From 8ea3ef0b62e0644afbab88e8d8b0bddd2e99fec2 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Tue, 11 Feb 2020 13:15:08 +0300
Subject: [PATCH] compiler: process empty []byte{} literals as ByteArrays

It is wrong to count an empty byte slice as an Array.
---
 pkg/compiler/analysis.go |  6 ++++++
 pkg/compiler/for_test.go | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/pkg/compiler/analysis.go b/pkg/compiler/analysis.go
index ad46b8b93..bf3272baa 100644
--- a/pkg/compiler/analysis.go
+++ b/pkg/compiler/analysis.go
@@ -189,6 +189,12 @@ func isBuiltin(expr ast.Expr) bool {
 
 func isByteArray(lit *ast.CompositeLit, tInfo *types.Info) bool {
 	if len(lit.Elts) == 0 {
+		if typ, ok := lit.Type.(*ast.ArrayType); ok {
+			if name, ok := typ.Elt.(*ast.Ident); ok {
+				return name.Name == "byte" || name.Name == "uint8"
+			}
+		}
+
 		return false
 	}
 
diff --git a/pkg/compiler/for_test.go b/pkg/compiler/for_test.go
index 83b460517..6c3f67b87 100644
--- a/pkg/compiler/for_test.go
+++ b/pkg/compiler/for_test.go
@@ -293,6 +293,18 @@ func TestAppendByte(t *testing.T) {
 	eval(t, src, []uint8{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06})
 }
 
+func TestAppendByteToEmpty(t *testing.T) {
+	src := `
+	package foo
+	func Main() []byte {
+		out := []byte{}
+		out = append(out, 1)
+		out = append(out, 2)
+		return out
+	}`
+	eval(t, src, []byte{1, 2})
+}
+
 func TestAppendString(t *testing.T) {
 	src := `
 	package foo