rust-analyzer/crates/ide/src/inlay_hints/bind_pat.rs

//! Implementation of "type" inlay hints:
//! ```no_run
//! fn f(a: i32, b: i32) -> i32 { a + b }
//! let _x /* i32 */= f(4, 4);
//! ```
use hir::{Semantics, TypeInfo};
use ide_db::{base_db::FileId, famous_defs::FamousDefs, RootDatabase};

use itertools::Itertools;
use syntax::{
    ast::{self, AstNode, HasName},
    match_ast,
};

use crate::{inlay_hints::closure_has_block_body, InlayHint, InlayHintsConfig, InlayKind};

use super::label_of_ty;

pub(super) fn hints(
    acc: &mut Vec<InlayHint>,
    famous_defs @ FamousDefs(sema, _): &FamousDefs<'_, '_>,
    config: &InlayHintsConfig,
    _file_id: FileId,
    pat: &ast::IdentPat,
) -> Option<()> {
    if !config.type_hints {
        return None;
    }

    let descended = sema.descend_node_into_attributes(pat.clone()).pop();
    let desc_pat = descended.as_ref().unwrap_or(pat);
    let ty = sema.type_of_pat(&desc_pat.clone().into())?.original;

    if should_not_display_type_hint(sema, config, pat, &ty) {
        return None;
    }

    let label = label_of_ty(famous_defs, config, ty)?;

    if config.hide_named_constructor_hints
        && is_named_constructor(sema, pat, &label.to_string()).is_some()
    {
        return None;
    }

    acc.push(InlayHint {
        range: match pat.name() {
            Some(name) => name.syntax().text_range(),
            None => pat.syntax().text_range(),
        },
        kind: InlayKind::Type,
        label,
    });

    Some(())
}

fn should_not_display_type_hint(
    sema: &Semantics<'_, RootDatabase>,
    config: &InlayHintsConfig,
    bind_pat: &ast::IdentPat,
    pat_ty: &hir::Type,
) -> bool {
    let db = sema.db;

    if pat_ty.is_unknown() {
        return true;
    }

    if let Some(hir::Adt::Struct(s)) = pat_ty.as_adt() {
        if s.fields(db).is_empty() && s.name(db).to_smol_str() == bind_pat.to_string() {
            return true;
        }
    }

    if config.hide_closure_initialization_hints {
        if let Some(parent) = bind_pat.syntax().parent() {
            if let Some(it) = ast::LetStmt::cast(parent) {
                if let Some(ast::Expr::ClosureExpr(closure)) = it.initializer() {
                    if closure_has_block_body(&closure) {
                        return true;
                    }
                }
            }
        }
    }

    for node in bind_pat.syntax().ancestors() {
        match_ast! {
            match node {
                ast::LetStmt(it) => return it.ty().is_some(),
                // FIXME: We might wanna show type hints in parameters for non-top level patterns as well
                ast::Param(it) => return it.ty().is_some(),
                ast::MatchArm(_) => return pat_is_enum_variant(db, bind_pat, pat_ty),
                ast::LetExpr(_) => return pat_is_enum_variant(db, bind_pat, pat_ty),
                ast::IfExpr(_) => return false,
                ast::WhileExpr(_) => return false,
                ast::ForExpr(it) => {
                    // We *should* display hint only if user provided "in {expr}" and we know the type of expr (and it's not unit).
                    // 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(TypeInfo::original)
                            .map_or(true, |iterable_ty| iterable_ty.is_unknown() || iterable_ty.is_unit())
                },
                _ => (),
            }
        }
    }
    false
}

fn is_named_constructor(
    sema: &Semantics<'_, RootDatabase>,
    pat: &ast::IdentPat,
    ty_name: &str,
) -> Option<()> {
    let let_node = pat.syntax().parent()?;
    let expr = match_ast! {
        match let_node {
            ast::LetStmt(it) => it.initializer(),
            ast::LetExpr(it) => it.expr(),
            _ => None,
        }
    }?;

    let expr = sema.descend_node_into_attributes(expr.clone()).pop().unwrap_or(expr);
    // unwrap postfix expressions
    let expr = match expr {
        ast::Expr::TryExpr(it) => it.expr(),
        ast::Expr::AwaitExpr(it) => it.expr(),
        expr => Some(expr),
    }?;
    let expr = match expr {
        ast::Expr::CallExpr(call) => match call.expr()? {
            ast::Expr::PathExpr(path) => path,
            _ => return None,
        },
        ast::Expr::PathExpr(path) => path,
        _ => return None,
    };
    let path = expr.path()?;

