path: root/crates/ra_hir_ty/src/tests/never_type.rs

use insta::assert_snapshot;

use super::{check_types, infer_with_mismatches};

#[test]
fn infer_never1() {
    check_types(
        r#"
fn test() {
    let t = return;
    t;
} //^ !
"#,
    );
}

#[test]
fn infer_never2() {
    check_types(
        r#"
fn gen<T>() -> T { loop {} }

fn test() {
    let a = gen();
    if false { a } else { loop {} };
    a;
} //^ !
"#,
    );
}

#[test]
fn infer_never3() {
    check_types(
        r#"
fn gen<T>() -> T { loop {} }

fn test() {
    let a = gen();
    if false { loop {} } else { a };
    a;
  //^ !
}
"#,
    );
}

#[test]
fn never_type_in_generic_args() {
    check_types(
        r#"
enum Option<T> { None, Some(T) }

fn test() {
    let a = if true { Option::None } else { Option::Some(return) };
    a;
} //^ Option<!>
"#,
    );
}

#[test]
fn never_type_can_be_reinferred1() {
    check_types(
        r#"
fn gen<T>() -> T { loop {} }

fn test() {
    let a = gen();
    if false { loop {} } else { a };
    a;
  //^ ()
    if false { a };
}
"#,
    );
}

#[test]
fn never_type_can_be_reinferred2() {
    check_types(
        r#"
enum Option<T> { None, Some(T) }

fn test() {
    let a = if true { Option::None } else { Option::Some(return) };
    a;
  //^ Option<i32>
    match 42 {
        42 => a,
        _ => Option::Some(42),
    };
}
"#,
    );
}

#[test]
fn never_type_can_be_reinferred3() {
    check_types(
        r#"
enum Option<T> { None, Some(T) }

fn test() {
    let a = if true { Option::None } else { Option::Some(return) };
    a;
  //^ Option<&str>
    match 42 {
        42 => a,
        _ => Option::Some("str"),
    };
}
"#,
    );
}

#[test]
fn match_no_arm() {
    check_types(
        r#"
enum Void {}

fn test(a: Void) {
    let t = match a {};
    t;
} //^ !
"#,
    );
}

#[test]
fn match_unknown_arm() {
    check_types(
        r#"
fn test(a: Option) {
    let t = match 0 {
        _ => unknown,
    };
    t;
} //^ {unknown}
"#,
    );
}

#[test]
fn if_never() {
    check_types(
        r#"
fn test() {
    let i = if true {
        loop {}
    } else {
        3.0
    };
    i;
} //^ f64
"#,
    );
}

#[test]
fn if_else_never() {
    check_types(
        r#"
fn test(input: bool) {
    let i = if input {
        2.0
    } else {
        return
    };
    i;
} //^ f64
"#,
    );
}

#[test]
fn match_first_arm_never() {
    check_types(
        r#"
fn test(a: i32) {
    let i = match a {
        1 => return,
        2 => 2.0,
        3 => loop {},
        _ => 3.0,
    };
    i;
} //^ f64
"#,
    );
}

#[test]
fn match_second_arm_never() {
    check_types(
        r#"
fn test(a: i32) {
    let i = match a {
        1 => 3.0,
        2 => loop {},
        3 => 3.0,
        _ => return,
    };
    i;
} //^ f64
"#,
    );
}

#[test]
fn match_all_arms_never() {
    check_types(
        r#"
fn test(a: i32) {
    let i = match a {
        2 => return,
        _ => loop {},
    };
    i;
} //^ !
"#,
    );
}

#[test]
fn match_no_never_arms() {
    check_types(
        r#"
fn test(a: i32) {
    let i = match a {
        2 => 2.0,
        _ => 3.0,
    };
    i;
} //^ f64
"#,
    );
}

