1 files changed, 493 insertions, 522 deletions

diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index d6dfa0183..9f2f6c80a 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -299,9 +299,8 @@ fn should_not_display_type_hint(
                     // Type of expr should be iterable.
                     return it.in_token().is_none() ||
                         it.iterable()
-                            .and_then(|iterable_expr|sema.type_of_expr(&iterable_expr))
-                            .map(|iterable_ty| iterable_ty.is_unknown() || iterable_ty.is_unit())
-                            .unwrap_or(true)
+                            .and_then(|iterable_expr| sema.type_of_expr(&iterable_expr))
+                            .map_or(true, |iterable_ty| iterable_ty.is_unknown() || iterable_ty.is_unit())
                 },
                 _ => (),
             }
@@ -319,8 +318,8 @@ fn should_hide_param_name_hint(
     // hide when:
     // - the parameter name is a suffix of the function's name
     // - the argument is an enum whose name is equal to the parameter
-    // - exact argument<->parameter match(ignoring leading underscore) or argument is a prefix/suffix
-    //   of parameter with _ splitting it off
+    // - exact argument<->parameter match(ignoring leading underscore) or parameter is a prefix/suffix
+    //   of argument with _ splitting it off
     // - param starts with `ra_fixture`
     // - param is a well known name in an unary function
 
@@ -342,23 +341,22 @@ fn should_hide_param_name_hint(
 }
 
 fn is_argument_similar_to_param_name(argument: &ast::Expr, param_name: &str) -> bool {
-    match get_string_representation(argument) {
-        None => false,
-        Some(argument) => {
-            let mut res = false;
-            if let Some(first) = argument.bytes().skip_while(|&c| c == b'_').position(|c| c == b'_')
-            {
-                res |= param_name == argument[..first].trim_start_matches('_');
-            }
-            if let Some(last) =
-                argument.bytes().rev().skip_while(|&c| c == b'_').position(|c| c == b'_')
-            {
-                res |= param_name == argument[last..].trim_end_matches('_');
-            }
-            res |= argument == param_name;
-            res
-        }
+    // check whether param_name and argument are the same or
+    // whether param_name is a prefix/suffix of argument(split at `_`)
+    let argument = match get_string_representation(argument) {
+        Some(argument) => argument,
+        None => return false,
+    };
+
+    let param_name = param_name.trim_start_matches('_');
+    let argument = argument.trim_start_matches('_');
+    if argument.strip_prefix(param_name).map_or(false, |s| s.starts_with('_')) {
+        return true;
     }
+    if argument.strip_suffix(param_name).map_or(false, |s| s.ends_with('_')) {
+        return true;
+    }
+    argument == param_name
 }
 
 /// Hide the parameter name of an unary function if it is a `_` - prefixed suffix of the function's name, or equal.
@@ -451,6 +449,42 @@ mod tests {
         check_with_config(TEST_CONFIG, ra_fixture);
     }
 
+    fn check_params(ra_fixture: &str) {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: true,
+                type_hints: false,
+                chaining_hints: false,
+                max_length: None,
+            },
+            ra_fixture,
+        );
+    }
+
+    fn check_types(ra_fixture: &str) {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: true,
+                chaining_hints: false,
+                max_length: None,
+            },
+            ra_fixture,
+        );
+    }
+
+    fn check_chains(ra_fixture: &str) {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: false,
+                chaining_hints: true,
+                max_length: None,
+            },
+            ra_fixture,
+        );
+    }
+
     fn check_with_config(config: InlayHintsConfig, ra_fixture: &str) {
         let ra_fixture =
             format!("//- /main.rs crate:main deps:core\n{}\n{}", ra_fixture, FamousDefs::FIXTURE);
@@ -471,17 +505,28 @@ mod tests {
     }
 
     #[test]
-    fn param_hints_only() {
+    fn hints_disabled() {
         check_with_config(
             InlayHintsConfig {
-                parameter_hints: true,
                 type_hints: false,
+                parameter_hints: false,
                 chaining_hints: false,
                 max_length: None,
             },
             r#"
 fn foo(a: i32, b: i32) -> i32 { a + b }
 fn main() {
+    let _x = foo(4, 4);
+}"#,
+        );
+    }
+
+    #[test]
+    fn param_hints_only() {
+        check_params(
+            r#"
+fn foo(a: i32, b: i32) -> i32 { a + b }
+fn main() {
     let _x = foo(
         4,
       //^ a
@@ -494,13 +539,7 @@ fn main() {
 