    let callable = sema.type_of_expr(&ast::Expr::PathExpr(expr))?.original.as_callable(sema.db);
    let callable_kind = callable.map(|it| it.kind());
    let qual_seg = match callable_kind {
        Some(hir::CallableKind::Function(_) | hir::CallableKind::TupleEnumVariant(_)) => {
            path.qualifier()?.segment()
        }
        _ => path.segment(),
    }?;

    let ctor_name = match qual_seg.kind()? {
        ast::PathSegmentKind::Name(name_ref) => {
            match qual_seg.generic_arg_list().map(|it| it.generic_args()) {
                Some(generics) => format!("{name_ref}<{}>", generics.format(", ")),
                None => name_ref.to_string(),
            }
        }
        ast::PathSegmentKind::Type { type_ref: Some(ty), trait_ref: None } => ty.to_string(),
        _ => return None,
    };
    (ctor_name == ty_name).then_some(())
}

fn pat_is_enum_variant(db: &RootDatabase, bind_pat: &ast::IdentPat, pat_ty: &hir::Type) -> bool {
    if let Some(hir::Adt::Enum(enum_data)) = pat_ty.as_adt() {
        let pat_text = bind_pat.to_string();
        enum_data
            .variants(db)
            .into_iter()
            .map(|variant| variant.name(db).to_smol_str())
            .any(|enum_name| enum_name == pat_text)
    } else {
        false
    }
}

#[cfg(test)]
mod tests {
    // This module also contains tests for super::closure_ret

    use expect_test::expect;
    use syntax::{TextRange, TextSize};
    use test_utils::extract_annotations;

    use crate::{fixture, inlay_hints::InlayHintsConfig};

    use crate::inlay_hints::tests::{
        check, check_expect, check_with_config, DISABLED_CONFIG, TEST_CONFIG,
    };
    use crate::ClosureReturnTypeHints;

    #[track_caller]
    fn check_types(ra_fixture: &str) {
        check_with_config(InlayHintsConfig { type_hints: true, ..DISABLED_CONFIG }, ra_fixture);
    }

    #[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 type_hints_bindings_after_at() {
        check_types(
            r#"
//- minicore: option
fn main() {
    let ref foo @ bar @ ref mut baz = 0;
          //^^^ &i32
                //^^^ i32
                              //^^^ &mut i32
    let [x @ ..] = [0];
       //^ [i32; 1]
    if let x @ Some(_) = Some(0) {}
         //^ Option<i32>
    let foo @ (bar, baz) = (3, 3);
      //^^^ (i32, i32)
             //^^^ i32
                  //^^^ 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#"
//- minicore: iterators
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 iterator_hint_regression_issue_12674() {
        // Ensure we don't crash while solving the projection type of iterators.
        check_expect(
            InlayHintsConfig { chaining_hints: true, ..DISABLED_CONFIG },
            r#"
//- minicore: iterators
struct S<T>(T);
impl<T> S<T> {
    fn iter(&self) -> Iter<'_, T> { loop {} }
}
struct Iter<'a, T: 'a>(&'a T);
impl<'a, T> Iterator for Iter<'a, T> {
    type Item = &'a T;
    fn next(&mut self) -> Option<Self::Item> { loop {} }
}
struct Container<'a> {
    elements: S<&'a str>,
}
struct SliceIter<'a, T>(&'a T);
impl<'a, T> Iterator for SliceIter<'a, T> {
    type Item = &'a T;
    fn next(&mut self) -> Option<Self::Item> { loop {} }
}

