From a6389aca5ef4ba058ba4aa44f4d6d7e5567c49dc Mon Sep 17 00:00:00 2001
From: Marc Vertes <mvertes@free.fr>
Date: Sat, 25 Apr 2020 17:16:03 +0200
Subject: [PATCH] fix: improve handling of nil

---
 _test/nil2.go  | 12 ++++++++++++
 interp/type.go | 21 ++++++++++++++++++---
 2 files changed, 30 insertions(+), 3 deletions(-)
 create mode 100644 _test/nil2.go

diff --git a/_test/nil2.go b/_test/nil2.go
new file mode 100644
index 00000000..05e897df
--- /dev/null
+++ b/_test/nil2.go
@@ -0,0 +1,12 @@
+package main
+
+func test() error { return nil }
+
+func main() {
+	if err := test(); nil == err {
+		println("err is nil")
+	}
+}
+
+// Output:
+// err is nil
diff --git a/interp/type.go b/interp/type.go
index 7c29d5bb..0bc74849 100644
--- a/interp/type.go
+++ b/interp/type.go
@@ -1204,6 +1204,9 @@ func isStruct(t *itype) bool {
 func isBool(t *itype) bool { return t.TypeOf().Kind() == reflect.Bool }
 
 func isInt(t reflect.Type) bool {
+	if t == nil {
+		return false
+	}
 	switch t.Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 		return true
@@ -1212,6 +1215,9 @@ func isInt(t reflect.Type) bool {
 }
 
 func isUint(t reflect.Type) bool {
+	if t == nil {
+		return false
+	}
 	switch t.Kind() {
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 		return true
@@ -1220,6 +1226,9 @@ func isUint(t reflect.Type) bool {
 }
 
 func isComplex(t reflect.Type) bool {
+	if t == nil {
+		return false
+	}
 	switch t.Kind() {
 	case reflect.Complex64, reflect.Complex128:
 		return true
@@ -1228,6 +1237,9 @@ func isComplex(t reflect.Type) bool {
 }
 
 func isFloat(t reflect.Type) bool {
+	if t == nil {
+		return false
+	}
 	switch t.Kind() {
 	case reflect.Float32, reflect.Float64:
 		return true
@@ -1236,11 +1248,14 @@ func isFloat(t reflect.Type) bool {
 }
 
 func isByteArray(t reflect.Type) bool {
+	if t == nil {
+		return false
+	}
 	k := t.Kind()
 	return (k == reflect.Array || k == reflect.Slice) && t.Elem().Kind() == reflect.Uint8
 }
 
-func isFloat32(t reflect.Type) bool { return t.Kind() == reflect.Float32 }
-func isFloat64(t reflect.Type) bool { return t.Kind() == reflect.Float64 }
+func isFloat32(t reflect.Type) bool { return t != nil && t.Kind() == reflect.Float32 }
+func isFloat64(t reflect.Type) bool { return t != nil && t.Kind() == reflect.Float64 }
 func isNumber(t reflect.Type) bool  { return isInt(t) || isFloat(t) || isComplex(t) }
-func isString(t reflect.Type) bool  { return t.Kind() == reflect.String }
+func isString(t reflect.Type) bool  { return t != nil && t.Kind() == reflect.String }