1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
// run-pass
#![warn(indirect_structural_match)]
// This test is checking our logic for structural match checking by enumerating
// the different kinds of const expressions. This test is collecting cases where
// we have accepted the const expression as a pattern in the past and wish to
// continue doing so.
//
// Even if a non-structural-match type is part of an expression in a const's
// definition, that does not necessarily disqualify the const from being a match
// pattern: in principle, we just need the types involved in the final value to
// be structurally matchable.
// See also RFC 1445
#![feature(type_ascription)]
#[derive(Copy, Clone, Debug)]
struct NoPartialEq(u32);
#[derive(Copy, Clone, Debug)]
struct NoDerive(u32);
// This impl makes `NoDerive` irreflexive.
impl PartialEq for NoDerive { fn eq(&self, _: &Self) -> bool { false } }
impl Eq for NoDerive { }
type OND = Option<NoDerive>;
fn main() {
const FIELD1: u32 = NoPartialEq(1).0;
match 1 { FIELD1 => dbg!(FIELD1), _ => panic!("whoops"), };
const FIELD2: u32 = NoDerive(1).0;
match 1 { FIELD2 => dbg!(FIELD2), _ => panic!("whoops"), };
enum CLike { One = 1, #[allow(dead_code)] Two = 2, }
const ONE_CAST: u32 = CLike::One as u32;
match 1 { ONE_CAST => dbg!(ONE_CAST), _ => panic!("whoops"), };
const NO_DERIVE_NONE: OND = None;
const INDIRECT: OND = NO_DERIVE_NONE;
match None { INDIRECT => dbg!(INDIRECT), _ => panic!("whoops"), };
const TUPLE: (OND, OND) = (None, None);
match (None, None) { TUPLE => dbg!(TUPLE), _ => panic!("whoops"), };
const TYPE_ASCRIPTION: OND = type_ascribe!(None, OND);
match None { TYPE_ASCRIPTION => dbg!(TYPE_ASCRIPTION), _ => panic!("whoops"), };
const ARRAY: [OND; 2] = [None, None];
match [None; 2] { ARRAY => dbg!(ARRAY), _ => panic!("whoops"), };
const REPEAT: [OND; 2] = [None; 2];
match [None, None] { REPEAT => dbg!(REPEAT), _ => panic!("whoops"), };
trait Trait: Sized { const ASSOC: Option<Self>; }
impl Trait for NoDerive { const ASSOC: Option<NoDerive> = None; }
match None { NoDerive::ASSOC => dbg!(NoDerive::ASSOC), _ => panic!("whoops"), };
const BLOCK: OND = { NoDerive(10); None };
match None { BLOCK => dbg!(BLOCK), _ => panic!("whoops"), };
const ADDR_OF: &OND = &None;
match &None { ADDR_OF => dbg!(ADDR_OF), _ => panic!("whoops"), };
}
|
