Auto merge of #86664 - m-ou-se:uninit-track-caller, r=JohnTitor

Add #[track_caller] for some function in core::mem. These functions can panic for some types. This makes the panic point to the code that calls e.g. mem::uninitialized(), instead of inside the definition of mem::uninitialized.

Author: bors

library/core/src/mem/maybe_uninit.rs

@@ -619,6 +619,7 @@ impl<T> MaybeUninit<T> {
  #[rustc_const_unstable(feature = "const_maybe_uninit_assume_init", issue = "none")]
  #[inline(always)]
  #[rustc_diagnostic_item = "assume_init"]
+ #[track_caller]
  pub const unsafe fn assume_init(self) -> T {
  // SAFETY: the caller must guarantee that `self` is initialized.
  // This also means that `self` must be a `value` variant.
@@ -690,6 +691,7 @@ impl<T> MaybeUninit<T> {
  #[unstable(feature = "maybe_uninit_extra", issue = "63567")]
  #[rustc_const_unstable(feature = "maybe_uninit_extra", issue = "63567")]
  #[inline(always)]
+ #[track_caller]
  pub const unsafe fn assume_init_read(&self) -> T {
  // SAFETY: the caller must guarantee that `self` is initialized.
  // Reading from `self.as_ptr()` is safe since `self` should be initialized.
@@ -937,6 +939,7 @@ impl<T> MaybeUninit<T> {
  /// ```
  #[unstable(feature = "maybe_uninit_array_assume_init", issue = "80908")]
  #[inline(always)]
+ #[track_caller]
  pub unsafe fn array_assume_init<const N: usize>(array: [Self; N]) -> [T; N] {
  // SAFETY:
  // * The caller guarantees that all elements of the array are initialized

library/core/src/mem/mod.rs

@@ -622,6 +622,7 @@ pub const fn needs_drop<T>() -> bool {
 #[allow(deprecated_in_future)]
 #[allow(deprecated)]
 #[rustc_diagnostic_item = "mem_zeroed"]
+#[track_caller]
 pub unsafe fn zeroed<T>() -> T {
  // SAFETY: the caller must guarantee that an all-zero value is valid for `T`.
  unsafe {
@@ -657,6 +658,7 @@ pub unsafe fn zeroed<T>() -> T {
 #[allow(deprecated_in_future)]
 #[allow(deprecated)]
 #[rustc_diagnostic_item = "mem_uninitialized"]
+#[track_caller]
 pub unsafe fn uninitialized<T>() -> T {
  // SAFETY: the caller must guarantee that an unitialized value is valid for `T`.
  unsafe {

src/test/ui/consts/assume-type-intrinsics.stderr

@@ -1,17 +1,9 @@
 error: any use of this value will cause an error
- --> $SRC_DIR/core/src/mem/maybe_uninit.rs:LL:COL
- |
-LL | intrinsics::assert_inhabited::<T>();
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
- | |
- | aborted execution: attempted to instantiate uninhabited type `!`
- | inside `MaybeUninit::<!>::assume_init` at $SRC_DIR/core/src/mem/maybe_uninit.rs:LL:COL
- | inside `_BAD` at $DIR/assume-type-intrinsics.rs:11:9
- | 
- ::: $DIR/assume-type-intrinsics.rs:10:5
+ --> $DIR/assume-type-intrinsics.rs:11:9
  |
 LL | / const _BAD: () = unsafe {
 LL | | MaybeUninit::<!>::uninit().assume_init();
+ | | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to instantiate uninhabited type `!`
 LL | | };
  | |______-
  |