compiler: allow to use type conversion in range

pkg/compiler/for_test.go

@@ -737,6 +737,20 @@ func TestForLoopRangeMap(t *testing.T) {
 	eval(t, src, big.NewInt(42))
 }
 
+func TestForLoopRangeTypeConversion(t *testing.T) {
+	src := `package foo
+	type intArr []int
+	func Main() int {
+		a := []int{1, 2, 3}
+		s := 0
+		for _, v := range intArr(a) {
+			s += v
+		}
+		return s
+	}`
+	eval(t, src, big.NewInt(6))
+}
+
 func TestForLoopComplexConditions(t *testing.T) {
 	src := `
 	package foo

pkg/compiler/func_scope.go

@@ -102,6 +102,11 @@ func (c *funcScope) analyzeVoidCalls(node ast.Node) bool {
 		}
 	case *ast.BinaryExpr:
 		return false
+	case *ast.RangeStmt:
+		ce, ok := n.X.(*ast.CallExpr)
+		if ok {
+			c.voidCalls[ce] = false
+		}
 	case *ast.IfStmt:
 		// we can't just return `false`, because we still need to process body
 		ce, ok := n.Cond.(*ast.CallExpr)