[GitHub] [arrow-rs] tustvold commented on a diff in pull request #3026: Make various i256 methods const

[GitBox <gi...@apache.org>]

tustvold commented on code in PR #3026:
URL: https://github.com/apache/arrow-rs/pull/3026#discussion_r1014727497


##########
arrow-buffer/src/bigint.rs:
##########
@@ -369,6 +373,20 @@ impl i256 {
     }
 }
 
+/// Temporary workaround due to lack of stable const array slicing
+/// See <https://github.com/rust-lang/rust/issues/90091>
+const fn split_array(vals: [u8; 32]) -> ([u8; 16], [u8; 16]) {
+    let mut a = [0; 16];
+    let mut b = [0; 16];
+    let mut i = 0;
+    while i != 16 {
+        a[i] = vals[i];
+        b[i] = vals[i + 16];
+        i += 1;
+    }
+    (a, b)
+}

Review Comment:
   Arrays are stack allocated, and in practice the compiler will optimise all of this away



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