Rollup merge of rust-lang#97675 - nvzqz:unsized-needs-drop, r=dtolnay

Make `std::mem::needs_drop` accept `?Sized`

This change attempts to make `needs_drop` work with types like `[u8]` and `str`.

This enables code in types like `Arc<T>` that was not possible before, such as rust-lang#97676.

Author: JohnTitor

core/src/intrinsics.rs

@@ -1162,7 +1162,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is [`mem::needs_drop`](crate::mem::needs_drop).
     #[rustc_const_stable(feature = "const_needs_drop", since = "1.40.0")]
-    pub fn needs_drop<T>() -> bool;
+    pub fn needs_drop<T: ?Sized>() -> bool;
 
     /// Calculates the offset from a pointer.
     ///

core/src/mem/mod.rs

@@ -592,7 +592,7 @@ pub const unsafe fn align_of_val_raw<T: ?Sized>(val: *const T) -> usize {
 #[stable(feature = "needs_drop", since = "1.21.0")]
 #[rustc_const_stable(feature = "const_mem_needs_drop", since = "1.36.0")]
 #[rustc_diagnostic_item = "needs_drop"]
-pub const fn needs_drop<T>() -> bool {
+pub const fn needs_drop<T: ?Sized>() -> bool {
     intrinsics::needs_drop::<T>()
 }