From 3cbd138b67e9a1b8b897891c10618094dffff78c Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Thu, 26 Mar 2020 15:35:15 +0300
Subject: [PATCH] compiler: allow to declare variables of struct type

Previously, struct variables were initialize with VM's nil value
which is of primitive type. Thus SETITEM used for struct's field
updating wasn't working.
---
 pkg/compiler/analysis.go    | 13 +++++++++++++
 pkg/compiler/codegen.go     |  5 +++++
 pkg/compiler/struct_test.go | 25 +++++++++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/pkg/compiler/analysis.go b/pkg/compiler/analysis.go
index 6ae160931..90dd5e318 100644
--- a/pkg/compiler/analysis.go
+++ b/pkg/compiler/analysis.go
@@ -203,6 +203,19 @@ func isByte(t types.Type) bool {
 	return ok && e.Kind() == types.Byte
 }
 
+func (c *codegen) isStructType(t ast.Expr) (int, bool) {
+	switch s := t.(type) {
+	case *ast.StructType:
+		return s.Fields.NumFields(), true
+	case *ast.Ident:
+		st, ok := c.typeInfo.Types[s].Type.Underlying().(*types.Struct)
+		if ok {
+			return st.NumFields(), true
+		}
+	}
+	return 0, false
+}
+
 func isByteArray(lit *ast.CompositeLit, tInfo *types.Info) bool {
 	if len(lit.Elts) == 0 {
 		if typ, ok := lit.Type.(*ast.ArrayType); ok {
diff --git a/pkg/compiler/codegen.go b/pkg/compiler/codegen.go
index 7980b9ac1..ddd07a48e 100644
--- a/pkg/compiler/codegen.go
+++ b/pkg/compiler/codegen.go
@@ -287,6 +287,11 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 					emit.Opcode(c.prog.BinWriter, opcode.NEWARRAY)
 					l := c.scope.newLocal(t.Names[0].Name)
 					c.emitStoreLocal(l)
+				} else if n, ok := c.isStructType(t.Type); ok {
+					emit.Int(c.prog.BinWriter, int64(n))
+					emit.Opcode(c.prog.BinWriter, opcode.NEWSTRUCT)
+					l := c.scope.newLocal(t.Names[0].Name)
+					c.emitStoreLocal(l)
 				}
 			}
 		}
diff --git a/pkg/compiler/struct_test.go b/pkg/compiler/struct_test.go
index 964edbbd4..1dd63e07f 100644
--- a/pkg/compiler/struct_test.go
+++ b/pkg/compiler/struct_test.go
@@ -302,6 +302,31 @@ var structTestCases = []testCase{
 		`,
 		big.NewInt(14),
 	},
+	{
+		"declare struct literal",
+		`package foo
+		func Main() int {
+			var x struct {
+				a int
+			}
+			x.a = 2
+			return x.a
+		}`,
+		big.NewInt(2),
+	},
+	{
+		"declare struct type",
+		`package foo
+		type withA struct {
+			a int
+		}
+		func Main() int {
+			var x withA
+			x.a = 2
+			return x.a
+		}`,
+		big.NewInt(2),
+	},
 }
 
 func TestStructs(t *testing.T) {