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Commit | Line | Data |
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b7449926 | 1 | // run-pass |
dc9dc135 XL |
2 | #![feature(transparent_unions)] |
3 | ||
1a4d82fc | 4 | use std::mem::size_of; |
0531ce1d XL |
5 | use std::num::NonZeroUsize; |
6 | use std::ptr::NonNull; | |
1a4d82fc JJ |
7 | use std::rc::Rc; |
8 | use std::sync::Arc; | |
9 | ||
85aaf69f | 10 | trait Trait { fn dummy(&self) { } } |
e9174d1e SL |
11 | trait Mirror { type Image; } |
12 | impl<T> Mirror for T { type Image = T; } | |
064997fb FG |
13 | struct ParamTypeStruct<T>(#[allow(unused_tuple_struct_fields)] T); |
14 | struct AssocTypeStruct<T>(#[allow(unused_tuple_struct_fields)] <T as Mirror>::Image); | |
dc9dc135 XL |
15 | #[repr(transparent)] |
16 | union MaybeUninitUnion<T: Copy> { | |
17 | _value: T, | |
18 | _uninit: (), | |
19 | } | |
1a4d82fc JJ |
20 | |
21 | fn main() { | |
22 | // Functions | |
c34b1796 AL |
23 | assert_eq!(size_of::<fn(isize)>(), size_of::<Option<fn(isize)>>()); |
24 | assert_eq!(size_of::<extern "C" fn(isize)>(), size_of::<Option<extern "C" fn(isize)>>()); | |
1a4d82fc JJ |
25 | |
26 | // Slices - &str / &[T] / &mut [T] | |
27 | assert_eq!(size_of::<&str>(), size_of::<Option<&str>>()); | |
c34b1796 AL |
28 | assert_eq!(size_of::<&[isize]>(), size_of::<Option<&[isize]>>()); |
29 | assert_eq!(size_of::<&mut [isize]>(), size_of::<Option<&mut [isize]>>()); | |
1a4d82fc JJ |
30 | |
31 | // Traits - Box<Trait> / &Trait / &mut Trait | |
dc9dc135 XL |
32 | assert_eq!(size_of::<Box<dyn Trait>>(), size_of::<Option<Box<dyn Trait>>>()); |
33 | assert_eq!(size_of::<&dyn Trait>(), size_of::<Option<&dyn Trait>>()); | |
34 | assert_eq!(size_of::<&mut dyn Trait>(), size_of::<Option<&mut dyn Trait>>()); | |
1a4d82fc JJ |
35 | |
36 | // Pointers - Box<T> | |
c34b1796 | 37 | assert_eq!(size_of::<Box<isize>>(), size_of::<Option<Box<isize>>>()); |
1a4d82fc | 38 | |
dc9dc135 | 39 | // The optimization can't apply to raw pointers or unions with a ZST field. |
c34b1796 | 40 | assert!(size_of::<Option<*const isize>>() != size_of::<*const isize>()); |
dc9dc135 XL |
41 | assert!(Some(std::ptr::null::<isize>()).is_some()); // Can't collapse None to null |
42 | assert_ne!(size_of::<fn(isize)>(), size_of::<Option<MaybeUninitUnion<fn(isize)>>>()); | |
43 | assert_ne!(size_of::<&str>(), size_of::<Option<MaybeUninitUnion<&str>>>()); | |
44 | assert_ne!(size_of::<NonNull<isize>>(), size_of::<Option<MaybeUninitUnion<NonNull<isize>>>>()); | |
1a4d82fc JJ |
45 | |
46 | struct Foo { | |
c34b1796 | 47 | _a: Box<isize> |
1a4d82fc | 48 | } |
064997fb | 49 | struct Bar(#[allow(unused_tuple_struct_fields)] Box<isize>); |
1a4d82fc JJ |
50 | |
51 | // Should apply through structs | |
52 | assert_eq!(size_of::<Foo>(), size_of::<Option<Foo>>()); | |
53 | assert_eq!(size_of::<Bar>(), size_of::<Option<Bar>>()); | |
54 | // and tuples | |
c34b1796 | 55 | assert_eq!(size_of::<(u8, Box<isize>)>(), size_of::<Option<(u8, Box<isize>)>>()); |
1a4d82fc | 56 | // and fixed-size arrays |
c34b1796 | 57 | assert_eq!(size_of::<[Box<isize>; 1]>(), size_of::<Option<[Box<isize>; 1]>>()); |
1a4d82fc JJ |
58 | |
59 | // Should apply to NonZero | |
0531ce1d XL |
60 | assert_eq!(size_of::<NonZeroUsize>(), size_of::<Option<NonZeroUsize>>()); |
61 | assert_eq!(size_of::<NonNull<i8>>(), size_of::<Option<NonNull<i8>>>()); | |
1a4d82fc JJ |
62 | |
63 | // Should apply to types that use NonZero internally | |
c34b1796 AL |
64 | assert_eq!(size_of::<Vec<isize>>(), size_of::<Option<Vec<isize>>>()); |
65 | assert_eq!(size_of::<Arc<isize>>(), size_of::<Option<Arc<isize>>>()); | |
66 | assert_eq!(size_of::<Rc<isize>>(), size_of::<Option<Rc<isize>>>()); | |
1a4d82fc JJ |
67 | |
68 | // Should apply to types that have NonZero transitively | |
69 | assert_eq!(size_of::<String>(), size_of::<Option<String>>()); | |
70 | ||
e9174d1e SL |
71 | // Should apply to types where the pointer is substituted |
72 | assert_eq!(size_of::<&u8>(), size_of::<Option<ParamTypeStruct<&u8>>>()); | |
73 | assert_eq!(size_of::<&u8>(), size_of::<Option<AssocTypeStruct<&u8>>>()); | |
1a4d82fc | 74 | } |