From e50f391f1e495c96747ab439091575b5a11b557b Mon Sep 17 00:00:00 2001
From: Roger Peppe <rogpeppe@gmail.com>
Date: Tue, 31 Mar 2020 17:05:42 +0100
Subject: [PATCH] avro: avoid error on empty Go struct type

---
 gotype.go      |  4 +++-
 gotype_test.go | 11 +++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/gotype.go b/gotype.go
index b43a61c..030d3b0 100644
--- a/gotype.go
+++ b/gotype.go
@@ -205,7 +205,9 @@ func (gts *goTypeSchema) schemaForGoType(t reflect.Type) (interface{}, error) {
 		if err != nil {
 			return nil, err
 		}
-		var fields []interface{}
+		// Note: don't start with nil fields because gogen-avro
+		// doesn't like the nil value.
+		fields := []interface{}{}
 		for i := 0; i < t.NumField(); i++ {
 			f := t.Field(i)
 			if f.Anonymous {
diff --git a/gotype_test.go b/gotype_test.go
index ac02d13..f6850ff 100644
--- a/gotype_test.go
+++ b/gotype_test.go
@@ -48,6 +48,17 @@ func TestSimpleGoType(t *testing.T) {
 	wg.Wait()
 }
 
+func TestEmptyGoStructType(t *testing.T) {
+	c := qt.New(t)
+	type T struct{}
+	data, wType, err := avro.Marshal(T{})
+	c.Assert(err, qt.Equals, nil)
+	var x T
+	_, err = avro.Unmarshal(data, &x, wType)
+	c.Assert(err, qt.Equals, nil)
+	c.Check(x, qt.Equals, T{})
+}
+
 func TestGoTypeWithOmittedFields(t *testing.T) {
 	c := qt.New(t)
 	type R struct {