rust-analyzer/crates/ra_hir_ty/src/tests/coercion.rs

use super::infer_with_mismatches;
use insta::assert_snapshot;
use test_utils::covers;

// Infer with some common definitions and impls.
fn infer(source: &str) -> String {
    let defs = r#"
        #[lang = "sized"]
        pub trait Sized {}
        #[lang = "unsize"]
        pub trait Unsize<T: ?Sized> {}
        #[lang = "coerce_unsized"]
        pub trait CoerceUnsized<T> {}

        impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
        impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
    "#;

    // Append to the end to keep positions unchanged.
    super::infer(&format!("{}{}", source, defs))
}

#[test]
fn infer_block_expr_type_mismatch() {
    assert_snapshot!(
        infer(r#"
fn test() {
    let a: i32 = { 1i64 };
}
"#),
        @r###"
    11..41 '{     ...4 }; }': ()
    21..22 'a': i32
    30..38 '{ 1i64 }': i64
    32..36 '1i64': i64
    "###);
}

#[test]
fn coerce_places() {
    assert_snapshot!(
        infer(r#"
struct S<T> { a: T }

fn f<T>(_: &[T]) -> T { loop {} }
fn g<T>(_: S<&[T]>) -> T { loop {} }

fn gen<T>() -> *mut [T; 2] { loop {} }
fn test1<U>() -> *mut [U] {
    gen()
}

fn test2() {
    let arr: &[u8; 1] = &[1];

    let a: &[_] = arr;
    let b = f(arr);
    let c: &[_] = { arr };
    let d = g(S { a: arr });
    let e: [&[_]; 1] = [arr];
    let f: [&[_]; 2] = [arr; 2];
    let g: (&[_], &[_]) = (arr, arr);
}
"#),
        @r###"
    31..32 '_': &[T]
    45..56 '{ loop {} }': T
    47..54 'loop {}': !
    52..54 '{}': ()
    65..66 '_': S<&[T]>
    82..93 '{ loop {} }': T
    84..91 'loop {}': !
    89..91 '{}': ()
    122..133 '{ loop {} }': *mut [T; _]
    124..131 'loop {}': !
    129..131 '{}': ()
    160..173 '{     gen() }': *mut [U]
    166..169 'gen': fn gen<U>() -> *mut [U; _]
    166..171 'gen()': *mut [U; _]
    186..420 '{     ...rr); }': ()
    196..199 'arr': &[u8; _]
    212..216 '&[1]': &[u8; _]
    213..216 '[1]': [u8; _]
    214..215 '1': u8
    227..228 'a': &[u8]
    237..240 'arr': &[u8; _]
    250..251 'b': u8
    254..255 'f': fn f<u8>(&[u8]) -> u8
    254..260 'f(arr)': u8
    256..259 'arr': &[u8; _]
    270..271 'c': &[u8]
    280..287 '{ arr }': &[u8]
    282..285 'arr': &[u8; _]
    297..298 'd': u8
    301..302 'g': fn g<u8>(S<&[u8]>) -> u8
    301..316 'g(S { a: arr })': u8
    303..315 'S { a: arr }': S<&[u8]>
    310..313 'arr': &[u8; _]
    326..327 'e': [&[u8]; _]
    341..346 '[arr]': [&[u8]; _]
    342..345 'arr': &[u8; _]
    356..357 'f': [&[u8]; _]
    371..379 '[arr; 2]': [&[u8]; _]
    372..375 'arr': &[u8; _]
    377..378 '2': usize
    389..390 'g': (&[u8], &[u8])
    407..417 '(arr, arr)': (&[u8], &[u8])
    408..411 'arr': &[u8; _]
    413..416 'arr': &[u8; _]
    "###
    );
}

#[test]
fn infer_let_stmt_coerce() {
    assert_snapshot!(
        infer(r#"
fn test() {
    let x: &[i32] = &[1];
}
"#),
        @r###"
    11..40 '{     ...[1]; }': ()
    21..22 'x': &[i32]
    33..37 '&[1]': &[i32; _]
    34..37 '[1]': [i32; _]
    35..36 '1': i32
    "###);
}

