Rollup merge of rust-lang#132732 - gavincrawford:as_ptr_attribute, r=Urgau

Use attributes for `dangling_pointers_from_temporaries` lint

Checking for dangling pointers by function name isn't ideal, and leaves out certain pointer-returning methods that don't follow the `as_ptr` naming convention. Using an attribute for this lint cleans things up and allows more thorough coverage of other methods, such as `UnsafeCell::get()`.

Author: jhpratt

Diff for: alloc/src/boxed.rs

@@ -1500,6 +1500,7 @@ impl<T: ?Sized, A: Allocator> Box<T, A> {
     /// [`as_ptr`]: Self::as_ptr
     #[unstable(feature = "box_as_ptr", issue = "129090")]
     #[rustc_never_returns_null_ptr]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[inline]
     pub fn as_mut_ptr(b: &mut Self) -> *mut T {
         // This is a primitive deref, not going through `DerefMut`, and therefore not materializing
@@ -1548,6 +1549,7 @@ impl<T: ?Sized, A: Allocator> Box<T, A> {
     /// [`as_ptr`]: Self::as_ptr
     #[unstable(feature = "box_as_ptr", issue = "129090")]
     #[rustc_never_returns_null_ptr]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[inline]
     pub fn as_ptr(b: &Self) -> *const T {
         // This is a primitive deref, not going through `DerefMut`, and therefore not materializing

Diff for: alloc/src/vec/mod.rs

@@ -1662,6 +1662,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[stable(feature = "vec_as_ptr", since = "1.37.0")]
     #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     #[rustc_never_returns_null_ptr]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[inline]
     pub const fn as_ptr(&self) -> *const T {
         // We shadow the slice method of the same name to avoid going through
@@ -1724,6 +1725,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[stable(feature = "vec_as_ptr", since = "1.37.0")]
     #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     #[rustc_never_returns_null_ptr]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[inline]
     pub const fn as_mut_ptr(&mut self) -> *mut T {
         // We shadow the slice method of the same name to avoid going through

Diff for: core/src/cell.rs

@@ -587,6 +587,7 @@ impl<T: ?Sized> Cell<T> {
     #[inline]
     #[stable(feature = "cell_as_ptr", since = "1.12.0")]
     #[rustc_const_stable(feature = "const_cell_as_ptr", since = "1.32.0")]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[rustc_never_returns_null_ptr]
     pub const fn as_ptr(&self) -> *mut T {
         self.value.get()
@@ -1149,6 +1150,7 @@ impl<T: ?Sized> RefCell<T> {
     /// ```
     #[inline]
     #[stable(feature = "cell_as_ptr", since = "1.12.0")]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[rustc_never_returns_null_ptr]
     pub fn as_ptr(&self) -> *mut T {
         self.value.get()
@@ -2158,6 +2160,7 @@ impl<T: ?Sized> UnsafeCell<T> {
     #[inline(always)]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_unsafecell_get", since = "1.32.0")]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[rustc_never_returns_null_ptr]
     pub const fn get(&self) -> *mut T {
         // We can just cast the pointer from `UnsafeCell<T>` to `T` because of
@@ -2271,6 +2274,7 @@ impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<UnsafeCell<U>> for UnsafeCell<T>
 /// See [`UnsafeCell`] for details.
 #[unstable(feature = "sync_unsafe_cell", issue = "95439")]
 #[repr(transparent)]
+#[rustc_diagnostic_item = "SyncUnsafeCell"]
 #[rustc_pub_transparent]
 pub struct SyncUnsafeCell<T: ?Sized> {
     value: UnsafeCell<T>,
@@ -2304,6 +2308,7 @@ impl<T: ?Sized> SyncUnsafeCell<T> {
     /// when casting to `&mut T`, and ensure that there are no mutations
     /// or mutable aliases going on when casting to `&T`
     #[inline]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[rustc_never_returns_null_ptr]
     pub const fn get(&self) -> *mut T {
         self.value.get()

Diff for: core/src/ffi/c_str.rs

@@ -500,6 +500,7 @@ impl CStr {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_str_as_ptr", since = "1.32.0")]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[rustc_never_returns_null_ptr]
     pub const fn as_ptr(&self) -> *const c_char {
         self.inner.as_ptr()

Diff for: core/src/mem/maybe_uninit.rs

@@ -525,6 +525,7 @@ impl<T> MaybeUninit<T> {
     /// until they are, it is advisable to avoid them.)
     #[stable(feature = "maybe_uninit", since = "1.36.0")]
     #[rustc_const_stable(feature = "const_maybe_uninit_as_ptr", since = "1.59.0")]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[inline(always)]
     pub const fn as_ptr(&self) -> *const T {
         // `MaybeUninit` and `ManuallyDrop` are both `repr(transparent)` so we can cast the pointer.
@@ -566,6 +567,7 @@ impl<T> MaybeUninit<T> {
     /// until they are, it is advisable to avoid them.)
     #[stable(feature = "maybe_uninit", since = "1.36.0")]
     #[rustc_const_stable(feature = "const_maybe_uninit_as_mut_ptr", since = "1.83.0")]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[inline(always)]
     pub const fn as_mut_ptr(&mut self) -> *mut T {
         // `MaybeUninit` and `ManuallyDrop` are both `repr(transparent)` so we can cast the pointer.

Diff for: core/src/slice/mod.rs

@@ -735,6 +735,7 @@ impl<T> [T] {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_slice_as_ptr", since = "1.32.0")]
     #[rustc_never_returns_null_ptr]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[inline(always)]
     #[must_use]
     pub const fn as_ptr(&self) -> *const T {
@@ -765,6 +766,7 @@ impl<T> [T] {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")]
     #[rustc_never_returns_null_ptr]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[inline(always)]
     #[must_use]
     pub const fn as_mut_ptr(&mut self) -> *mut T {

Diff for: core/src/str/mod.rs

@@ -373,6 +373,7 @@ impl str {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "rustc_str_as_ptr", since = "1.32.0")]
     #[rustc_never_returns_null_ptr]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[must_use]
     #[inline(always)]
     pub const fn as_ptr(&self) -> *const u8 {
@@ -390,6 +391,7 @@ impl str {
     #[stable(feature = "str_as_mut_ptr", since = "1.36.0")]
     #[rustc_const_stable(feature = "const_str_as_mut", since = "1.83.0")]
     #[rustc_never_returns_null_ptr]
+    #[cfg_attr(not(bootstrap), rustc_as_ptr)]
     #[must_use]
     #[inline(always)]
     pub const fn as_mut_ptr(&mut self) -> *mut u8 {