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
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
#![warn(clippy::transmute_undefined_repr)]
#![allow(clippy::unit_arg, clippy::transmute_ptr_to_ref, clippy::useless_transmute)]
use core::any::TypeId;
use core::ffi::c_void;
use core::mem::{size_of, transmute, MaybeUninit};
use core::ptr::NonNull;
fn value<T>() -> T {
unimplemented!()
}
struct Empty;
struct Ty<T>(T);
struct Ty2<T, U>(T, U);
#[repr(C)]
struct Ty2C<T, U>(T, U);
fn main() {
unsafe {
let _: () = transmute(value::<Empty>());
let _: Empty = transmute(value::<()>());
let _: Ty<u32> = transmute(value::<u32>());
let _: Ty<u32> = transmute(value::<u32>());
let _: Ty2C<u32, i32> = transmute(value::<Ty2<u32, i32>>()); // Lint, Ty2 is unordered
let _: Ty2<u32, i32> = transmute(value::<Ty2C<u32, i32>>()); // Lint, Ty2 is unordered
let _: Ty2<u32, i32> = transmute(value::<Ty<Ty2<u32, i32>>>()); // Ok, Ty2 types are the same
let _: Ty<Ty2<u32, i32>> = transmute(value::<Ty2<u32, i32>>()); // Ok, Ty2 types are the same
let _: Ty2<u32, f32> = transmute(value::<Ty<Ty2<u32, i32>>>()); // Lint, different Ty2 instances
let _: Ty<Ty2<u32, i32>> = transmute(value::<Ty2<u32, f32>>()); // Lint, different Ty2 instances
let _: Ty<&()> = transmute(value::<&()>());
let _: &() = transmute(value::<Ty<&()>>());
let _: &Ty2<u32, f32> = transmute(value::<Ty<&Ty2<u32, i32>>>()); // Lint, different Ty2 instances
let _: Ty<&Ty2<u32, i32>> = transmute(value::<&Ty2<u32, f32>>()); // Lint, different Ty2 instances
let _: Ty<usize> = transmute(value::<&Ty2<u32, i32>>()); // Ok, pointer to usize conversion
let _: &Ty2<u32, i32> = transmute(value::<Ty<usize>>()); // Ok, pointer to usize conversion
let _: Ty<[u8; 8]> = transmute(value::<Ty2<u32, i32>>()); // Ok, transmute to byte array
let _: Ty2<u32, i32> = transmute(value::<Ty<[u8; 8]>>()); // Ok, transmute from byte array
// issue #8417
let _: Ty2C<Ty2<u32, i32>, ()> = transmute(value::<Ty2<u32, i32>>()); // Ok, Ty2 types are the same
let _: Ty2<u32, i32> = transmute(value::<Ty2C<Ty2<u32, i32>, ()>>()); // Ok, Ty2 types are the same
let _: &'static mut Ty2<u32, u32> = transmute(value::<Box<Ty2<u32, u32>>>()); // Ok, Ty2 types are the same
let _: Box<Ty2<u32, u32>> = transmute(value::<&'static mut Ty2<u32, u32>>()); // Ok, Ty2 types are the same
let _: *mut Ty2<u32, u32> = transmute(value::<Box<Ty2<u32, u32>>>()); // Ok, Ty2 types are the same
let _: Box<Ty2<u32, u32>> = transmute(value::<*mut Ty2<u32, u32>>()); // Ok, Ty2 types are the same
let _: &'static mut Ty2<u32, f32> = transmute(value::<Box<Ty2<u32, u32>>>()); // Lint, different Ty2 instances
let _: Box<Ty2<u32, u32>> = transmute(value::<&'static mut Ty2<u32, f32>>()); // Lint, different Ty2 instances
let _: *const () = transmute(value::<Ty<&Ty2<u32, f32>>>()); // Ok, type erasure
let _: Ty<&Ty2<u32, f32>> = transmute(value::<*const ()>()); // Ok, reverse type erasure
let _: *const c_void = transmute(value::<Ty<&Ty2<u32, f32>>>()); // Ok, type erasure
let _: Ty<&Ty2<u32, f32>> = transmute(value::<*const c_void>()); // Ok, reverse type erasure
enum Erase {}
let _: *const Erase = transmute(value::<Ty<&Ty2<u32, f32>>>()); // Ok, type erasure
let _: Ty<&Ty2<u32, f32>> = transmute(value::<*const Erase>()); // Ok, reverse type erasure
struct Erase2(
[u8; 0],
core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
);
let _: *const Erase2 = transmute(value::<Ty<&Ty2<u32, f32>>>()); // Ok, type erasure
let _: Ty<&Ty2<u32, f32>> = transmute(value::<*const Erase2>()); // Ok, reverse type erasure
