Check if regexp matcher is nil.

engine_test.go

@@ -1582,6 +1582,18 @@ func TestStarPanic197(t *testing.T) {
 	require.Len(rows, 3)
 }
 
+func TestInvalidRegexp(t *testing.T) {
+	require := require.New(t)
+	e := newEngine(t)
+
+	ctx := newCtx()
+	_, iter, err := e.Query(ctx, `SELECT * FROM mytable WHERE s REGEXP("*main.go")`)
+	require.NoError(err)
+
+	_, err = sql.RowIterToRows(iter)
+	require.Error(err)
+}
+
 func TestIndexes(t *testing.T) {
 	e := newEngine(t)
 

sql/expression/comparison.go

@@ -259,7 +259,9 @@ func (re *Regexp) compareRegexp(ctx *sql.Context, row sql.Row) (interface{}, err
 				},
 			}
 		}
-		matcher = re.pool.Get().(regex.Matcher)
+		if obj := re.pool.Get(); obj != nil {
+			matcher = obj.(regex.Matcher)
+		}
 	}
 	if matcher == nil {
 		return nil, err

sql/expression/comparison_test.go

@@ -210,6 +210,19 @@ func testRegexpCases(t *testing.T) {
 	}
 }
 
+func TestInvalidRegexp(t *testing.T) {
+	t.Helper()
+	require := require.New(t)
+
+	col1 := NewGetField(0, sql.Text, "col1", true)
+	invalid := NewLiteral("*col1", sql.Text)
+	r := NewRegexp(col1, invalid)
+	row := sql.NewRow("col1")
+
+	_, err := r.Eval(sql.NewEmptyContext(), row)
+	require.Error(err)
+}
+
 func TestIn(t *testing.T) {
 	testCases := []struct {
 		name   string