From 9a6e335601a3bf7f1a736633472081375f8204ce Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Tue, 17 Dec 2024 20:39:27 +0800
Subject: [PATCH] cgen: fix assign optional aliases of fixed array (fix #23185)
 (#23188)

---
 vlib/v/gen/c/assign.v                         | 20 ++++++++++++++-----
 .../assign_option_of_fixed_array_test.v       |  8 ++++++++
 2 files changed, 23 insertions(+), 5 deletions(-)
 create mode 100644 vlib/v/tests/assign/assign_option_of_fixed_array_test.v

diff --git a/vlib/v/gen/c/assign.v b/vlib/v/gen/c/assign.v
index 2b03545b6..1204a4ae7 100644
--- a/vlib/v/gen/c/assign.v
+++ b/vlib/v/gen/c/assign.v
@@ -492,11 +492,21 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 				g.write(' = ')
 				g.expr_with_opt(val, val_type, var_type)
 			} else if unaliased_right_sym.kind == .array_fixed && val is ast.CastExpr {
-				g.write('memcpy(')
-				g.expr(left)
-				g.write(', ')
-				g.expr(val)
-				g.writeln(', sizeof(${g.styp(var_type)}));')
+				if var_type.has_flag(.option) {
+					g.expr(left)
+					g.writeln('.state = 0;')
+					g.write('memcpy(')
+					g.expr(left)
+					g.write('.data, ')
+					g.expr(val)
+					g.writeln(', sizeof(${g.styp(var_type.clear_flag(.option))}));')
+				} else {
+					g.write('memcpy(')
+					g.expr(left)
+					g.write(', ')
+					g.expr(val)
+					g.writeln(', sizeof(${g.styp(var_type)}));')
+				}
 			} else {
 				mut v_var := ''
 				arr_typ := styp.trim('*')
diff --git a/vlib/v/tests/assign/assign_option_of_fixed_array_test.v b/vlib/v/tests/assign/assign_option_of_fixed_array_test.v
new file mode 100644
index 000000000..c3a316ed7
--- /dev/null
+++ b/vlib/v/tests/assign/assign_option_of_fixed_array_test.v
@@ -0,0 +1,8 @@
+type Addr = [4]u8
+
+fn test_assign_option_of_fixed_array() {
+	mut addr := ?Addr(none)
+	addr = Addr([u8(1), 2, 3, 4]!)
+	println(addr)
+	assert '${addr}' == 'Option(Addr([1, 2, 3, 4]))'
+}
-- 
2.39.5