From c45b8d492aec66df5f13f01cc0f2456374eefb83 Mon Sep 17 00:00:00 2001
From: Swastik Baranwal <swstkbaranwal@gmail.com>
Date: Mon, 2 Dec 2024 10:57:32 +0530
Subject: [PATCH] cgen: fix struct update embed expr for fixed arrays (fix
 #22999) (#23040)

---
 vlib/v/gen/c/array.v                          | 20 +++++++++++--
 vlib/v/gen/c/struct.v                         |  3 +-
 .../fixed_array_update_embed_expr_test.v      | 30 +++++++++++++++++++
 3 files changed, 50 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/tests/fixed_array_update_embed_expr_test.v

diff --git a/vlib/v/gen/c/array.v b/vlib/v/gen/c/array.v
index c2399b942..982a46858 100644
--- a/vlib/v/gen/c/array.v
+++ b/vlib/v/gen/c/array.v
@@ -1649,7 +1649,7 @@ fn (mut g Gen) fixed_array_init_with_cast(expr ast.ArrayInit, typ ast.Type) {
 	}
 }
 
-fn (mut g Gen) fixed_array_update_expr_field(expr_str string, field_type ast.Type, field_name string, is_auto_deref bool, elem_type ast.Type, size int) {
+fn (mut g Gen) fixed_array_update_expr_field(expr_str string, field_type ast.Type, field_name string, is_auto_deref bool, elem_type ast.Type, size int, is_update_embed bool) {
 	elem_sym := g.table.sym(elem_type)
 	if !g.inside_array_fixed_struct {
 		g.write('{')
@@ -1665,7 +1665,7 @@ fn (mut g Gen) fixed_array_update_expr_field(expr_str string, field_type ast.Typ
 				'${expr_str}->${c_name(field_name)}[${i}]'
 			}
 			g.fixed_array_update_expr_field(init_str, field_type, field_name, is_auto_deref,
-				elem_sym.info.elem_type, elem_sym.info.size)
+				elem_sym.info.elem_type, elem_sym.info.size, is_update_embed)
 		} else {
 			g.write(expr_str)
 			if !expr_str.ends_with(']') {
@@ -1674,6 +1674,22 @@ fn (mut g Gen) fixed_array_update_expr_field(expr_str string, field_type ast.Typ
 				} else {
 					g.write('.')
 				}
+				if is_update_embed {
+					update_sym := g.table.sym(field_type)
+					_, embeds := g.table.find_field_from_embeds(update_sym, field_name) or {
+						ast.StructField{}, []ast.Type{}
+					}
+					for embed in embeds {
+						esym := g.table.sym(embed)
+						ename := esym.embed_name()
+						g.write(ename)
+						if embed.is_ptr() {
+							g.write('->')
+						} else {
+							g.write('.')
+						}
+					}
+				}
 				g.write(c_name(field_name))
 			}
 			if !expr_str.starts_with('(') && !expr_str.starts_with('{') {
diff --git a/vlib/v/gen/c/struct.v b/vlib/v/gen/c/struct.v
index 91638d537..9a1d66637 100644
--- a/vlib/v/gen/c/struct.v
+++ b/vlib/v/gen/c/struct.v
@@ -311,7 +311,8 @@ fn (mut g Gen) struct_init(node ast.StructInit) {
 						is_arr_fixed = true
 						g.fixed_array_update_expr_field(g.expr_string(node.update_expr),
 							node.update_expr_type, field.name, node.update_expr.is_auto_deref_var(),
-							update_expr_sym.info.elem_type, update_expr_sym.info.size)
+							update_expr_sym.info.elem_type, update_expr_sym.info.size,
+							node.is_update_embed)
 					} else {
 						g.write('(')
 						g.expr(node.update_expr)
diff --git a/vlib/v/tests/fixed_array_update_embed_expr_test.v b/vlib/v/tests/fixed_array_update_embed_expr_test.v
new file mode 100644
index 000000000..375a6ff03
--- /dev/null
+++ b/vlib/v/tests/fixed_array_update_embed_expr_test.v
@@ -0,0 +1,30 @@
+module main
+
+type Mat4 = [14]f32
+
+struct GameObject {
+mut:
+	transform Mat4
+}
+
+struct Ship {
+	GameObject
+}
+
+fn (mut ship Ship) instance() &Ship {
+	return &Ship{
+		...ship
+	}
+}
+
+fn test_fixed_array_update_embed_expr() {
+	mut v := Ship{}
+	mut v2 := v.instance()
+
+	assert v2.transform.len == 14
+	assert v2.transform[0] == 0
+	assert v2.transform[13] == 0
+	assert v2.transform.all(it == 0)
+
+	dump('V=${v2}')
+}
-- 
2.39.5