From c6dc95eb7e8760d6224e8ecded5f3c4ddff9d639 Mon Sep 17 00:00:00 2001
From: Marc Vertes <mvertes@free.fr>
Date: Sat, 31 Jul 2021 10:59:22 +0200
Subject: [PATCH] interp: improve handling of interface struct field

Wrap non empty interface value  in struct field, to allow method
lookup.

Fixes #1208.
---
 _test/issue-1208.go | 23 +++++++++++++++++++++++
 interp/run.go       |  2 ++
 2 files changed, 25 insertions(+)
 create mode 100644 _test/issue-1208.go

diff --git a/_test/issue-1208.go b/_test/issue-1208.go
new file mode 100644
index 000000000..9d2ee4aa8
--- /dev/null
+++ b/_test/issue-1208.go
@@ -0,0 +1,23 @@
+package main
+
+type Enabler interface {
+	Enabled() bool
+}
+
+type Logger struct {
+	core Enabler
+}
+
+func (log *Logger) GetCore() Enabler { return log.core }
+
+type T struct{}
+
+func (t *T) Enabled() bool { return true }
+
+func main() {
+	base := &Logger{&T{}}
+	println(base.GetCore().Enabled())
+}
+
+// Output:
+// true
diff --git a/interp/run.go b/interp/run.go
index 745a5c7bc..1f839be32 100644
--- a/interp/run.go
+++ b/interp/run.go
@@ -2543,6 +2543,8 @@ func doComposite(n *node, hasType bool, keyed bool) {
 			values[fieldIndex] = genValueInterfaceArray(val)
 		case isRecursiveType(ft, rft):
 			values[fieldIndex] = genValueRecursiveInterface(val, rft)
+		case isInterfaceSrc(ft) && !isEmptyInterface(ft):
+			values[fieldIndex] = genValueInterface(val)
 		case isInterface(ft):
 			values[fieldIndex] = genInterfaceWrapper(val, rft)
 		default: