fix sign for alised var for Vint::quotRem

include/mcl/vint.hpp

@@ -1544,10 +1544,12 @@ public:
 	*/
 	static void quotRem(VintT *q, VintT& r, const VintT& x, const VintT& y)
 	{
+		assert(q != &r);
 		VintT yy = y;
-		bool qsign = x.isNeg_ ^ y.isNeg_;
+		bool yNeg = y.isNeg_;
+		bool qsign = x.isNeg_ ^ yNeg;
 		udiv(q, r, x.buf_, x.size(), y.buf_, y.size());
-		r.isNeg_ = y.isNeg_;
+		r.isNeg_ = yNeg;
 		if (q) q->isNeg_ = qsign;
 		if (!r.isZero() && qsign) {
 			if (q) {

test/vint_test.cpp

@@ -973,6 +973,33 @@ CYBOZU_TEST_AUTO(Vint)
 		CYBOZU_TEST_EQUAL(q2, tbl[i].q2);
 		CYBOZU_TEST_EQUAL(r2, tbl[i].r2);
 		CYBOZU_TEST_EQUAL(q2 * b + r2, a);
+		r2 = 0;
+		Vint::quotRem(&b, r2, a, b);
+		CYBOZU_TEST_EQUAL(b, tbl[i].q2);
+		CYBOZU_TEST_EQUAL(r2, tbl[i].r2);
+		b = tbl[i].b;
+		r2 = 0;
+		Vint::quotRem(&a, r2, a, b);
+		CYBOZU_TEST_EQUAL(a, tbl[i].q2);
+		CYBOZU_TEST_EQUAL(r2, tbl[i].r2);
+		a = tbl[i].a;
+		q = 0;
+		Vint::quotRem(&q, a, a, b);
+		CYBOZU_TEST_EQUAL(q, tbl[i].q2);
+		CYBOZU_TEST_EQUAL(a, tbl[i].r2);
+		a = tbl[i].a;
+		q = 0;
+		Vint::quotRem(&q, a, a, b);
+		CYBOZU_TEST_EQUAL(q, tbl[i].q2);
+		CYBOZU_TEST_EQUAL(a, tbl[i].r2);
+		a = tbl[i].a;
+		q = 0;
+		Vint::quotRem(&q, b, a, b);
+		CYBOZU_TEST_EQUAL(q, tbl[i].q2);
+		CYBOZU_TEST_EQUAL(b, tbl[i].r2);
+		Vint::quotRem(&q, a, a, a);
+		CYBOZU_TEST_EQUAL(q, 1);
+		CYBOZU_TEST_EQUAL(a, 0);
 	}
 	CYBOZU_TEST_EQUAL(Vint("15") / Vint("3"), Vint("5"));
 	CYBOZU_TEST_EQUAL(Vint("15") / Vint("-3"), Vint("-5"));