     #[test]
     fn param_name_similar_to_fn_name_still_hints() {
-        check_with_config(
-            InlayHintsConfig {
-                parameter_hints: true,
-                type_hints: false,
-                chaining_hints: false,
-                max_length: None,
-            },
+        check_params(
             r#"
 fn max(x: i32, y: i32) -> i32 { x + y }
 fn main() {
@@ -516,13 +555,7 @@ fn main() {
 
     #[test]
     fn param_name_similar_to_fn_name() {
-        check_with_config(
-            InlayHintsConfig {
-                parameter_hints: true,
-                type_hints: false,
-                chaining_hints: false,
-                max_length: None,
-            },
+        check_params(
             r#"
 fn param_with_underscore(with_underscore: i32) -> i32 { with_underscore }
 fn main() {
@@ -535,13 +568,7 @@ fn main() {
 
     #[test]
     fn param_name_same_as_fn_name() {
-        check_with_config(
-            InlayHintsConfig {
-                parameter_hints: true,
-                type_hints: false,
-                chaining_hints: false,
-                max_length: None,
-            },
+        check_params(
             r#"
 fn foo(foo: i32) -> i32 { foo }
 fn main() {
@@ -554,13 +581,7 @@ fn main() {
 
     #[test]
     fn never_hide_param_when_multiple_params() {
-        check_with_config(
-            InlayHintsConfig {
-                parameter_hints: true,
-                type_hints: false,
-                chaining_hints: false,
-                max_length: None,
-            },
+        check_params(
             r#"
 fn foo(bar: i32, baz: i32) -> i32 { bar + baz }
 fn main() {
@@ -575,209 +596,56 @@ fn main() {
     }
 
     #[test]
-    fn hints_disabled() {
-        check_with_config(
-            InlayHintsConfig {
-                type_hints: false,
-                parameter_hints: false,
-                chaining_hints: false,
-                max_length: None,
-            },
-            r#"
-fn foo(a: i32, b: i32) -> i32 { a + b }
-fn main() {
-    let _x = foo(4, 4);
-}"#,
-        );
-    }
-
-    #[test]
-    fn type_hints_only() {
-        check_with_config(
-            InlayHintsConfig {
-                type_hints: true,
-                parameter_hints: false,
-                chaining_hints: false,
-                max_length: None,
-            },
-            r#"
-fn foo(a: i32, b: i32) -> i32 { a + b }
-fn main() {
-    let _x = foo(4, 4);
-      //^^ i32
-}"#,
-        );
-    }
-
-    #[test]
-    fn default_generic_types_should_not_be_displayed() {
-        check(
-            r#"
-struct Test<K, T = u8> { k: K, t: T }
-
-fn main() {
-    let zz = Test { t: 23u8, k: 33 };
-      //^^ Test<i32>
-    let zz_ref = &zz;
-      //^^^^^^ &Test<i32>
-    let test = || zz;
-      //^^^^ || -> Test<i32>
-}"#,
-        );
-    }
-
-    #[test]
-    fn let_statement() {
-        check(
-            r#"
-#[derive(PartialEq)]
-enum Option<T> { None, Some(T) }
-
-#[derive(PartialEq)]
-struct Test { a: Option<u32>, b: u8 }
-
-fn main() {
-    struct InnerStruct {}
-
-    let test = 54;
-      //^^^^ i32
-    let test: i32 = 33;
-    let mut test = 33;
-      //^^^^^^^^ i32
-    let _ = 22;
-    let test = "test";
-      //^^^^ &str
-    let test = InnerStruct {};
-      //^^^^ InnerStruct
-
-    let test = unresolved();
-
-    let test = (42, 'a');
-      //^^^^ (i32, char)
-    let (a,    (b,     (c,)) = (2, (3, (9.2,));
-       //^ i32  ^ i32   ^ f64
-    let &x = &92;
-       //^ i32
-}"#,
-        );
-    }
-
-    #[test]
-    fn closure_parameters() {
-        check(
-            r#"
-fn main() {
-    let mut start = 0;
-      //^^^^^^^^^ i32
-    (0..2).for_each(|increment| { start += increment; });
-                   //^^^^^^^^^ i32
-
-    let multiply =
-      //^^^^^^^^ |…| -> i32
-      | a,     b| a * b
-      //^ i32  ^ i32
-    ;
-
-    let _: i32 = multiply(1, 2);
-    let multiply_ref = &multiply;
-      //^^^^^^^^^^^^ &|…| -> i32
-
-    let return_42 = || 42;
-      //^^^^^^^^^ || -> i32
-}"#,
-        );
-    }
-
-    #[test]
-    fn if_expr() {
-        check(
-            r#"
-enum Option<T> { None, Some(T) }
-use Option::*;
-
-struct Test { a: Option<u32>, b: u8 }
-
-fn main() {
-    let test = Some(Test { a: Some(3), b: 1 });
-      //^^^^ Option<Test>
-    if let None = &test {};
-    if let test = &test {};
-         //^^^^ &Option<Test>
-    if let Some(test) = &test {};
-              //^^^^ &Test
-    if let Some(Test { a,             b }) = &test {};
-                     //^ &Option<u32> ^ &u8
-    if let Some(Test { a: x,             b: y }) = &test {};
-                        //^ &Option<u32>    ^ &u8
-    if let Some(Test { a: Some(x),  b: y }) = &test {};
-                             //^ &u32  ^ &u8
-    if let Some(Test { a: None,  b: y }) = &test {};
-                                  //^ &u8
-    if let Some(Test { b: y, .. }) = &test {};
-                        //^ &u8
-    if test == None {}
-}"#,
-        );
-    }
-
-    #[test]
-    fn while_expr() {
-        check(
+    fn hide_param_hints_for_clones() {
+        check_params(
             r#"
-enum Option<T> { None, Some(T) }
-use Option::*;
-
-struct Test { a: Option<u32>, b: u8 }
+fn foo(bar: i32, baz: String, qux: f32) {}
 