#[test]
fn infer_custom_coerce_unsized() {
    assert_snapshot!(
        infer(r#"
struct A<T: ?Sized>(*const T);
struct B<T: ?Sized>(*const T);
struct C<T: ?Sized> { inner: *const T }

impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<B<U>> for B<T> {}
impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<C<U>> for C<T> {}

fn foo1<T>(x: A<[T]>) -> A<[T]> { x }
fn foo2<T>(x: B<[T]>) -> B<[T]> { x }
fn foo3<T>(x: C<[T]>) -> C<[T]> { x }

fn test(a: A<[u8; 2]>, b: B<[u8; 2]>, c: C<[u8; 2]>) {
    let d = foo1(a);
    let e = foo2(b);
    let f = foo3(c);
}
"#),
        @r###"
    258..259 'x': A<[T]>
    279..284 '{ x }': A<[T]>
    281..282 'x': A<[T]>
    296..297 'x': B<[T]>
    317..322 '{ x }': B<[T]>
    319..320 'x': B<[T]>
    334..335 'x': C<[T]>
    355..360 '{ x }': C<[T]>
    357..358 'x': C<[T]>
    370..371 'a': A<[u8; _]>
    385..386 'b': B<[u8; _]>
    400..401 'c': C<[u8; _]>
    415..481 '{     ...(c); }': ()
    425..426 'd': A<[{unknown}]>
    429..433 'foo1': fn foo1<{unknown}>(A<[{unknown}]>) -> A<[{unknown}]>
    429..436 'foo1(a)': A<[{unknown}]>
    434..435 'a': A<[u8; _]>
    446..447 'e': B<[u8]>
    450..454 'foo2': fn foo2<u8>(B<[u8]>) -> B<[u8]>
    450..457 'foo2(b)': B<[u8]>
    455..456 'b': B<[u8; _]>
    467..468 'f': C<[u8]>
    471..475 'foo3': fn foo3<u8>(C<[u8]>) -> C<[u8]>
    471..478 'foo3(c)': C<[u8]>
    476..477 'c': C<[u8; _]>
    "###
    );
}

#[test]
fn infer_if_coerce() {
    assert_snapshot!(
        infer(r#"
fn foo<T>(x: &[T]) -> &[T] { loop {} }
fn test() {
    let x = if true {
        foo(&[1])
    } else {
        &[1]
    };
}
"#),
        @r###"
    11..12 'x': &[T]
    28..39 '{ loop {} }': &[T]
    30..37 'loop {}': !
    35..37 '{}': ()
    50..126 '{     ...  }; }': ()
    60..61 'x': &[i32]
    64..123 'if tru...     }': &[i32]
    67..71 'true': bool
    72..97 '{     ...     }': &[i32]
    82..85 'foo': fn foo<i32>(&[i32]) -> &[i32]
    82..91 'foo(&[1])': &[i32]
    86..90 '&[1]': &[i32; _]
    87..90 '[1]': [i32; _]
    88..89 '1': i32
    103..123 '{     ...     }': &[i32; _]
    113..117 '&[1]': &[i32; _]
    114..117 '[1]': [i32; _]
    115..116 '1': i32
    "###
    );
}

#[test]
fn infer_if_else_coerce() {
    assert_snapshot!(
        infer(r#"
fn foo<T>(x: &[T]) -> &[T] { loop {} }
fn test() {
    let x = if true {
        &[1]
    } else {
        foo(&[1])
    };
}
"#),
        @r###"
    11..12 'x': &[T]
    28..39 '{ loop {} }': &[T]
    30..37 'loop {}': !
    35..37 '{}': ()
    50..126 '{     ...  }; }': ()
    60..61 'x': &[i32]
    64..123 'if tru...     }': &[i32]
    67..71 'true': bool
    72..92 '{     ...     }': &[i32; _]
    82..86 '&[1]': &[i32; _]
    83..86 '[1]': [i32; _]
    84..85 '1': i32
    98..123 '{     ...     }': &[i32]
    108..111 'foo': fn foo<i32>(&[i32]) -> &[i32]
    108..117 'foo(&[1])': &[i32]
    112..116 '&[1]': &[i32; _]
    113..116 '[1]': [i32; _]
    114..115 '1': i32
    "###
    );
}

