compiler: extend possible returned values

All integer values (int32, uint64...) should be able to be returned.

pkg/compiler/codegen.go

@@ -123,7 +123,9 @@ func (c *codegen) emitLoadConst(t types.TypeAndValue) {
 
 func (c *codegen) convertBasicType(t types.TypeAndValue, typ *types.Basic) {
 	switch typ.Kind() {
-	case types.Int, types.UntypedInt, types.Uint:
+	case types.Int, types.UntypedInt, types.Uint,
+		types.Int16, types.Uint16,
+		types.Int32, types.Uint32, types.Int64, types.Uint64:
 		val, _ := constant.Int64Val(t.Value)
 		emit.Int(c.prog.BinWriter, val)
 	case types.String, types.UntypedString:

pkg/compiler/return_test.go

@@ -5,6 +5,14 @@ import (
 	"testing"
 )
 
+func TestReturnInt64(t *testing.T) {
+	src := `package foo
+	func Main() int64 {
+		return 1
+	}`
+	eval(t, src, big.NewInt(1))
+}
+
 func TestMultipleReturn1(t *testing.T) {
 	src := `
 		package hello