compiler: allow to alias interop packages

Fix #397.

pkg/compiler/analysis.go

@@ -226,7 +226,7 @@ func isSyscall(fun *funcScope) bool {
 	if fun.selector == nil || fun.pkg == nil || !isInteropPath(fun.pkg.Path()) {
 		return false
 	}
-	_, ok := syscalls[fun.selector.Name][fun.name]
+	_, ok := syscalls[fun.pkg.Name()][fun.name]
 	return ok
 }
 

pkg/compiler/codegen.go

@@ -873,7 +873,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 				emit.Opcode(c.prog.BinWriter, opcode.CALLA)
 			}
 		case isSyscall(f):
-			c.convertSyscall(n, f.selector.Name, f.name)
+			c.convertSyscall(n, f.pkg.Name(), f.name)
 		default:
 			emit.Call(c.prog.BinWriter, opcode.CALLL, f.label)
 		}

pkg/compiler/interop_test.go

@@ -60,6 +60,19 @@ func TestFromAddress(t *testing.T) {
 
 		eval(t, src, append(addr1.BytesBE(), addr2.BytesBE()...))
 	})
+
+	t.Run("AliasPackage", func(t *testing.T) {
+		src := `
+		package foo
+		import uu "github.com/nspcc-dev/neo-go/pkg/interop/util"
+		func Main() []byte {
+			addr1 := uu.FromAddress("` + as1 + `")
+			addr2 := uu.FromAddress("` + as2 + `")
+			sum := append(addr1, addr2...)
+			return sum
+		}`
+		eval(t, src, append(addr1.BytesBE(), addr2.BytesBE()...))
+	})
 }
 
 func spawnVM(t *testing.T, ic *interop.Context, src string) *vm.VM {
@@ -167,6 +180,19 @@ func TestAppCall(t *testing.T) {
 
 		assertResult(t, v, big.NewInt(42))
 	})
+
+	t.Run("AliasPackage", func(t *testing.T) {
+		src := `package foo
+		import ee "github.com/nspcc-dev/neo-go/pkg/interop/engine"
+		func Main() int {
+			var addr = []byte(` + fmt.Sprintf("%#v", string(ih.BytesBE())) + `)
+			result := ee.AppCall(addr, "add3", 39)
+			return result.(int)
+		}`
+		v := spawnVM(t, ic, src)
+		require.NoError(t, v.Run())
+		assertResult(t, v, big.NewInt(42))
+	})
 }
 
 func getAppCallScript(h string) string {