#[test]
fn infer_match_first_coerce() {
    assert_snapshot!(
        infer(r#"
fn foo<T>(x: &[T]) -> &[T] { loop {} }
fn test(i: i32) {
    let x = match i {
        2 => foo(&[2]),
        1 => &[1],
        _ => &[3],
    };
}
"#),
        @r###"
    11..12 'x': &[T]
    28..39 '{ loop {} }': &[T]
    30..37 'loop {}': !
    35..37 '{}': ()
    48..49 'i': i32
    56..150 '{     ...  }; }': ()
    66..67 'x': &[i32]
    70..147 'match ...     }': &[i32]
    76..77 'i': i32
    88..89 '2': i32
    88..89 '2': i32
    93..96 'foo': fn foo<i32>(&[i32]) -> &[i32]
    93..102 'foo(&[2])': &[i32]
    97..101 '&[2]': &[i32; _]
    98..101 '[2]': [i32; _]
    99..100 '2': i32
    112..113 '1': i32
    112..113 '1': i32
    117..121 '&[1]': &[i32; _]
    118..121 '[1]': [i32; _]
    119..120 '1': i32
    131..132 '_': i32
    136..140 '&[3]': &[i32; _]
    137..140 '[3]': [i32; _]
    138..139 '3': i32
    "###
    );
}

#[test]
fn infer_match_second_coerce() {
    assert_snapshot!(
        infer(r#"
fn foo<T>(x: &[T]) -> &[T] { loop {} }
fn test(i: i32) {
    let x = match i {
        1 => &[1],
        2 => foo(&[2]),
        _ => &[3],
    };
}
"#),
        @r###"
    11..12 'x': &[T]
    28..39 '{ loop {} }': &[T]
    30..37 'loop {}': !
    35..37 '{}': ()
    48..49 'i': i32
    56..150 '{     ...  }; }': ()
    66..67 'x': &[i32]
    70..147 'match ...     }': &[i32]
    76..77 'i': i32
    88..89 '1': i32
    88..89 '1': i32
    93..97 '&[1]': &[i32; _]
    94..97 '[1]': [i32; _]
    95..96 '1': i32
    107..108 '2': i32
    107..108 '2': i32
    112..115 'foo': fn foo<i32>(&[i32]) -> &[i32]
    112..121 'foo(&[2])': &[i32]
    116..120 '&[2]': &[i32; _]
    117..120 '[2]': [i32; _]
    118..119 '2': i32
    131..132 '_': i32
    136..140 '&[3]': &[i32; _]
    137..140 '[3]': [i32; _]
    138..139 '3': i32
    "###
    );
}

#[test]
fn coerce_merge_one_by_one1() {
    covers!(coerce_merge_fail_fallback);

    assert_snapshot!(
        infer(r#"
fn test() {
    let t = &mut 1;
    let x = match 1 {
        1 => t as *mut i32,
        2 => t as &i32,
        _ => t as *const i32,
    };
}
"#),
        @r###"
    11..145 '{     ...  }; }': ()
    21..22 't': &mut i32
    25..31 '&mut 1': &mut i32
    30..31 '1': i32
    41..42 'x': *const i32
    45..142 'match ...     }': *const i32
    51..52 '1': i32
    63..64 '1': i32
    63..64 '1': i32
    68..69 't': &mut i32
    68..81 't as *mut i32': *mut i32
    91..92 '2': i32
    91..92 '2': i32
    96..97 't': &mut i32
    96..105 't as &i32': &i32
    115..116 '_': i32
    120..121 't': &mut i32
    120..135 't as *const i32': *const i32
    "###
    );
}

#[test]
fn return_coerce_unknown() {
    assert_snapshot!(
        infer_with_mismatches(r#"
fn foo() -> u32 {
    return unknown;
}
"#, true),
        @r###"
    17..40 '{     ...own; }': u32
    23..37 'return unknown': !
    30..37 'unknown': u32
    "###
    );
}

#[test]
fn coerce_autoderef() {
    assert_snapshot!(
        infer_with_mismatches(r#"
struct Foo;
fn takes_ref_foo(x: &Foo) {}
fn test() {
    takes_ref_foo(&Foo);
    takes_ref_foo(&&Foo);
    takes_ref_foo(&&&Foo);
}
"#, true),
        @r###"
    30..31 'x': &Foo
    39..41 '{}': ()
    52..133 '{     ...oo); }': ()
    58..71 'takes_ref_foo': fn takes_ref_foo(&Foo)
    58..77 'takes_...(&Foo)': ()
    72..76 '&Foo': &Foo
    73..76 'Foo': Foo
    83..96 'takes_ref_foo': fn takes_ref_foo(&Foo)
    83..103 'takes_...&&Foo)': ()
    97..102 '&&Foo': &&Foo
    98..102 '&Foo': &Foo
    99..102 'Foo': Foo
    109..122 'takes_ref_foo': fn takes_ref_foo(&Foo)
    109..130 'takes_...&&Foo)': ()
    123..129 '&&&Foo': &&&Foo
    124..129 '&&Foo': &&Foo
    125..129 '&Foo': &Foo
    126..129 'Foo': Foo
    "###
    );
}

