rust/library/coretests/tests/mem.rs

use core::mem::*;
use core::{array, ptr};
use std::cell::Cell;
#[cfg(panic = "unwind")]
use std::rc::Rc;

#[test]
fn size_of_basic() {
    assert_eq!(size_of::<u8>(), 1);
    assert_eq!(size_of::<u16>(), 2);
    assert_eq!(size_of::<u32>(), 4);
    assert_eq!(size_of::<u64>(), 8);
}

#[test]
#[cfg(target_pointer_width = "16")]
fn size_of_16() {
    assert_eq!(size_of::<usize>(), 2);
    assert_eq!(size_of::<*const usize>(), 2);
}

#[test]
#[cfg(target_pointer_width = "32")]
fn size_of_32() {
    assert_eq!(size_of::<usize>(), 4);
    assert_eq!(size_of::<*const usize>(), 4);
}

#[test]
#[cfg(target_pointer_width = "64")]
fn size_of_64() {
    assert_eq!(size_of::<usize>(), 8);
    assert_eq!(size_of::<*const usize>(), 8);
}

#[test]
fn size_of_val_basic() {
    assert_eq!(size_of_val(&1u8), 1);
    assert_eq!(size_of_val(&1u16), 2);
    assert_eq!(size_of_val(&1u32), 4);
    assert_eq!(size_of_val(&1u64), 8);
}

#[test]
fn align_of_basic() {
    assert_eq!(align_of::<u8>(), 1);
    assert_eq!(align_of::<u16>(), 2);
    assert_eq!(align_of::<u32>(), 4);
}

#[test]
#[cfg(target_pointer_width = "16")]
fn align_of_16() {
    assert_eq!(align_of::<usize>(), 2);
    assert_eq!(align_of::<*const usize>(), 2);
}

#[test]
#[cfg(target_pointer_width = "32")]
fn align_of_32() {
    assert_eq!(align_of::<usize>(), 4);
    assert_eq!(align_of::<*const usize>(), 4);
}

#[test]
#[cfg(target_pointer_width = "64")]
fn align_of_64() {
    assert_eq!(align_of::<usize>(), 8);
    assert_eq!(align_of::<*const usize>(), 8);
}

#[test]
fn align_of_val_basic() {
    assert_eq!(align_of_val(&1u8), 1);
    assert_eq!(align_of_val(&1u16), 2);
    assert_eq!(align_of_val(&1u32), 4);
}

#[test]
fn align_of_val_raw_packed() {
    #[repr(C, packed)]
    struct B {
        f: [u32],
    }
    let storage = [0u8; 4];
    let b: *const B = ptr::from_raw_parts(storage.as_ptr(), 1);
    assert_eq!(unsafe { align_of_val_raw(b) }, 1);

    const ALIGN_OF_VAL_RAW: usize = {
        let storage = [0u8; 4];
        let b: *const B = ptr::from_raw_parts(storage.as_ptr(), 1);
        unsafe { align_of_val_raw(b) }
    };
    assert_eq!(ALIGN_OF_VAL_RAW, 1);
}

#[test]
fn test_swap() {
    let mut x = 31337;
    let mut y = 42;
    swap(&mut x, &mut y);
    assert_eq!(x, 42);
    assert_eq!(y, 31337);
}

#[test]
fn test_replace() {
    let mut x = Some("test".to_string());
    let y = replace(&mut x, None);
    assert!(x.is_none());
    assert!(y.is_some());
}

#[test]
fn test_transmute_copy() {
    assert_eq!(1, unsafe { transmute_copy(&1) });
}

#[test]
fn test_transmute_copy_shrink() {
    assert_eq!(0_u8, unsafe { transmute_copy(&0_u64) });
}

#[test]
fn test_transmute_copy_unaligned() {
    #[repr(C)]
    #[derive(Default)]
    struct Unaligned {
        a: u8,
        b: [u8; 8],
    }

    let u = Unaligned::default();
    assert_eq!(0_u64, unsafe { transmute_copy(&u.b) });
}

