(a: A<u32>) { a.$0 }
 "#,
             expect![[r#"
-                me the_method() fn the_method(&self)
+                me the_method() -> ()
             "#]],
         )
     }
@@ -213,7 +213,7 @@ impl Trait for A {}
 fn foo(a: A) { a.$0 }
 "#,
             expect![[r#"
-                me the_method() fn the_method(&self)
+                me the_method() -> ()
             "#]],
         );
     }
@@ -228,7 +228,7 @@ impl<T> Trait for T {}
 fn foo(a: &A) { a.$0 }
 ",
             expect![[r#"
-                me the_method() fn the_method(&self)
+                me the_method() -> ()
             "#]],
         );
     }
@@ -246,7 +246,7 @@ impl Trait for A {}
 fn foo(a: A) { a.$0 }
 ",
             expect![[r#"
-                me the_method() fn the_method(&self)
+                me the_method() -> ()
             "#]],
         );
     }
@@ -300,7 +300,7 @@ impl T {
 }
 "#,
             expect![[r#"
-                me blah() pub fn blah(&self)
+                me blah() -> ()
             "#]],
         );
     }
@@ -409,7 +409,7 @@ fn foo() {
 }
 "#,
             expect![[r#"
-                me the_method() pub fn the_method(&self)
+                me the_method() -> ()
             "#]],
         );
     }
@@ -424,7 +424,7 @@ macro_rules! make_s { () => { S }; }
 fn main() { make_s!().f$0; }
 "#,
             expect![[r#"
-                me foo() fn foo(&self)
+                me foo() -> ()
             "#]],
         )
     }
diff --git a/crates/completion/src/completions/flyimport.rs b/crates/completion/src/completions/flyimport.rs
index dc0b38a165d..6591127b1de 100644
--- a/crates/completion/src/completions/flyimport.rs
+++ b/crates/completion/src/completions/flyimport.rs
@@ -366,8 +366,8 @@ fn main() {
         check(
             fixture,
             expect![[r#"
-            fn weird_function() (dep::test_mod::TestTrait) fn weird_function()
-        "#]],
+                fn weird_function() (dep::test_mod::TestTrait) -> ()
+            "#]],
         );
 
         check_edit(
@@ -459,8 +459,8 @@ fn main() {
         check(
             fixture,
             expect![[r#"
-            me random_method() (dep::test_mod::TestTrait) fn random_method(&self)
-        "#]],
+                me random_method() (dep::test_mod::TestTrait) -> ()
+            "#]],
         );
 
         check_edit(
@@ -629,8 +629,8 @@ fn main() {
 }
         "#,
             expect![[r#"
-                        me random_method() (dep::test_mod::TestTrait) fn random_method(&self) DEPRECATED
-                "#]],
+                me random_method() (dep::test_mod::TestTrait) -> () DEPRECATED
+            "#]],
         );
 
