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
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
use enumcapsulate::TryInto;
trait HasAssoc {
type Assoc: Sized;
}
pub struct VariantA;
pub struct VariantB;
pub struct VariantC<'l>(&'l i8);
pub struct VariantD<const N: usize>([i16; N]);
pub struct VariantE<T>(T);
pub struct VariantF<'l, const N: usize, T>(&'l [T; N]);
pub struct VariantT;
impl HasAssoc for VariantT {
type Assoc = i32;
}
pub struct VariantU;
trait HasT {
// This associated type intentionally has the same name
// as the generic type param of the enum subject.
//
// The point of this is to detect false positives
// from the generic param detection, which should falsely
// detect `VariantU::T` as a use of the type param `T`:
type T: Sized;
}
impl HasT for VariantU {
type T = i64;
}
#[derive(TryInto)]
pub enum Enum<'l, const N: usize, T>
where
T: HasAssoc,
{
Unit,
// We expect this variant to get derived:
OwnedSpecificType(VariantA),
// We expect this variant to get derived:
BorrowedSpecificType(&'l VariantB),
// We expect this variant to get derived:
OwnedWithGenericLifetime(VariantC<'l>),
// We expect this variant to NOT get derived (due to its use of a const param):
OwnedGenericTypeWithConstParam(VariantD<N>),
// We expect this variant to NOT get derived (due to its use of a type param):
OwnedGenericTypeWithTypeParam(VariantE<T>),
// We expect this variant to NOT get derived (due to its use of const and type params):
OwnedGenericTypeWithMixedParams(VariantF<'l, N, T>),
// We expect this variant to NOT get derived (due to its use of a type param):
OwnedGenericParam(T),
// We expect this variant to NOT get derived (due to its use of a type param):
BorrowedGenericParam(&'l T),
// We expect this variant to NOT get derived (due to its use of a type param):
OwnedAssocTypeOfGenericParam(T::Assoc),
// We expect this variant to NOT get derived (due to its use of a type param):
OwnedAssocTypeOfGenericParamBehindCast(<T as HasAssoc>::Assoc),
// We expect this variant to get derived:
OwnedAssocTypeOfSpecificTypeBehindCast(<VariantU as HasT>::T),
}
fn main() {
type Subject<'x> = Enum<'x, 42, VariantT>;
{
let subject = Subject::Unit;
let _: Result<VariantA, Subject<'_>> = subject.try_into();
}
{
let subject = Subject::Unit;
let _: Result<&'_ VariantB, Subject<'_>> = subject.try_into();
}
{
let subject = Subject::Unit;
let _: Result<VariantC<'_>, Subject<'_>> = subject.try_into();
}
{
let subject = Subject::Unit;
let _: Result<<VariantU as HasT>::T, Subject<'_>> = subject.try_into();
}
}