#[test]
fn diverging_expression_1() {
    let t = infer_with_mismatches(
        r#"
//- /main.rs
fn test1() {
    let x: u32 = return;
}
fn test2() {
    let x: u32 = { return; };
}
fn test3() {
    let x: u32 = loop {};
}
fn test4() {
    let x: u32 = { loop {} };
}
fn test5() {
    let x: u32 = { if true { loop {}; } else { loop {}; } };
}
fn test6() {
    let x: u32 = { let y: u32 = { loop {}; }; };
}
"#,
        true,
    );
    assert_snapshot!(t, @r###"
    11..39 '{     ...urn; }': ()
    21..22 'x': u32
    30..36 'return': !
    51..84 '{     ...; }; }': ()
    61..62 'x': u32
    70..81 '{ return; }': u32
    72..78 'return': !
    96..125 '{     ... {}; }': ()
    106..107 'x': u32
    115..122 'loop {}': !
    120..122 '{}': ()
    137..170 '{     ...} }; }': ()
    147..148 'x': u32
    156..167 '{ loop {} }': u32
    158..165 'loop {}': !
    163..165 '{}': ()
    182..246 '{     ...} }; }': ()
    192..193 'x': u32
    201..243 '{ if t...}; } }': u32
    203..241 'if tru... {}; }': u32
    206..210 'true': bool
    211..223 '{ loop {}; }': u32
    213..220 'loop {}': !
    218..220 '{}': ()
    229..241 '{ loop {}; }': u32
    231..238 'loop {}': !
    236..238 '{}': ()
    258..310 '{     ...; }; }': ()
    268..269 'x': u32
    277..307 '{ let ...; }; }': u32
    283..284 'y': u32
    292..304 '{ loop {}; }': u32
    294..301 'loop {}': !
    299..301 '{}': ()
    "###);
}

#[test]
fn diverging_expression_2() {
    let t = infer_with_mismatches(
        r#"
//- /main.rs
fn test1() {
    // should give type mismatch
    let x: u32 = { loop {}; "foo" };
}
"#,
        true,
    );
    assert_snapshot!(t, @r###"
    11..84 '{     ..." }; }': ()
    54..55 'x': u32
    63..81 '{ loop...foo" }': &str
    65..72 'loop {}': !
    70..72 '{}': ()
    74..79 '"foo"': &str
    63..81: expected u32, got &str
    74..79: expected u32, got &str
    "###);
}

#[test]
fn diverging_expression_3_break() {
    let t = infer_with_mismatches(
        r#"
//- /main.rs
fn test1() {
    // should give type mismatch
    let x: u32 = { loop { break; } };
}
fn test2() {
    // should give type mismatch
    let x: u32 = { for a in b { break; }; };
    // should give type mismatch as well
    let x: u32 = { for a in b {}; };
    // should give type mismatch as well
    let x: u32 = { for a in b { return; }; };
}
fn test3() {
    // should give type mismatch
    let x: u32 = { while true { break; }; };
    // should give type mismatch as well -- there's an implicit break, even if it's never hit
    let x: u32 = { while true {}; };
    // should give type mismatch as well
    let x: u32 = { while true { return; }; };
}
"#,
        true,
    );
    assert_snapshot!(t, @r###"
    11..85 '{     ...} }; }': ()
    54..55 'x': u32
    63..82 '{ loop...k; } }': ()
    65..80 'loop { break; }': ()
    70..80 '{ break; }': ()
    72..77 'break': !
    63..82: expected u32, got ()
    65..80: expected u32, got ()
    97..343 '{     ...; }; }': ()
    140..141 'x': u32
    149..175 '{ for ...; }; }': ()
    151..172 'for a ...eak; }': ()
    155..156 'a': {unknown}
    160..161 'b': {unknown}
    162..172 '{ break; }': ()
    164..169 'break': !
    226..227 'x': u32
    235..253 '{ for ... {}; }': ()
    237..250 'for a in b {}': ()
    241..242 'a': {unknown}
    246..247 'b': {unknown}
    248..250 '{}': ()
    304..305 'x': u32
    313..340 '{ for ...; }; }': ()
    315..337 'for a ...urn; }': ()
    319..320 'a': {unknown}
    324..325 'b': {unknown}
    326..337 '{ return; }': ()
    328..334 'return': !
    149..175: expected u32, got ()
    235..253: expected u32, got ()
    313..340: expected u32, got ()
    355..654 '{     ...; }; }': ()
    398..399 'x': u32
    407..433 '{ whil...; }; }': ()
    409..430 'while ...eak; }': ()
    415..419 'true': bool
    420..430 '{ break; }': ()
    422..427 'break': !
    537..538 'x': u32
    546..564 '{ whil... {}; }': ()
    548..561 'while true {}': ()
    554..558 'true': bool
    559..561 '{}': ()
    615..616 'x': u32
    624..651 '{ whil...; }; }': ()
    626..648 'while ...urn; }': ()
    632..636 'true': bool
    637..648 '{ return; }': ()
    639..645 'return': !
    407..433: expected u32, got ()
    546..564: expected u32, got ()
    624..651: expected u32, got ()
    "###);
}