From df034374004a4f0cb0c1bfab055a176ec6496332 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=AE=B8=E6=9D=B0=E5=8F=8B=20Jieyou=20Xu=20=28Joe=29?=
 <39484203+jieyouxu@users.noreply.github.com>
Date: Sat, 28 Sep 2024 21:15:07 +0800
Subject: [PATCH] Use minicore in `tests/abi/compatibility.rs` as an example

---
 tests/ui/abi/compatibility.rs | 68 +++++++----------------------------
 1 file changed, 12 insertions(+), 56 deletions(-)

diff --git a/tests/ui/abi/compatibility.rs b/tests/ui/abi/compatibility.rs
index b439a4bcf867b..0d39af9371502 100644
--- a/tests/ui/abi/compatibility.rs
+++ b/tests/ui/abi/compatibility.rs
@@ -58,8 +58,10 @@
 //@ revisions: nvptx64
 //@[nvptx64] compile-flags: --target nvptx64-nvidia-cuda
 //@[nvptx64] needs-llvm-components: nvptx
-#![feature(rustc_attrs, unsized_fn_params, transparent_unions)]
-#![cfg_attr(not(host), feature(no_core, lang_items), no_std, no_core)]
+#![feature(no_core, rustc_attrs, lang_items)]
+#![feature(unsized_fn_params, transparent_unions)]
+#![no_std]
+#![no_core]
 #![allow(unused, improper_ctypes_definitions, internal_features)]
 
 // FIXME: some targets are broken in various ways.
@@ -67,67 +69,22 @@
 // sparc64: https://github.com/rust-lang/rust/issues/115336
 // mips64: https://github.com/rust-lang/rust/issues/115404
 
-#[cfg(host)]
-use std::{
-    any::Any, marker::PhantomData, mem::ManuallyDrop, num::NonZero, ptr::NonNull, rc::Rc, sync::Arc,
-};
+//@ use-minicore
+extern crate minicore;
+use minicore::*;
 
-/// To work cross-target this test must be no_core.
-/// This little prelude supplies what we need.
-#[cfg(not(host))]
+/// To work cross-target this test must be no_core. This little prelude supplies what we need.
+///
+/// Note that `minicore` provides a very minimal subset of `core` items (not yet complete). This
+/// prelude contains `alloc` and non-`core` (but in `std`) items that minicore does not stub out.
 mod prelude {
-    #[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 {}
+    use minicore::*;
 
     #[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]
@@ -185,7 +142,6 @@ mod prelude {
         alloc: A,
     }
 }
-#[cfg(not(host))]
 use prelude::*;
 
 macro_rules! test_abi_compatible {