use insta::assert_snapshot;
use ra_db::fixture::WithFixture;
use test_utils::mark;

use crate::test_db::TestDB;

use super::{infer, infer_with_mismatches, type_at, type_at_pos};

#[test]
fn infer_await() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:core

struct IntFuture;

impl Future for IntFuture {
    type Output = u64;
}

fn test() {
    let r = IntFuture;
    let v = r.await;
    v<|>;
}

//- /core.rs crate:core
#[prelude_import] use future::*;
mod future {
    #[lang = "future_trait"]
    trait Future {
        type Output;
    }
}

"#,
    );
    assert_eq!("u64", type_at_pos(&db, pos));
}

#[test]
fn infer_async() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:core

async fn foo() -> u64 {
    128
}

fn test() {
    let r = foo();
    let v = r.await;
    v<|>;
}

//- /core.rs crate:core
#[prelude_import] use future::*;
mod future {
    #[lang = "future_trait"]
    trait Future {
        type Output;
    }
}

"#,
    );
    assert_eq!("u64", type_at_pos(&db, pos));
}

#[test]
fn infer_desugar_async() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:core

async fn foo() -> u64 {
    128
}

fn test() {
    let r = foo();
    r<|>;
}

//- /core.rs crate:core
#[prelude_import] use future::*;
mod future {
    trait Future {
        type Output;
    }
}

"#,
    );
    assert_eq!("impl Future<Output = u64>", type_at_pos(&db, pos));
}

#[test]
fn infer_try() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:core

fn test() {
    let r: Result<i32, u64> = Result::Ok(1);
    let v = r?;
    v<|>;
}

//- /core.rs crate:core

#[prelude_import] use ops::*;
mod ops {
    trait Try {
        type Ok;
        type Error;
    }
}

#[prelude_import] use result::*;
mod result {
    enum Result<O, E> {
        Ok(O),
        Err(E)
    }

    impl<O, E> crate::ops::Try for Result<O, E> {
        type Ok = O;
        type Error = E;
    }
}

"#,
    );
    assert_eq!("i32", type_at_pos(&db, pos));
}

#[test]
fn infer_for_loop() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:core,alloc

use alloc::collections::Vec;

fn test() {
    let v = Vec::new();
    v.push("foo");
    for x in v {
        x<|>;
    }
}

//- /core.rs crate:core

#[prelude_import] use iter::*;
mod iter {
    trait IntoIterator {
        type Item;
    }
}

//- /alloc.rs crate:alloc deps:core

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

    impl<T> IntoIterator for Vec<T> {
        type Item=T;
    }
}
"#,
    );
    assert_eq!("&str", type_at_pos(&db, pos));
}

#[test]
fn infer_ops_neg() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:std

struct Bar;
struct Foo;

impl std::ops::Neg for Bar {
    type Output = Foo;
}

fn test() {
    let a = Bar;
    let b = -a;
    b<|>;
}

//- /std.rs crate:std

#[prelude_import] use ops::*;
mod ops {
    #[lang = "neg"]
    pub trait Neg {
        type Output;
    }
}
"#,
    );
    assert_eq!("Foo", type_at_pos(&db, pos));
}

#[test]
fn infer_ops_not() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:std

struct Bar;
struct Foo;

impl std::ops::Not for Bar {
    type Output = Foo;
}

fn test() {
    let a = Bar;
    let b = !a;
    b<|>;
}

//- /std.rs crate:std

#[prelude_import] use ops::*;
mod ops {
    #[lang = "not"]
    pub trait Not {
        type Output;
    }
}
"#,
    );
    assert_eq!("Foo", type_at_pos(&db, pos));
}

#[test]
fn infer_from_bound_1() {
    assert_snapshot!(
        infer(r#"
trait Trait<T> {}
struct S<T>(T);
impl<U> Trait<U> for S<U> {}
fn foo<T: Trait<u32>>(t: T) {}
fn test() {
    let s = S(unknown);
    foo(s);
}
"#),
        @r###"
    85..86 't': T
    91..93 '{}': ()
    104..143 '{     ...(s); }': ()
    114..115 's': S<u32>
    118..119 'S': S<u32>(u32) -> S<u32>
    118..128 'S(unknown)': S<u32>
    120..127 'unknown': u32
    134..137 'foo': fn foo<S<u32>>(S<u32>)
    134..140 'foo(s)': ()
    138..139 's': S<u32>
    "###
    );
}

#[test]
fn infer_from_bound_2() {
    assert_snapshot!(
        infer(r#"
trait Trait<T> {}
struct S<T>(T);
impl<U> Trait<U> for S<U> {}
fn foo<U, T: Trait<U>>(t: T) -> U {}
fn test() {
    let s = S(unknown);
    let x: u32 = foo(s);
}
"#),
        @r###"
    86..87 't': T
    97..99 '{}': ()
    110..162 '{     ...(s); }': ()
    120..121 's': S<u32>
    124..125 'S': S<u32>(u32) -> S<u32>
    124..134 'S(unknown)': S<u32>
    126..133 'unknown': u32
    144..145 'x': u32
    153..156 'foo': fn foo<u32, S<u32>>(S<u32>) -> u32
    153..159 'foo(s)': u32
    157..158 's': S<u32>
    "###
    );
}

#[test]
fn trait_default_method_self_bound_implements_trait() {
    mark::check!(trait_self_implements_self);
    assert_snapshot!(
        infer(r#"
trait Trait {
    fn foo(&self) -> i64;
    fn bar(&self) -> {
        let x = self.foo();
    }
}
"#),
        @r###"
    26..30 'self': &Self
    52..56 'self': &Self
    61..96 '{     ...     }': ()
    75..76 'x': i64
    79..83 'self': &Self
    79..89 'self.foo()': i64
    "###
    );
}

#[test]
fn trait_default_method_self_bound_implements_super_trait() {
    assert_snapshot!(
        infer(r#"
trait SuperTrait {
    fn foo(&self) -> i64;
}
trait Trait: SuperTrait {
    fn bar(&self) -> {
        let x = self.foo();
    }
}
"#),
        @r###"
    31..35 'self': &Self
    85..89 'self': &Self
    94..129 '{     ...     }': ()
    108..109 'x': i64
    112..116 'self': &Self
    112..122 'self.foo()': i64
    "###
    );
}

#[test]
fn infer_project_associated_type() {
    assert_snapshot!(
        infer(r#"
trait Iterable {
   type Item;
}
struct S;
impl Iterable for S { type Item = u32; }
fn test<T: Iterable>() {
    let x: <S as Iterable>::Item = 1;
    let y: <T as Iterable>::Item = no_matter;
    let z: T::Item = no_matter;
    let a: <T>::Item = no_matter;
}
"#),
        @r###"
    107..260 '{     ...ter; }': ()
    117..118 'x': u32
    144..145 '1': u32
    155..156 'y': Iterable::Item<T>
    182..191 'no_matter': Iterable::Item<T>
    201..202 'z': Iterable::Item<T>
    214..223 'no_matter': Iterable::Item<T>
    233..234 'a': Iterable::Item<T>
    248..257 'no_matter': Iterable::Item<T>
    "###
    );
}

#[test]
fn infer_return_associated_type() {
    assert_snapshot!(
        infer(r#"
trait Iterable {
   type Item;
}
struct S;
impl Iterable for S { type Item = u32; }
fn foo1<T: Iterable>(t: T) -> T::Item {}
fn foo2<T: Iterable>(t: T) -> <T as Iterable>::Item {}
fn foo3<T: Iterable>(t: T) -> <T>::Item {}
fn test() {
    let x = foo1(S);
    let y = foo2(S);
    let z = foo3(S);
}
"#),
        @r###"
    105..106 't': T
    122..124 '{}': ()
    146..147 't': T
    177..179 '{}': ()
    201..202 't': T
    220..222 '{}': ()
    233..299 '{     ...(S); }': ()
    243..244 'x': u32
    247..251 'foo1': fn foo1<S>(S) -> <S as Iterable>::Item
    247..254 'foo1(S)': u32
    252..253 'S': S
    264..265 'y': u32
    268..272 'foo2': fn foo2<S>(S) -> <S as Iterable>::Item
    268..275 'foo2(S)': u32
    273..274 'S': S
    285..286 'z': u32
    289..293 'foo3': fn foo3<S>(S) -> <S as Iterable>::Item
    289..296 'foo3(S)': u32
    294..295 'S': S
    "###
    );
}

#[test]
fn infer_associated_type_bound() {
    assert_snapshot!(
        infer(r#"
trait Iterable {
   type Item;
}
fn test<T: Iterable<Item=u32>>() {
    let y: T::Item = unknown;
}
"#),
        @r###"
    66..99 '{     ...own; }': ()
    76..77 'y': u32
    89..96 'unknown': u32
    "###
    );
}

#[test]
fn infer_const_body() {
    assert_snapshot!(
        infer(r#"
const A: u32 = 1 + 1;
static B: u64 = { let x = 1; x };
"#),
        @r###"
    15..16 '1': u32
    15..20 '1 + 1': u32
    19..20 '1': u32
    38..54 '{ let ...1; x }': u64
    44..45 'x': u64
    48..49 '1': u64
    51..52 'x': u64
    "###
    );
}

#[test]
fn tuple_struct_fields() {
    assert_snapshot!(
        infer(r#"
struct S(i32, u64);
fn test() -> u64 {
    let a = S(4, 6);
    let b = a.0;
    a.1
}
"#),
        @r###"
    37..86 '{     ... a.1 }': u64
    47..48 'a': S
    51..52 'S': S(i32, u64) -> S
    51..58 'S(4, 6)': S
    53..54 '4': i32
    56..57 '6': u64
    68..69 'b': i32
    72..73 'a': S
    72..75 'a.0': i32
    81..82 'a': S
    81..84 'a.1': u64
    "###
    );
}

