Saturate the conversions in BitUint::set_bit

Author: cuviper

src/biguint.rs

@@ -2743,12 +2743,16 @@ impl BigUint {
     /// Note that setting a bit greater than the current bit length, a reallocation may be needed
     /// to store the new digits
     pub fn set_bit(&mut self, bit: u64, value: bool) {
+        // Note: we're saturating `digit_index` and `new_len` -- any such case is guaranteed to
+        // fail allocation, and that's more consistent than adding our own overflow panics.
         let bits_per_digit = u64::from(big_digit::BITS);
-        let digit_index = (bit / bits_per_digit).to_usize().unwrap();
+        let digit_index = (bit / bits_per_digit)
+            .to_usize()
+            .unwrap_or(core::usize::MAX);
         let bit_mask = (1 as BigDigit) << (bit % bits_per_digit);
         if value {
             if digit_index >= self.data.len() {
-                let new_len = digit_index.checked_add(1).unwrap();
+                let new_len = digit_index.saturating_add(1);
                 self.data.resize(new_len, 0);
             }
             self.data[digit_index] |= bit_mask;