From 8b922c057cb1c0e55e43a72b23995ac2d1525ef1 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Wed, 29 Jan 2020 17:04:49 +0300
Subject: [PATCH] compiler: fix a bug with assignment to underscore

When using underscore it does not appear in the list
of local variables, so it can't be assigned.
In this commit the value is dropped.
---
 pkg/compiler/codegen.go     |  8 ++++++--
 pkg/compiler/return_test.go | 15 +++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/pkg/compiler/codegen.go b/pkg/compiler/codegen.go
index 1cce7c6e7..3ab378404 100644
--- a/pkg/compiler/codegen.go
+++ b/pkg/compiler/codegen.go
@@ -253,8 +253,12 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 						ast.Walk(c, n.Rhs[i])
 					}
 
-					l := c.scope.loadLocal(t.Name)
-					c.emitStoreLocal(l)
+					if t.Name == "_" {
+						emitOpcode(c.prog.BinWriter, opcode.DROP)
+					} else {
+						l := c.scope.loadLocal(t.Name)
+						c.emitStoreLocal(l)
+					}
 				}
 
 			case *ast.SelectorExpr:
diff --git a/pkg/compiler/return_test.go b/pkg/compiler/return_test.go
index 03a8589fa..a97c3a25a 100644
--- a/pkg/compiler/return_test.go
+++ b/pkg/compiler/return_test.go
@@ -37,6 +37,21 @@ func TestMultipleReturn2(t *testing.T) {
 	eval(t, src, big.NewInt(9))
 }
 
+func TestMultipleReturnUnderscore(t *testing.T) {
+	src := `
+		package hello
+		func f3() (int, int, int) {
+			return 5, 6, 7
+		}
+
+		func Main() int {
+			a, _, c := f3()
+			return a+c
+		}
+	`
+	eval(t, src, big.NewInt(12))
+}
+
 func TestMultipleReturnWithArg(t *testing.T) {
 	src := `
 		package hello