fn main(a: SliceIter<'_, Container>) {
    a
    .filter_map(|c| Some(c.elements.iter().filter_map(|v| Some(v))))
    .map(|e| e);
}
            "#,
            expect![[r#"
                [
                    InlayHint {
                        range: 484..554,
                        kind: Chaining,
                        label: [
                            "impl ",
                            InlayHintLabelPart {
                                text: "Iterator",
                                linked_location: Some(
                                    FileRange {
                                        file_id: FileId(
                                            1,
                                        ),
                                        range: 2248..2256,
                                    },
                                ),
                                tooltip: "",
                            },
                            "<Item = impl ",
                            InlayHintLabelPart {
                                text: "Iterator",
                                linked_location: Some(
                                    FileRange {
                                        file_id: FileId(
                                            1,
                                        ),
                                        range: 2248..2256,
                                    },
                                ),
                                tooltip: "",
                            },
                            "<Item = &&str>>",
                        ],
                    },
                    InlayHint {
                        range: 484..485,
                        kind: Chaining,
                        label: [
                            "",
                            InlayHintLabelPart {
                                text: "SliceIter",
                                linked_location: Some(
                                    FileRange {
                                        file_id: FileId(
                                            0,
                                        ),
                                        range: 289..298,
                                    },
                                ),
                                tooltip: "",
                            },
                            "<",
                            InlayHintLabelPart {
                                text: "Container",
                                linked_location: Some(
                                    FileRange {
                                        file_id: FileId(
                                            0,
                                        ),
                                        range: 238..247,
                                    },
                                ),
                                tooltip: "",
                            },
                            ">",
                        ],
                    },
                ]
            "#]],
        );
    }

    #[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#"
//- minicore: fn, 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
    let foo = foo7();
     // ^^^ *const impl Fn(f64, f64) -> u32
}
"#,
        )
    }

    #[test]
    fn check_hint_range_limit() {
        let fixture = r#"
        //- minicore: fn, 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();
            let foo = foo1();
            let foo = foo2();
             // ^^^ impl Fn(f64, f64)
            let foo = foo3();
             // ^^^ impl Fn(f64, f64) -> u32
            let foo = foo4();
            let foo = foo5();
            let foo = foo6();
            let foo = foo7();
        }
        "#;
        let (analysis, file_id) = fixture::file(fixture);
        let expected = extract_annotations(&analysis.file_text(file_id).unwrap());
        let inlay_hints = analysis
            .inlay_hints(
                &InlayHintsConfig { type_hints: true, ..DISABLED_CONFIG },
                file_id,
                Some(TextRange::new(TextSize::from(500), TextSize::from(600))),
            )
            .unwrap();
        let actual =
            inlay_hints.into_iter().map(|it| (it.range, it.label.to_string())).collect::<Vec<_>>();
        assert_eq!(expected, actual, "\nExpected:\n{expected:#?}\n\nActual:\n{actual:#?}");
    }

    #[test]
    fn fn_hints_ptr_rpit_fn_parentheses() {
        check_types(
            r#"
//- minicore: fn, sized
trait Trait {}

fn foo1() -> *const impl Fn() { loop {} }
fn foo2() -> *const (impl Fn() + Sized) { loop {} }
fn foo3() -> *const (impl Fn() + ?Sized) { loop {} }
fn foo4() -> *const (impl Sized + Fn()) { loop {} }
fn foo5() -> *const (impl ?Sized + Fn()) { loop {} }
fn foo6() -> *const (impl Fn() + Trait) { loop {} }
fn foo7() -> *const (impl Fn() + Sized + Trait) { loop {} }
fn foo8() -> *const (impl Fn() + ?Sized + Trait) { loop {} }
fn foo9() -> *const (impl Fn() -> u8 + ?Sized) { loop {} }
fn foo10() -> *const (impl Fn() + Sized + ?Sized) { loop {} }

fn main() {
    let foo = foo1();
    //  ^^^ *const impl Fn()
    let foo = foo2();
    //  ^^^ *const impl Fn()
    let foo = foo3();
    //  ^^^ *const (impl Fn() + ?Sized)
    let foo = foo4();
    //  ^^^ *const impl Fn()
    let foo = foo5();
    //  ^^^ *const (impl Fn() + ?Sized)
    let foo = foo6();
    //  ^^^ *const (impl Fn() + Trait)
    let foo = foo7();
    //  ^^^ *const (impl Fn() + Trait)
    let foo = foo8();
    //  ^^^ *const (impl Fn() + Trait + ?Sized)
    let foo = foo9();
    //  ^^^ *const (impl Fn() -> u8 + ?Sized)
    let foo = foo10();
    //  ^^^ *const impl Fn()
}
"#,
        )
    }

