Fix tidy errors

Author: Voultapher

library/core/src/slice/sort/select.rs

@@ -92,7 +92,10 @@ fn partition_at_index_loop<'a, T, F>(
         // slice. Partition the slice into elements equal to and elements greater than the pivot.
         // This case is usually hit when the slice contains many duplicate elements.
         if let Some(p) = ancestor_pivot {
-            if !is_less(p, unsafe { v.get_unchecked(pivot_pos) }) {
+            // SAFETY: choose_pivot promises to return a valid pivot position.
+            let pivot = unsafe { v.get_unchecked(pivot_pos) };
+
+            if !is_less(p, pivot) {
                 let num_lt = partition(v, pivot_pos, &mut |a, b| !is_less(b, a));
 
                 // Continue sorting elements greater than the pivot. We know that `mid` contains

library/core/src/slice/sort/shared/smallsort.rs

@@ -177,6 +177,8 @@ fn small_sort_fallback<T, F: FnMut(&T, &T) -> bool>(v: &mut [T], is_less: &mut F
 fn small_sort_general<T: FreezeMarker, F: FnMut(&T, &T) -> bool>(v: &mut [T], is_less: &mut F) {
     let mut stack_array = MaybeUninit::<[T; SMALL_SORT_GENERAL_SCRATCH_LEN]>::uninit();
 
+    // SAFETY: The memory is backed by `stack_array`, and the operation is safe as long as the len
+    // is the same.
     let scratch = unsafe {
         slice::from_raw_parts_mut(
             stack_array.as_mut_ptr() as *mut MaybeUninit<T>,
@@ -327,8 +329,9 @@ where
         }
 
         // SAFETY: The right side of `v` based on `len_div_2` is guaranteed in-bounds.
-        region =
-            unsafe { &mut *ptr::slice_from_raw_parts_mut(v_base.add(len_div_2), len - len_div_2) };
+        unsafe {
+            region = &mut *ptr::slice_from_raw_parts_mut(v_base.add(len_div_2), len - len_div_2)
+        };
     }
 
     // SAFETY: We checked that T is Freeze and thus observation safe.
@@ -812,14 +815,6 @@ pub(crate) const fn has_efficient_in_place_swap<T>() -> bool {
     mem::size_of::<T>() <= 8 // mem::size_of::<u64>()
 }
 
-#[test]
-fn type_info() {
-    assert!(has_efficient_in_place_swap::<i32>());
-    assert!(has_efficient_in_place_swap::<u64>());
-    assert!(!has_efficient_in_place_swap::<u128>());
-    assert!(!has_efficient_in_place_swap::<String>());
-}
-
 /// SAFETY: Only used for run-time optimization heuristic.
 #[rustc_unsafe_specialization_marker]
 trait CopyMarker {}

library/core/src/slice/sort/stable/quicksort.rs

@@ -256,12 +256,3 @@ const fn has_direct_interior_mutability<T>() -> bool {
     // Otherwise a type like Mutex<Option<Box<str>>> could lead to double free.
     !T::is_freeze()
 }
-
-#[test]
-fn freeze_check() {
-    assert!(!has_direct_interior_mutability::<u32>());
-    assert!(!has_direct_interior_mutability::<[u128; 2]>());
-
-    assert!(has_direct_interior_mutability::<crate::cell::Cell<u32>>());
-    assert!(has_direct_interior_mutability::<crate::sync::Mutex<u32>>());
-}

library/core/src/slice/sort/unstable/quicksort.rs

@@ -325,6 +325,8 @@ struct GapGuard<T> {
 
 impl<T> Drop for GapGuard<T> {
     fn drop(&mut self) {
+        // SAFETY: `self` MUST be constructed in a way that makes copying the gap value into
+        // `self.pos` sound.
         unsafe {
             ptr::copy_nonoverlapping(&*self.value, self.pos, 1);
         }
@@ -340,6 +342,8 @@ struct GapGuardRaw<T> {
 
 impl<T> Drop for GapGuardRaw<T> {
     fn drop(&mut self) {
+        // SAFETY: `self` MUST be constructed in a way that makes copying the gap value into
+        // `self.pos` sound.
         unsafe {
             ptr::copy_nonoverlapping(self.value, self.pos, 1);
         }

library/core/tests/slice.rs

@@ -1803,7 +1803,6 @@ fn brute_force_rotate_test_1() {
 #[test]
 #[cfg(not(target_arch = "wasm32"))]
 fn sort_unstable() {
-    // use core::cmp::Ordering::{Equal, Greater, Less};
     use rand::Rng;
 
     // Miri is too slow (but still need to `chain` to make the types match)