let _: *const () = transmute(value::<&&[u8]>()); // Ok, type erasure
let _: &&[u8] = transmute(value::<*const ()>()); // Ok, reverse type erasure
let _: *mut c_void = transmute(value::<&mut &[u8]>()); // Ok, type erasure
let _: &mut &[u8] = transmute(value::<*mut c_void>()); // Ok, reverse type erasure
let _: [u8; size_of::<&[u8]>()] = transmute(value::<&[u8]>()); // Ok, transmute to byte array
let _: &[u8] = transmute(value::<[u8; size_of::<&[u8]>()]>()); // Ok, transmute from byte array
let _: [usize; 2] = transmute(value::<&[u8]>()); // Ok, transmute to int array
let _: &[u8] = transmute(value::<[usize; 2]>()); // Ok, transmute from int array
let _: *const [u8] = transmute(value::<Box<[u8]>>()); // Ok
let _: Box<[u8]> = transmute(value::<*mut [u8]>()); // Ok
let _: Ty2<u32, u32> = transmute(value::<(Ty2<u32, u32>,)>()); // Ok
let _: (Ty2<u32, u32>,) = transmute(value::<Ty2<u32, u32>>()); // Ok
let _: Ty2<u32, u32> = transmute(value::<(Ty2<u32, u32>, ())>()); // Ok
let _: (Ty2<u32, u32>, ()) = transmute(value::<Ty2<u32, u32>>()); // Ok
let _: Ty2<u32, u32> = transmute(value::<((), Ty2<u32, u32>)>()); // Ok
let _: ((), Ty2<u32, u32>) = transmute(value::<Ty2<u32, u32>>()); // Ok
let _: (usize, usize) = transmute(value::<&[u8]>()); // Ok
let _: &[u8] = transmute(value::<(usize, usize)>()); // Ok
trait Trait {}
let _: (isize, isize) = transmute(value::<&dyn Trait>()); // Ok
let _: &dyn Trait = transmute(value::<(isize, isize)>()); // Ok
let _: MaybeUninit<Ty2<u32, u32>> = transmute(value::<Ty2<u32, u32>>()); // Ok
let _: Ty2<u32, u32> = transmute(value::<MaybeUninit<Ty2<u32, u32>>>()); // Ok
let _: Ty<&[u32]> = transmute::<&[u32], _>(value::<&Vec<u32>>()); // Ok
let _: *const Ty2<u32, u32> = transmute(value::<*const Ty2C<Ty2<u32, u32>, u32>>()); // Ok
let _: *const Ty2C<Ty2<u32, u32>, u32> = transmute(value::<*const Ty2<u32, u32>>()); // Ok
let _: *const Ty2<u32, u32> = transmute(value::<*const Ty2C<(), Ty2<u32, u32>>>()); // Ok
let _: *const Ty2C<(), Ty2<u32, u32>> = transmute(value::<*const Ty2<u32, u32>>()); // Ok
let _: *const Ty2<u32, u32> = transmute(value::<*const Ty2C<u32, Ty2<u32, u32>>>()); // Err
let _: *const Ty2C<u32, Ty2<u32, u32>> = transmute(value::<*const Ty2<u32, u32>>()); // Err
let _: NonNull<u8> = transmute(value::<NonNull<(String, String)>>()); // Ok
let _: NonNull<(String, String)> = transmute(value::<NonNull<u8>>()); // Ok
}
}
fn _with_generics<T: 'static, U: 'static>() {
if TypeId::of::<T>() != TypeId::of::<u32>() || TypeId::of::<T>() != TypeId::of::<U>() {
return;
}
unsafe {
let _: &u32 = transmute(value::<&T>()); // Ok
let _: &T = transmute(value::<&u32>()); // Ok
let _: Vec<U> = transmute(value::<Vec<T>>()); // Ok
let _: Vec<T> = transmute(value::<Vec<U>>()); // Ok
let _: Ty<&u32> = transmute(value::<&T>()); // Ok
let _: Ty<&T> = transmute(value::<&u32>()); // Ok
let _: Vec<u32> = transmute(value::<Vec<T>>()); // Ok
let _: Vec<T> = transmute(value::<Vec<u32>>()); // Ok
let _: &Ty2<u32, u32> = transmute(value::<&Ty2<T, U>>()); // Ok
let _: &Ty2<T, U> = transmute(value::<&Ty2<u32, u32>>()); // Ok
let _: Vec<Vec<u32>> = transmute(value::<Vec<Vec<T>>>()); // Ok
let _: Vec<Vec<T>> = transmute(value::<Vec<Vec<u32>>>()); // Ok
let _: Vec<Ty2<T, u32>> = transmute(value::<Vec<Ty2<U, i32>>>()); // Err
let _: Vec<Ty2<U, i32>> = transmute(value::<Vec<Ty2<T, u32>>>()); // Err
let _: *const u32 = transmute(value::<Box<T>>()); // Ok
let _: Box<T> = transmute(value::<*const u32>()); // Ok
}
}
|