math/big: fix destination leak into result value
This code would panic:
z := big.NewInt(1)
z.SetBit(big.NewInt(0), 2, 1)
if z.Cmp(big.NewInt(1<<2)) != 0 {
panic("fail")
}
R=rsc, gri
CC=golang-dev
https://golang.org/cl/5437081
diff --git a/src/pkg/math/big/int_test.go b/src/pkg/math/big/int_test.go
index 163c662..aa7c194 100644
--- a/src/pkg/math/big/int_test.go
+++ b/src/pkg/math/big/int_test.go
@@ -1242,10 +1242,14 @@
x.SetString(test.x, 0)
b := x.Bit(test.i)
if b != test.b {
-
- t.Errorf("#%d want %v got %v", i, test.b, b)
+ t.Errorf("#%d got %v want %v", i, b, test.b)
}
}
+ z := NewInt(1)
+ z.SetBit(NewInt(0), 2, 1)
+ if z.Cmp(NewInt(4)) != 0 {
+ t.Errorf("destination leaked into result; got %s want 4", z)
+ }
}
func BenchmarkBitset(b *testing.B) {
