From 4f93be7f19aec37fe776aeebfb88a8c50679136d Mon Sep 17 00:00:00 2001
From: Marc Vertes <mvertes@free.fr>
Date: Mon, 16 Dec 2019 19:00:07 +0100
Subject: [PATCH] fix: emulate struct by interface{} only for recursive struct
 types

---
 _test/struct29.go | 19 +++++++++++++++++++
 _test/struct30.go | 19 +++++++++++++++++++
 interp/gta.go     |  1 +
 interp/run.go     |  2 +-
 interp/type.go    |  4 +++-
 5 files changed, 43 insertions(+), 2 deletions(-)
 create mode 100644 _test/struct29.go
 create mode 100644 _test/struct30.go

diff --git a/_test/struct29.go b/_test/struct29.go
new file mode 100644
index 00000000..75159e07
--- /dev/null
+++ b/_test/struct29.go
@@ -0,0 +1,19 @@
+package main
+
+type T1 struct {
+	A []T2
+	B []T2
+}
+
+type T2 struct {
+	name string
+}
+
+var t = T1{}
+
+func main() {
+	println("ok")
+}
+
+// Output:
+// ok
diff --git a/_test/struct30.go b/_test/struct30.go
new file mode 100644
index 00000000..e872ba9d
--- /dev/null
+++ b/_test/struct30.go
@@ -0,0 +1,19 @@
+package main
+
+type T1 struct {
+	A []T2
+	M map[uint64]T2
+}
+
+type T2 struct {
+	name string
+}
+
+var t = T1{}
+
+func main() {
+	println("ok")
+}
+
+// Output:
+// ok
diff --git a/interp/gta.go b/interp/gta.go
index 6658f03a..b85e3cfe 100644
--- a/interp/gta.go
+++ b/interp/gta.go
@@ -30,6 +30,7 @@ func (interp *Interpreter) gta(root *node, rpath string) ([]*node, error) {
 		case defineStmt:
 			var atyp *itype
 			if n.nleft+n.nright < len(n.child) {
+				// Type is declared explicitly in the assign expression.
 				if atyp, err = nodeType(interp, sc, n.child[n.nleft]); err != nil {
 					return false
 				}
diff --git a/interp/run.go b/interp/run.go
index 843d2c4b..48c4eb25 100644
--- a/interp/run.go
+++ b/interp/run.go
@@ -239,7 +239,7 @@ func isRecursiveStruct(t *itype, rtype reflect.Type) bool {
 	if t.cat == structT && rtype.Kind() == reflect.Interface {
 		return true
 	}
-	if t.cat == ptrT {
+	if t.cat == ptrT && t.rtype != nil {
 		return isRecursiveStruct(t.val, t.rtype.Elem())
 	}
 	return false
diff --git a/interp/type.go b/interp/type.go
index db5b20ec..74ada6ed 100644
--- a/interp/type.go
+++ b/interp/type.go
@@ -885,7 +885,9 @@ func (t *itype) refType(defined map[string]bool) reflect.Type {
 			panic(err)
 		}
 	}
-	if t.val != nil && defined[t.val.name] {
+	if t.val != nil && defined[t.val.name] && !t.val.incomplete && t.val.rtype == nil {
+		// Replace reference to self (direct or indirect) by an interface{} to handle
+		// recursive types with reflect.
 		t.val.rtype = interf
 	}
 	switch t.cat {