From 8ed77f0d25e7fec4b1ee2459945d85ada49bf62d Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Fri, 22 May 2020 11:49:36 +0300
Subject: [PATCH 1/2] core: make GetUnspentCoins interop return array, fix
 #978.

---
 pkg/core/interop_neo.go | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/pkg/core/interop_neo.go b/pkg/core/interop_neo.go
index c0156c3a9..20fbcec56 100644
--- a/pkg/core/interop_neo.go
+++ b/pkg/core/interop_neo.go
@@ -7,6 +7,7 @@ import (
 	"math"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
+	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
@@ -177,10 +178,20 @@ func (ic *interopContext) txGetUnspentCoins(v *vm.VM) error {
 		return errors.New("value is not a transaction")
 	}
 	ucs, err := ic.dao.GetUnspentCoinState(tx.Hash())
-	if err != nil {
+	if err == storage.ErrKeyNotFound {
+		v.Estack().PushVal([]vm.StackItem{})
+		return nil
+	} else if err != nil {
 		return errors.New("no unspent coin state found")
 	}
-	v.Estack().PushVal(vm.NewInteropItem(ucs))
+
+	items := make([]vm.StackItem, 0, len(ucs.States))
+	for i := range items {
+		if ucs.States[i].State&state.CoinSpent == 0 {
+			items = append(items, vm.NewInteropItem(&ucs.States[i].Output))
+		}
+	}
+	v.Estack().PushVal(items)
 	return nil
 }
 

From eeeb05fc2cb7c1d1487252ed0165732f029a4dbf Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Fri, 22 May 2020 12:18:03 +0300
Subject: [PATCH 2/2] compiler: restore support for GetUnspentCoins

Revert a587274.
---
 pkg/compiler/syscall.go                | 17 +++++++++--------
 pkg/interop/transaction/transaction.go |  6 ++++++
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/pkg/compiler/syscall.go b/pkg/compiler/syscall.go
index 26307270d..086112040 100644
--- a/pkg/compiler/syscall.go
+++ b/pkg/compiler/syscall.go
@@ -62,14 +62,15 @@ var syscalls = map[string]map[string]string{
 		"GetTransaction":      "Neo.Block.GetTransaction",
 	},
 	"transaction": {
-		"GetAttributes": "Neo.Transaction.GetAttributes",
-		"GetHash":       "Neo.Transaction.GetHash",
-		"GetInputs":     "Neo.Transaction.GetInputs",
-		"GetOutputs":    "Neo.Transaction.GetOutputs",
-		"GetReferences": "Neo.Transaction.GetReferences",
-		"GetScript":     "Neo.InvocationTransaction.GetScript",
-		"GetType":       "Neo.Transaction.GetType",
-		"GetWitnesses":  "Neo.Transaction.GetWitnesses",
+		"GetAttributes":   "Neo.Transaction.GetAttributes",
+		"GetHash":         "Neo.Transaction.GetHash",
+		"GetInputs":       "Neo.Transaction.GetInputs",
+		"GetOutputs":      "Neo.Transaction.GetOutputs",
+		"GetReferences":   "Neo.Transaction.GetReferences",
+		"GetScript":       "Neo.InvocationTransaction.GetScript",
+		"GetType":         "Neo.Transaction.GetType",
+		"GetUnspentCoins": "Neo.Transaction.GetUnspentCoins",
+		"GetWitnesses":    "Neo.Transaction.GetWitnesses",
 	},
 	"asset": {
 		"Create":       "Neo.Asset.Create",
diff --git a/pkg/interop/transaction/transaction.go b/pkg/interop/transaction/transaction.go
index 00d06c25e..e354d7baf 100644
--- a/pkg/interop/transaction/transaction.go
+++ b/pkg/interop/transaction/transaction.go
@@ -53,6 +53,12 @@ func GetReferences(t Transaction) []interface{} {
 	return []interface{}{}
 }
 
+// GetUnspentCoins returns a slice of not yet spent ouputs of a given transaction.
+// This function uses `Neo.Transaction.GetUnspentCoint` syscall.
+func GetUnspentCoins(t Transaction) []output.Output {
+	return []output.Output{}
+}
+
 // GetInputs returns a slice of inputs of a given Transaction. Refer to input
 // package on how to use them. This function uses `Neo.Transaction.GetInputs`
 // syscall.