rust/crates/test_utils/src/minicore.rs

//! This is a fixture we use for tests that need lang items.
//!
//! We want to include the minimal subset of core for each test, so this file
//! supports "conditional compilation". Tests use the following syntax to include minicore:
//!
//!  //- minicore: flag1, flag2
//!
//! We then strip all the code marked with other flags.
//!
//! Available flags:
//!     sized:
//!     slice:
//!     unsize: sized
//!     deref: sized
//!     coerce_unsized: unsize

pub mod marker {
    // region:sized
    #[lang = "sized"]
    #[fundamental]
    #[rustc_specialization_trait]
    pub trait Sized {}
    // endregion:sized

    // region:unsize
    #[lang = "unsize"]
    pub trait Unsize<T: ?Sized> {}
    // endregion:unsize
}

pub mod ops {
    // region:coerce_unsized
    mod unsize {
        use crate::marker::Unsize;

        #[lang = "coerce_unsized"]
        pub trait CoerceUnsized<T: ?Sized> {}

        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {}
        impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b mut T {}
        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for &'a mut T {}
        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a mut T {}

        impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a T {}

        impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
        impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *mut T {}
        impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
    }
    pub use self::unsize::CoerceUnsized;
    // endregion:coerce_unsized

    // region:deref
    mod deref {
        #[lang = "deref"]
        pub trait Deref {
            #[lang = "deref_target"]
            type Target: ?Sized;
            fn deref(&self) -> &Self::Target;
        }
    }
    pub use self::deref::Deref;
    // endregion:deref
}

// region:slice
pub mod slice {
    #[lang = "slice"]
    impl<T> [T] {
        pub fn len(&self) -> usize { loop {} }
    }
}
// endregion:slice

pub mod prelude {
    pub mod v1 {
        pub use crate::marker::Sized; // :sized
    }

    pub mod rust_2015 {
        pub use super::v1::*;
    }

    pub mod rust_2018 {
        pub use super::v1::*;
    }

    pub mod rust_2021 {
        pub use super::v1::*;
    }
}

#[prelude_import]
#[allow(unused)]
use prelude::v1::*;