fix: added null safe operator precendence rule (#12306)

Signed-off-by: Harshit Gangal <harshit@planetscale.com>
Co-authored-by: Harshit Gangal <harshit@planetscale.com>

go/vt/sqlparser/precedence.go

@@ -59,7 +59,7 @@ func precedenceFor(in Expr) Precendence {
 		return P12
 	case *ComparisonExpr:
 		switch node.Operator {
-		case EqualOp, NotEqualOp, GreaterThanOp, GreaterEqualOp, LessThanOp, LessEqualOp, LikeOp, InOp, RegexpOp:
+		case EqualOp, NotEqualOp, GreaterThanOp, GreaterEqualOp, LessThanOp, LessEqualOp, LikeOp, InOp, RegexpOp, NullSafeEqualOp:
 			return P11
 		}
 	case *IsExpr:

go/vt/sqlparser/precedence_test.go

@@ -198,6 +198,7 @@ func TestParens(t *testing.T) {
 		{in: "10 - 2 - 1", expected: "10 - 2 - 1"},
 		{in: "(10 - 2) - 1", expected: "10 - 2 - 1"},
 		{in: "10 - (2 - 1)", expected: "10 - (2 - 1)"},
+		{in: "0 <=> (1 and 0)", expected: "0 <=> (1 and 0)"},
 	}
 
 	for _, tc := range tests {