mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-23 15:23:46 +00:00
76 lines
3.1 KiB
Rust
76 lines
3.1 KiB
Rust
//@ run-pass
|
|
#![feature(generic_nonzero)]
|
|
#![feature(transparent_unions)]
|
|
|
|
use std::mem::size_of;
|
|
use std::num::NonZero;
|
|
use std::ptr::NonNull;
|
|
use std::rc::Rc;
|
|
use std::sync::Arc;
|
|
|
|
trait Trait { fn dummy(&self) { } } //~ WARN method `dummy` is never used
|
|
trait Mirror { type Image; }
|
|
impl<T> Mirror for T { type Image = T; }
|
|
struct ParamTypeStruct<T>(#[allow(dead_code)] T);
|
|
struct AssocTypeStruct<T>(#[allow(dead_code)] <T as Mirror>::Image);
|
|
#[repr(transparent)]
|
|
union MaybeUninitUnion<T: Copy> {
|
|
_value: T,
|
|
_uninit: (),
|
|
}
|
|
|
|
fn main() {
|
|
// Functions
|
|
assert_eq!(size_of::<fn(isize)>(), size_of::<Option<fn(isize)>>());
|
|
assert_eq!(size_of::<extern "C" fn(isize)>(), size_of::<Option<extern "C" fn(isize)>>());
|
|
|
|
// Slices - &str / &[T] / &mut [T]
|
|
assert_eq!(size_of::<&str>(), size_of::<Option<&str>>());
|
|
assert_eq!(size_of::<&[isize]>(), size_of::<Option<&[isize]>>());
|
|
assert_eq!(size_of::<&mut [isize]>(), size_of::<Option<&mut [isize]>>());
|
|
|
|
// Traits - Box<Trait> / &Trait / &mut Trait
|
|
assert_eq!(size_of::<Box<dyn Trait>>(), size_of::<Option<Box<dyn Trait>>>());
|
|
assert_eq!(size_of::<&dyn Trait>(), size_of::<Option<&dyn Trait>>());
|
|
assert_eq!(size_of::<&mut dyn Trait>(), size_of::<Option<&mut dyn Trait>>());
|
|
|
|
// Pointers - Box<T>
|
|
assert_eq!(size_of::<Box<isize>>(), size_of::<Option<Box<isize>>>());
|
|
|
|
// The optimization can't apply to raw pointers or unions with a ZST field.
|
|
assert!(size_of::<Option<*const isize>>() != size_of::<*const isize>());
|
|
assert!(Some(std::ptr::null::<isize>()).is_some()); // Can't collapse None to null
|
|
assert_ne!(size_of::<fn(isize)>(), size_of::<Option<MaybeUninitUnion<fn(isize)>>>());
|
|
assert_ne!(size_of::<&str>(), size_of::<Option<MaybeUninitUnion<&str>>>());
|
|
assert_ne!(size_of::<NonNull<isize>>(), size_of::<Option<MaybeUninitUnion<NonNull<isize>>>>());
|
|
|
|
struct Foo {
|
|
_a: Box<isize>
|
|
}
|
|
struct Bar(#[allow(dead_code)] Box<isize>);
|
|
|
|
// Should apply through structs
|
|
assert_eq!(size_of::<Foo>(), size_of::<Option<Foo>>());
|
|
assert_eq!(size_of::<Bar>(), size_of::<Option<Bar>>());
|
|
// and tuples
|
|
assert_eq!(size_of::<(u8, Box<isize>)>(), size_of::<Option<(u8, Box<isize>)>>());
|
|
// and fixed-size arrays
|
|
assert_eq!(size_of::<[Box<isize>; 1]>(), size_of::<Option<[Box<isize>; 1]>>());
|
|
|
|
// Should apply to NonZero
|
|
assert_eq!(size_of::<NonZero<usize>>(), size_of::<Option<NonZero<usize>>>());
|
|
assert_eq!(size_of::<NonNull<i8>>(), size_of::<Option<NonNull<i8>>>());
|
|
|
|
// Should apply to types that use NonZero internally
|
|
assert_eq!(size_of::<Vec<isize>>(), size_of::<Option<Vec<isize>>>());
|
|
assert_eq!(size_of::<Arc<isize>>(), size_of::<Option<Arc<isize>>>());
|
|
assert_eq!(size_of::<Rc<isize>>(), size_of::<Option<Rc<isize>>>());
|
|
|
|
// Should apply to types that have NonZero transitively
|
|
assert_eq!(size_of::<String>(), size_of::<Option<String>>());
|
|
|
|
// Should apply to types where the pointer is substituted
|
|
assert_eq!(size_of::<&u8>(), size_of::<Option<ParamTypeStruct<&u8>>>());
|
|
assert_eq!(size_of::<&u8>(), size_of::<Option<AssocTypeStruct<&u8>>>());
|
|
}
|