 fn main() {
-    let test = Some(Test { a: Some(3), b: 1 });
-      //^^^^ Option<Test>
-    while let Some(Test { a: Some(x),  b: y }) = &test {};
-                                //^ &u32  ^ &u8
-}"#,
+    let bar = 3;
+    let baz = &"baz";
+    let fez = 1.0;
+    foo(bar.clone(), baz.clone(), fez.clone());
+                                //^^^^^^^^^^^ qux
+}
+"#,
         );
     }
 
     #[test]
-    fn match_arm_list() {
-        check(
+    fn self_param_hints() {
+        check_params(
             r#"
-enum Option<T> { None, Some(T) }
-use Option::*;
+struct Foo;
 
-struct Test { a: Option<u32>, b: u8 }
+impl Foo {
+    fn foo(self: Self) {}
+    fn bar(self: &Self) {}
+}
 
 fn main() {
-    match Some(Test { a: Some(3), b: 1 }) {
-        None => (),
-        test => (),
-      //^^^^ Option<Test>
-        Some(Test { a: Some(x), b: y }) => (),
-                          //^ u32  ^ u8
-        _ => {}
-    }
-}"#,
-        );
+    Foo::foo(Foo);
+           //^^^ self
+    Foo::bar(&Foo);
+           //^^^^ self
+}
+"#,
+        )
     }
 
     #[test]
-    fn hint_truncation() {
-        check_with_config(
-            InlayHintsConfig { max_length: Some(8), ..TEST_CONFIG },
-            r#"
-struct Smol<T>(T);
-
-struct VeryLongOuterName<T>(T);
-
+    fn param_name_hints_show_for_literals() {
+        check_params(
+            r#"pub fn test(a: i32, b: i32) -> [i32; 2] { [a, b] }
 fn main() {
-    let a = Smol(0u32);
-      //^ Smol<u32>
-    let b = VeryLongOuterName(0usize);
-      //^ VeryLongOuterName<…>
-    let c = Smol(Smol(0u32))
-      //^ Smol<Smol<…>>
+    test(
+        0x0fab272b,
+      //^^^^^^^^^^ a
+        0x0fab272b
+      //^^^^^^^^^^ b
+    );
 }"#,
-        );
+        )
     }
 