#[test]
fn coerce_autoderef_generic() {
    assert_snapshot!(
        infer_with_mismatches(r#"
struct Foo;
fn takes_ref<T>(x: &T) -> T { *x }
fn test() {
    takes_ref(&Foo);
    takes_ref(&&Foo);
    takes_ref(&&&Foo);
}
"#, true),
        @r###"
    29..30 'x': &T
    41..47 '{ *x }': T
    43..45 '*x': T
    44..45 'x': &T
    58..127 '{     ...oo); }': ()
    64..73 'takes_ref': fn takes_ref<Foo>(&Foo) -> Foo
    64..79 'takes_ref(&Foo)': Foo
    74..78 '&Foo': &Foo
    75..78 'Foo': Foo
    85..94 'takes_ref': fn takes_ref<&Foo>(&&Foo) -> &Foo
    85..101 'takes_...&&Foo)': &Foo
    95..100 '&&Foo': &&Foo
    96..100 '&Foo': &Foo
    97..100 'Foo': Foo
    107..116 'takes_ref': fn takes_ref<&&Foo>(&&&Foo) -> &&Foo
    107..124 'takes_...&&Foo)': &&Foo
    117..123 '&&&Foo': &&&Foo
    118..123 '&&Foo': &&Foo
    119..123 '&Foo': &Foo
    120..123 'Foo': Foo
    "###
    );
}

#[test]
fn coerce_autoderef_block() {
    assert_snapshot!(
        infer_with_mismatches(r#"
struct String {}
#[lang = "deref"]
trait Deref { type Target; }
impl Deref for String { type Target = str; }
fn takes_ref_str(x: &str) {}
fn returns_string() -> String { loop {} }
fn test() {
    takes_ref_str(&{ returns_string() });
}
"#, true),
        @r###"
    127..128 'x': &str
    136..138 '{}': ()
    169..180 '{ loop {} }': String
    171..178 'loop {}': !
    176..178 '{}': ()
    191..236 '{     ... }); }': ()
    197..210 'takes_ref_str': fn takes_ref_str(&str)
    197..233 'takes_...g() })': ()
    211..232 '&{ ret...ng() }': &String
    212..232 '{ retu...ng() }': String
    214..228 'returns_string': fn returns_string() -> String
    214..230 'return...ring()': String
    "###
    );
}

#[test]
fn closure_return_coerce() {
    assert_snapshot!(
        infer_with_mismatches(r#"
fn foo() {
    let x = || {
        if true {
            return &1u32;
        }
        &&1u32
    };
}
"#, true),
        @r###"
    10..106 '{     ...  }; }': ()
    20..21 'x': || -> &u32
    24..103 '|| {  ...     }': || -> &u32
    27..103 '{     ...     }': &u32
    37..82 'if tru...     }': ()
    40..44 'true': bool
    45..82 '{     ...     }': ()
    59..71 'return &1u32': !
    66..71 '&1u32': &u32
    67..71 '1u32': u32
    91..97 '&&1u32': &&u32
    92..97 '&1u32': &u32
    93..97 '1u32': u32
    "###
    );
}

#[test]
fn coerce_fn_item_to_fn_ptr() {
    assert_snapshot!(
        infer_with_mismatches(r#"
fn foo(x: u32) -> isize { 1 }
fn test() {
    let f: fn(u32) -> isize = foo;
}
"#, true),
        @r###"
    8..9 'x': u32
    25..30 '{ 1 }': isize
    27..28 '1': isize
    41..79 '{     ...foo; }': ()
    51..52 'f': fn(u32) -> isize
    73..76 'foo': fn foo(u32) -> isize
    "###
    );
}

#[test]
fn coerce_closure_to_fn_ptr() {
    assert_snapshot!(
        infer_with_mismatches(r#"
fn test() {
    let f: fn(u32) -> isize = |x| { 1 };
}
"#, true),
        @r###"
    11..55 '{     ...1 }; }': ()
    21..22 'f': fn(u32) -> isize
    43..52 '|x| { 1 }': |u32| -> isize
    44..45 'x': u32
    47..52 '{ 1 }': isize
    49..50 '1': isize
    "###
    );
}

