Rollup merge of rust-lang#100820 - WaffleLapkin:use_ptr_is_aligned_methods, r=scottmcm

Use pointer `is_aligned*` methods

This PR replaces some manual alignment checks with calls to `pointer::{is_aligned, is_aligned_to}` and removes a useless pointer cast.

r? `@scottmcm`

_split off from #100746_

Author: Dylan-DPC

library/alloc/src/vec/into_iter.rs

@@ -148,7 +148,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
 
     #[inline]
     fn next(&mut self) -> Option<T> {
-        if self.ptr as *const _ == self.end {
+        if self.ptr == self.end {
             None
         } else if mem::size_of::<T>() == 0 {
             // purposefully don't use 'ptr.offset' because for

library/alloc/tests/lib.rs

@@ -38,6 +38,7 @@
 #![feature(const_str_from_utf8)]
 #![feature(nonnull_slice_from_raw_parts)]
 #![feature(panic_update_hook)]
+#![feature(pointer_is_aligned)]
 #![feature(slice_flatten)]
 #![feature(thin_box)]
 #![feature(bench_black_box)]

library/alloc/tests/thin_box.rs

@@ -48,11 +48,11 @@ fn verify_aligned<T>(ptr: *const T) {
     // practice these checks are mostly just smoke-detectors for an extremely
     // broken `ThinBox` impl, since it's an extremely subtle piece of code.
     let ptr = core::hint::black_box(ptr);
-    let align = core::mem::align_of::<T>();
     assert!(
-        (ptr.addr() & (align - 1)) == 0 && !ptr.is_null(),
-        "misaligned ThinBox data; valid pointers to `{}` should be aligned to {align}: {ptr:p}",
-        core::any::type_name::<T>(),
+        ptr.is_aligned() && !ptr.is_null(),
+        "misaligned ThinBox data; valid pointers to `{ty}` should be aligned to {align}: {ptr:p}",
+        ty = core::any::type_name::<T>(),
+        align = core::mem::align_of::<T>(),
     );
 }
 

library/core/src/intrinsics.rs

@@ -2139,7 +2139,7 @@ pub(crate) use assert_unsafe_precondition;
 /// Checks whether `ptr` is properly aligned with respect to
 /// `align_of::<T>()`.
 pub(crate) fn is_aligned_and_not_null<T>(ptr: *const T) -> bool {
-    !ptr.is_null() && ptr.addr() % mem::align_of::<T>() == 0
+    !ptr.is_null() && ptr.is_aligned()
 }
 
 /// Checks whether the regions of memory starting at `src` and `dst` of size

library/std/src/lib.rs

@@ -296,6 +296,7 @@
 #![feature(panic_can_unwind)]
 #![feature(panic_info_message)]
 #![feature(panic_internals)]
+#![feature(pointer_is_aligned)]
 #![feature(portable_simd)]
 #![feature(prelude_2024)]
 #![feature(provide_any)]

library/std/src/sys/sgx/abi/usercalls/alloc.rs

@@ -117,7 +117,7 @@ pub unsafe trait UserSafe {
     /// * the pointer is null.
     /// * the pointed-to range is not in user memory.
     unsafe fn check_ptr(ptr: *const Self) {
-        let is_aligned = |p: *const u8| -> bool { 0 == p.addr() & (Self::align_of() - 1) };
+        let is_aligned = |p: *const u8| -> bool { p.is_aligned_to(Self::align_of()) };
 
         assert!(is_aligned(ptr as *const u8));
         assert!(is_user_range(ptr as _, mem::size_of_val(unsafe { &*ptr })));
@@ -386,7 +386,7 @@ pub(crate) unsafe fn copy_to_userspace(src: *const u8, dst: *mut u8, len: usize)
         unsafe {
             copy_bytewise_to_userspace(src, dst, len);
         }
-    } else if len % 8 == 0 && dst as usize % 8 == 0 {
+    } else if len % 8 == 0 && dst.is_aligned_to(8) {
         // Copying 8-byte aligned quadwords: copy quad word per quad word
         unsafe {
             copy_quadwords(src, dst, len);