Auto merge of #139301 - matthiaskrgr:rollup-sa6ali8, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #139080 (Experimental feature gate for `super let`)
 - #139145 (slice: Remove some uses of unsafe in first/last chunk methods)
 - #139149 (unstable book: document import_trait_associated_functions)
 - #139273 (Apply requested API changes to `cell_update`)
 - #139282 (rustdoc: make settings checkboxes always square)
 - #139283 (Rustc dev guide subtree update)
 - #139294 (Fix the `f16`/`f128` feature gates on integer literals)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 24 insertions, 0 deletions

diff --git a/tests/codegen/slice-split-at.rs b/tests/codegen/slice-split-at.rs
new file mode 100644
index 00000000000..07018cf9c91
--- /dev/null
+++ b/tests/codegen/slice-split-at.rs
@@ -0,0 +1,24 @@
+//@ compile-flags: -Copt-level=3
+#![crate_type = "lib"]
+
+// Check that no panic is generated in `split_at` when calculating the index for
+// the tail chunk using `checked_sub`.
+//
+// Tests written for refactored implementations of:
+// `<[T]>::{split_last_chunk, split_last_chunk_mut, last_chunk, last_chunk_mut}`
+
+// CHECK-LABEL: @split_at_last_chunk
+#[no_mangle]
+pub fn split_at_last_chunk(s: &[u8], chunk_size: usize) -> Option<(&[u8], &[u8])> {
+    // CHECK-NOT: panic
+    let Some(index) = s.len().checked_sub(chunk_size) else { return None };
+    Some(s.split_at(index))
+}
+
+// CHECK-LABEL: @split_at_mut_last_chunk
+#[no_mangle]
+pub fn split_at_mut_last_chunk(s: &mut [u8], chunk_size: usize) -> Option<(&mut [u8], &mut [u8])> {
+    // CHECK-NOT: panic
+    let Some(index) = s.len().checked_sub(chunk_size) else { return None };
+    Some(s.split_at_mut(index))
+}