#[test]
fn tuple_struct_with_fn() {
    assert_snapshot!(
        infer(r#"
struct S(fn(u32) -> u64);
fn test() -> u64 {
    let a = S(|i| 2*i);
    let b = a.0(4);
    a.0(2)
}
"#),
        @r###"
    43..101 '{     ...0(2) }': u64
    53..54 'a': S
    57..58 'S': S(fn(u32) -> u64) -> S
    57..67 'S(|i| 2*i)': S
    59..66 '|i| 2*i': |u32| -> u64
    60..61 'i': u32
    63..64 '2': u32
    63..66 '2*i': u32
    65..66 'i': u32
    77..78 'b': u64
    81..82 'a': S
    81..84 'a.0': fn(u32) -> u64
    81..87 'a.0(4)': u64
    85..86 '4': u32
    93..94 'a': S
    93..96 'a.0': fn(u32) -> u64
    93..99 'a.0(2)': u64
    97..98 '2': u32
    "###
    );
}

#[test]
fn indexing_arrays() {
    assert_snapshot!(
        infer("fn main() { &mut [9][2]; }"),
        @r###"
    10..26 '{ &mut...[2]; }': ()
    12..23 '&mut [9][2]': &mut {unknown}
    17..20 '[9]': [i32; _]
    17..23 '[9][2]': {unknown}
    18..19 '9': i32
    21..22 '2': i32
    "###
    )
}

#[test]
fn infer_ops_index() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:std

struct Bar;
struct Foo;

impl std::ops::Index<u32> for Bar {
    type Output = Foo;
}

fn test() {
    let a = Bar;
    let b = a[1u32];
    b<|>;
}

//- /std.rs crate:std

#[prelude_import] use ops::*;
mod ops {
    #[lang = "index"]
    pub trait Index<Idx> {
        type Output;
    }
}
"#,
    );
    assert_eq!("Foo", type_at_pos(&db, pos));
}

#[test]
fn infer_ops_index_autoderef() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:std
fn test() {
    let a = &[1u32, 2, 3];
    let b = a[1u32];
    b<|>;
}

//- /std.rs crate:std
impl<T> ops::Index<u32> for [T] {
    type Output = T;
}

#[prelude_import] use ops::*;
mod ops {
    #[lang = "index"]
    pub trait Index<Idx> {
        type Output;
    }
}
"#,
    );
    assert_eq!("u32", type_at_pos(&db, pos));
}

#[test]
fn deref_trait() {
    let t = type_at(
        r#"
//- /main.rs
#[lang = "deref"]
trait Deref {
    type Target;
    fn deref(&self) -> &Self::Target;
}

struct Arc<T>;
impl<T> Deref for Arc<T> {
    type Target = T;
}

struct S;
impl S {
    fn foo(&self) -> u128 {}
}

fn test(s: Arc<S>) {
    (*s, s.foo())<|>;
}
"#,
    );
    assert_eq!(t, "(S, u128)");
}

#[test]
fn deref_trait_with_inference_var() {
    let t = type_at(
        r#"
//- /main.rs
#[lang = "deref"]
trait Deref {
    type Target;
    fn deref(&self) -> &Self::Target;
}

struct Arc<T>;
fn new_arc<T>() -> Arc<T> {}
impl<T> Deref for Arc<T> {
    type Target = T;
}

struct S;
fn foo(a: Arc<S>) {}

fn test() {
    let a = new_arc();
    let b = (*a)<|>;
    foo(a);
}
"#,
    );
    assert_eq!(t, "S");
}

#[test]
fn deref_trait_infinite_recursion() {
    let t = type_at(
        r#"
//- /main.rs
#[lang = "deref"]
trait Deref {
    type Target;
    fn deref(&self) -> &Self::Target;
}

struct S;

impl Deref for S {
    type Target = S;
}

fn test(s: S) {
    s.foo()<|>;
}
"#,
    );
    assert_eq!(t, "{unknown}");
}

#[test]
fn deref_trait_with_question_mark_size() {
    let t = type_at(
        r#"
//- /main.rs
#[lang = "deref"]
trait Deref {
    type Target;
    fn deref(&self) -> &Self::Target;
}

struct Arc<T>;
impl<T> Deref for Arc<T> {
    type Target = T;
}

struct S;
impl S {
    fn foo(&self) -> u128 {}
}

fn test(s: Arc<S>) {
    (*s, s.foo())<|>;
}
"#,
    );
    assert_eq!(t, "(S, u128)");
}

#[test]
fn obligation_from_function_clause() {
    let t = type_at(
        r#"
//- /main.rs
struct S;

trait Trait<T> {}
impl Trait<u32> for S {}

fn foo<T: Trait<U>, U>(t: T) -> U {}

fn test(s: S) {
    foo(s)<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn obligation_from_method_clause() {
    let t = type_at(
        r#"
//- /main.rs
struct S;

trait Trait<T> {}
impl Trait<isize> for S {}

struct O;
impl O {
    fn foo<T: Trait<U>, U>(&self, t: T) -> U {}
}

fn test() {
    O.foo(S)<|>;
}
"#,
    );
    assert_eq!(t, "isize");
}

#[test]
fn obligation_from_self_method_clause() {
    let t = type_at(
        r#"
//- /main.rs
struct S;

trait Trait<T> {}
impl Trait<i64> for S {}

impl S {
    fn foo<U>(&self) -> U where Self: Trait<U> {}
}

fn test() {
    S.foo()<|>;
}
"#,
    );
    assert_eq!(t, "i64");
}

#[test]
fn obligation_from_impl_clause() {
    let t = type_at(
        r#"
//- /main.rs
struct S;

trait Trait<T> {}
impl Trait<&str> for S {}

struct O<T>;
impl<U, T: Trait<U>> O<T> {
    fn foo(&self) -> U {}
}

fn test(o: O<S>) {
    o.foo()<|>;
}
"#,
    );
    assert_eq!(t, "&str");
}

#[test]
fn generic_param_env_1() {
    let t = type_at(
        r#"
//- /main.rs
trait Clone {}
trait Trait { fn foo(self) -> u128; }
struct S;
impl Clone for S {}
impl<T> Trait for T where T: Clone {}
fn test<T: Clone>(t: T) { t.foo()<|>; }
"#,
    );
    assert_eq!(t, "u128");
}

#[test]
fn generic_param_env_1_not_met() {
    let t = type_at(
        r#"
//- /main.rs
trait Clone {}
trait Trait { fn foo(self) -> u128; }
struct S;
impl Clone for S {}
impl<T> Trait for T where T: Clone {}
fn test<T>(t: T) { t.foo()<|>; }
"#,
    );
    assert_eq!(t, "{unknown}");
}

#[test]
fn generic_param_env_2() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait { fn foo(self) -> u128; }
struct S;
impl Trait for S {}
fn test<T: Trait>(t: T) { t.foo()<|>; }
"#,
    );
    assert_eq!(t, "u128");
}

#[test]
fn generic_param_env_2_not_met() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait { fn foo(self) -> u128; }
struct S;
impl Trait for S {}
fn test<T>(t: T) { t.foo()<|>; }
"#,
    );
    assert_eq!(t, "{unknown}");
}

#[test]
fn generic_param_env_deref() {
    let t = type_at(
        r#"
//- /main.rs
#[lang = "deref"]
trait Deref {
    type Target;
}
trait Trait {}
impl<T> Deref for T where T: Trait {
    type Target = i128;
}
fn test<T: Trait>(t: T) { (*t)<|>; }
"#,
    );
    assert_eq!(t, "i128");
}

#[test]
fn associated_type_placeholder() {
    let t = type_at(
        r#"
//- /main.rs
pub trait ApplyL {
    type Out;
}

pub struct RefMutL<T>;

impl<T> ApplyL for RefMutL<T> {
    type Out = <T as ApplyL>::Out;
}

fn test<T: ApplyL>() {
    let y: <RefMutL<T> as ApplyL>::Out = no_matter;
    y<|>;
}
"#,
    );
    // inside the generic function, the associated type gets normalized to a placeholder `ApplL::Out<T>` [https://rust-lang.github.io/rustc-guide/traits/associated-types.html#placeholder-associated-types].
    assert_eq!(t, "ApplyL::Out<T>");
}

#[test]
fn associated_type_placeholder_2() {
    let t = type_at(
        r#"
//- /main.rs
pub trait ApplyL {
    type Out;
}
fn foo<T: ApplyL>(t: T) -> <T as ApplyL>::Out;

fn test<T: ApplyL>(t: T) {
    let y = foo(t);
    y<|>;
}
"#,
    );
    assert_eq!(t, "ApplyL::Out<T>");
}

