fix: arbitrary for integer types

crates/dyn-abi/proptest-regressions/arbitrary.txt

@@ -0,0 +1,10 @@
+# Seeds for failure cases proptest has generated in the past. It is
+# automatically read and these particular cases re-run before any
+# novel cases are generated.
+#
+# It is recommended to check this file in to source control so that
+# everyone who runs the test benefits from these saved cases.
+cc de8751d56f475233e49dbbe6a4aff294553e6152d874aea3a472a8d11004f799 # shrinks to bytes = [0, 0, 0, 24]
+cc 5d629bdbb7a88bb18b2881e37de092a514711427a02eaa868e42a736d281e4f8 # shrinks to value = Int(0, 8)
+cc 840a037239bc6da9189c193c5e5ac7157016d70b97e37e398adf8196310d7f1a # shrinks to bytes = [0, 0, 0, 24, 87, 160, 45, 46, 6, 152, 28, 233, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
+cc 9ea2dc1c967e6193abcba4f4ebe248af405e9338d378a5b0b77f4b8330d11344 # shrinks to value = Int(33175087460508630782460469446745374746564684181783761617988838507891017121792, 256)

crates/dyn-abi/src/arbitrary.rs

@@ -523,8 +523,13 @@ fn int_strategy<T: Arbitrary>() -> impl Strategy<Value = (ValueOfStrategy<T::Str
 #[inline]
 fn adjust_int(mut int: I256, size: usize) -> I256 {
     if size < 256 {
-        int &= (I256::ONE << size).wrapping_sub(I256::ONE);
+        if int.bit(size) {
+            int |= I256::MINUS_ONE - (I256::ONE << size).wrapping_sub(I256::ONE);
+        } else {
+            int &= (I256::ONE << size).wrapping_sub(I256::ONE);
+        }
     }
+
     int
 }