     #[test]
@@ -939,10 +807,129 @@ fn main() {
         );
     }
 
+    // Type-Hint tests
+
+    #[test]
+    fn type_hints_only() {
+        check_types(
+            r#"
+fn foo(a: i32, b: i32) -> i32 { a + b }
+fn main() {
+    let _x = foo(4, 4);
+      //^^ i32
+}"#,
+        );
+    }
+
+    #[test]
+    fn default_generic_types_should_not_be_displayed() {
+        check(
+            r#"
+struct Test<K, T = u8> { k: K, t: T }
+
+fn main() {
+    let zz = Test { t: 23u8, k: 33 };
+      //^^ Test<i32>
+    let zz_ref = &zz;
+      //^^^^^^ &Test<i32>
+    let test = || zz;
+      //^^^^ || -> Test<i32>
+}"#,
+        );
+    }
+
+    #[test]
+    fn shorten_iterators_in_associated_params() {
+        check_types(
+            r#"
+use core::iter;
+
+pub struct SomeIter<T> {}
+
+impl<T> SomeIter<T> {
+    pub fn new() -> Self { SomeIter {} }
+    pub fn push(&mut self, t: T) {}
+}
+
+impl<T> Iterator for SomeIter<T> {
+    type Item = T;
+    fn next(&mut self) -> Option<Self::Item> {
+        None
+    }
+}
+
+fn main() {
+    let mut some_iter = SomeIter::new();
+      //^^^^^^^^^^^^^ SomeIter<Take<Repeat<i32>>>
+      some_iter.push(iter::repeat(2).take(2));
+    let iter_of_iters = some_iter.take(2);
+      //^^^^^^^^^^^^^ impl Iterator<Item = impl Iterator<Item = i32>>
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn infer_call_method_return_associated_types_with_generic() {
+        check_types(
+            r#"
+            pub trait Default {
+                fn default() -> Self;
+            }
+            pub trait Foo {
+                type Bar: Default;
+            }
+
+            pub fn quux<T: Foo>() -> T::Bar {
+                let y = Default::default();
+                  //^ <T as Foo>::Bar
+
+                y
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn fn_hints() {
+        check_types(
+            r#"
+trait Sized {}
+
+fn foo() -> impl Fn() { loop {} }
+fn foo1() -> impl Fn(f64) { loop {} }
+fn foo2() -> impl Fn(f64, f64) { loop {} }
+fn foo3() -> impl Fn(f64, f64) -> u32 { loop {} }
+fn foo4() -> &'static dyn Fn(f64, f64) -> u32 { loop {} }
+fn foo5() -> &'static dyn Fn(&'static dyn Fn(f64, f64) -> u32, f64) -> u32 { loop {} }
+fn foo6() -> impl Fn(f64, f64) -> u32 + Sized { loop {} }
+fn foo7() -> *const (impl Fn(f64, f64) -> u32 + Sized) { loop {} }
+
+fn main() {
+    let foo = foo();
+     // ^^^ impl Fn()
+    let foo = foo1();
+     // ^^^ impl Fn(f64)
+    let foo = foo2();
+     // ^^^ impl Fn(f64, f64)
+    let foo = foo3();
+     // ^^^ impl Fn(f64, f64) -> u32
+    let foo = foo4();
+     // ^^^ &dyn Fn(f64, f64) -> u32
+    let foo = foo5();
+     // ^^^ &dyn Fn(&dyn Fn(f64, f64) -> u32, f64) -> u32
+    let foo = foo6();
+     // ^^^ impl Fn(f64, f64) -> u32 + Sized
+    let foo = foo7();
+     // ^^^ *const (impl Fn(f64, f64) -> u32 + Sized)
+}
+"#,
+        )
+    }
+
     #[test]
     fn unit_structs_have_no_type_hints() {
-        check_with_config(
-            InlayHintsConfig { max_length: Some(8), ..TEST_CONFIG },
+        check_types(
             r#"
 enum Result<T, E> { Ok(T), Err(E) }
 use Result::*;
@@ -959,159 +946,116 @@ fn main() {
     }
 