#[test]
fn argument_impl_trait() {
    assert_snapshot!(
        infer_with_mismatches(r#"
trait Trait<T> {
    fn foo(&self) -> T;
    fn foo2(&self) -> i64;
}
fn bar(x: impl Trait<u16>) {}
struct S<T>(T);
impl<T> Trait<T> for S<T> {}

fn test(x: impl Trait<u64>, y: &impl Trait<u32>) {
    x;
    y;
    let z = S(1);
    bar(z);
    x.foo();
    y.foo();
    z.foo();
    x.foo2();
    y.foo2();
    z.foo2();
}
"#, true),
        @r###"
    29..33 'self': &Self
    54..58 'self': &Self
    77..78 'x': impl Trait<u16>
    97..99 '{}': ()
    154..155 'x': impl Trait<u64>
    174..175 'y': &impl Trait<u32>
    195..323 '{     ...2(); }': ()
    201..202 'x': impl Trait<u64>
    208..209 'y': &impl Trait<u32>
    219..220 'z': S<u16>
    223..224 'S': S<u16>(u16) -> S<u16>
    223..227 'S(1)': S<u16>
    225..226 '1': u16
    233..236 'bar': fn bar(S<u16>)
    233..239 'bar(z)': ()
    237..238 'z': S<u16>
    245..246 'x': impl Trait<u64>
    245..252 'x.foo()': u64
    258..259 'y': &impl Trait<u32>
    258..265 'y.foo()': u32
    271..272 'z': S<u16>
    271..278 'z.foo()': u16
    284..285 'x': impl Trait<u64>
    284..292 'x.foo2()': i64
    298..299 'y': &impl Trait<u32>
    298..306 'y.foo2()': i64
    312..313 'z': S<u16>
    312..320 'z.foo2()': i64
    "###
    );
}

#[test]
fn argument_impl_trait_type_args_1() {
    assert_snapshot!(
        infer_with_mismatches(r#"
trait Trait {}
trait Foo {
    // this function has an implicit Self param, an explicit type param,
    // and an implicit impl Trait param!
    fn bar<T>(x: impl Trait) -> T { loop {} }
}
fn foo<T>(x: impl Trait) -> T { loop {} }
struct S;
impl Trait for S {}
struct F;
impl Foo for F {}

fn test() {
    Foo::bar(S);
    <F as Foo>::bar(S);
    F::bar(S);
    Foo::bar::<u32>(S);
    <F as Foo>::bar::<u32>(S);

    foo(S);
    foo::<u32>(S);
    foo::<u32, i32>(S); // we should ignore the extraneous i32
}
"#, true),
        @r###"
    155..156 'x': impl Trait
    175..186 '{ loop {} }': T
    177..184 'loop {}': !
    182..184 '{}': ()
    199..200 'x': impl Trait
    219..230 '{ loop {} }': T
    221..228 'loop {}': !
    226..228 '{}': ()
    300..509 '{     ... i32 }': ()
    306..314 'Foo::bar': fn bar<{unknown}, {unknown}>(S) -> {unknown}
    306..317 'Foo::bar(S)': {unknown}
    315..316 'S': S
    323..338 '<F as Foo>::bar': fn bar<F, {unknown}>(S) -> {unknown}
    323..341 '<F as ...bar(S)': {unknown}
    339..340 'S': S
    347..353 'F::bar': fn bar<F, {unknown}>(S) -> {unknown}
    347..356 'F::bar(S)': {unknown}
    354..355 'S': S
    362..377 'Foo::bar::<u32>': fn bar<{unknown}, u32>(S) -> u32
    362..380 'Foo::b...32>(S)': u32
    378..379 'S': S
    386..408 '<F as ...:<u32>': fn bar<F, u32>(S) -> u32
    386..411 '<F as ...32>(S)': u32
    409..410 'S': S
    418..421 'foo': fn foo<{unknown}>(S) -> {unknown}
    418..424 'foo(S)': {unknown}
    422..423 'S': S
    430..440 'foo::<u32>': fn foo<u32>(S) -> u32
    430..443 'foo::<u32>(S)': u32
    441..442 'S': S
    449..464 'foo::<u32, i32>': fn foo<u32>(S) -> u32
    449..467 'foo::<...32>(S)': u32
    465..466 'S': S
    "###
    );
}

#[test]
fn argument_impl_trait_type_args_2() {
    assert_snapshot!(
        infer_with_mismatches(r#"
trait Trait {}
struct S;
impl Trait for S {}
struct F<T>;
impl<T> F<T> {
    fn foo<U>(self, x: impl Trait) -> (T, U) { loop {} }
}

fn test() {
    F.foo(S);
    F::<u32>.foo(S);
    F::<u32>.foo::<i32>(S);
    F::<u32>.foo::<i32, u32>(S); // extraneous argument should be ignored
}
"#, true),
        @r###"
    87..91 'self': F<T>
    93..94 'x': impl Trait
    118..129 '{ loop {} }': (T, U)
    120..127 'loop {}': !
    125..127 '{}': ()
    143..283 '{     ...ored }': ()
    149..150 'F': F<{unknown}>
    149..157 'F.foo(S)': ({unknown}, {unknown})
    155..156 'S': S
    163..171 'F::<u32>': F<u32>
    163..178 'F::<u32>.foo(S)': (u32, {unknown})
    176..177 'S': S
    184..192 'F::<u32>': F<u32>
    184..206 'F::<u3...32>(S)': (u32, i32)
    204..205 'S': S
    212..220 'F::<u32>': F<u32>
    212..239 'F::<u3...32>(S)': (u32, i32)
    237..238 'S': S
    "###
    );
}

#[test]
fn argument_impl_trait_to_fn_pointer() {
    assert_snapshot!(
        infer_with_mismatches(r#"
trait Trait {}
fn foo(x: impl Trait) { loop {} }
struct S;
impl Trait for S {}

fn test() {
    let f: fn(S) -> () = foo;
}
"#, true),
        @r###"
    22..23 'x': impl Trait
    37..48 '{ loop {} }': ()
    39..46 'loop {}': !
    44..46 '{}': ()
    90..123 '{     ...foo; }': ()
    100..101 'f': fn(S)
    117..120 'foo': fn foo(S)
    "###
    );
}

#[test]
fn impl_trait() {
    assert_snapshot!(
        infer(r#"
trait Trait<T> {
    fn foo(&self) -> T;
    fn foo2(&self) -> i64;
}
fn bar() -> impl Trait<u64> {}

fn test(x: impl Trait<u64>, y: &impl Trait<u64>) {
    x;
    y;
    let z = bar();
    x.foo();
    y.foo();
    z.foo();
    x.foo2();
    y.foo2();
    z.foo2();
}
"#),
        @r###"
    29..33 'self': &Self
    54..58 'self': &Self
    98..100 '{}': ()
    110..111 'x': impl Trait<u64>
    130..131 'y': &impl Trait<u64>
    151..268 '{     ...2(); }': ()
    157..158 'x': impl Trait<u64>
    164..165 'y': &impl Trait<u64>
    175..176 'z': impl Trait<u64>
    179..182 'bar': fn bar() -> impl Trait<u64>
    179..184 'bar()': impl Trait<u64>
    190..191 'x': impl Trait<u64>
    190..197 'x.foo()': u64
    203..204 'y': &impl Trait<u64>
    203..210 'y.foo()': u64
    216..217 'z': impl Trait<u64>
    216..223 'z.foo()': u64
    229..230 'x': impl Trait<u64>
    229..237 'x.foo2()': i64
    243..244 'y': &impl Trait<u64>
    243..251 'y.foo2()': i64
    257..258 'z': impl Trait<u64>
    257..265 'z.foo2()': i64
    "###
    );
}

#[test]
fn simple_return_pos_impl_trait() {
    mark::check!(lower_rpit);
    assert_snapshot!(
        infer(r#"
trait Trait<T> {
    fn foo(&self) -> T;
}
fn bar() -> impl Trait<u64> { loop {} }

fn test() {
    let a = bar();
    a.foo();
}
"#),
        @r###"
    29..33 'self': &Self
    71..82 '{ loop {} }': !
    73..80 'loop {}': !
    78..80 '{}': ()
    94..129 '{     ...o(); }': ()
    104..105 'a': impl Trait<u64>
    108..111 'bar': fn bar() -> impl Trait<u64>
    108..113 'bar()': impl Trait<u64>
    119..120 'a': impl Trait<u64>
    119..126 'a.foo()': u64
    "###
    );
}

#[test]
fn more_return_pos_impl_trait() {
    assert_snapshot!(
        infer(r#"
trait Iterator {
    type Item;
    fn next(&mut self) -> Self::Item;
}
trait Trait<T> {
    fn foo(&self) -> T;
}
fn bar() -> (impl Iterator<Item = impl Trait<u32>>, impl Trait<u64>) { loop {} }
fn baz<T>(t: T) -> (impl Iterator<Item = impl Trait<T>>, impl Trait<T>) { loop {} }

fn test() {
    let (a, b) = bar();
    a.next().foo();
    b.foo();
    let (c, d) = baz(1u128);
    c.next().foo();
    d.foo();
}
"#),
        @r###"
    49..53 'self': &mut Self
    101..105 'self': &Self
    184..195 '{ loop {} }': ({unknown}, {unknown})
    186..193 'loop {}': !
    191..193 '{}': ()
    206..207 't': T
    268..279 '{ loop {} }': ({unknown}, {unknown})
    270..277 'loop {}': !
    275..277 '{}': ()
    291..413 '{     ...o(); }': ()
    301..307 '(a, b)': (impl Iterator<Item = impl Trait<u32>>, impl Trait<u64>)
    302..303 'a': impl Iterator<Item = impl Trait<u32>>
    305..306 'b': impl Trait<u64>
    310..313 'bar': fn bar() -> (impl Iterator<Item = impl Trait<u32>>, impl Trait<u64>)
    310..315 'bar()': (impl Iterator<Item = impl Trait<u32>>, impl Trait<u64>)
    321..322 'a': impl Iterator<Item = impl Trait<u32>>
    321..329 'a.next()': impl Trait<u32>
    321..335 'a.next().foo()': u32
    341..342 'b': impl Trait<u64>
    341..348 'b.foo()': u64
    358..364 '(c, d)': (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
    359..360 'c': impl Iterator<Item = impl Trait<u128>>
    362..363 'd': impl Trait<u128>
    367..370 'baz': fn baz<u128>(u128) -> (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
    367..377 'baz(1u128)': (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
    371..376 '1u128': u128
    383..384 'c': impl Iterator<Item = impl Trait<u128>>
    383..391 'c.next()': impl Trait<u128>
    383..397 'c.next().foo()': u128
    403..404 'd': impl Trait<u128>
    403..410 'd.foo()': u128
    "###
    );
}