#[test]
#[cfg(panic = "unwind")]
fn test_transmute_copy_grow_panics() {
    use std::panic;

    let err = panic::catch_unwind(panic::AssertUnwindSafe(|| unsafe {
        let _unused: u64 = transmute_copy(&1_u8);
    }));

    match err {
        Ok(_) => unreachable!(),
        Err(payload) => {
            payload
                .downcast::<&'static str>()
                .and_then(|s| {
                    if *s == "cannot transmute_copy if Dst is larger than Src" {
                        Ok(s)
                    } else {
                        Err(s)
                    }
                })
                .unwrap_or_else(|p| panic::resume_unwind(p));
        }
    }
}

#[test]
#[allow(dead_code)]
fn test_discriminant_send_sync() {
    enum Regular {
        A,
        B(i32),
    }
    enum NotSendSync {
        A(*const i32),
    }

    fn is_send_sync<T: Send + Sync>() {}

    is_send_sync::<Discriminant<Regular>>();
    is_send_sync::<Discriminant<NotSendSync>>();
}

#[test]
fn assume_init_good() {
    const TRUE: bool = unsafe { MaybeUninit::<bool>::new(true).assume_init() };

    assert!(TRUE);
}

#[test]
fn uninit_array_assume_init() {
    let mut array = [MaybeUninit::<i16>::uninit(); 5];
    array[0].write(3);
    array[1].write(1);
    array[2].write(4);
    array[3].write(1);
    array[4].write(5);

    let array = unsafe { array.transpose().assume_init() };

    assert_eq!(array, [3, 1, 4, 1, 5]);

    let [] = unsafe { [MaybeUninit::<!>::uninit(); 0].transpose().assume_init() };
}

#[test]
fn uninit_write_copy_of_slice() {
    let mut dst = [MaybeUninit::new(255); 64];
    let src = [0; 64];

    assert_eq!(dst.write_copy_of_slice(&src), &src);
}

#[test]
#[should_panic(expected = "source slice length (32) does not match destination slice length (64)")]
fn uninit_write_copy_of_slice_panic_lt() {
    let mut dst = [MaybeUninit::uninit(); 64];
    let src = [0; 32];

    dst.write_copy_of_slice(&src);
}

#[test]
#[should_panic(expected = "source slice length (128) does not match destination slice length (64)")]
fn uninit_write_copy_of_slice_panic_gt() {
    let mut dst = [MaybeUninit::uninit(); 64];
    let src = [0; 128];

    dst.write_copy_of_slice(&src);
}

#[test]
fn uninit_write_clone_of_slice() {
    let mut dst = [MaybeUninit::new(255); 64];
    let src = [0; 64];

    assert_eq!(dst.write_clone_of_slice(&src), &src);
}

#[test]
#[should_panic(expected = "destination and source slices have different lengths")]
fn uninit_write_clone_of_slice_panic_lt() {
    let mut dst = [MaybeUninit::uninit(); 64];
    let src = [0; 32];

    dst.write_clone_of_slice(&src);
}

#[test]
#[should_panic(expected = "destination and source slices have different lengths")]
fn uninit_write_clone_of_slice_panic_gt() {
    let mut dst = [MaybeUninit::uninit(); 64];
    let src = [0; 128];

    dst.write_clone_of_slice(&src);
}

#[test]
#[cfg(panic = "unwind")]
fn uninit_write_clone_of_slice_mid_panic() {
    use std::panic;

    enum IncrementOrPanic {
        Increment(Rc<()>),
        ExpectedPanic,
        UnexpectedPanic,
    }

    impl Clone for IncrementOrPanic {
        fn clone(&self) -> Self {
            match self {
                Self::Increment(rc) => Self::Increment(rc.clone()),
                Self::ExpectedPanic => panic!("expected panic on clone"),
                Self::UnexpectedPanic => panic!("unexpected panic on clone"),
            }
        }
    }

    let rc = Rc::new(());

    let mut dst = [
        MaybeUninit::uninit(),
        MaybeUninit::uninit(),
        MaybeUninit::uninit(),
        MaybeUninit::uninit(),
    ];