     #[test]
-    fn chaining_hints_ignore_comments() {
-        check_expect(
-            InlayHintsConfig {
-                parameter_hints: false,
-                type_hints: false,
-                chaining_hints: true,
-                max_length: None,
-            },
+    fn let_statement() {
+        check_types(
             r#"
-struct A(B);
-impl A { fn into_b(self) -> B { self.0 } }
-struct B(C);
-impl B { fn into_c(self) -> C { self.0 } }
-struct C;
+#[derive(PartialEq)]
+enum Option<T> { None, Some(T) }
+
+#[derive(PartialEq)]
+struct Test { a: Option<u32>, b: u8 }
 
 fn main() {
-    let c = A(B(C))
-        .into_b() // This is a comment
-        // This is another comment
-        .into_c();
-}
-"#,
-            expect![[r#"
-                [
-                    InlayHint {
-                        range: 148..173,
-                        kind: ChainingHint,
-                        label: "B",
-                    },
-                    InlayHint {
-                        range: 148..155,
-                        kind: ChainingHint,
-                        label: "A",
-                    },
-                ]
-            "#]],
+    struct InnerStruct {}
+
+    let test = 54;
+      //^^^^ i32
+    let test: i32 = 33;
+    let mut test = 33;
+      //^^^^^^^^ i32
+    let _ = 22;
+    let test = "test";
+      //^^^^ &str
+    let test = InnerStruct {};
+      //^^^^ InnerStruct
+
+    let test = unresolved();
+
+    let test = (42, 'a');
+      //^^^^ (i32, char)
+    let (a,    (b,     (c,)) = (2, (3, (9.2,));
+       //^ i32  ^ i32   ^ f64
+    let &x = &92;
+       //^ i32
+}"#,
         );
     }
 
     #[test]
-    fn chaining_hints_without_newlines() {
-        check_with_config(
-            InlayHintsConfig {
-                parameter_hints: false,
-                type_hints: false,
-                chaining_hints: true,
-                max_length: None,
-            },
+    fn if_expr() {
+        check_types(
             r#"
-struct A(B);
-impl A { fn into_b(self) -> B { self.0 } }
-struct B(C);
-impl B { fn into_c(self) -> C { self.0 } }
-struct C;
+enum Option<T> { None, Some(T) }
+use Option::*;
+
+struct Test { a: Option<u32>, b: u8 }
 
 fn main() {
-    let c = A(B(C)).into_b().into_c();
+    let test = Some(Test { a: Some(3), b: 1 });
+      //^^^^ Option<Test>
+    if let None = &test {};
+    if let test = &test {};
+         //^^^^ &Option<Test>
+    if let Some(test) = &test {};
+              //^^^^ &Test
+    if let Some(Test { a,             b }) = &test {};
+                     //^ &Option<u32> ^ &u8
+    if let Some(Test { a: x,             b: y }) = &test {};
+                        //^ &Option<u32>    ^ &u8
+    if let Some(Test { a: Some(x),  b: y }) = &test {};
+                             //^ &u32  ^ &u8
+    if let Some(Test { a: None,  b: y }) = &test {};
+                                  //^ &u8
+    if let Some(Test { b: y, .. }) = &test {};
+                        //^ &u8
+    if test == None {}
 }"#,
         );
     }
 
     #[test]
-    fn struct_access_chaining_hints() {
-        check_expect(
-            InlayHintsConfig {
-                parameter_hints: false,
-                type_hints: false,
-                chaining_hints: true,
-                max_length: None,
-            },
+    fn while_expr() {
+        check_types(
             r#"
-struct A { pub b: B }
-struct B { pub c: C }
-struct C(pub bool);
-struct D;
+enum Option<T> { None, Some(T) }
+use Option::*;
 
-impl D {
-    fn foo(&self) -> i32 { 42 }
-}
+struct Test { a: Option<u32>, b: u8 }
 
 fn main() {
-    let x = A { b: B { c: C(true) } }
-        .b
-        .c
-        .0;
-    let x = D
-        .foo();
+    let test = Some(Test { a: Some(3), b: 1 });
+      //^^^^ Option<Test>
+    while let Some(Test { a: Some(x),  b: y }) = &test {};
+                                //^ &u32  ^ &u8
 }"#,
-            expect![[r#"
-                [
-                    InlayHint {
-                        range: 144..191,
-                        kind: ChainingHint,
-                        label: "C",
-                    },
-                    InlayHint {
-                        range: 144..180,
-                        kind: ChainingHint,
-                        label: "B",
-                    },
-                ]
-            "#]],
         );
     }
 
     #[test]
-    fn generic_chaining_hints() {
-        check_expect(
-            InlayHintsConfig {
-                parameter_hints: false,
-                type_hints: false,
-                chaining_hints: true,
-                max_length: None,
-            },
+    fn match_arm_list() {
+        check_types(
             r#"
-struct A<T>(T);
-struct B<T>(T);
-struct C<T>(T);
-struct X<T,R>(T, R);
+enum Option<T> { None, Some(T) }
+use Option::*;
+
+struct Test { a: Option<u32>, b: u8 }
 