#[test]
fn dyn_trait() {
    assert_snapshot!(
        infer(r#"
trait Trait<T> {
    fn foo(&self) -> T;
    fn foo2(&self) -> i64;
}
fn bar() -> dyn Trait<u64> {}

fn test(x: dyn Trait<u64>, y: &dyn Trait<u64>) {
    x;
    y;
    let z = bar();
    x.foo();
    y.foo();
    z.foo();
    x.foo2();
    y.foo2();
    z.foo2();
}
"#),
        @r###"
    29..33 'self': &Self
    54..58 'self': &Self
    97..99 '{}': ()
    109..110 'x': dyn Trait<u64>
    128..129 'y': &dyn Trait<u64>
    148..265 '{     ...2(); }': ()
    154..155 'x': dyn Trait<u64>
    161..162 'y': &dyn Trait<u64>
    172..173 'z': dyn Trait<u64>
    176..179 'bar': fn bar() -> dyn Trait<u64>
    176..181 'bar()': dyn Trait<u64>
    187..188 'x': dyn Trait<u64>
    187..194 'x.foo()': u64
    200..201 'y': &dyn Trait<u64>
    200..207 'y.foo()': u64
    213..214 'z': dyn Trait<u64>
    213..220 'z.foo()': u64
    226..227 'x': dyn Trait<u64>
    226..234 'x.foo2()': i64
    240..241 'y': &dyn Trait<u64>
    240..248 'y.foo2()': i64
    254..255 'z': dyn Trait<u64>
    254..262 'z.foo2()': i64
    "###
    );
}

#[test]
fn dyn_trait_in_impl() {
    assert_snapshot!(
        infer(r#"
trait Trait<T, U> {
    fn foo(&self) -> (T, U);
}
struct S<T, U> {}
impl<T, U> S<T, U> {
    fn bar(&self) -> &dyn Trait<T, U> { loop {} }
}
trait Trait2<T, U> {
    fn baz(&self) -> (T, U);
}
impl<T, U> Trait2<T, U> for dyn Trait<T, U> { }

fn test(s: S<u32, i32>) {
    s.bar().baz();
}
"#),
        @r###"
    32..36 'self': &Self
    102..106 'self': &S<T, U>
    128..139 '{ loop {} }': &dyn Trait<T, U>
    130..137 'loop {}': !
    135..137 '{}': ()
    175..179 'self': &Self
    251..252 's': S<u32, i32>
    267..289 '{     ...z(); }': ()
    273..274 's': S<u32, i32>
    273..280 's.bar()': &dyn Trait<u32, i32>
    273..286 's.bar().baz()': (u32, i32)
    "###
    );
}

#[test]
fn dyn_trait_bare() {
    assert_snapshot!(
        infer(r#"
trait Trait {
    fn foo(&self) -> u64;
}
fn bar() -> Trait {}

fn test(x: Trait, y: &Trait) -> u64 {
    x;
    y;
    let z = bar();
    x.foo();
    y.foo();
    z.foo();
}
"#),
        @r###"
    26..30 'self': &Self
    60..62 '{}': ()
    72..73 'x': dyn Trait
    82..83 'y': &dyn Trait
    100..175 '{     ...o(); }': ()
    106..107 'x': dyn Trait
    113..114 'y': &dyn Trait
    124..125 'z': dyn Trait
    128..131 'bar': fn bar() -> dyn Trait
    128..133 'bar()': dyn Trait
    139..140 'x': dyn Trait
    139..146 'x.foo()': u64
    152..153 'y': &dyn Trait
    152..159 'y.foo()': u64
    165..166 'z': dyn Trait
    165..172 'z.foo()': u64
    "###
    );
}

#[test]
fn weird_bounds() {
    assert_snapshot!(
        infer(r#"
trait Trait {}
fn test(a: impl Trait + 'lifetime, b: impl 'lifetime, c: impl (Trait), d: impl ('lifetime), e: impl ?Sized, f: impl Trait + ?Sized) {
}
"#),
        @r###"
    23..24 'a': impl Trait + {error}
    50..51 'b': impl {error}
    69..70 'c': impl Trait
    86..87 'd': impl {error}
    107..108 'e': impl {error}
    123..124 'f': impl Trait + {error}
    147..150 '{ }': ()
    "###
    );
}

#[test]
#[ignore]
fn error_bound_chalk() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait {
    fn foo(&self) -> u32 {}
}

fn test(x: (impl Trait + UnknownTrait)) {
    x.foo()<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn assoc_type_bindings() {
    assert_snapshot!(
        infer(r#"
trait Trait {
    type Type;
}

fn get<T: Trait>(t: T) -> <T as Trait>::Type {}
fn get2<U, T: Trait<Type = U>>(t: T) -> U {}
fn set<T: Trait<Type = u64>>(t: T) -> T {t}

struct S<T>;
impl<T> Trait for S<T> { type Type = T; }

fn test<T: Trait<Type = u32>>(x: T, y: impl Trait<Type = i64>) {
    get(x);
    get2(x);
    get(y);
    get2(y);
    get(set(S));
    get2(set(S));
    get2(S::<str>);
}
"#),
        @r###"
    49..50 't': T
    77..79 '{}': ()
    111..112 't': T
    122..124 '{}': ()
    154..155 't': T
    165..168 '{t}': T
    166..167 't': T
    256..257 'x': T
    262..263 'y': impl Trait<Type = i64>
    289..397 '{     ...r>); }': ()
    295..298 'get': fn get<T>(T) -> <T as Trait>::Type
    295..301 'get(x)': u32
    299..300 'x': T
    307..311 'get2': fn get2<u32, T>(T) -> u32
    307..314 'get2(x)': u32
    312..313 'x': T
    320..323 'get': fn get<impl Trait<Type = i64>>(impl Trait<Type = i64>) -> <impl Trait<Type = i64> as Trait>::Type
    320..326 'get(y)': i64
    324..325 'y': impl Trait<Type = i64>
    332..336 'get2': fn get2<i64, impl Trait<Type = i64>>(impl Trait<Type = i64>) -> i64
    332..339 'get2(y)': i64
    337..338 'y': impl Trait<Type = i64>
    345..348 'get': fn get<S<u64>>(S<u64>) -> <S<u64> as Trait>::Type
    345..356 'get(set(S))': u64
    349..352 'set': fn set<S<u64>>(S<u64>) -> S<u64>
    349..355 'set(S)': S<u64>
    353..354 'S': S<u64>
    362..366 'get2': fn get2<u64, S<u64>>(S<u64>) -> u64
    362..374 'get2(set(S))': u64
    367..370 'set': fn set<S<u64>>(S<u64>) -> S<u64>
    367..373 'set(S)': S<u64>
    371..372 'S': S<u64>
    380..384 'get2': fn get2<str, S<str>>(S<str>) -> str
    380..394 'get2(S::<str>)': str
    385..393 'S::<str>': S<str>
    "###
    );
}

#[test]
fn impl_trait_assoc_binding_projection_bug() {
    let (db, pos) = TestDB::with_position(
        r#"
//- /main.rs crate:main deps:std
pub trait Language {
    type Kind;
}
pub enum RustLanguage {}
impl Language for RustLanguage {
    type Kind = SyntaxKind;
}
struct SyntaxNode<L> {}
fn foo() -> impl Iterator<Item = SyntaxNode<RustLanguage>> {}

trait Clone {
    fn clone(&self) -> Self;
}

fn api_walkthrough() {
    for node in foo() {
        node.clone()<|>;
    }
}

//- /std.rs crate:std
#[prelude_import] use iter::*;
mod iter {
    trait IntoIterator {
        type Item;
    }
    trait Iterator {
        type Item;
    }
    impl<T: Iterator> IntoIterator for T {
        type Item = <T as Iterator>::Item;
    }
}
"#,
    );
    assert_eq!("{unknown}", type_at_pos(&db, pos));
}

#[test]
fn projection_eq_within_chalk() {
    assert_snapshot!(
        infer(r#"
trait Trait1 {
    type Type;
}
trait Trait2<T> {
    fn foo(self) -> T;
}
impl<T, U> Trait2<T> for U where U: Trait1<Type = T> {}

fn test<T: Trait1<Type = u32>>(x: T) {
    x.foo();
}
"#),
        @r###"
    61..65 'self': Self
    163..164 'x': T
    169..185 '{     ...o(); }': ()
    175..176 'x': T
    175..182 'x.foo()': u32
    "###
    );
}

#[test]
fn where_clause_trait_in_scope_for_method_resolution() {
    let t = type_at(
        r#"
//- /main.rs
mod foo {
    trait Trait {
        fn foo(&self) -> u32 {}
    }
}

fn test<T: foo::Trait>(x: T) {
    x.foo()<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn super_trait_method_resolution() {
    assert_snapshot!(
        infer(r#"
mod foo {
    trait SuperTrait {
        fn foo(&self) -> u32 {}
    }
}
trait Trait1: foo::SuperTrait {}
trait Trait2 where Self: foo::SuperTrait {}

fn test<T: Trait1, U: Trait2>(x: T, y: U) {
    x.foo();
    y.foo();
}
"#),
        @r###"
    49..53 'self': &Self
    62..64 '{}': ()
    181..182 'x': T
    187..188 'y': U
    193..222 '{     ...o(); }': ()
    199..200 'x': T
    199..206 'x.foo()': u32
    212..213 'y': U
    212..219 'y.foo()': u32
    "###
    );
}

