C error: when `flag` is imported and a `const` is used as default value in `struct`

[larpon]

V version: V 0.4.9 4cc6f25, press to see full `v doctor` output

V full version	V 0.4.9 89d1aac.4cc6f25
OS	linux, "EndeavourOS Linux"
Processor	16 cpus, 64bit, little endian, AMD Ryzen 7 8845HS w/ Radeon 780M Graphics
Memory	13.3GB/30.64GB
V executable	/home/lmp/Projects/v/v
V last modified time	2025-03-11 08:11:28
V home dir	OK, value: /home/lmp/Projects/v
VMODULES	OK, value: /home/lmp/.vmodules
VTMP	OK, value: /dev/shm
Current working dir	OK, value: /home/lmp/Projects/v
Git version	git version 2.48.1
V git status	weekly.2025.11-2-g4cc6f254 (3 commit(s) behind V master)
.git/config present	true
cc version	cc (GCC) 14.2.1 20250207
gcc version	gcc (GCC) 14.2.1 20250207
clang version	clang version 19.1.7
tcc version	tcc version 0.9.28rc 2024-07-31 HEAD@1cee0908 (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 0134e9b9
emcc version	shared:INFO: old sanity: 4.0.3-git
glibc version	ldd (GNU libc) 2.41

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

module main

import flag

const c_default_port = u16(12345)

struct Options {
	headless bool
	port     u16 = c_default_port @[short: p]
}

fn main() {
	args := arguments()
	_, _ := flag.to_struct[Options](args, style: .v, skip: 1)!
}

What did you see?

================== C compilation error (from tcc): ==============
cc: /dev/shm/t.01JP2QZNKWBQS2M3NH32QF2VR5.tmp.c:8982: error: '_const_main__c_default_port' undeclared
=================================================================
(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 .

What did you expect to see?

A clean compile and run

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[huly-for-github]

Connected to Huly®: V_0.6-22311

[larpon]

Running the same file with -no-skip-unused works