FEAT: allow SIGNED word as a key word in vector construction dialect as a oposite to already supported UNSIGNED

Implements: metaeducation/rebol-issues#2395

Author: Oldes

src/core/t-vector.c

@@ -484,10 +484,12 @@ void Set_Vector_Row(REBSER *ser, REBVAL *blk)
 	REBSER *vect;
 	REBVAL *iblk = 0;
 
-	// UNSIGNED
-	if (IS_WORD(bp) && VAL_WORD_CANON(bp) == SYM_UNSIGNED) { 
-		sign = 1;
-		bp++;
+	// SIGNED / UNSIGNED
+	if (IS_WORD(bp)) {
+		switch (VAL_WORD_CANON(bp)) {
+		case SYM_UNSIGNED: sign = 1; bp++; break;
+		case SYM_SIGNED:   sign = 0; bp++; break;
+		}
 	}
 
 	// INTEGER! or DECIMAL!

src/tests/units/vector-test.r3

@@ -92,6 +92,11 @@ Rebol [
 	--assert 2 = index? v: make vector! [integer! 16 [1 2] 2]
 	--assert 2 = index? v: make vector! [integer! 16 #{01000200} 2]
 
+--test-- "issue/2395"
+	;@@ https://github.com/rebol/rebol-issues/issues/2395
+	--assert "make vector! [integer! 32 2 [0 0]]" = mold make vector! [signed integer! 32 2]
+	--assert "make vector! [unsigned integer! 32 2 [0 0]]" = mold make vector! [unsigned integer! 32 2]
+
 --test-- "MOLD/flat on vector"
 	;@@ https://github.com/rebol/rebol-issues/issues/2349
 	--assert (mold/flat make vector! [integer! 8 12]) = {make vector! [integer! 8 12 [0 0 0 0 0 0 0 0 0 0 0 0]]}