#[test]
fn super_trait_impl_trait_method_resolution() {
    assert_snapshot!(
        infer(r#"
mod foo {
    trait SuperTrait {
        fn foo(&self) -> u32 {}
    }
}
trait Trait1: foo::SuperTrait {}

fn test(x: &impl Trait1) {
    x.foo();
}
"#),
        @r###"
    49..53 'self': &Self
    62..64 '{}': ()
    115..116 'x': &impl Trait1
    132..148 '{     ...o(); }': ()
    138..139 'x': &impl Trait1
    138..145 'x.foo()': u32
    "###
    );
}

#[test]
fn super_trait_cycle() {
    // This just needs to not crash
    assert_snapshot!(
        infer(r#"
trait A: B {}
trait B: A {}

fn test<T: A>(x: T) {
    x.foo();
}
"#),
        @r###"
    43..44 'x': T
    49..65 '{     ...o(); }': ()
    55..56 'x': T
    55..62 'x.foo()': {unknown}
    "###
    );
}

#[test]
fn super_trait_assoc_type_bounds() {
    assert_snapshot!(
        infer(r#"
trait SuperTrait { type Type; }
trait Trait where Self: SuperTrait {}

fn get2<U, T: Trait<Type = U>>(t: T) -> U {}
fn set<T: Trait<Type = u64>>(t: T) -> T {t}

struct S<T>;
impl<T> SuperTrait for S<T> { type Type = T; }
impl<T> Trait for S<T> {}

fn test() {
    get2(set(S));
}
"#),
        @r###"
    102..103 't': T
    113..115 '{}': ()
    145..146 't': T
    156..159 '{t}': T
    157..158 't': T
    258..279 '{     ...S)); }': ()
    264..268 'get2': fn get2<u64, S<u64>>(S<u64>) -> u64
    264..276 'get2(set(S))': u64
    269..272 'set': fn set<S<u64>>(S<u64>) -> S<u64>
    269..275 'set(S)': S<u64>
    273..274 'S': S<u64>
    "###
    );
}

#[test]
fn fn_trait() {
    assert_snapshot!(
        infer(r#"
trait FnOnce<Args> {
    type Output;

    fn call_once(self, args: Args) -> <Self as FnOnce<Args>>::Output;
}

fn test<F: FnOnce(u32, u64) -> u128>(f: F) {
    f.call_once((1, 2));
}
"#),
        @r###"
    56..60 'self': Self
    62..66 'args': Args
    149..150 'f': F
    155..183 '{     ...2)); }': ()
    161..162 'f': F
    161..180 'f.call...1, 2))': u128
    173..179 '(1, 2)': (u32, u64)
    174..175 '1': u32
    177..178 '2': u64
    "###
    );
}

#[test]
fn fn_ptr_and_item() {
    assert_snapshot!(
        infer(r#"
#[lang="fn_once"]
trait FnOnce<Args> {
    type Output;

    fn call_once(self, args: Args) -> Self::Output;
}

trait Foo<T> {
    fn foo(&self) -> T;
}

struct Bar<T>(T);

impl<A1, R, F: FnOnce(A1) -> R> Foo<(A1, R)> for Bar<F> {
    fn foo(&self) -> (A1, R) {}
}

enum Opt<T> { None, Some(T) }
impl<T> Opt<T> {
    fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Opt<U> {}
}

fn test() {
    let bar: Bar<fn(u8) -> u32>;
    bar.foo();

    let opt: Opt<u8>;
    let f: fn(u8) -> u32;
    opt.map(f);
}
"#),
        @r###"
    74..78 'self': Self
    80..84 'args': Args
    139..143 'self': &Self
    243..247 'self': &Bar<F>
    260..262 '{}': ()
    346..350 'self': Opt<T>
    352..353 'f': F
    368..370 '{}': ()
    384..500 '{     ...(f); }': ()
    394..397 'bar': Bar<fn(u8) -> u32>
    423..426 'bar': Bar<fn(u8) -> u32>
    423..432 'bar.foo()': (u8, u32)
    443..446 'opt': Opt<u8>
    465..466 'f': fn(u8) -> u32
    487..490 'opt': Opt<u8>
    487..497 'opt.map(f)': Opt<u32>
    495..496 'f': fn(u8) -> u32
    "###
    );
}

#[test]
fn fn_trait_deref_with_ty_default() {
    assert_snapshot!(
        infer(r#"
#[lang = "deref"]
trait Deref {
    type Target;

    fn deref(&self) -> &Self::Target;
}

#[lang="fn_once"]
trait FnOnce<Args> {
    type Output;

    fn call_once(self, args: Args) -> Self::Output;
}

struct Foo;

impl Foo {
    fn foo(&self) -> usize {}
}

struct Lazy<T, F = fn() -> T>(F);

impl<T, F> Lazy<T, F> {
    pub fn new(f: F) -> Lazy<T, F> {}
}

impl<T, F: FnOnce() -> T> Deref for Lazy<T, F> {
    type Target = T;
}

fn test() {
    let lazy1: Lazy<Foo, _> = Lazy::new(|| Foo);
    let r1 = lazy1.foo();

    fn make_foo_fn() -> Foo {}
    let make_foo_fn_ptr: fn() -> Foo = make_foo_fn;
    let lazy2: Lazy<Foo, _> = Lazy::new(make_foo_fn_ptr);
    let r2 = lazy2.foo();
}
"#),
        @r###"
    64..68 'self': &Self
    165..169 'self': Self
    171..175 'args': Args
    239..243 'self': &Foo
    254..256 '{}': ()
    334..335 'f': F
    354..356 '{}': ()
    443..689 '{     ...o(); }': ()
    453..458 'lazy1': Lazy<Foo, || -> Foo>
    475..484 'Lazy::new': fn new<Foo, || -> Foo>(|| -> Foo) -> Lazy<Foo, || -> Foo>
    475..492 'Lazy::...| Foo)': Lazy<Foo, || -> Foo>
    485..491 '|| Foo': || -> Foo
    488..491 'Foo': Foo
    502..504 'r1': usize
    507..512 'lazy1': Lazy<Foo, || -> Foo>
    507..518 'lazy1.foo()': usize
    560..575 'make_foo_fn_ptr': fn() -> Foo
    591..602 'make_foo_fn': fn make_foo_fn() -> Foo
    612..617 'lazy2': Lazy<Foo, fn() -> Foo>
    634..643 'Lazy::new': fn new<Foo, fn() -> Foo>(fn() -> Foo) -> Lazy<Foo, fn() -> Foo>
    634..660 'Lazy::...n_ptr)': Lazy<Foo, fn() -> Foo>
    644..659 'make_foo_fn_ptr': fn() -> Foo
    670..672 'r2': usize
    675..680 'lazy2': Lazy<Foo, fn() -> Foo>
    675..686 'lazy2.foo()': usize
    549..551 '{}': ()
    "###
    );
}

#[test]
fn closure_1() {
    assert_snapshot!(
        infer(r#"
#[lang = "fn_once"]
trait FnOnce<Args> {
    type Output;
}

enum Option<T> { Some(T), None }
impl<T> Option<T> {
    fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Option<U> {}
}

fn test() {
    let x = Option::Some(1u32);
    x.map(|v| v + 1);
    x.map(|_v| 1u64);
    let y: Option<i64> = x.map(|_v| 1);
}
"#),
        @r###"
    147..151 'self': Option<T>
    153..154 'f': F
    172..174 '{}': ()
    188..307 '{     ... 1); }': ()
    198..199 'x': Option<u32>
    202..214 'Option::Some': Some<u32>(u32) -> Option<u32>
    202..220 'Option...(1u32)': Option<u32>
    215..219 '1u32': u32
    226..227 'x': Option<u32>
    226..242 'x.map(...v + 1)': Option<u32>
    232..241 '|v| v + 1': |u32| -> u32
    233..234 'v': u32
    236..237 'v': u32
    236..241 'v + 1': u32
    240..241 '1': u32
    248..249 'x': Option<u32>
    248..264 'x.map(... 1u64)': Option<u64>
    254..263 '|_v| 1u64': |u32| -> u64
    255..257 '_v': u32
    259..263 '1u64': u64
    274..275 'y': Option<i64>
    291..292 'x': Option<u32>
    291..304 'x.map(|_v| 1)': Option<i64>
    297..303 '|_v| 1': |u32| -> i64
    298..300 '_v': u32
    302..303 '1': i64
    "###
    );
}

#[test]
fn closure_2() {
    assert_snapshot!(
        infer(r#"
trait FnOnce<Args> {
    type Output;
}

fn test<F: FnOnce(u32) -> u64>(f: F) {
    f(1);
    let g = |v| v + 1;
    g(1u64);
    let h = |v| 1u128 + v;
}
"#),
        @r###"
    72..73 'f': F
    78..154 '{     ...+ v; }': ()
    84..85 'f': F
    84..88 'f(1)': {unknown}
    86..87 '1': i32
    98..99 'g': |u64| -> i32
    102..111 '|v| v + 1': |u64| -> i32
    103..104 'v': u64
    106..107 'v': u64
    106..111 'v + 1': i32
    110..111 '1': i32
    117..118 'g': |u64| -> i32
    117..124 'g(1u64)': i32
    119..123 '1u64': u64
    134..135 'h': |u128| -> u128
    138..151 '|v| 1u128 + v': |u128| -> u128
    139..140 'v': u128
    142..147 '1u128': u128
    142..151 '1u128 + v': u128
    150..151 'v': u128
    "###
    );
}