    let src = [
        IncrementOrPanic::Increment(rc.clone()),
        IncrementOrPanic::Increment(rc.clone()),
        IncrementOrPanic::ExpectedPanic,
        IncrementOrPanic::UnexpectedPanic,
    ];

    let err = panic::catch_unwind(panic::AssertUnwindSafe(|| {
        dst.write_clone_of_slice(&src);
    }));

    drop(src);

    match err {
        Ok(_) => unreachable!(),
        Err(payload) => {
            payload
                .downcast::<&'static str>()
                .and_then(|s| if *s == "expected panic on clone" { Ok(s) } else { Err(s) })
                .unwrap_or_else(|p| panic::resume_unwind(p));

            assert_eq!(Rc::strong_count(&rc), 1)
        }
    }
}

#[derive(Clone)]
struct Bomb;

impl Drop for Bomb {
    fn drop(&mut self) {
        panic!("dropped a bomb! kaboom!")
    }
}

#[test]
fn uninit_write_clone_of_slice_no_drop() {
    let mut dst = [MaybeUninit::uninit()];
    let src = [Bomb];

    dst.write_clone_of_slice(&src);

    forget(src);
}

#[test]
fn uninit_write_filled() {
    let mut dst = [MaybeUninit::new(255); 64];
    let expect = [0; 64];

    assert_eq!(dst.write_filled(0), &expect);
}

#[cfg(panic = "unwind")]
struct CloneUntilPanic {
    limit: usize,
    rc: Rc<()>,
}

#[cfg(panic = "unwind")]
impl Clone for CloneUntilPanic {
    fn clone(&self) -> Self {
        if Rc::strong_count(&self.rc) >= self.limit {
            panic!("expected panic on clone");
        }
        Self { limit: self.limit, rc: self.rc.clone() }
    }
}

#[test]
#[cfg(panic = "unwind")]
fn uninit_write_filled_panic_drop() {
    use std::panic;

    let rc = Rc::new(());

    let mut dst = [MaybeUninit::uninit(), MaybeUninit::uninit(), MaybeUninit::uninit()];

    let src = CloneUntilPanic { limit: 3, rc: rc.clone() };
    let err = panic::catch_unwind(panic::AssertUnwindSafe(|| {
        dst.write_filled(src);
    }));

    match err {
        Ok(_) => unreachable!(),
        Err(payload) => {
            payload
                .downcast::<&'static str>()
                .and_then(|s| if *s == "expected panic on clone" { Ok(s) } else { Err(s) })
                .unwrap_or_else(|p| panic::resume_unwind(p));
            assert_eq!(Rc::strong_count(&rc), 1)
        }
    }
}

#[test]
#[cfg(panic = "unwind")]
fn uninit_write_filled_no_drop_clones() {
    let mut dst = [MaybeUninit::uninit(), MaybeUninit::uninit(), MaybeUninit::uninit()];

    dst.write_filled(Bomb);
}

#[test]
fn uninit_write_with() {
    let mut dst = [MaybeUninit::new(255usize); 64];
    let expect = array::from_fn::<usize, 64, _>(|idx| idx);

    assert_eq!(dst.write_with(|idx| idx), &expect);
}

#[test]
#[cfg(panic = "unwind")]
fn uninit_write_with_mid_panic() {
    use std::panic;

    let rc = Rc::new(());

    let mut dst = [MaybeUninit::uninit(), MaybeUninit::uninit(), MaybeUninit::uninit()];

    let src = CloneUntilPanic { limit: 3, rc: rc.clone() };
    let err = panic::catch_unwind(panic::AssertUnwindSafe(|| {
        dst.write_with(|_| src.clone());
    }));

    drop(src);

    match err {
        Ok(_) => unreachable!(),
        Err(payload) => {
            payload
                .downcast::<&'static str>()
                .and_then(|s| if *s == "expected panic on clone" { Ok(s) } else { Err(s) })
                .unwrap_or_else(|p| panic::resume_unwind(p));

            assert_eq!(Rc::strong_count(&rc), 1)
        }
    }
}

#[test]
#[cfg(panic = "unwind")]
fn uninit_write_with_no_drop() {
    let mut dst = [MaybeUninit::uninit()];
    let src = Bomb;

    dst.write_with(|_| src.clone());

    forget(src);
}

#[test]
fn uninit_write_iter() {
    let mut dst = [MaybeUninit::new(255); 64];
    let src = [0; 64];

    let (initted, remainder) = dst.write_iter(src.into_iter());
    assert_eq!(initted, &src);
    assert_eq!(remainder.len(), 0);
}

