Properly handle SINT_MIN in small_to_big()

As there is no overflow for signed integers, -SINT_MIN is undefined behaviour
and the cast to unsigned needs to happen before negation. SINT_MIN denotes the
minimum value that can be stored in the Sint type.

beam/big.c:1512:6: runtime error: negation of -9223372036854775808 cannot be represented in type 'Sint' (aka 'long'); cast to an unsigned type to negate this value to itself

1 files changed, 4 insertions, 2 deletions

diff --git a/erts/emulator/beam/big.c b/erts/emulator/beam/big.c
index 41a041eba6..4d087bf967 100644
--- a/erts/emulator/beam/big.c
+++ b/erts/emulator/beam/big.c
@@ -1506,13 +1506,15 @@ Eterm uword_to_big(UWord x, Eterm *y)
 */
 Eterm small_to_big(Sint x, Eterm *y)
 {
+    Uint xu;
     if (x >= 0) {
+        xu = x;
 	*y = make_pos_bignum_header(1);
     } else {
-	x = -x;
+        xu = -(Uint)x;
 	*y = make_neg_bignum_header(1);
     }
-    BIG_DIGIT(y, 0) = x;
+    BIG_DIGIT(y, 0) = xu;
     return make_big(y);
 }