#[test]
fn closure_as_argument_inference_order() {
    assert_snapshot!(
        infer(r#"
#[lang = "fn_once"]
trait FnOnce<Args> {
    type Output;
}

fn foo1<T, U, F: FnOnce(T) -> U>(x: T, f: F) -> U {}
fn foo2<T, U, F: FnOnce(T) -> U>(f: F, x: T) -> U {}

struct S;
impl S {
    fn method(self) -> u64;

    fn foo1<T, U, F: FnOnce(T) -> U>(self, x: T, f: F) -> U {}
    fn foo2<T, U, F: FnOnce(T) -> U>(self, f: F, x: T) -> U {}
}

fn test() {
    let x1 = foo1(S, |s| s.method());
    let x2 = foo2(|s| s.method(), S);
    let x3 = S.foo1(S, |s| s.method());
    let x4 = S.foo2(|s| s.method(), S);
}
"#),
        @r###"
    94..95 'x': T
    100..101 'f': F
    111..113 '{}': ()
    147..148 'f': F
    153..154 'x': T
    164..166 '{}': ()
    201..205 'self': S
    253..257 'self': S
    259..260 'x': T
    265..266 'f': F
    276..278 '{}': ()
    316..320 'self': S
    322..323 'f': F
    328..329 'x': T
    339..341 '{}': ()
    355..514 '{     ... S); }': ()
    365..367 'x1': u64
    370..374 'foo1': fn foo1<S, u64, |S| -> u64>(S, |S| -> u64) -> u64
    370..393 'foo1(S...hod())': u64
    375..376 'S': S
    378..392 '|s| s.method()': |S| -> u64
    379..380 's': S
    382..383 's': S
    382..392 's.method()': u64
    403..405 'x2': u64
    408..412 'foo2': fn foo2<S, u64, |S| -> u64>(|S| -> u64, S) -> u64
    408..431 'foo2(|...(), S)': u64
    413..427 '|s| s.method()': |S| -> u64
    414..415 's': S
    417..418 's': S
    417..427 's.method()': u64
    429..430 'S': S
    441..443 'x3': u64
    446..447 'S': S
    446..471 'S.foo1...hod())': u64
    453..454 'S': S
    456..470 '|s| s.method()': |S| -> u64
    457..458 's': S
    460..461 's': S
    460..470 's.method()': u64
    481..483 'x4': u64
    486..487 'S': S
    486..511 'S.foo2...(), S)': u64
    493..507 '|s| s.method()': |S| -> u64
    494..495 's': S
    497..498 's': S
    497..507 's.method()': u64
    509..510 'S': S
    "###
    );
}

#[test]
fn unselected_projection_in_trait_env_1() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait {
    type Item;
}

trait Trait2 {
    fn foo(&self) -> u32;
}

fn test<T: Trait>() where T::Item: Trait2 {
    let x: T::Item = no_matter;
    x.foo()<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn unselected_projection_in_trait_env_2() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait<T> {
    type Item;
}

trait Trait2 {
    fn foo(&self) -> u32;
}

fn test<T, U>() where T::Item: Trait2, T: Trait<U::Item>, U: Trait<()> {
    let x: T::Item = no_matter;
    x.foo()<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn unselected_projection_on_impl_self() {
    assert_snapshot!(infer(
        r#"
//- /main.rs
trait Trait {
    type Item;

    fn f(&self, x: Self::Item);
}

struct S;

impl Trait for S {
    type Item = u32;
    fn f(&self, x: Self::Item) { let y = x; }
}

struct S2;

impl Trait for S2 {
    type Item = i32;
    fn f(&self, x: <Self>::Item) { let y = x; }
}
"#,
    ), @r###"
    40..44 'self': &Self
    46..47 'x': Trait::Item<Self>
    126..130 'self': &S
    132..133 'x': u32
    147..161 '{ let y = x; }': ()
    153..154 'y': u32
    157..158 'x': u32
    228..232 'self': &S2
    234..235 'x': i32
    251..265 '{ let y = x; }': ()
    257..258 'y': i32
    261..262 'x': i32
    "###);
}

#[test]
fn unselected_projection_on_trait_self() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait {
    type Item;

    fn f(&self) -> Self::Item { loop {} }
}

struct S;
impl Trait for S {
    type Item = u32;
}

fn test() {
    S.f()<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn unselected_projection_chalk_fold() {
    let t = type_at(
        r#"
//- /main.rs
trait Interner {}
trait Fold<I: Interner, TI = I> {
    type Result;
}

struct Ty<I: Interner> {}
impl<I: Interner, TI: Interner> Fold<I, TI> for Ty<I> {
    type Result = Ty<TI>;
}

fn fold<I: Interner, T>(interner: &I, t: T) -> T::Result
where
    T: Fold<I, I>,
{
    loop {}
}

fn foo<I: Interner>(interner: &I, t: Ty<I>) {
    fold(interner, t)<|>;
}
"#,
    );
    assert_eq!(t, "Ty<I>");
}

#[test]
fn trait_impl_self_ty() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait<T> {
   fn foo(&self);
}

struct S;

impl Trait<Self> for S {}

fn test() {
    S.foo()<|>;
}
"#,
    );
    assert_eq!(t, "()");
}

#[test]
fn trait_impl_self_ty_cycle() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait {
   fn foo(&self);
}

struct S<T>;

impl Trait for S<Self> {}

fn test() {
    S.foo()<|>;
}
"#,
    );
    assert_eq!(t, "{unknown}");
}

#[test]
fn unselected_projection_in_trait_env_cycle_1() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait {
    type Item;
}

trait Trait2<T> {}

fn test<T: Trait>() where T: Trait2<T::Item> {
    let x: T::Item = no_matter<|>;
}
"#,
    );
    // this is a legitimate cycle
    assert_eq!(t, "{unknown}");
}

#[test]
fn unselected_projection_in_trait_env_cycle_2() {
    let t = type_at(
        r#"
//- /main.rs
trait Trait<T> {
    type Item;
}

fn test<T, U>() where T: Trait<U::Item>, U: Trait<T::Item> {
    let x: T::Item = no_matter<|>;
}
"#,
    );
    // this is a legitimate cycle
    assert_eq!(t, "{unknown}");
}

#[test]
fn inline_assoc_type_bounds_1() {
    let t = type_at(
        r#"
//- /main.rs
trait Iterator {
    type Item;
}
trait OtherTrait<T> {
    fn foo(&self) -> T;
}

// workaround for Chalk assoc type normalization problems
pub struct S<T>;
impl<T: Iterator> Iterator for S<T> {
    type Item = <T as Iterator>::Item;
}

fn test<I: Iterator<Item: OtherTrait<u32>>>() {
    let x: <S<I> as Iterator>::Item;
    x.foo()<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn inline_assoc_type_bounds_2() {
    let t = type_at(
        r#"
//- /main.rs
trait Iterator {
    type Item;
}

fn test<I: Iterator<Item: Iterator<Item = u32>>>() {
    let x: <<I as Iterator>::Item as Iterator>::Item;
    x<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn proc_macro_server_types() {
    assert_snapshot!(
        infer(r#"
macro_rules! with_api {
    ($S:ident, $self:ident, $m:ident) => {
        $m! {
            TokenStream {
                fn new() -> $S::TokenStream;
            },
            Group {
            },
        }
    };
}
macro_rules! associated_item {
    (type TokenStream) =>
        (type TokenStream: 'static;);
    (type Group) =>
        (type Group: 'static;);
    ($($item:tt)*) => ($($item)*;)
}
macro_rules! declare_server_traits {
    ($($name:ident {
        $(fn $method:ident($($arg:ident: $arg_ty:ty),* $(,)?) $(-> $ret_ty:ty)?;)*
    }),* $(,)?) => {
        pub trait Types {
            $(associated_item!(type $name);)*
        }

        $(pub trait $name: Types {
            $(associated_item!(fn $method($($arg: $arg_ty),*) $(-> $ret_ty)?);)*
        })*

        pub trait Server: Types $(+ $name)* {}
        impl<S: Types $(+ $name)*> Server for S {}
    }
}

with_api!(Self, self_, declare_server_traits);
struct G {}
struct T {}
struct Rustc;
impl Types for Rustc {
    type TokenStream = T;
    type Group = G;
}

fn make<T>() -> T { loop {} }
impl TokenStream for Rustc {
    fn new() -> Self::TokenStream {
        let group: Self::Group = make();
        make()
    }
}
"#),
        @r###"
    1061..1072 '{ loop {} }': T
    1063..1070 'loop {}': !
    1068..1070 '{}': ()
    1136..1199 '{     ...     }': T
    1150..1155 'group': G
    1171..1175 'make': fn make<G>() -> G
    1171..1177 'make()': G
    1187..1191 'make': fn make<T>() -> T
    1187..1193 'make()': T
    "###
    );
}

