From eed8c4671ffe1ecc29db48739f73fb2e468d345e Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Mon, 9 Aug 2021 06:49:30 +0800
Subject: [PATCH] cgen: fix fn mut arg of array (#11104)

---
 vlib/v/gen/c/fn.v                       |  3 ++-
 vlib/v/tests/fn_mut_arg_of_array_test.v | 24 ++++++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/tests/fn_mut_arg_of_array_test.v

diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 5e21567cbf..5fc8720be3 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -1296,7 +1296,8 @@ fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type ast.Type, lang as
 	} else if arg_is_ptr && !expr_is_ptr {
 		if arg.is_mut {
 			if exp_sym.kind == .array {
-				if arg.expr is ast.Ident && (arg.expr as ast.Ident).kind == .variable {
+				if (arg.expr is ast.Ident && (arg.expr as ast.Ident).kind == .variable)
+					|| arg.expr is ast.SelectorExpr {
 					g.write('&/*arr*/')
 					g.expr(arg.expr)
 				} else {
diff --git a/vlib/v/tests/fn_mut_arg_of_array_test.v b/vlib/v/tests/fn_mut_arg_of_array_test.v
new file mode 100644
index 0000000000..012d5bcafe
--- /dev/null
+++ b/vlib/v/tests/fn_mut_arg_of_array_test.v
@@ -0,0 +1,24 @@
+fn test_fn_mut_arg_of_array() {
+	mut a := App{}
+	a.data << 1
+	a.do_something()
+	assert a.data.len == 2
+}
+
+struct App {
+pub mut:
+	data []int
+}
+
+fn (mut a App) do_something() {
+	assert a.data.len == 1
+	mut p := Proc{}
+	p.make_a(mut a.data)
+	assert a.data.len == 2
+}
+
+struct Proc {}
+
+fn (mut p Proc) make_a(mut data []int) {
+	data << 2
+}