-impl<T> A<T> {
-    fn new(t: T) -> Self { A(t) }
-    fn into_b(self) -> B<T> { B(self.0) }
-}
-impl<T> B<T> {
-    fn into_c(self) -> C<T> { C(self.0) }
-}
 fn main() {
-    let c = A::new(X(42, true))
-        .into_b()
-        .into_c();
-}
-"#,
-            expect![[r#"
-                [
-                    InlayHint {
-                        range: 247..284,
-                        kind: ChainingHint,
-                        label: "B<X<i32, bool>>",
-                    },
-                    InlayHint {
-                        range: 247..266,
-                        kind: ChainingHint,
-                        label: "A<X<i32, bool>>",
-                    },
-                ]
-            "#]],
+    match Some(Test { a: Some(3), b: 1 }) {
+        None => (),
+        test => (),
+      //^^^^ Option<Test>
+        Some(Test { a: Some(x), b: y }) => (),
+                          //^ u32  ^ u8
+        _ => {}
+    }
+}"#,
         );
     }
 
     #[test]
     fn incomplete_for_no_hint() {
-        check(
+        check_types(
             r#"
 fn main() {
     let data = &[1i32, 2, 3];
@@ -1146,7 +1090,7 @@ fn main() {
 
     #[test]
     fn complete_for_hint() {
-        check(
+        check_types(
             r#"
 pub struct Vec<T> {}
 
@@ -1175,13 +1119,7 @@ fn main() {
 
     #[test]
     fn multi_dyn_trait_bounds() {
-        check_with_config(
-            InlayHintsConfig {
-                type_hints: true,
-                parameter_hints: false,
-                chaining_hints: false,
-                max_length: None,
-            },
+        check_types(
             r#"
 pub struct Vec<T> {}
 
@@ -1208,13 +1146,7 @@ fn main() {
 
     #[test]
     fn shorten_iterator_hints() {
-        check_with_config(
-            InlayHintsConfig {
-                parameter_hints: false,
-                type_hints: true,
-                chaining_hints: false,
-                max_length: None,
-            },
+        check_types(
             r#"
 use core::iter;
 
@@ -1244,7 +1176,55 @@ fn main() {
     }
 
     #[test]
-    fn shorten_iterator_chaining_hints() {
+    fn closures() {
+        check(
+            r#"
+fn main() {
+    let mut start = 0;
+      //^^^^^^^^^ i32
+    (0..2).for_each(|increment| { start += increment; });
+                   //^^^^^^^^^ i32
+
+    let multiply =
+      //^^^^^^^^ |…| -> i32
+      | a,     b| a * b
+      //^ i32  ^ i32
+    ;
+
+    let _: i32 = multiply(1, 2);
+    let multiply_ref = &multiply;
+      //^^^^^^^^^^^^ &|…| -> i32
+
+    let return_42 = || 42;
+      //^^^^^^^^^ || -> i32
+}"#,
+        );
+    }
+
+    #[test]
+    fn hint_truncation() {
+        check_with_config(
+            InlayHintsConfig { max_length: Some(8), ..TEST_CONFIG },
+            r#"
+struct Smol<T>(T);
+
+struct VeryLongOuterName<T>(T);
+
+fn main() {
+    let a = Smol(0u32);
+      //^ Smol<u32>
+    let b = VeryLongOuterName(0usize);
+      //^ VeryLongOuterName<…>
+    let c = Smol(Smol(0u32))
+      //^ Smol<Smol<…>>
+}"#,
+        );
+    }
+
+    // Chaining hint tests
+
+    #[test]
+    fn chaining_hints_ignore_comments() {
         check_expect(
             InlayHintsConfig {
                 parameter_hints: false,
@@ -1253,46 +1233,30 @@ fn main() {
                 max_length: None,
             },
             r#"
-use core::iter;
-
-struct MyIter;
-
-impl Iterator for MyIter {
-    type Item = ();
-    fn next(&mut self) -> Option<Self::Item> {
-        None
-    }
-}
+struct A(B);
+impl A { fn into_b(self) -> B { self.0 } }
+struct B(C);
+impl B { fn into_c(self) -> C { self.0 } }
+struct C;
 