         check(
@@ -660,8 +660,8 @@ fn main() {
 "#,
             expect![[r#"
                 ct SPECIAL_CONST (dep::test_mod::TestTrait) DEPRECATED
-                fn weird_function() (dep::test_mod::TestTrait) fn weird_function() DEPRECATED
-        "#]],
+                fn weird_function() (dep::test_mod::TestTrait) -> () DEPRECATED
+            "#]],
         );
     }
 }
diff --git a/crates/completion/src/completions/qualified_path.rs b/crates/completion/src/completions/qualified_path.rs
index 33df2676156..bbeaab49657 100644
--- a/crates/completion/src/completions/qualified_path.rs
+++ b/crates/completion/src/completions/qualified_path.rs
@@ -359,8 +359,8 @@ impl S {
 fn foo() { let _ = S::$0 }
 "#,
             expect![[r#"
-                fn a()  fn a()
-                me b(…) fn b(&self)
+                fn a()  -> ()
+                me b(…) -> ()
                 ct C    const C: i32 = 42;
                 ta T    type T = i32;
             "#]],
@@ -387,7 +387,7 @@ mod m {
 fn foo() { let _ = S::$0 }
 "#,
             expect![[r#"
-                fn public_method() pub(crate) fn public_method()
+                fn public_method() -> ()
                 ct PUBLIC_CONST    pub(crate) const PUBLIC_CONST: u32 = 1;
                 ta PublicType      pub(crate) type PublicType = u32;
             "#]],
@@ -404,7 +404,7 @@ impl E { fn m() { } }
 fn foo() { let _ = E::$0 }
         "#,
             expect![[r#"
-                fn m() fn m()
+                fn m() -> ()
             "#]],
         );
     }
@@ -419,7 +419,7 @@ impl U { fn m() { } }
 fn foo() { let _ = U::$0 }
 "#,
             expect![[r#"
-                fn m() fn m()
+                fn m() -> ()
             "#]],
         );
     }
@@ -449,7 +449,7 @@ trait Trait { fn m(); }
 fn foo() { let _ = Trait::$0 }
 "#,
             expect![[r#"
-                fn m() fn m()
+                fn m() -> ()
             "#]],
         );
     }
@@ -466,7 +466,7 @@ impl Trait for S {}
 fn foo() { let _ = S::$0 }
 "#,
             expect![[r#"
-                fn m() fn m()
+                fn m() -> ()
             "#]],
         );
     }
@@ -483,7 +483,7 @@ impl Trait for S {}
 fn foo() { let _ = <S as Trait>::$0 }
 "#,
             expect![[r#"
-                fn m() fn m()
+                fn m() -> ()
             "#]],
         );
     }
@@ -512,11 +512,11 @@ fn foo<T: Sub>() { T::$0 }
                 ta SubTy        type SubTy;
                 ta Ty           type Ty;
                 ct C2           const C2: ();
-                fn subfunc()    fn subfunc()
-                me submethod(…) fn submethod(&self)
+                fn subfunc()    -> ()
+                me submethod(…) -> ()
                 ct CONST        const CONST: u8;
-                fn func()       fn func()
-                me method(…)    fn method(&self)
+                fn func()       -> ()
+                me method(…)    -> ()
             "#]],
         );
     }
@@ -552,11 +552,11 @@ impl<T> Sub for Wrap<T> {
                 ta SubTy        type SubTy;
                 ta Ty           type Ty;
                 ct CONST        const CONST: u8 = 0;
-                fn func()       fn func()
-                me method(…)    fn method(&self)
+                fn func()       -> ()
+                me method(…)    -> ()
                 ct C2           const C2: () = ();
-                fn subfunc()    fn subfunc()
-                me submethod(…) fn submethod(&self)
+                fn subfunc()    -> ()
+                me submethod(…) -> ()
             "#]],
         );
     }
@@ -573,8 +573,8 @@ impl T { fn bar() {} }
 fn main() { T::$0; }
 "#,
             expect![[r#"
-                fn foo() fn foo()
-                fn bar() fn bar()
+                fn foo() -> ()
+                fn bar() -> ()
             "#]],
         );
     }
@@ -589,7 +589,7 @@ macro_rules! foo { () => {} }
 fn main() { let _ = crate::$0 }
         "#,
             expect![[r##"
-                fn main()  fn main()
+                fn main()  -> ()
                 ma foo!(…) #[macro_export] macro_rules! foo
             "##]],
         );
@@ -633,7 +633,7 @@ mod p {
 "#,
             expect![[r#"
                 ct RIGHT_CONST
-                fn right_fn()  fn wrong_fn()
+                fn right_fn()  -> ()
                 st RightType
             "#]],
         );
@@ -680,8 +680,8 @@ fn main() { m!(self::f$0); }
 fn foo() {}
 "#,
             expect![[r#"
-                fn main() fn main()
-                fn foo()  fn foo()
