Add minicore test auxiliary

Author: jieyouxu

tests/auxiliary/minicore.rs

@@ -0,0 +1,116 @@
+//! Auxiliary `minicore` prelude which stubs out std preludes for tests that need to work in
+//! cross-compilation scenarios where no `std` is available (that don't need to `-Zbuild-std`).
+
+#![feature(no_core, lang_items, rustc_attrs, unsized_fn_params, transparent_unions)]
+#![allow(unused, improper_ctypes_definitions, internal_features)]
+#![no_std]
+#![no_core]
+
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "receiver"]
+pub trait Receiver {}
+impl<T: ?Sized> Receiver for &T {}
+impl<T: ?Sized> Receiver for &mut T {}
+
+#[lang = "copy"]
+pub trait Copy: Sized {}
+impl Copy for i32 {}
+impl Copy for f32 {}
+impl<T: ?Sized> Copy for &T {}
+impl<T: ?Sized> Copy for *const T {}
+impl<T: ?Sized> Copy for *mut T {}
+
+#[lang = "clone"]
+pub trait Clone: Sized {
+    fn clone(&self) -> Self;
+}
+
+#[lang = "phantom_data"]
+pub struct PhantomData<T: ?Sized>;
+impl<T: ?Sized> Copy for PhantomData<T> {}
+
+#[lang = "unsafe_cell"]
+#[repr(transparent)]
+pub struct UnsafeCell<T: ?Sized> {
+    value: T,
+}
+
+pub trait Any: 'static {}
+
+pub enum Option<T> {
+    None,
+    Some(T),
+}
+impl<T: Copy> Copy for Option<T> {}
+
+pub enum Result<T, E> {
+    Ok(T),
+    Err(E),
+}
+impl<T: Copy, E: Copy> Copy for Result<T, E> {}
+
+#[lang = "manually_drop"]
+#[repr(transparent)]
+pub struct ManuallyDrop<T: ?Sized> {
+    value: T,
+}
+impl<T: Copy + ?Sized> Copy for ManuallyDrop<T> {}
+
+#[repr(transparent)]
+#[rustc_layout_scalar_valid_range_start(1)]
+#[rustc_nonnull_optimization_guaranteed]
+pub struct NonNull<T: ?Sized> {
+    pointer: *const T,
+}
+impl<T: ?Sized> Copy for NonNull<T> {}
+
+#[repr(transparent)]
+#[rustc_layout_scalar_valid_range_start(1)]
+#[rustc_nonnull_optimization_guaranteed]
+pub struct NonZero<T>(T);
+
+// This just stands in for a non-trivial type.
+pub struct Vec<T> {
+    ptr: NonNull<T>,
+    cap: usize,
+    len: usize,
+}
+
+pub struct Unique<T: ?Sized> {
+    pub pointer: NonNull<T>,
+    pub _marker: PhantomData<T>,
+}
+
+#[lang = "global_alloc_ty"]
+pub struct Global;
+
+#[lang = "owned_box"]
+pub struct Box<T: ?Sized, A = Global>(Unique<T>, A);
+
+#[repr(C)]
+struct RcBox<T: ?Sized> {
+    strong: UnsafeCell<usize>,
+    weak: UnsafeCell<usize>,
+    value: T,
+}
+pub struct Rc<T: ?Sized, A = Global> {
+    ptr: NonNull<RcBox<T>>,
+    phantom: PhantomData<RcBox<T>>,
+    alloc: A,
+}
+
+#[repr(C, align(8))]
+struct AtomicUsize(usize);
+#[repr(C)]
+struct ArcInner<T: ?Sized> {
+    strong: AtomicUsize,
+    weak: AtomicUsize,
+    data: T,
+}
+pub struct Arc<T: ?Sized, A = Global> {
+    ptr: NonNull<ArcInner<T>>,
+    phantom: PhantomData<ArcInner<T>>,
+    alloc: A,
+}