Auto merge of #79684 - usbalbin:const_copy, r=oli-obk

Make copy[_nonoverlapping] const

Constifies
* `intrinsics::copy` and `intrinsics::copy_nonoverlapping`
* `ptr::read` and `ptr::read_unaligned`
  * `*const T::read` and `*const T::read_unaligned`
  * `*mut T::read` and `*mut T::read_unaligned`
* `MaybeUninit::assume_init_read`

2 files changed, 70 insertions, 0 deletions

diff --git a/src/test/ui/const-ptr/out_of_bounds_read.rs b/src/test/ui/const-ptr/out_of_bounds_read.rs
new file mode 100644
index 00000000000..183aa9e5122
--- /dev/null
+++ b/src/test/ui/const-ptr/out_of_bounds_read.rs
@@ -0,0 +1,16 @@
+// error-pattern: any use of this value will cause an error
+
+#![feature(const_ptr_read)]
+#![feature(const_ptr_offset)]
+
+fn main() {
+    use std::ptr;
+
+    const DATA: [u32; 1] = [42];
+
+    const PAST_END_PTR: *const u32 = unsafe { DATA.as_ptr().add(1) };
+
+    const _READ: u32 = unsafe { ptr::read(PAST_END_PTR) };
+    const _CONST_READ: u32 = unsafe { PAST_END_PTR.read() };
+    const _MUT_READ: u32 = unsafe { (PAST_END_PTR as *mut u32).read() };
+}
diff --git a/src/test/ui/const-ptr/out_of_bounds_read.stderr b/src/test/ui/const-ptr/out_of_bounds_read.stderr
new file mode 100644
index 00000000000..ca65a079947
--- /dev/null
+++ b/src/test/ui/const-ptr/out_of_bounds_read.stderr
@@ -0,0 +1,54 @@
+error: any use of this value will cause an error
+  --> $SRC_DIR/core/src/intrinsics.rs:LL:COL
+   |
+LL |     unsafe { copy_nonoverlapping(src, dst, count) }
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |              |
+   |              memory access failed: pointer must be in-bounds at offset 8, but is outside bounds of alloc6 which has size 4
+   |              inside `copy_nonoverlapping::<u32>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL
+   |              inside `std::ptr::read::<u32>` at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
+   |              inside `_READ` at $DIR/out_of_bounds_read.rs:13:33
+   | 
+  ::: $DIR/out_of_bounds_read.rs:13:5
+   |
+LL |     const _READ: u32 = unsafe { ptr::read(PAST_END_PTR) };
+   |     ------------------------------------------------------
+   |
+   = note: `#[deny(const_err)]` on by default
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/core/src/intrinsics.rs:LL:COL
+   |
+LL |     unsafe { copy_nonoverlapping(src, dst, count) }
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |              |
+   |              memory access failed: pointer must be in-bounds at offset 8, but is outside bounds of alloc6 which has size 4
+   |              inside `copy_nonoverlapping::<u32>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL
+   |              inside `std::ptr::read::<u32>` at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
+   |              inside `ptr::const_ptr::<impl *const u32>::read` at $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
+   |              inside `_CONST_READ` at $DIR/out_of_bounds_read.rs:14:39
+   | 
+  ::: $DIR/out_of_bounds_read.rs:14:5
+   |
+LL |     const _CONST_READ: u32 = unsafe { PAST_END_PTR.read() };
+   |     --------------------------------------------------------
+
+error: any use of this value will cause an error
+  --> $SRC_DIR/core/src/intrinsics.rs:LL:COL
+   |
+LL |     unsafe { copy_nonoverlapping(src, dst, count) }
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |              |
+   |              memory access failed: pointer must be in-bounds at offset 8, but is outside bounds of alloc6 which has size 4
+   |              inside `copy_nonoverlapping::<u32>` at $SRC_DIR/core/src/intrinsics.rs:LL:COL
+   |              inside `std::ptr::read::<u32>` at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
+   |              inside `ptr::mut_ptr::<impl *mut u32>::read` at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
+   |              inside `_MUT_READ` at $DIR/out_of_bounds_read.rs:15:37
+   | 
+  ::: $DIR/out_of_bounds_read.rs:15:5
+   |
+LL |     const _MUT_READ: u32 = unsafe { (PAST_END_PTR as *mut u32).read() };
+   |     --------------------------------------------------------------------
+
+error: aborting due to 3 previous errors
+