    #[test]
    fn unit_structs_have_no_type_hints() {
        check_types(
            r#"
//- minicore: result
struct SyntheticSyntax;

fn main() {
    match Ok(()) {
        Ok(_) => (),
        Err(SyntheticSyntax) => (),
    }
}"#,
        );
    }

    #[test]
    fn let_statement() {
        check_types(
            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 if_expr() {
        check_types(
            r#"
//- minicore: 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_types(
            r#"
//- minicore: option
struct Test { a: Option<u32>, b: u8 }

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
}"#,
        );
    }

    #[test]
    fn match_arm_list() {
        check_types(
            r#"
//- minicore: option
struct Test { a: Option<u32>, b: u8 }

fn main() {
    match Some(Test { a: Some(3), b: 1 }) {
        None => (),
        test => (),
      //^^^^ Option<Test>
        Some(Test { a: Some(x), b: y }) => (),
                          //^ u32  ^ u8
        _ => {}
    }
}"#,
        );
    }

    #[test]
    fn complete_for_hint() {
        check_types(
            r#"
//- minicore: iterator
pub struct Vec<T> {}

impl<T> Vec<T> {
    pub fn new() -> Self { Vec {} }
    pub fn push(&mut self, t: T) {}
}

impl<T> IntoIterator for Vec<T> {
    type Item = T;
    type IntoIter = IntoIter<T>;
}

struct IntoIter<T> {}

impl<T> Iterator for IntoIter<T> {
    type Item = T;
}

fn main() {
    let mut data = Vec::new();
          //^^^^ Vec<&str>
    data.push("foo");
    for i in data {
      //^ &str
      let z = i;
        //^ &str
    }
}
"#,
        );
    }

    #[test]
    fn multi_dyn_trait_bounds() {
        check_types(
            r#"
pub struct Vec<T> {}

impl<T> Vec<T> {
    pub fn new() -> Self { Vec {} }
}

pub struct Box<T> {}

trait Display {}
auto trait Sync {}

fn main() {
    // The block expression wrapping disables the constructor hint hiding logic
    let _v = { Vec::<Box<&(dyn Display + Sync)>>::new() };
      //^^ Vec<Box<&(dyn Display + Sync)>>
    let _v = { Vec::<Box<*const (dyn Display + Sync)>>::new() };
      //^^ Vec<Box<*const (dyn Display + Sync)>>
    let _v = { Vec::<Box<dyn Display + Sync>>::new() };
      //^^ Vec<Box<dyn Display + Sync>>
}
"#,
        );
    }

    #[test]
    fn shorten_iterator_hints() {
        check_types(
            r#"
//- minicore: iterators
use core::iter;

struct MyIter;

impl Iterator for MyIter {
    type Item = ();
    fn next(&mut self) -> Option<Self::Item> {
        None
    }
}

fn main() {
    let _x = MyIter;
      //^^ MyIter
    let _x = iter::repeat(0);
      //^^ impl Iterator<Item = i32>
    fn generic<T: Clone>(t: T) {
        let _x = iter::repeat(t);
          //^^ impl Iterator<Item = T>
        let _chained = iter::repeat(t).take(10);
          //^^^^^^^^ impl Iterator<Item = T>
    }
}
"#,
        );
    }

    #[test]
    fn skip_constructor_and_enum_type_hints() {
        check_with_config(
            InlayHintsConfig {
                type_hints: true,
                hide_named_constructor_hints: true,
                ..DISABLED_CONFIG
            },
            r#"
//- minicore: try, option
use core::ops::ControlFlow;

mod x {
    pub mod y { pub struct Foo; }
    pub struct Foo;
    pub enum AnotherEnum {
        Variant()
    };
}
struct Struct;
struct TupleStruct();

impl Struct {
    fn new() -> Self {
        Struct
    }
    fn try_new() -> ControlFlow<(), Self> {
        ControlFlow::Continue(Struct)
    }
}

struct Generic<T>(T);
impl Generic<i32> {
    fn new() -> Self {
        Generic(0)
    }
}

enum Enum {
    Variant(u32)
}

fn times2(value: i32) -> i32 {
    2 * value
}

fn main() {
    let enumb = Enum::Variant(0);

    let strukt = x::Foo;
    let strukt = x::y::Foo;
    let strukt = Struct;
    let strukt = Struct::new();

    let tuple_struct = TupleStruct();

