From 0880e88fa5b1d258fb4e3aa08a97798c66e1f280 Mon Sep 17 00:00:00 2001
From: Anthony De Meulemeester <anthony@academiclabs.co>
Date: Sat, 20 Oct 2018 07:11:00 +0200
Subject: [PATCH] Fixed bug in else stmts (CityOfZion/neo-storm#42)

* Fixed bug in else stmts

* Fixed if else bug

* Back to %v for formatting instructions

Imported from CityOfZion/neo-storm (ea8440e1454207753c8d209ce7c2cf724fd4ea16).
---
 cli/smartcontract/smart_contract.go |  3 +--
 pkg/vm/compiler/codegen.go          | 18 ++++++++++--------
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/cli/smartcontract/smart_contract.go b/cli/smartcontract/smart_contract.go
index 0ae5e2585..2c7a7b12a 100644
--- a/cli/smartcontract/smart_contract.go
+++ b/cli/smartcontract/smart_contract.go
@@ -173,8 +173,7 @@ func testInvoke(ctx *cli.Context) error {
 	// On the long term the internal VM will run the script.
 	// TODO: remove RPC dependency, hardcoded node.
 	endpoint := "http://seed5.bridgeprotocol.io:10332"
-	opts := rpc.ClientOptions{}
-	client, err := rpc.NewClient(context.TODO(), endpoint, opts)
+	client, err := rpc.NewClient(context.TODO(), endpoint, rpc.ClientOptions{})
 	if err != nil {
 		return cli.NewExitError(err, 1)
 	}
diff --git a/pkg/vm/compiler/codegen.go b/pkg/vm/compiler/codegen.go
index 0c4d3b991..9457c4130 100644
--- a/pkg/vm/compiler/codegen.go
+++ b/pkg/vm/compiler/codegen.go
@@ -257,11 +257,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			log.Fatal("multiple returns not supported.")
 		}
 
-		// @OPTIMIZE: We could skip these 3 instructions for each return statement.
-		// To be backwards compatible we will put them them in.
-		// See issue #65 (https://github.com/CityOfZion/neo-go/issues/65)
 		l := c.newLabel()
-		// emitJmp(c.prog, vm.JMP, int16(l))
 		c.setLabel(l)
 
 		if len(n.Results) > 0 {
@@ -276,6 +272,8 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 	case *ast.IfStmt:
 		lIf := c.newLabel()
 		lElse := c.newLabel()
+		lElseEnd := c.newLabel()
+
 		if n.Cond != nil {
 			ast.Walk(c, n.Cond)
 			emitJmp(c.prog, vm.JMPIFNOT, int16(lElse))
@@ -283,15 +281,15 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 
 		c.setLabel(lIf)
 		ast.Walk(c, n.Body)
-
 		if n.Else != nil {
-			// TODO: handle else statements.
-			// emitJmp(c.prog, vm.JMP, int16(lEnd))
+			emitJmp(c.prog, vm.JMP, int16(lElseEnd))
 		}
+
 		c.setLabel(lElse)
 		if n.Else != nil {
 			ast.Walk(c, n.Else)
 		}
+		c.setLabel(lElseEnd)
 		return nil
 
 	case *ast.BasicLit:
@@ -659,7 +657,11 @@ func (c *codegen) convertToken(tok token.Token) {
 	case token.GEQ:
 		emitOpcode(c.prog, vm.GTE)
 	case token.EQL:
-		emitOpcode(c.prog, vm.NUMEQUAL)
+		// It seems that (looking to the python compiler) that comparing for
+		// equal (==) needs to return the instruction EQUAL. Where comparing
+		// (anything) to not equal (!=) needs to use the opcode NUMNOTEQUAL
+		// even for comparing strings.
+		emitOpcode(c.prog, vm.EQUAL)
 	case token.NEQ:
 		emitOpcode(c.prog, vm.NUMNOTEQUAL)
 	case token.DEC: