From 68cf7aba36c2a926caf58d29d1e544ca1a8a3b14 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 25 Mar 2026 16:42:16 +0300
Subject: [PATCH] checker: fix inline array index assignment with literals
 (fixes #9691)

---
 .../assign/inline_array_index_assign_test.v   | 70 +++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 vlib/v/tests/assign/inline_array_index_assign_test.v

diff --git a/vlib/v/tests/assign/inline_array_index_assign_test.v b/vlib/v/tests/assign/inline_array_index_assign_test.v
new file mode 100644
index 000000000..8af1cd1e2
--- /dev/null
+++ b/vlib/v/tests/assign/inline_array_index_assign_test.v
@@ -0,0 +1,70 @@
+fn test_inline_array_index_assign_uses_full_expression() {
+	mut ram := []u8{len: 0x10000}
+	rom := [u8(0x00), 0x12, 0x00, 0x00]
+	pc := 0
+	value := u8(0x0f)
+
+	address := u16(rom[pc + 2]) << 8 | u16(rom[pc + 1])
+	ram[address] = value
+	assert ram[0x0012] == value
+	assert ram[0] == 0
+
+	mut ram2 := []u8{len: 0x10000}
+	ram2[u16(rom[pc + 2]) << 8 | u16(rom[pc + 1])] = value
+	assert ram2[0x0012] == value
+	assert ram2[0] == 0
+}
+
+fn test_inline_fixed_array_index_assign_uses_full_expression() {
+	mut ram := [0x10000]u8{}
+	rom := [u8(0x00), 0x12, 0x00, 0x00]!
+	pc := 0
+	value := u8(0x0f)
+
+	address := u16(rom[pc + 2]) << 8 | u16(rom[pc + 1])
+	ram[address] = value
+	assert ram[0x0012] == value
+	assert ram[0] == 0
+
+	mut ram2 := [0x10000]u8{}
+	ram2[u16(rom[pc + 2]) << 8 | u16(rom[pc + 1])] = value
+	assert ram2[0x0012] == value
+	assert ram2[0] == 0
+}
+
+struct MemoryState {
+mut:
+	a   u8
+	pc  int
+	ram [0x10000]u8
+	rom [4]u8
+}
+
+fn (mut state MemoryState) write_with_temp() {
+	address := u16(state.rom[state.pc + 2]) << 8 | u16(state.rom[state.pc + 1])
+	state.ram[address] = state.a
+}
+
+fn (mut state MemoryState) write_inline() {
+	state.ram[u16(state.rom[state.pc + 2]) << 8 | u16(state.rom[state.pc + 1])] = state.a
+}
+
+fn test_inline_struct_fixed_array_index_assign_uses_full_expression() {
+	mut temp_state := MemoryState{
+		a:   0x0f
+		pc:  0
+		rom: [u8(0x00), 0x12, 0x00, 0x00]!
+	}
+	temp_state.write_with_temp()
+	assert temp_state.ram[0x0012] == temp_state.a
+	assert temp_state.ram[0] == 0
+
+	mut inline_state := MemoryState{
+		a:   0x0f
+		pc:  0
+		rom: [u8(0x00), 0x12, 0x00, 0x00]!
+	}
+	inline_state.write_inline()
+	assert inline_state.ram[0x0012] == inline_state.a
+	assert inline_state.ram[0] == 0
+}
-- 
2.39.5