+                fn main() -> ()
+                fn foo()  -> ()
             "#]],
         );
     }
@@ -699,7 +699,7 @@ mod m {
 "#,
             expect![[r#"
                 md z
-                fn z() pub fn z()
+                fn z() -> ()
             "#]],
         );
     }
@@ -719,7 +719,7 @@ fn foo() {
 }
 "#,
             expect![[r#"
-                fn new() pub fn new() -> HashMap<K, V, RandomState>
+                fn new() -> HashMap<K, V, RandomState>
             "#]],
         );
     }
@@ -752,8 +752,8 @@ fn main() {
 }
 "#,
             expect![[r#"
-                fn main() fn main()
-                fn foo(…) fn foo(a: i32, b: i32)
+                fn main() -> ()
+                fn foo(…) -> ()
             "#]],
         );
     }
@@ -776,7 +776,7 @@ impl Foo {
             expect![[r#"
                 ev Bar    ()
                 ev Baz    ()
-                me foo(…) fn foo(self)
+                me foo(…) -> ()
             "#]],
         );
     }
diff --git a/crates/completion/src/completions/trait_impl.rs b/crates/completion/src/completions/trait_impl.rs
index f258ad9c3f0..b999540b84d 100644
--- a/crates/completion/src/completions/trait_impl.rs
+++ b/crates/completion/src/completions/trait_impl.rs
@@ -679,11 +679,6 @@ impl Test for () {
     #[test]
     fn complete_without_name() {
         let test = |completion: &str, hint: &str, completed: &str, next_sibling: &str| {
-            println!(
-                "completion='{}', hint='{}', next_sibling='{}'",
-                completion, hint, next_sibling
-            );
-
             check_edit(
                 completion,
                 &format!(
diff --git a/crates/completion/src/completions/unqualified_path.rs b/crates/completion/src/completions/unqualified_path.rs
index a289efc34eb..5d62fab9743 100644
--- a/crates/completion/src/completions/unqualified_path.rs
+++ b/crates/completion/src/completions/unqualified_path.rs
@@ -167,7 +167,7 @@ fn quux(x: i32) {
             expect![[r#"
                 lc y       i32
                 lc x       i32
-                fn quux(…) fn quux(x: i32)
+                fn quux(…) -> ()
             "#]],
         );
     }
@@ -189,7 +189,7 @@ fn quux() {
             expect![[r#"
                 lc b      i32
                 lc a
-                fn quux() fn quux()
+                fn quux() -> ()
             "#]],
         );
     }
@@ -204,7 +204,7 @@ fn quux() {
 "#,
             expect![[r#"
                 lc x
-                fn quux() fn quux()
+                fn quux() -> ()
             "#]],
         );
     }
@@ -235,14 +235,14 @@ fn main() {
             r#"fn quux<T>() { $0 }"#,
             expect![[r#"
                 tp T
-                fn quux() fn quux<T>()
+                fn quux() -> ()
             "#]],
         );
         check(
             r#"fn quux<const C: usize>() { $0 }"#,
             expect![[r#"
                 cp C
-                fn quux() fn quux<const C: usize>()
+                fn quux() -> ()
             "#]],
         );
     }
@@ -253,7 +253,7 @@ fn main() {
         check(
             r#"fn quux<'a>() { $0 }"#,
             expect![[r#"
-                fn quux() fn quux<'a>()
+                fn quux() -> ()
             "#]],
         );
     }
@@ -291,7 +291,7 @@ fn quux() { $0 }
 "#,
             expect![[r#"
                 st S
-                fn quux() fn quux()
+                fn quux() -> ()
                 en E
             "#]],
         );
@@ -344,7 +344,7 @@ mod m {
 }
 "#,
             expect![[r#"
-                fn quux() fn quux()
+                fn quux() -> ()
                 st Bar
             "#]],
         );
@@ -359,7 +359,7 @@ fn x() -> $0
 "#,
             expect![[r#"
                 st Foo
-                fn x() fn x()
+                fn x() -> ()
             "#]],
         );
     }
@@ -380,7 +380,7 @@ fn foo() {
             expect![[r#"
                 lc bar   i32
                 lc bar   i32
-                fn foo() fn foo()
+                fn foo() -> ()
             "#]],
         );
     }
@@ -410,7 +410,7 @@ use prelude::*;
 mod prelude { struct Option; }
 "#,
             expect![[r#"
-                fn foo()  fn foo()
+                fn foo()  -> ()
                 md std
                 st Option
             "#]],
@@ -440,7 +440,7 @@ mod macros {
 }
 "#,
             expect![[r##"
-                fn f()        fn f()
+                fn f()        -> ()
                 ma concat!(…) #[macro_export] macro_rules! concat
                 md std