 fn main() {
-    let _x = MyIter.by_ref()
-        .take(5)
-        .by_ref()
-        .take(5)
-        .by_ref();
+    let c = A(B(C))
+        .into_b() // This is a comment
+        // This is another comment
+        .into_c();
 }
 "#,
             expect![[r#"
                 [
                     InlayHint {
-                        range: 175..242,
-                        kind: ChainingHint,
-                        label: "impl Iterator<Item = ()>",
-                    },
-                    InlayHint {
-                        range: 175..225,
-                        kind: ChainingHint,
-                        label: "impl Iterator<Item = ()>",
-                    },
-                    InlayHint {
-                        range: 175..207,
+                        range: 148..173,
                         kind: ChainingHint,
-                        label: "impl Iterator<Item = ()>",
+                        label: "B",
                     },
                     InlayHint {
-                        range: 175..190,
+                        range: 148..155,
                         kind: ChainingHint,
-                        label: "&mut MyIter",
+                        label: "A",
                     },
                 ]
             "#]],
@@ -1300,156 +1264,163 @@ fn main() {
     }
 
     #[test]
-    fn shorten_iterators_in_associated_params() {
-        check_with_config(
+    fn chaining_hints_without_newlines() {
+        check_chains(
+            r#"
+struct A(B);
+impl A { fn into_b(self) -> B { self.0 } }
+struct B(C);
+impl B { fn into_c(self) -> C { self.0 } }
+struct C;
+
+fn main() {
+    let c = A(B(C)).into_b().into_c();
+}"#,
+        );
+    }
+
+    #[test]
+    fn struct_access_chaining_hints() {
+        check_expect(
             InlayHintsConfig {
                 parameter_hints: false,
-                type_hints: true,
-                chaining_hints: false,
+                type_hints: false,
+                chaining_hints: true,
                 max_length: None,
             },
             r#"
-use core::iter;
-
-pub struct SomeIter<T> {}
-
-impl<T> SomeIter<T> {
-    pub fn new() -> Self { SomeIter {} }
-    pub fn push(&mut self, t: T) {}
-}
+struct A { pub b: B }
+struct B { pub c: C }
+struct C(pub bool);
+struct D;
 
-impl<T> Iterator for SomeIter<T> {
-    type Item = T;
-    fn next(&mut self) -> Option<Self::Item> {
-        None
-    }
+impl D {
+    fn foo(&self) -> i32 { 42 }
 }
 
 fn main() {
-    let mut some_iter = SomeIter::new();
-      //^^^^^^^^^^^^^ SomeIter<Take<Repeat<i32>>>
-      some_iter.push(iter::repeat(2).take(2));
-    let iter_of_iters = some_iter.take(2);
-      //^^^^^^^^^^^^^ impl Iterator<Item = impl Iterator<Item = i32>>
-}
-"#,
+    let x = A { b: B { c: C(true) } }
+        .b
+        .c
+        .0;
+    let x = D
+        .foo();
+}"#,
+            expect![[r#"
+                [
+                    InlayHint {
+                        range: 144..191,
+                        kind: ChainingHint,
+                        label: "C",
+                    },
+                    InlayHint {
+                        range: 144..180,
+                        kind: ChainingHint,
+                        label: "B",
+                    },
+                ]
+            "#]],
         );
     }
 
     #[test]
-    fn hide_param_hints_for_clones() {
-        check_with_config(
+    fn generic_chaining_hints() {
+        check_expect(
             InlayHintsConfig {
-                parameter_hints: true,
+                parameter_hints: false,
                 type_hints: false,
-                chaining_hints: false,
+                chaining_hints: true,
                 max_length: None,
             },
             r#"
-fn foo(bar: i32, baz: String, qux: f32) {}
+struct A<T>(T);
+struct B<T>(T);
+struct C<T>(T);
+struct X<T,R>(T, R);
 
+impl<T> A<T> {
+    fn new(t: T) -> Self { A(t) }
+    fn into_b(self) -> B<T> { B(self.0) }
+}
+impl<T> B<T> {
+    fn into_c(self) -> C<T> { C(self.0) }
+}
 fn main() {
-    let bar = 3;
-    let baz = &"baz";
-    let fez = 1.0;
-    foo(bar.clone(), baz.clone(), fez.clone());
-                                //^^^^^^^^^^^ qux
+    let c = A::new(X(42, true))
+        .into_b()
+        .into_c();
 }
 "#,
+            expect![[r#"
+                [
+                    InlayHint {
+                        range: 247..284,
+                        kind: ChainingHint,
+                        label: "B<X<i32, bool>>",
+                    },
+                    InlayHint {
+                        range: 247..266,
+                        kind: ChainingHint,
+                        label: "A<X<i32, bool>>",
+                    },
+                ]
+            "#]],
         );
     }
 
