Add #[rustc_never_returns_null_ptr] to std functions

Add the attribute to standard library functions that
are guaranteed to never return null pointers, as their
originating data wouldn't allow it.

7 files changed, 16 insertions, 0 deletions

diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index bf4c682d33e..82e24644414 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -543,6 +543,7 @@ 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_never_returns_null_ptr)]
     pub const fn as_ptr(&self) -> *mut T {
         self.value.get()
     }
@@ -1076,6 +1077,7 @@ impl<T: ?Sized> RefCell<T> {
     /// ```
     #[inline]
     #[stable(feature = "cell_as_ptr", since = "1.12.0")]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     pub fn as_ptr(&self) -> *mut T {
         self.value.get()
     }
@@ -2071,6 +2073,7 @@ 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_never_returns_null_ptr)]
     pub const fn get(&self) -> *mut T {
         // We can just cast the pointer from `UnsafeCell<T>` to `T` because of
         // #[repr(transparent)]. This exploits std's special status, there is
@@ -2213,6 +2216,7 @@ 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_never_returns_null_ptr)]
     pub const fn get(&self) -> *mut T {
         self.value.get()
     }
diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index b59ec12790d..388a545d3d9 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -509,6 +509,7 @@ 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_never_returns_null_ptr)]
     pub const fn as_ptr(&self) -> *const c_char {
         self.inner.as_ptr()
     }
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index 5f094ac4e7e..84cc2e474a1 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -698,6 +698,7 @@ where
 #[inline(always)]
 #[must_use]
 #[unstable(feature = "ptr_from_ref", issue = "106116")]
+#[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
 #[rustc_diagnostic_item = "ptr_from_ref"]
 pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
     r
@@ -710,6 +711,7 @@ pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
 #[inline(always)]
 #[must_use]
 #[unstable(feature = "ptr_from_ref", issue = "106116")]
+#[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
 #[rustc_diagnostic_item = "ptr_from_mut"]
 pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T {
     r
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index 9582ca9e0be..77a2e0775a3 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -320,6 +320,7 @@ impl<T: ?Sized> NonNull<T> {
     /// ```
     #[stable(feature = "nonnull", since = "1.25.0")]
     #[rustc_const_stable(feature = "const_nonnull_as_ptr", since = "1.32.0")]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     #[must_use]
     #[inline(always)]
     pub const fn as_ptr(self) -> *mut T {
@@ -579,6 +580,7 @@ impl<T> NonNull<[T]> {
     #[must_use]
     #[unstable(feature = "slice_ptr_get", issue = "74265")]
     #[rustc_const_unstable(feature = "slice_ptr_get", issue = "74265")]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     pub const fn as_mut_ptr(self) -> *mut T {
         self.as_non_null_ptr().as_ptr()
     }
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index d95662afddd..0d635aced85 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -730,6 +730,7 @@ impl<T> [T] {
     /// [`as_mut_ptr`]: slice::as_mut_ptr
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_slice_as_ptr", since = "1.32.0")]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     #[inline(always)]
     #[must_use]
     pub const fn as_ptr(&self) -> *const T {
@@ -760,6 +761,7 @@ impl<T> [T] {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")]
     #[rustc_allow_const_fn_unstable(const_mut_refs)]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     #[inline(always)]
     #[must_use]
     pub const fn as_mut_ptr(&mut self) -> *mut T {
diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index 71c03f7bfc5..569707a40f3 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -387,6 +387,7 @@ impl str {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "rustc_str_as_ptr", since = "1.32.0")]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     #[must_use]
     #[inline(always)]
     pub const fn as_ptr(&self) -> *const u8 {
@@ -402,6 +403,7 @@ impl str {
     /// It is your responsibility to make sure that the string slice only gets
     /// modified in a way that it remains valid UTF-8.
     #[stable(feature = "str_as_mut_ptr", since = "1.36.0")]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     #[must_use]
     #[inline(always)]
     pub fn as_mut_ptr(&mut self) -> *mut u8 {
diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs
index 22a1c09782c..cf1fbe2d389 100644
--- a/library/core/src/sync/atomic.rs
+++ b/library/core/src/sync/atomic.rs
@@ -1018,6 +1018,7 @@ impl AtomicBool {
     #[inline]
     #[stable(feature = "atomic_as_ptr", since = "1.70.0")]
     #[rustc_const_stable(feature = "atomic_as_ptr", since = "1.70.0")]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     pub const fn as_ptr(&self) -> *mut bool {
         self.v.get().cast()
     }
@@ -1953,6 +1954,7 @@ impl<T> AtomicPtr<T> {
     #[inline]
     #[stable(feature = "atomic_as_ptr", since = "1.70.0")]
     #[rustc_const_stable(feature = "atomic_as_ptr", since = "1.70.0")]
+    #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
     pub const fn as_ptr(&self) -> *mut *mut T {
         self.p.get()
     }
@@ -2891,6 +2893,7 @@ macro_rules! atomic_int {
             #[inline]
             #[stable(feature = "atomic_as_ptr", since = "1.70.0")]
             #[rustc_const_stable(feature = "atomic_as_ptr", since = "1.70.0")]
+            #[cfg_attr(not(bootstrap), rustc_never_returns_null_ptr)]
             pub const fn as_ptr(&self) -> *mut $int_type {
                 self.v.get()
             }