             "##]],
@@ -467,7 +467,7 @@ use prelude::*;
 mod prelude { struct String; }
 "#,
             expect![[r#"
-                fn foo()  fn foo()
+                fn foo()  -> ()
                 md std
                 md core
                 st String
@@ -498,7 +498,7 @@ fn main() { let v = $0 }
             expect![[r##"
                 md m1
                 ma baz!(…) #[macro_export] macro_rules! baz
-                fn main()  fn main()
+                fn main()  -> ()
                 md m2
                 ma bar!(…) macro_rules! bar
                 ma foo!(…) macro_rules! foo
@@ -514,7 +514,7 @@ macro_rules! foo { () => {} }
 fn foo() { $0 }
 "#,
             expect![[r#"
-                fn foo()   fn foo()
+                fn foo()   -> ()
                 ma foo!(…) macro_rules! foo
             "#]],
         );
@@ -528,7 +528,7 @@ macro_rules! foo { () => {} }
 fn main() { let x: $0 }
 "#,
             expect![[r#"
-                fn main()  fn main()
+                fn main()  -> ()
                 ma foo!(…) macro_rules! foo
             "#]],
         );
@@ -542,7 +542,7 @@ macro_rules! foo { () => {} }
 fn main() { $0 }
 "#,
             expect![[r#"
-                fn main()  fn main()
+                fn main()  -> ()
                 ma foo!(…) macro_rules! foo
             "#]],
         );
@@ -558,8 +558,8 @@ fn main() {
 }
 "#,
             expect![[r#"
-                fn frobnicate() fn frobnicate()
-                fn main()       fn main()
+                fn frobnicate() -> ()
+                fn main()       -> ()
             "#]],
         );
     }
@@ -577,7 +577,7 @@ fn quux(x: i32) {
             expect![[r#"
                 lc y       i32
                 lc x       i32
-                fn quux(…) fn quux(x: i32)
+                fn quux(…) -> ()
                 ma m!(…)   macro_rules! m
             "#]],
         );
@@ -596,7 +596,7 @@ fn quux(x: i32) {
             expect![[r#"
                 lc y       i32
                 lc x       i32
-                fn quux(…) fn quux(x: i32)
+                fn quux(…) -> ()
                 ma m!(…)   macro_rules! m
             "#]],
         );
@@ -615,7 +615,7 @@ fn quux(x: i32) {
             expect![[r#"
                 lc y       i32
                 lc x       i32
-                fn quux(…) fn quux(x: i32)
+                fn quux(…) -> ()
                 ma m!(…)   macro_rules! m
             "#]],
         );
@@ -630,7 +630,7 @@ use spam::Quux;
 fn main() { $0 }
 "#,
             expect![[r#"
-                fn main() fn main()
+                fn main() -> ()
                 ?? Quux
             "#]],
         );
@@ -708,7 +708,7 @@ fn main() { let foo: Foo = Q$0 }
                 ev Foo::Baz  ()
                 ev Foo::Quux ()
                 en Foo
-                fn main()    fn main()
+                fn main()    -> ()
             "#]],
         )
     }
@@ -723,7 +723,7 @@ fn f() -> m::E { V$0 }
             expect![[r#"
                 ev m::E::V ()
                 md m
-                fn f()     fn f() -> m::E
+                fn f()     -> E
             "#]],
         )
     }
diff --git a/crates/completion/src/item.rs b/crates/completion/src/item.rs
index d2e6a6aeb4f..eeb952ec3c5 100644
--- a/crates/completion/src/item.rs
+++ b/crates/completion/src/item.rs
@@ -398,14 +398,13 @@ impl Builder {
         self.insert_text_format = InsertTextFormat::Snippet;
         self.text_edit(edit)
     }
-    #[allow(unused)]
     pub(crate) fn detail(self, detail: impl Into<String>) -> Builder {
         self.set_detail(Some(detail))
     }
     pub(crate) fn set_detail(mut self, detail: Option<impl Into<String>>) -> Builder {
         self.detail = detail.map(Into::into);
         if let Some(detail) = &self.detail {
-            if assert_never!(detail.contains('\n'), "multiline detail: {}", detail) {
+            if assert_never!(detail.contains('\n'), "multiline detail:\n{}", detail) {
                 self.detail = Some(detail.splitn(2, '\n').next().unwrap().to_string());
             }
         }
diff --git a/crates/completion/src/lib.rs b/crates/completion/src/lib.rs
index 2c4e5452497..50329b4990f 100644
--- a/crates/completion/src/lib.rs
+++ b/crates/completion/src/lib.rs
@@ -227,7 +227,7 @@ mod tests {
                 bar.fo$0;
             }
             "#,
-            DetailAndDocumentation { detail: "fn foo(&self)", documentation: "Do the foo" },
+            DetailAndDocumentation { detail: "-> ()", documentation: "Do the foo" },
         );
     }
 
