Merging upstream version 1.71.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 19 insertions, 17 deletions

diff --git a/compiler/rustc_middle/src/ty/list.rs b/compiler/rustc_middle/src/ty/list.rs
index 79365ef28..71911a5a6 100644
--- a/compiler/rustc_middle/src/ty/list.rs
+++ b/compiler/rustc_middle/src/ty/list.rs
@@ -1,4 +1,5 @@
 use crate::arena::Arena;
+use rustc_data_structures::aligned::{align_of, Aligned};
 use rustc_serialize::{Encodable, Encoder};
 use std::alloc::Layout;
 use std::cmp::Ordering;
@@ -198,22 +199,23 @@ impl<'a, T: Copy> IntoIterator for &'a List<T> {
 
 unsafe impl<T: Sync> Sync for List<T> {}
 
-unsafe impl<'a, T: 'a> rustc_data_structures::tagged_ptr::Pointer for &'a List<T> {
-    const BITS: usize = std::mem::align_of::<usize>().trailing_zeros() as usize;
-
-    #[inline]
-    fn into_usize(self) -> usize {
-        self as *const List<T> as usize
-    }
-
-    #[inline]
-    unsafe fn from_usize(ptr: usize) -> &'a List<T> {
-        &*(ptr as *const List<T>)
-    }
+// We need this since `List` uses extern type `OpaqueListContents`.
+#[cfg(parallel_compiler)]
+use rustc_data_structures::sync::DynSync;
+#[cfg(parallel_compiler)]
+unsafe impl<T: DynSync> DynSync for List<T> {}
+
+// Safety:
+// Layouts of `Equivalent<T>` and `List<T>` are the same, modulo opaque tail,
+// thus aligns of `Equivalent<T>` and `List<T>` must be the same.
+unsafe impl<T> Aligned for List<T> {
+    const ALIGN: ptr::Alignment = {
+        #[repr(C)]
+        struct Equivalent<T> {
+            _len: usize,
+            _data: [T; 0],
+        }
 
-    unsafe fn with_ref<R, F: FnOnce(&Self) -> R>(ptr: usize, f: F) -> R {
-        // `Self` is `&'a List<T>` which impls `Copy`, so this is fine.
-        let ptr = Self::from_usize(ptr);
-        f(&ptr)
-    }
+        align_of::<Equivalent<T>>()
+    };
 }