#[test]
fn unify_impl_trait() {
    assert_snapshot!(
        infer_with_mismatches(r#"
trait Trait<T> {}

fn foo(x: impl Trait<u32>) { loop {} }
fn bar<T>(x: impl Trait<T>) -> T { loop {} }

struct S<T>(T);
impl<T> Trait<T> for S<T> {}

fn default<T>() -> T { loop {} }

fn test() -> impl Trait<i32> {
    let s1 = S(default());
    foo(s1);
    let x: i32 = bar(S(default()));
    S(default())
}
"#, true),
        @r###"
    26..27 'x': impl Trait<u32>
    46..57 '{ loop {} }': ()
    48..55 'loop {}': !
    53..55 '{}': ()
    68..69 'x': impl Trait<T>
    91..102 '{ loop {} }': T
    93..100 'loop {}': !
    98..100 '{}': ()
    171..182 '{ loop {} }': T
    173..180 'loop {}': !
    178..180 '{}': ()
    213..309 '{     ...t()) }': S<{unknown}>
    223..225 's1': S<u32>
    228..229 'S': S<u32>(u32) -> S<u32>
    228..240 'S(default())': S<u32>
    230..237 'default': fn default<u32>() -> u32
    230..239 'default()': u32
    246..249 'foo': fn foo(S<u32>)
    246..253 'foo(s1)': ()
    250..252 's1': S<u32>
    263..264 'x': i32
    272..275 'bar': fn bar<i32>(S<i32>) -> i32
    272..289 'bar(S(...lt()))': i32
    276..277 'S': S<i32>(i32) -> S<i32>
    276..288 'S(default())': S<i32>
    278..285 'default': fn default<i32>() -> i32
    278..287 'default()': i32
    295..296 'S': S<{unknown}>({unknown}) -> S<{unknown}>
    295..307 'S(default())': S<{unknown}>
    297..304 'default': fn default<{unknown}>() -> {unknown}
    297..306 'default()': {unknown}
    "###
    );
}

#[test]
fn assoc_types_from_bounds() {
    assert_snapshot!(
        infer(r#"
//- /main.rs
#[lang = "fn_once"]
trait FnOnce<Args> {
    type Output;
}

trait T {
    type O;
}

impl T for () {
    type O = ();
}

fn f<X, F>(_v: F)
where
    X: T,
    F: FnOnce(&X::O),
{ }

fn main() {
    f::<(), _>(|z| { z; });
}
"#),
        @r###"
    133..135 '_v': F
    178..181 '{ }': ()
    193..224 '{     ... }); }': ()
    199..209 'f::<(), _>': fn f<(), |&()| -> ()>(|&()| -> ())
    199..221 'f::<()... z; })': ()
    210..220 '|z| { z; }': |&()| -> ()
    211..212 'z': &()
    214..220 '{ z; }': ()
    216..217 'z': &()
    "###
    );
}

#[test]
fn associated_type_bound() {
    let t = type_at(
        r#"
//- /main.rs
pub trait Trait {
    type Item: OtherTrait<u32>;
}
pub trait OtherTrait<T> {
    fn foo(&self) -> T;
}

// this is just a workaround for chalk#234
pub struct S<T>;
impl<T: Trait> Trait for S<T> {
    type Item = <T as Trait>::Item;
}

fn test<T: Trait>() {
    let y: <S<T> as Trait>::Item = no_matter;
    y.foo()<|>;
}
"#,
    );
    assert_eq!(t, "u32");
}

#[test]
fn dyn_trait_through_chalk() {
    let t = type_at(
        r#"
//- /main.rs
struct Box<T> {}
#[lang = "deref"]
trait Deref {
    type Target;
}
impl<T> Deref for Box<T> {
    type Target = T;
}
trait Trait {
    fn foo(&self);
}

fn test(x: Box<dyn Trait>) {
    x.foo()<|>;
}
"#,
    );
    assert_eq!(t, "()");
}

#[test]
fn string_to_owned() {
    let t = type_at(
        r#"
//- /main.rs
struct String {}
pub trait ToOwned {
    type Owned;
    fn to_owned(&self) -> Self::Owned;
}
impl ToOwned for str {
    type Owned = String;
}
fn test() {
    "foo".to_owned()<|>;
}
"#,
    );
    assert_eq!(t, "String");
}

#[test]
fn iterator_chain() {
    assert_snapshot!(
        infer(r#"
//- /main.rs
#[lang = "fn_once"]
trait FnOnce<Args> {
    type Output;
}
#[lang = "fn_mut"]
trait FnMut<Args>: FnOnce<Args> { }

enum Option<T> { Some(T), None }
use Option::*;

pub trait Iterator {
    type Item;

    fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F>
    where
        F: FnMut(Self::Item) -> Option<B>,
    { loop {} }

    fn for_each<F>(self, f: F)
    where
        F: FnMut(Self::Item),
    { loop {} }
}

pub trait IntoIterator {
    type Item;
    type IntoIter: Iterator<Item = Self::Item>;
    fn into_iter(self) -> Self::IntoIter;
}

pub struct FilterMap<I, F> { }
impl<B, I: Iterator, F> Iterator for FilterMap<I, F>
where
    F: FnMut(I::Item) -> Option<B>,
{
    type Item = B;
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<I: Iterator> IntoIterator for I {
    type Item = I::Item;
    type IntoIter = I;

    fn into_iter(self) -> I {
        self
    }
}

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

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

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

fn main() {
    Vec::<i32>::new().into_iter()
      .filter_map(|x| if x > 0 { Some(x as u32) } else { None })
      .for_each(|y| { y; });
}
"#),
        @r###"
    226..230 'self': Self
    232..233 'f': F
    317..328 '{ loop {} }': FilterMap<Self, F>
    319..326 'loop {}': !
    324..326 '{}': ()
    349..353 'self': Self
    355..356 'f': F
    405..416 '{ loop {} }': ()
    407..414 'loop {}': !
    412..414 '{}': ()
    525..529 'self': Self
    854..858 'self': I
    865..885 '{     ...     }': I
    875..879 'self': I
    944..955 '{ loop {} }': Vec<T>
    946..953 'loop {}': !
    951..953 '{}': ()
    1142..1273 '{     ... }); }': ()
    1148..1163 'Vec::<i32>::new': fn new<i32>() -> Vec<i32>
    1148..1165 'Vec::<...:new()': Vec<i32>
    1148..1177 'Vec::<...iter()': IntoIter<i32>
    1148..1242 'Vec::<...one })': FilterMap<IntoIter<i32>, |i32| -> Option<u32>>
    1148..1270 'Vec::<... y; })': ()
    1196..1241 '|x| if...None }': |i32| -> Option<u32>
    1197..1198 'x': i32
    1200..1241 'if x >...None }': Option<u32>
    1203..1204 'x': i32
    1203..1208 'x > 0': bool
    1207..1208 '0': i32
    1209..1227 '{ Some...u32) }': Option<u32>
    1211..1215 'Some': Some<u32>(u32) -> Option<u32>
    1211..1225 'Some(x as u32)': Option<u32>
    1216..1217 'x': i32
    1216..1224 'x as u32': u32
    1233..1241 '{ None }': Option<u32>
    1235..1239 'None': Option<u32>
    1259..1269 '|y| { y; }': |u32| -> ()
    1260..1261 'y': u32
    1263..1269 '{ y; }': ()
    1265..1266 'y': u32
    "###
    );
}

#[test]
fn nested_assoc() {
    let t = type_at(
        r#"
//- /main.rs
struct Bar;
struct Foo;

trait A {
    type OutputA;
}

impl A for Bar {
    type OutputA = Foo;
}

trait B {
    type Output;
    fn foo() -> Self::Output;
}

impl<T:A> B for T {
    type Output = T::OutputA;
    fn foo() -> Self::Output { loop {} }
}

fn main() {
    Bar::foo()<|>;
}
"#,
    );
    assert_eq!(t, "Foo");
}

#[test]
fn trait_object_no_coercion() {
    assert_snapshot!(
        infer_with_mismatches(r#"
trait Foo {}

fn foo(x: &dyn Foo) {}

fn test(x: &dyn Foo) {
    foo(x);
}
"#, true),
        @r###"
    21..22 'x': &dyn Foo
    34..36 '{}': ()
    46..47 'x': &dyn Foo
    59..74 '{     foo(x); }': ()
    65..68 'foo': fn foo(&dyn Foo)
    65..71 'foo(x)': ()
    69..70 'x': &dyn Foo
    "###
    );
}

#[test]
fn builtin_copy() {
    assert_snapshot!(
        infer_with_mismatches(r#"
#[lang = "copy"]
trait Copy {}

struct IsCopy;
impl Copy for IsCopy {}
struct NotCopy;

trait Test { fn test(&self) -> bool; }
impl<T: Copy> Test for T {}

fn test() {
    IsCopy.test();
    NotCopy.test();
    (IsCopy, IsCopy).test();
    (IsCopy, NotCopy).test();
}
"#, true),
        @r###"
    110..114 'self': &Self
    166..267 '{     ...t(); }': ()
    172..178 'IsCopy': IsCopy
    172..185 'IsCopy.test()': bool
    191..198 'NotCopy': NotCopy
    191..205 'NotCopy.test()': {unknown}
    211..227 '(IsCop...sCopy)': (IsCopy, IsCopy)
    211..234 '(IsCop...test()': bool
    212..218 'IsCopy': IsCopy
    220..226 'IsCopy': IsCopy
    240..257 '(IsCop...tCopy)': (IsCopy, NotCopy)
    240..264 '(IsCop...test()': {unknown}
    241..247 'IsCopy': IsCopy
    249..256 'NotCopy': NotCopy
    "###
    );
}