#[test]
fn uninit_write_iter_partial() {
    let mut dst = [MaybeUninit::new(255); 64];
    let src = [0; 48];

    let (initted, remainder) = dst.write_iter(src.into_iter());
    assert_eq!(initted, &src);
    assert_eq!(remainder.len(), 16);
}

#[test]
fn uninit_write_iter_overfill() {
    let mut dst = [MaybeUninit::new(255); 64];
    let src = [0; 72];

    let (initted, remainder) = dst.write_iter(src.into_iter());
    assert_eq!(initted, &src[0..64]);
    assert_eq!(remainder.len(), 0);
}

#[test]
fn uninit_write_iter_empty() {
    let mut dst = [MaybeUninit::new(255); 64];
    let src = [0; 0];

    let (initted, remainder) = dst.write_iter(src.into_iter());
    assert_eq!(initted, &src[0..0]);
    assert_eq!(remainder.len(), 64);
}

#[test]
#[cfg(panic = "unwind")]
fn uninit_write_iter_mid_panic() {
    use std::panic;

    struct IterUntilPanic {
        limit: usize,
        rc: Rc<()>,
    }

    impl Iterator for IterUntilPanic {
        type Item = Rc<()>;
        fn next(&mut self) -> Option<Self::Item> {
            if Rc::strong_count(&self.rc) >= self.limit {
                panic!("expected panic on next");
            }
            Some(self.rc.clone())
        }
    }

    let rc = Rc::new(());

    let mut dst = [
        MaybeUninit::uninit(),
        MaybeUninit::uninit(),
        MaybeUninit::uninit(),
        MaybeUninit::uninit(),
    ];

    let src = IterUntilPanic { limit: 3, rc: rc.clone() };

    let err = panic::catch_unwind(panic::AssertUnwindSafe(|| {
        dst.write_iter(src);
    }));

    match err {
        Ok(_) => unreachable!(),
        Err(payload) => {
            payload
                .downcast::<&'static str>()
                .and_then(|s| if *s == "expected panic on next" { Ok(s) } else { Err(s) })
                .unwrap_or_else(|p| panic::resume_unwind(p));

            assert_eq!(Rc::strong_count(&rc), 1)
        }
    }
}

#[test]
#[cfg(panic = "unwind")]
fn uninit_write_iter_no_drop() {
    let mut dst = [MaybeUninit::uninit()];
    let src = [Bomb];

    dst.write_iter(src.iter());

    forget(src);
}

#[test]
fn uninit_const_assume_init_read() {
    const FOO: u32 = unsafe { MaybeUninit::new(42).assume_init_read() };
    assert_eq!(FOO, 42);
}

#[test]
fn const_maybe_uninit() {
    use std::ptr;

    #[derive(Debug, PartialEq)]
    struct Foo {
        x: u8,
        y: u8,
    }

    const FIELD_BY_FIELD: Foo = unsafe {
        let mut val = MaybeUninit::uninit();
        init_y(&mut val); // order shouldn't matter
        init_x(&mut val);
        val.assume_init()
    };

    const fn init_x(foo: &mut MaybeUninit<Foo>) {
        unsafe {
            *ptr::addr_of_mut!((*foo.as_mut_ptr()).x) = 1;
        }
    }

    const fn init_y(foo: &mut MaybeUninit<Foo>) {
        unsafe {
            *ptr::addr_of_mut!((*foo.as_mut_ptr()).y) = 2;
        }
    }

    assert_eq!(FIELD_BY_FIELD, Foo { x: 1, y: 2 });
}

#[test]
fn offset_of() {
    #[repr(C)]
    struct Foo {
        x: u8,
        y: u16,
        z: Bar,
    }

