Merge pull request #2644 from nspcc-dev/fix-gen-decl

compiler: allow multi-return variables declaration

pkg/compiler/codegen.go

@@ -582,6 +582,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		for _, spec := range n.Specs {
 			switch t := spec.(type) {
 			case *ast.ValueSpec:
+				multiRet := n.Tok == token.VAR && len(t.Values) != 0 && len(t.Names) != len(t.Values)
 				for _, id := range t.Names {
 					if id.Name != "_" {
 						if c.scope == nil {
@@ -590,12 +591,16 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 						} else {
 							c.scope.newLocal(id.Name)
 						}
-						c.registerDebugVariable(id.Name, t.Type)
+						if !multiRet {
+							c.registerDebugVariable(id.Name, t.Type)
+						}
 					}
 				}
 				for i := range t.Names {
 					if len(t.Values) != 0 {
-						ast.Walk(c, t.Values[i])
+						if i == 0 || !multiRet {
+							ast.Walk(c, t.Values[i])
+						}
 					} else {
 						c.emitDefault(c.typeOf(t.Type))
 					}

pkg/compiler/vardecl_test.go

@@ -0,0 +1,31 @@
+package compiler_test
+
+import (
+	"math/big"
+	"testing"
+)
+
+func TestGenDeclWithMultiRet(t *testing.T) {
+	t.Run("global var decl", func(t *testing.T) {
+		src := `package foo
+				func Main() int {
+					var a, b = f()
+					return a + b
+				}
+				func f() (int, int) {
+					return 1, 2
+				}`
+		eval(t, src, big.NewInt(3))
+	})
+	t.Run("local var decl", func(t *testing.T) {
+		src := `package foo
+				var a, b = f()
+				func Main() int {
+					return a + b
+				}
+				func f() (int, int) {
+					return 1, 2
+				}`
+		eval(t, src, big.NewInt(3))
+	})
+}