C error on returning fixed array type alias as Option

[gechandesu]

V doctor:

V full version: V 0.4.8 5ec9bb5.a9ae376
OS: linux, Linux version 6.6.8-arch1-1 (linux@archlinux) (gcc (GCC) 13.2.1 20230801, GNU ld (GNU Binutils) 2.41.0) #1 SMP PREEMPT_DYNAMIC Thu, 21 Dec 2023 19:01:01 +0000
Processor: 16 cpus, 64bit, little endian, 12th Gen Intel(R) Core(TM) i5-1240P

getwd: /home/ge/Code/v/netaddr
vexe: /home/ge/.vlang/v
vexe mtime: 2024-11-18 21:13:58

vroot: OK, value: /home/ge/.vlang
VMODULES: OK, value: /home/ge/.vmodules
VTMP: OK, value: /tmp/v_1000

Git version: git version 2.46.1
Git vroot status: weekly.2024.46-72-ga9ae3765
.git/config present: true

CC version: cc (GCC) 14.2.1 20240910
emcc version: N/A
thirdparty/tcc status: thirdparty-linux-amd64 0134e9b9

What did you do?
./v -g -o vdbg cmd/v && ./vdbg fixed_arr_option_return_issue.v

module main

import encoding.binary

type Addr = [4]u8

fn Addr.from_u32(a u32) Addr {
	mut bytes := [4]u8{}
	binary.big_endian_put_u32_fixed(mut bytes, a)
	return Addr(bytes)
}

fn (a Addr) str() string {
	return '${a[0]}.${a[1]}.${a[2]}.${a[3]}'
}

fn (a Addr) u32() u32 {
	return binary.big_endian_u32_fixed(a)
}

struct Net {
	netaddr   Addr
	broadcast Addr
mut:
	h u32
}

fn (mut n Net) next() ?Addr {
	if n.h >= n.broadcast.u32() + 1 {
		return none
	}
	defer {
		n.h++
	}
	return Addr.from_u32(n.h)
}

fn main() {
	net := Net{
		netaddr:   Addr([u8(172), 16, 16, 0]!)
		broadcast: Addr([u8(172), 16, 16, 3]!)
		h:         u32(2886733824)
	}
	for addr in net {
		println(addr)
	}
	// Expected output:
	// 172.16.16.0
	// 172.16.16.1
	// 172.16.16.2
	// 172.16.16.3
}

What did you expect to see?

No compilation errors. This issue may be related to #22910

What did you see instead?

================== C compilation error (from tcc): ==============
cc: /tmp/v_1000/fixed_arr_option_return_issue.01JD0J512XKSPKATNP2YJA0QB9.tmp.c:14350: warning: cast between pointer and integer of different size
cc: /tmp/v_1000/fixed_arr_option_return_issue.01JD0J512XKSPKATNP2YJA0QB9.tmp.c:14350: error: struct or union expected
... (the original output was 5 lines long, and was truncated to 2 lines)
=================================================================
(You can pass `-cg`, or `-show-c-output` as well, to print all the C error messages).
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .

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_{Huly®: V_0.6-21354}