From a1f2d3bf1dae85749847b367e6c6cbe36ea4554c Mon Sep 17 00:00:00 2001
From: Marc Vertes <mvertes@free.fr>
Date: Thu, 19 Dec 2019 18:32:04 +0100
Subject: [PATCH] fix: isNil was not forwarding result when used in a branch
 expression

---
 _test/nil1.go | 12 ++++++++++++
 interp/run.go |  8 ++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 _test/nil1.go

diff --git a/_test/nil1.go b/_test/nil1.go
new file mode 100644
index 000000000..040699bde
--- /dev/null
+++ b/_test/nil1.go
@@ -0,0 +1,12 @@
+package main
+
+func main() {
+	var a error = nil
+
+	if a == nil || a.Error() == "nil" {
+		println("a is nil")
+	}
+}
+
+// Output:
+// a is nil
diff --git a/interp/run.go b/interp/run.go
index 48c4eb255..9582aefde 100644
--- a/interp/run.go
+++ b/interp/run.go
@@ -2420,17 +2420,19 @@ func isNil(n *node) {
 		value = genValue(n.child[0])
 	}
 	tnext := getExec(n.tnext)
+	i := n.findex
 
 	if n.fnext != nil {
 		fnext := getExec(n.fnext)
 		n.exec = func(f *frame) bltn {
 			if value(f).IsNil() {
+				f.data[i].SetBool(true)
 				return tnext
 			}
+			f.data[i].SetBool(false)
 			return fnext
 		}
 	} else {
-		i := n.findex
 		n.exec = func(f *frame) bltn {
 			f.data[i].SetBool(value(f).IsNil())
 			return tnext
@@ -2446,17 +2448,19 @@ func isNotNil(n *node) {
 		value = genValue(n.child[0])
 	}
 	tnext := getExec(n.tnext)
+	i := n.findex
 
 	if n.fnext != nil {
 		fnext := getExec(n.fnext)
 		n.exec = func(f *frame) bltn {
 			if value(f).IsNil() {
+				f.data[i].SetBool(false)
 				return fnext
 			}
+			f.data[i].SetBool(true)
 			return tnext
 		}
 	} else {
-		i := n.findex
 		n.exec = func(f *frame) bltn {
 			f.data[i].SetBool(!value(f).IsNil())
 			return tnext