@@ -253,7 +253,7 @@ mod tests {
                 bar.fo$0;
             }
             "#,
-            DetailAndDocumentation { detail: "fn foo(&self)", documentation: " Do the foo" },
+            DetailAndDocumentation { detail: "-> ()", documentation: " Do the foo" },
         );
     }
 
@@ -277,10 +277,7 @@ mod tests {
                 for c in fo$0
             }
             "#,
-            DetailAndDocumentation {
-                detail: "fn foo() -> &'static str",
-                documentation: "Do the foo",
-            },
+            DetailAndDocumentation { detail: "-> &str", documentation: "Do the foo" },
         );
     }
 }
diff --git a/crates/completion/src/render.rs b/crates/completion/src/render.rs
index fa594b5e527..6eb20df2bf4 100644
--- a/crates/completion/src/render.rs
+++ b/crates/completion/src/render.rs
@@ -523,7 +523,7 @@ fn main() { let _: m::Spam = S$0 }
                             Function,
                         ),
                         lookup: "main",
-                        detail: "fn main()",
+                        detail: "-> ()",
                     },
                 ]
             "#]],
@@ -552,7 +552,7 @@ fn main() { som$0 }
                             Function,
                         ),
                         lookup: "main",
-                        detail: "fn main()",
+                        detail: "-> ()",
                     },
                     CompletionItem {
                         label: "something_deprecated()",
@@ -563,7 +563,7 @@ fn main() { som$0 }
                             Function,
                         ),
                         lookup: "something_deprecated",
-                        detail: "fn something_deprecated()",
+                        detail: "-> ()",
                         deprecated: true,
                     },
                     CompletionItem {
@@ -575,7 +575,7 @@ fn main() { som$0 }
                             Function,
                         ),
                         lookup: "something_else_deprecated",
-                        detail: "fn something_else_deprecated()",
+                        detail: "-> ()",
                         deprecated: true,
                     },
                 ]
@@ -626,7 +626,7 @@ impl S {
                         insert: "bar()$0",
                         kind: Method,
                         lookup: "bar",
-                        detail: "fn bar(self)",
+                        detail: "-> ()",
                         documentation: Documentation(
                             "Method docs",
                         ),
@@ -726,7 +726,7 @@ fn foo(s: S) { s.$0 }
                         insert: "the_method()$0",
                         kind: Method,
                         lookup: "the_method",
-                        detail: "fn the_method(&self)",
+                        detail: "-> ()",
                     },
                 ]
             "#]],
diff --git a/crates/completion/src/render/function.rs b/crates/completion/src/render/function.rs
index 2d616b1fb54..e46e21d243f 100644
--- a/crates/completion/src/render/function.rs
+++ b/crates/completion/src/render/function.rs
@@ -1,8 +1,8 @@
 //! Renderer for function calls.
 
-use hir::{HasSource, Type};
+use hir::{HasSource, HirDisplay, Type};
 use ide_db::SymbolKind;
-use syntax::{ast::Fn, display::function_declaration};
+use syntax::ast::Fn;
 use test_utils::mark;
 
 use crate::{
@@ -55,7 +55,8 @@ impl<'a> FunctionRender<'a> {
     }
 
     fn detail(&self) -> String {
-        function_declaration(&self.ast_node)
+        let ty = self.func.ret_type(self.ctx.db());
+        format!("-> {}", ty.display(self.ctx.db()))
     }
 
     fn add_arg(&self, arg: &str, ty: &Type) -> String {