allow regexp args to be converted

Author: andy-wm-arthur

enginetest/queries/queries.go

@@ -4879,7 +4879,14 @@ var QueryTests = []QueryTest{
 			{"XXXXX XXX"},
 		},
 	},
-
+	{
+		Query:    `SELECT 20 REGEXP '^[-]?2[0-9]+$'`,
+		Expected: []sql.Row{{true}},
+	},
+	{
+		Query:    `SELECT 30 REGEXP '^[-]?2[0-9]+$'`,
+		Expected: []sql.Row{{false}},
+	},
 	{
 		Query: "SELECT * FROM newlinetable WHERE s LIKE '%text%'",
 		Expected: []sql.Row{

sql/expression/comparison.go

@@ -392,7 +392,7 @@ func NewRegexp(left sql.Expression, right sql.Expression) *Regexp {
 
 // Eval implements the Expression interface.
 func (re *Regexp) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
-	if sql.IsText(re.Left().Type()) && sql.IsText(re.Right().Type()) {
+	if sql.IsText(re.Right().Type()) {
 		return re.compareRegexp(ctx, row)
 	}