#[test]
fn coerce_placeholder_ref() {
    // placeholders should unify, even behind references
    assert_snapshot!(
        infer_with_mismatches(r#"
struct S<T> { t: T }
impl<TT> S<TT> {
    fn get(&self) -> &TT {
        &self.t
    }
}
"#, true),
        @r###"
    51..55 'self': &S<TT>
    64..87 '{     ...     }': &TT
    74..81 '&self.t': &TT
    75..79 'self': &S<TT>
    75..81 'self.t': TT
    "###
    );
}

#[test]
fn coerce_unsize_array() {
    assert_snapshot!(
        infer_with_mismatches(r#"
#[lang = "unsize"]
pub trait Unsize<T> {}
#[lang = "coerce_unsized"]
pub trait CoerceUnsized<T> {}

impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}

fn test() {
    let f: &[usize] = &[1, 2, 3];
}
"#, true),
        @r###"
    162..199 '{     ... 3]; }': ()
    172..173 'f': &[usize]
    186..196 '&[1, 2, 3]': &[usize; _]
    187..196 '[1, 2, 3]': [usize; _]
    188..189 '1': usize
    191..192 '2': usize
    194..195 '3': usize
    "###
    );
}

#[test]
fn coerce_unsize_trait_object() {
    assert_snapshot!(
        infer_with_mismatches(r#"
#[lang = "unsize"]
pub trait Unsize<T> {}
#[lang = "coerce_unsized"]
pub trait CoerceUnsized<T> {}

impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}

trait Foo<T, U> {}
trait Bar<U, T, X>: Foo<T, U> {}
trait Baz<T, X>: Bar<usize, T, X> {}

struct S<T, X>;
impl<T, X> Foo<T, usize> for S<T, X> {}
impl<T, X> Bar<usize, T, X> for S<T, X> {}
impl<T, X> Baz<T, X> for S<T, X> {}

fn test() {
    let obj: &dyn Baz<i8, i16> = &S;
    let obj: &dyn Bar<_, _, _> = obj;
    let obj: &dyn Foo<_, _> = obj;
    let obj2: &dyn Baz<i8, i16> = &S;
    let _: &dyn Foo<_, _> = obj2;
}
"#, true),
        @r###"
    388..573 '{     ...bj2; }': ()
    398..401 'obj': &dyn Baz<i8, i16>
    423..425 '&S': &S<i8, i16>
    424..425 'S': S<i8, i16>
    435..438 'obj': &dyn Bar<usize, i8, i16>
    460..463 'obj': &dyn Baz<i8, i16>
    473..476 'obj': &dyn Foo<i8, usize>
    495..498 'obj': &dyn Bar<usize, i8, i16>
    508..512 'obj2': &dyn Baz<i8, i16>
    534..536 '&S': &S<i8, i16>
    535..536 'S': S<i8, i16>
    546..547 '_': &dyn Foo<i8, usize>
    566..570 'obj2': &dyn Baz<i8, i16>
    "###
    );
}

#[test]
fn coerce_unsize_super_trait_cycle() {
    assert_snapshot!(
        infer_with_mismatches(r#"
#[lang = "unsize"]
pub trait Unsize<T> {}
#[lang = "coerce_unsized"]
pub trait CoerceUnsized<T> {}

impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}

trait A {}
trait B: C + A {}
trait C: B {}
trait D: C

struct S;
impl A for S {}
impl B for S {}
impl C for S {}
impl D for S {}

fn test() {
    let obj: &dyn D = &S;
    let obj: &dyn A = obj;
}
"#, true),
        @r###"
    292..348 '{     ...obj; }': ()
    302..305 'obj': &dyn D
    316..318 '&S': &S
    317..318 'S': S
    328..331 'obj': &dyn A
    342..345 'obj': &dyn D
    "###
    );
}

#[ignore]
#[test]
fn coerce_unsize_generic() {
    // FIXME: Implement this
    // https://doc.rust-lang.org/reference/type-coercions.html#unsized-coercions
    assert_snapshot!(
        infer_with_mismatches(r#"
#[lang = "unsize"]
pub trait Unsize<T> {}
#[lang = "coerce_unsized"]
pub trait CoerceUnsized<T> {}

impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}

struct Foo<T> { t: T };
struct Bar<T>(Foo<T>);

fn test() {
    let _: &Foo<[usize]> = &Foo { t: [1, 2, 3] };
    let _: &Bar<[usize]> = &Bar(Foo { t: [1, 2, 3] });
}
"#, true),
        @r###"
    "###
    );
}