    let generic0 = Generic::new();
    //  ^^^^^^^^ Generic<i32>
    let generic1 = Generic(0);
    //  ^^^^^^^^ Generic<i32>
    let generic2 = Generic::<i32>::new();
    let generic3 = <Generic<i32>>::new();
    let generic4 = Generic::<i32>(0);


    let option = Some(0);
    //  ^^^^^^ Option<i32>
    let func = times2;
    //  ^^^^ fn times2(i32) -> i32
    let closure = |x: i32| x * 2;
    //  ^^^^^^^ |i32| -> i32
}

fn fallible() -> ControlFlow<()> {
    let strukt = Struct::try_new()?;
}
"#,
        );
    }

    #[test]
    fn shows_constructor_type_hints_when_enabled() {
        check_types(
            r#"
//- minicore: try
use core::ops::ControlFlow;

struct Struct;
struct TupleStruct();

impl Struct {
    fn new() -> Self {
        Struct
    }
    fn try_new() -> ControlFlow<(), Self> {
        ControlFlow::Continue(Struct)
    }
}

struct Generic<T>(T);
impl Generic<i32> {
    fn new() -> Self {
        Generic(0)
    }
}

fn main() {
    let strukt = Struct::new();
     // ^^^^^^ Struct
    let tuple_struct = TupleStruct();
     // ^^^^^^^^^^^^ TupleStruct
    let generic0 = Generic::new();
     // ^^^^^^^^ Generic<i32>
    let generic1 = Generic::<i32>::new();
     // ^^^^^^^^ Generic<i32>
    let generic2 = <Generic<i32>>::new();
     // ^^^^^^^^ Generic<i32>
}

fn fallible() -> ControlFlow<()> {
    let strukt = Struct::try_new()?;
     // ^^^^^^ Struct
}
"#,
        );
    }

    #[test]
    fn closures() {
        check(
            r#"
fn main() {
    let mut start = 0;
          //^^^^^ i32
    (0..2).for_each(|increment      | { start += increment; });
                   //^^^^^^^^^ i32

    let multiply =
      //^^^^^^^^ |i32, i32| -> i32
      | a,     b| a * b
      //^ i32  ^ i32

    ;

    let _: i32 = multiply(1,  2);
                        //^ a ^ b
    let multiply_ref = &multiply;
      //^^^^^^^^^^^^ &|i32, i32| -> i32

    let return_42 = || 42;
      //^^^^^^^^^ || -> i32
      || { 42 };
    //^^ i32
}"#,
        );
    }

    #[test]
    fn return_type_hints_for_closure_without_block() {
        check_with_config(
            InlayHintsConfig {
                closure_return_type_hints: ClosureReturnTypeHints::Always,
                ..DISABLED_CONFIG
            },
            r#"
fn main() {
    let a = || { 0 };
          //^^ i32
    let b = || 0;
          //^^ i32
}"#,
        );
    }

    #[test]
    fn skip_closure_type_hints() {
        check_with_config(
            InlayHintsConfig {
                type_hints: true,
                hide_closure_initialization_hints: true,
                ..DISABLED_CONFIG
            },
            r#"
//- minicore: fn
fn main() {
    let multiple_2 = |x: i32| { x * 2 };

    let multiple_2 = |x: i32| x * 2;
    //  ^^^^^^^^^^ |i32| -> i32

    let (not) = (|x: bool| { !x });
    //   ^^^ |bool| -> bool

    let (is_zero, _b) = (|x: usize| { x == 0 }, false);
    //   ^^^^^^^ |usize| -> bool
    //            ^^ bool

    let plus_one = |x| { x + 1 };
    //              ^ u8
    foo(plus_one);

    let add_mul = bar(|x: u8| { x + 1 });
    //  ^^^^^^^ impl FnOnce(u8) -> u8 + ?Sized

    let closure = if let Some(6) = add_mul(2).checked_sub(1) {
    //  ^^^^^^^ fn(i32) -> i32
        |x: i32| { x * 2 }
    } else {
        |x: i32| { x * 3 }
    };
}

fn foo(f: impl FnOnce(u8) -> u8) {}

fn bar(f: impl FnOnce(u8) -> u8) -> impl FnOnce(u8) -> u8 {
    move |x: u8| f(x) * 2
}
"#,
        );
    }

    #[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<…>>
}"#,
        );
    }
}