#[test]
fn builtin_fn_def_copy() {
    assert_snapshot!(
        infer_with_mismatches(r#"
#[lang = "copy"]
trait Copy {}

fn foo() {}
fn bar<T: Copy>(T) -> T {}
struct Struct(usize);
enum Enum { Variant(usize) }

trait Test { fn test(&self) -> bool; }
impl<T: Copy> Test for T {}

fn test() {
    foo.test();
    bar.test();
    Struct.test();
    Enum::Variant.test();
}
"#, true),
        @r###"
    41..43 '{}': ()
    60..61 'T': {unknown}
    68..70 '{}': ()
    68..70: expected T, got ()
    145..149 'self': &Self
    201..281 '{     ...t(); }': ()
    207..210 'foo': fn foo()
    207..217 'foo.test()': bool
    223..226 'bar': fn bar<{unknown}>({unknown}) -> {unknown}
    223..233 'bar.test()': bool
    239..245 'Struct': Struct(usize) -> Struct
    239..252 'Struct.test()': bool
    258..271 'Enum::Variant': Variant(usize) -> Enum
    258..278 'Enum::...test()': bool
    "###
    );
}

#[test]
fn builtin_fn_ptr_copy() {
    assert_snapshot!(
        infer_with_mismatches(r#"
#[lang = "copy"]
trait Copy {}

trait Test { fn test(&self) -> bool; }
impl<T: Copy> Test for T {}

fn test(f1: fn(), f2: fn(usize) -> u8, f3: fn(u8, u8) -> &u8) {
    f1.test();
    f2.test();
    f3.test();
}
"#, true),
        @r###"
    54..58 'self': &Self
    108..110 'f1': fn()
    118..120 'f2': fn(usize) -> u8
    139..141 'f3': fn(u8, u8) -> &u8
    162..210 '{     ...t(); }': ()
    168..170 'f1': fn()
    168..177 'f1.test()': bool
    183..185 'f2': fn(usize) -> u8
    183..192 'f2.test()': bool
    198..200 'f3': fn(u8, u8) -> &u8
    198..207 'f3.test()': bool
    "###
    );
}

#[test]
fn builtin_sized() {
    assert_snapshot!(
        infer_with_mismatches(r#"
#[lang = "sized"]
trait Sized {}

trait Test { fn test(&self) -> bool; }
impl<T: Sized> Test for T {}

fn test() {
    1u8.test();
    (*"foo").test(); // not Sized
    (1u8, 1u8).test();
    (1u8, *"foo").test(); // not Sized
}
"#, true),
        @r###"
    56..60 'self': &Self
    113..228 '{     ...ized }': ()
    119..122 '1u8': u8
    119..129 '1u8.test()': bool
    135..150 '(*"foo").test()': {unknown}
    136..142 '*"foo"': str
    137..142 '"foo"': &str
    169..179 '(1u8, 1u8)': (u8, u8)
    169..186 '(1u8, ...test()': bool
    170..173 '1u8': u8
    175..178 '1u8': u8
    192..205 '(1u8, *"foo")': (u8, str)
    192..212 '(1u8, ...test()': {unknown}
    193..196 '1u8': u8
    198..204 '*"foo"': str
    199..204 '"foo"': &str
    "###
    );
}

#[test]
fn integer_range_iterate() {
    let t = type_at(
        r#"
//- /main.rs crate:main deps:core
fn test() {
    for x in 0..100 { x<|>; }
}

//- /core.rs crate:core
pub mod ops {
    pub struct Range<Idx> {
        pub start: Idx,
        pub end: Idx,
    }
}

pub mod iter {
    pub trait Iterator {
        type Item;
    }

    pub trait IntoIterator {
        type Item;
        type IntoIter: Iterator<Item = Self::Item>;
    }

    impl<T> IntoIterator for T where T: Iterator {
        type Item = <T as Iterator>::Item;
        type IntoIter = Self;
    }
}

trait Step {}
impl Step for i32 {}
impl Step for i64 {}

impl<A: Step> iter::Iterator for ops::Range<A> {
    type Item = A;
}
"#,
    );
    assert_eq!(t, "i32");
}

#[test]
fn infer_closure_arg() {
    assert_snapshot!(
        infer(
            r#"
            //- /lib.rs

            enum Option<T> {
                None,
                Some(T)
            }

            fn foo() {
                let s = Option::None;
                let f = |x: Option<i32>| {};
                (&f)(s)
            }
        "#
        ),
        @r###"
    52..126 '{     ...)(s) }': ()
    62..63 's': Option<i32>
    66..78 'Option::None': Option<i32>
    88..89 'f': |Option<i32>| -> ()
    92..111 '|x: Op...2>| {}': |Option<i32>| -> ()
    93..94 'x': Option<i32>
    109..111 '{}': ()
    117..124 '(&f)(s)': ()
    118..120 '&f': &|Option<i32>| -> ()
    119..120 'f': |Option<i32>| -> ()
    122..123 's': Option<i32>
    "###
    );
}

#[test]
fn infer_fn_trait_arg() {
    assert_snapshot!(
        infer(
            r#"
            //- /lib.rs deps:std

            #[lang = "fn_once"]
            pub trait FnOnce<Args> {
                type Output;

                extern "rust-call" fn call_once(&self, args: Args) -> Self::Output;
            }

            #[lang = "fn"]
            pub trait Fn<Args>:FnOnce<Args> {
                extern "rust-call" fn call(&self, args: Args) -> Self::Output;
            }

            enum Option<T> {
                None,
                Some(T)
            }

            fn foo<F, T>(f: F) -> T
            where
                F: Fn(Option<i32>) -> T,
            {
                let s = None;
                f(s)
            }
        "#
        ),
        @r###"
    101..105 'self': &Self
    107..111 'args': Args
    220..224 'self': &Self
    226..230 'args': Args
    313..314 'f': F
    359..389 '{     ...f(s) }': T
    369..370 's': Option<i32>
    373..377 'None': Option<i32>
    383..384 'f': F
    383..387 'f(s)': T
    385..386 's': Option<i32>
    "###
    );
}

#[test]
fn infer_box_fn_arg() {
    assert_snapshot!(
        infer(
            r#"
            //- /lib.rs deps:std

            #[lang = "fn_once"]
            pub trait FnOnce<Args> {
                type Output;

                extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
            }

            #[lang = "deref"]
            pub trait Deref {
                type Target: ?Sized;

                fn deref(&self) -> &Self::Target;
            }

            #[lang = "owned_box"]
            pub struct Box<T: ?Sized> {
                inner: *mut T,
            }

            impl<T: ?Sized> Deref for Box<T> {
                type Target = T;

                fn deref(&self) -> &T {
                    &self.inner
                }
            }

            enum Option<T> {
                None,
                Some(T)
            }

            fn foo() {
                let s = Option::None;
                let f: Box<dyn FnOnce(&Option<i32>)> = box (|ps| {});
                f(&s)
            }
        "#
        ),
        @r###"
    100..104 'self': Self
    106..110 'args': Args
    214..218 'self': &Self
    384..388 'self': &Box<T>
    396..423 '{     ...     }': &T
    406..417 '&self.inner': &*mut T
    407..411 'self': &Box<T>
    407..417 'self.inner': *mut T
    478..575 '{     ...(&s) }': FnOnce::Output<dyn FnOnce<(&Option<i32>,)>, (&Option<i32>,)>
    488..489 's': Option<i32>
    492..504 'Option::None': Option<i32>
    514..515 'f': Box<dyn FnOnce<(&Option<i32>,)>>
    549..562 'box (|ps| {})': Box<|{unknown}| -> ()>
    554..561 '|ps| {}': |{unknown}| -> ()
    555..557 'ps': {unknown}
    559..561 '{}': ()
    568..569 'f': Box<dyn FnOnce<(&Option<i32>,)>>
    568..573 'f(&s)': FnOnce::Output<dyn FnOnce<(&Option<i32>,)>, (&Option<i32>,)>
    570..572 '&s': &Option<i32>
    571..572 's': Option<i32>
    "###
    );
}

#[test]
fn infer_dyn_fn_output() {
    assert_snapshot!(
        infer(
            r#"
            //- /lib.rs deps:std

            #[lang = "fn_once"]
            pub trait FnOnce<Args> {
                type Output;

                extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
            }

            #[lang = "fn"]
            pub trait Fn<Args>:FnOnce<Args> {
                extern "rust-call" fn call(&self, args: Args) -> Self::Output;
            }

            #[lang = "deref"]
            pub trait Deref {
                type Target: ?Sized;

                fn deref(&self) -> &Self::Target;
            }

            #[lang = "owned_box"]
            pub struct Box<T: ?Sized> {
                inner: *mut T,
            }

            impl<T: ?Sized> Deref for Box<T> {
                type Target = T;

                fn deref(&self) -> &T {
                    &self.inner
                }
            }

            fn foo() {
                let f: Box<dyn Fn() -> i32> = box(|| 5);
                let x = f();
            }
        "#
        ),
        @r###"
    100..104 'self': Self
    106..110 'args': Args
    219..223 'self': &Self
    225..229 'args': Args
    333..337 'self': &Self
    503..507 'self': &Box<T>
    515..542 '{     ...     }': &T
    525..536 '&self.inner': &*mut T
    526..530 'self': &Box<T>
    526..536 'self.inner': *mut T
    555..620 '{     ...f(); }': ()
    565..566 'f': Box<dyn Fn<(), Output = i32>>
    591..600 'box(|| 5)': Box<|| -> i32>
    595..599 '|| 5': || -> i32
    598..599 '5': i32
    610..611 'x': FnOnce::Output<dyn Fn<(), Output = i32>, ()>
    614..615 'f': Box<dyn Fn<(), Output = i32>>
    614..617 'f()': FnOnce::Output<dyn Fn<(), Output = i32>, ()>
    "###
    );
}