    #[repr(C)]
    struct Bar(u8, u8);

    assert_eq!(offset_of!(Foo, x), 0);
    assert_eq!(offset_of!(Foo, y), 2);
    assert_eq!(offset_of!(Foo, z.0), 4);
    assert_eq!(offset_of!(Foo, z.1), 5);

    // Layout of tuples is unstable
    assert!(offset_of!((u8, u16), 0) <= size_of::<(u8, u16)>() - 1);
    assert!(offset_of!((u8, u16), 1) <= size_of::<(u8, u16)>() - 2);

    #[repr(C)]
    struct Generic<T> {
        x: u8,
        y: u32,
        z: T,
    }

    trait Trait {}

    // Ensure that this type of generics works
    fn offs_of_z<T>() -> usize {
        offset_of!(Generic<T>, z)
    }

    assert_eq!(offset_of!(Generic<u8>, z), 8);
    assert_eq!(offs_of_z::<u8>(), 8);

    // Ensure that it works with the implicit lifetime in `Box<dyn Trait + '_>`.
    assert_eq!(offset_of!(Generic<Box<dyn Trait>>, z), 8);
}

#[test]
fn offset_of_union() {
    #[repr(C)]
    union Foo {
        x: u8,
        y: u16,
        z: Bar,
    }

    #[repr(C)]
    #[derive(Copy, Clone)]
    struct Bar(u8, u8);

    assert_eq!(offset_of!(Foo, x), 0);
    assert_eq!(offset_of!(Foo, y), 0);
    assert_eq!(offset_of!(Foo, z.0), 0);
    assert_eq!(offset_of!(Foo, z.1), 1);
}

#[test]
fn offset_of_dst() {
    #[repr(C)]
    struct Alpha {
        x: u8,
        y: u16,
        z: [u8],
    }

    trait Trait {}

    #[repr(C)]
    struct Beta {
        x: u8,
        y: u16,
        z: dyn Trait,
    }

    unsafe extern "C" {
        type Extern;
    }

    #[repr(C)]
    struct Gamma {
        x: u8,
        y: u16,
        z: Extern,
    }

    assert_eq!(offset_of!(Alpha, x), 0);
    assert_eq!(offset_of!(Alpha, y), 2);

    assert_eq!(offset_of!(Beta, x), 0);
    assert_eq!(offset_of!(Beta, y), 2);

    assert_eq!(offset_of!(Gamma, x), 0);
    assert_eq!(offset_of!(Gamma, y), 2);
}

#[test]
fn offset_of_packed() {
    #[repr(C, packed)]
    struct Foo {
        x: u8,
        y: u16,
    }

    assert_eq!(offset_of!(Foo, x), 0);
    assert_eq!(offset_of!(Foo, y), 1);
}

#[test]
fn offset_of_projection() {
    #[repr(C)]
    struct Foo {
        x: u8,
        y: u16,
    }

    trait Projector {
        type Type;
    }

    impl Projector for () {
        type Type = Foo;
    }

    assert_eq!(offset_of!(<() as Projector>::Type, x), 0);
    assert_eq!(offset_of!(<() as Projector>::Type, y), 2);
}

#[test]
fn offset_of_alias() {
    #[repr(C)]
    struct Foo {
        x: u8,
        y: u16,
    }

    type Bar = Foo;

    assert_eq!(offset_of!(Bar, x), 0);
    assert_eq!(offset_of!(Bar, y), 2);
}

#[test]
fn const_offset_of() {
    #[repr(C)]
    struct Foo {
        x: u8,
        y: u16,
    }

    const X_OFFSET: usize = offset_of!(Foo, x);
    const Y_OFFSET: usize = offset_of!(Foo, y);

    assert_eq!(X_OFFSET, 0);
    assert_eq!(Y_OFFSET, 2);
}

#[test]
fn offset_of_without_const_promotion() {
    #[repr(C)]
    struct Foo<SuppressConstPromotion> {
        x: u8,
        y: u16,
        _scp: SuppressConstPromotion,
    }

