X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=library%2Falloc%2Ftests%2Fboxed.rs;h=0d7acfed8c6a1b36f0354714fa375f9de8efd9b4;hb=1591dcb659917de87254297073b078b9ade56612;hp=bfe66b2687ef4d89644a76df2901784bb35a7f19;hpb=081493da7fc7cf1b24ca87883d9e55e0acfe34cc;p=rust.git

diff --git a/library/alloc/tests/boxed.rs b/library/alloc/tests/boxed.rs
index bfe66b2687e..0d7acfed8c6 100644
--- a/library/alloc/tests/boxed.rs
+++ b/library/alloc/tests/boxed.rs
@@ -1,6 +1,7 @@
-use std::cell::Cell;
-use std::mem::MaybeUninit;
-use std::ptr::NonNull;
+use core::alloc::{AllocError, Allocator, Layout};
+use core::cell::Cell;
+use core::mem::MaybeUninit;
+use core::ptr::NonNull;
 
 #[test]
 fn uninitialized_zero_size_box() {
@@ -57,3 +58,110 @@ fn box_deref_lval() {
     x.set(1000);
     assert_eq!(x.get(), 1000);
 }
+
+pub struct ConstAllocator;
+
+unsafe impl const Allocator for ConstAllocator {
+    fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        match layout.size() {
+            0 => Ok(NonNull::slice_from_raw_parts(layout.dangling(), 0)),
+            _ => unsafe {
+                let ptr = core::intrinsics::const_allocate(layout.size(), layout.align());
+                Ok(NonNull::new_unchecked(ptr as *mut [u8; 0] as *mut [u8]))
+            },
+        }
+    }
+
+    unsafe fn deallocate(&self, _ptr: NonNull<u8>, layout: Layout) {
+        match layout.size() {
+            0 => { /* do nothing */ }
+            _ => { /* do nothing too */ }
+        }
+    }
+
+    fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        let ptr = self.allocate(layout)?;
+        if layout.size() > 0 {
+            unsafe {
+                ptr.as_mut_ptr().write_bytes(0, layout.size());
+            }
+        }
+        Ok(ptr)
+    }
+
+    unsafe fn grow(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        debug_assert!(
+            new_layout.size() >= old_layout.size(),
+            "`new_layout.size()` must be greater than or equal to `old_layout.size()`"
+        );
+
+        let new_ptr = self.allocate(new_layout)?;
+        if new_layout.size() > 0 {
+            new_ptr.as_mut_ptr().copy_from_nonoverlapping(ptr.as_ptr(), old_layout.size());
+            self.deallocate(ptr, old_layout);
+        }
+        Ok(new_ptr)
+    }
+
+    unsafe fn grow_zeroed(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        let new_ptr = self.grow(ptr, old_layout, new_layout)?;
+        if new_layout.size() > 0 {
+            let old_size = old_layout.size();
+            let new_size = new_layout.size();
+            let raw_ptr = new_ptr.as_mut_ptr();
+            raw_ptr.add(old_size).write_bytes(0, new_size - old_size);
+        }
+        Ok(new_ptr)
+    }
+
+    unsafe fn shrink(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        debug_assert!(
+            new_layout.size() <= old_layout.size(),
+            "`new_layout.size()` must be smaller than or equal to `old_layout.size()`"
+        );
+
+        let new_ptr = self.allocate(new_layout)?;
+        if new_layout.size() > 0 {
+            new_ptr.as_mut_ptr().copy_from_nonoverlapping(ptr.as_ptr(), new_layout.size());
+            self.deallocate(ptr, old_layout);
+        }
+        Ok(new_ptr)
+    }
+
+    fn by_ref(&self) -> &Self
+    where
+        Self: Sized,
+    {
+        self
+    }
+}
+
+#[test]
+fn const_box() {
+    const VALUE: u32 = {
+        let mut boxed = Box::new_in(1u32, ConstAllocator);
+        assert!(*boxed == 1);
+
+        *boxed = 42;
+        assert!(*boxed == 42);
+
+        *boxed
+    };
+
+    assert!(VALUE == 42);
+}