From 73a75cc27a76bb943b0404bf16cd6a0cce0e2669 Mon Sep 17 00:00:00 2001
From: Evgeniy Stratonikov <evgeniy@nspcc.ru>
Date: Fri, 5 Feb 2021 13:06:42 +0300
Subject: [PATCH] compiler: do not convert interop types on assertion

---
 pkg/compiler/analysis.go | 9 +++++++++
 pkg/compiler/codegen.go  | 7 +++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/pkg/compiler/analysis.go b/pkg/compiler/analysis.go
index bc55364d5..70df4d99f 100644
--- a/pkg/compiler/analysis.go
+++ b/pkg/compiler/analysis.go
@@ -284,3 +284,12 @@ func isInteropPath(s string) bool {
 func isNativeHelpersPath(s string) bool {
 	return strings.HasPrefix(s, interopPrefix+"/native")
 }
+
+// canConvert returns true if type doesn't need to be converted on type assertion.
+func canConvert(s string) bool {
+	if isInteropPath(s) {
+		s = s[len(interopPrefix):]
+		return s != "/iterator.Iterator" && s != "/storage.Context"
+	}
+	return true
+}
diff --git a/pkg/compiler/codegen.go b/pkg/compiler/codegen.go
index 57652b405..3bb330422 100644
--- a/pkg/compiler/codegen.go
+++ b/pkg/compiler/codegen.go
@@ -1197,8 +1197,11 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 	// not the assertion type.
 	case *ast.TypeAssertExpr:
 		ast.Walk(c, n.X)
-		typ := toNeoType(c.typeOf(n.Type))
-		emit.Instruction(c.prog.BinWriter, opcode.CONVERT, []byte{byte(typ)})
+		goTyp := c.typeOf(n.Type)
+		if canConvert(goTyp.String()) {
+			typ := toNeoType(goTyp)
+			emit.Instruction(c.prog.BinWriter, opcode.CONVERT, []byte{byte(typ)})
+		}
 		return nil
 	}
 	return c