    // Normally, offset_of is always const promoted.
    // The generic parameter prevents this from happening.
    // This is needed to test the codegen impl of offset_of
    fn inner<SuppressConstPromotion>() {
        assert_eq!(offset_of!(Foo<SuppressConstPromotion>, x), 0);
        assert_eq!(offset_of!(Foo<SuppressConstPromotion>, y), 2);
    }

    inner::<()>();
}

#[test]
fn offset_of_addr() {
    #[repr(C)]
    struct Foo {
        x: u8,
        y: u16,
        z: Bar,
    }

    #[repr(C)]
    struct Bar(u8, u8);

    let base = Foo { x: 0, y: 0, z: Bar(0, 0) };

    assert_eq!(ptr::addr_of!(base).addr() + offset_of!(Foo, x), ptr::addr_of!(base.x).addr());
    assert_eq!(ptr::addr_of!(base).addr() + offset_of!(Foo, y), ptr::addr_of!(base.y).addr());
    assert_eq!(ptr::addr_of!(base).addr() + offset_of!(Foo, z.0), ptr::addr_of!(base.z.0).addr());
    assert_eq!(ptr::addr_of!(base).addr() + offset_of!(Foo, z.1), ptr::addr_of!(base.z.1).addr());
}

#[test]
fn const_maybe_uninit_zeroed() {
    // Sanity check for `MaybeUninit::zeroed` in a realistic const situation (plugin array term)

    // It is crucial that this type has no padding!
    #[repr(C)]
    struct Foo {
        a: Option<&'static u8>,
        b: Bar,
        c: f32,
        _pad: u32,
        d: *const u8,
    }

    #[repr(C)]
    struct Bar(usize);

    struct FooPtr(*const Foo);
    unsafe impl Sync for FooPtr {}

    static UNINIT: FooPtr = FooPtr([unsafe { MaybeUninit::zeroed().assume_init() }].as_ptr());
    const SIZE: usize = size_of::<Foo>();

    assert_eq!(unsafe { (*UNINIT.0.cast::<[[u8; SIZE]; 1]>())[0] }, [0u8; SIZE]);
}

#[test]
fn drop_guards_only_dropped_by_closure_when_run() {
    let value_drops = Cell::new(0);
    let value = DropGuard::new((), |()| value_drops.set(1 + value_drops.get()));
    let closure_drops = Cell::new(0);
    let guard = DropGuard::new(value, |_| closure_drops.set(1 + closure_drops.get()));
    assert_eq!(value_drops.get(), 0);
    assert_eq!(closure_drops.get(), 0);
    drop(guard);
    assert_eq!(value_drops.get(), 1);
    assert_eq!(closure_drops.get(), 1);
}

#[test]
fn drop_guard_into_inner() {
    let dropped = Cell::new(false);
    let value = DropGuard::new(42, |_| dropped.set(true));
    let guard = DropGuard::new(value, |_| dropped.set(true));
    let inner = DropGuard::into_inner(guard);
    assert_eq!(dropped.get(), false);
    assert_eq!(*inner, 42);
}

#[test]
#[cfg(panic = "unwind")]
fn drop_guard_always_drops_value_if_closure_drop_unwinds() {
    // Create a value with a destructor, which we will validate ran successfully.
    let mut value_was_dropped = false;
    let value_with_tracked_destruction = DropGuard::new((), |_| value_was_dropped = true);

    // Create a closure that will begin unwinding when dropped.
    let drop_bomb = DropGuard::new((), |_| panic!());
    let closure_that_panics_on_drop = move |_| {
        let _drop_bomb = drop_bomb;
    };

    // This will run the closure, which will panic when dropped. This should
    // run the destructor of the value we passed, which we validate.
    let _ = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
        let guard = DropGuard::new(value_with_tracked_destruction, closure_that_panics_on_drop);
        DropGuard::into_inner(guard);
    }));
    assert!(value_was_dropped);
}