     #[test]
-    fn infer_call_method_return_associated_types_with_generic() {
-        check(
+    fn shorten_iterator_chaining_hints() {
+        check_expect(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: false,
+                chaining_hints: true,
+                max_length: None,
+            },
             r#"
-            pub trait Default {
-                fn default() -> Self;
-            }
-            pub trait Foo {
-                type Bar: Default;
-            }
+use core::iter;
 
-            pub fn quux<T: Foo>() -> T::Bar {
-                let y = Default::default();
-                  //^ <T as Foo>::Bar
+struct MyIter;
 
-                y
-            }
-            "#,
-        );
+impl Iterator for MyIter {
+    type Item = ();
+    fn next(&mut self) -> Option<Self::Item> {
+        None
     }
-
-    #[test]
-    fn self_param_hints() {
-        check(
-            r#"
-struct Foo;
-
-impl Foo {
-    fn foo(self: Self) {}
-    fn bar(self: &Self) {}
 }
 
 fn main() {
-    Foo::foo(Foo);
-           //^^^ self
-    Foo::bar(&Foo);
-           //^^^^ self
-}
-"#,
-        )
-    }
-
-    #[test]
-    fn fn_hints() {
-        check(
-            r#"
-trait Sized {}
-
-fn foo() -> impl Fn() { loop {} }
-fn foo1() -> impl Fn(f64) { loop {} }
-fn foo2() -> impl Fn(f64, f64) { loop {} }
-fn foo3() -> impl Fn(f64, f64) -> u32 { loop {} }
-fn foo4() -> &'static dyn Fn(f64, f64) -> u32 { loop {} }
-fn foo5() -> &'static dyn Fn(&'static dyn Fn(f64, f64) -> u32, f64) -> u32 { loop {} }
-fn foo6() -> impl Fn(f64, f64) -> u32 + Sized { loop {} }
-fn foo7() -> *const (impl Fn(f64, f64) -> u32 + Sized) { loop {} }
-
-fn main() {
-    let foo = foo();
-     // ^^^ impl Fn()
-    let foo = foo1();
-     // ^^^ impl Fn(f64)
-    let foo = foo2();
-     // ^^^ impl Fn(f64, f64)
-    let foo = foo3();
-     // ^^^ impl Fn(f64, f64) -> u32
-    let foo = foo4();
-     // ^^^ &dyn Fn(f64, f64) -> u32
-    let foo = foo5();
-     // ^^^ &dyn Fn(&dyn Fn(f64, f64) -> u32, f64) -> u32
-    let foo = foo6();
-     // ^^^ impl Fn(f64, f64) -> u32 + Sized
-    let foo = foo7();
-     // ^^^ *const (impl Fn(f64, f64) -> u32 + Sized)
+    let _x = MyIter.by_ref()
+        .take(5)
+        .by_ref()
+        .take(5)
+        .by_ref();
 }
 "#,
-        )
-    }
-
-    #[test]
-    fn param_name_hints_show_for_literals() {
-        check(
-            r#"pub fn test(a: i32, b: i32) -> [i32; 2] { [a, b] }
-fn main() {
-    test(
-        0x0fab272b,
-      //^^^^^^^^^^ a
-        0x0fab272b
-      //^^^^^^^^^^ b
-    );
-}"#,
-        )
+            expect![[r#"
+                [
+                    InlayHint {
+                        range: 175..242,
+                        kind: ChainingHint,
+                        label: "impl Iterator<Item = ()>",
+                    },
+                    InlayHint {
+                        range: 175..225,
+                        kind: ChainingHint,
+                        label: "impl Iterator<Item = ()>",
+                    },
+                    InlayHint {
+                        range: 175..207,
+                        kind: ChainingHint,
+                        label: "impl Iterator<Item = ()>",
+                    },
+                    InlayHint {
+                        range: 175..190,
+                        kind: ChainingHint,
+                        label: "&mut MyIter",
+                    },
+                ]
+            "#]],
+        );
     }
 }