array pass to variadic fn C error

[kitech]

Describe the bug

Code: https://play.vlang.io/p/425ebf8d52

import x.json2

fn foo(a int, args ...json2.Any) {
    println(args)
}

foo(1, [json2.Any(42)])

Reproduction Steps

click run

Expected Behavior

compile ok

Current Behavior

Output:

/box/code.v:7: error: cannot convert 'struct x__json2__Any' to 'struct array'
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 .
Exited with error status 1

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.12 dafa6fd0aaaa329a72c724297e895d6097303265.b01273e

Environment details (OS name and version, etc.)

|V full version      |V 0.4.12 dafa6fd0aaaa329a72c724297e895d6097303265.b01273e
|:-------------------|:-------------------
|OS                  |linux, Debian GNU/Linux 12 (bookworm) (VM)
|Processor           |2 cpus, 64bit, little endian, Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GHz
|Memory              |0.62GB/2.02GB
|                    |
|V executable        |/home/admin/v/v
|V last modified time|2025-12-05 04:25:30
|                    |
|V home dir          |OK, value: /home/admin/v
|VMODULES            |OK, value: .vmodules
|VTMP                |OK, value: /tmp/v_0
|Current working dir |OK, value: /home/admin/playground
|                    |
|Git version         |git version 2.39.5
|V git status        |N/A
|.git/config present |true
|                    |
|cc version          |cc (Debian 12.2.0-14+deb12u1) 12.2.0
|gcc version         |gcc (Debian 12.2.0-14+deb12u1) 12.2.0
|clang version       |Debian clang version 14.0.6
|tcc version         |tcc version 0.9.28rc 2025-02-13 HEAD@f8bd136d (x86_64 Linux)
|tcc git status      |Error: fatal: detected dubious ownership in repository at '/home/admin/v/thirdparty/tcc'
To add an exception for this directory, call:

	git config --global --add safe.directory /home/admin/v/thirdparty/tcc
 Error: fatal: detected dubious ownership in repository at '/home/admin/v/thirdparty/tcc'
To add an exception for this directory, call:

	git config --global --add safe.directory /home/admin/v/thirdparty/tcc

|emcc version        |N/A
|glibc version       |ldd (Debian GLIBC 2.36-9+deb12u10) 2.36

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[JalonSolov]

It works if you pass the parameter as a normal parameter, instead of an array:

import x.json2

fn foo(a int, args ...json2.Any) {
    println(args)
}

foo(1, json2.Any(42))

output is

[42]

[kitech]

If no first arg, compiler will show a message,

import x.json2

fn foo(args ...json2.Any) {
    println(args)
}

foo([json2.Any(42)])

[kitech]

x := json2.Any( [json2.Any(42)] )

This should be valid Any that contains an array.

In this case, I'm not mean expend the array.