Define '[]map[string]?Any' when it comes to time? Any 'type cannot be converted to JSON type

[CryingN]

Describe the bug

This is a rather bizarre issue. When I use the following code, if the User struct does not include a time.Time field, or if the field is defined as []map[string]Any instead of []map[string]?Any, it runs normally without any errors.

Reproduction Steps

import json
import time

type Any = string | []map[string]?Any | time.Time

struct Users {
mut:
    id         string
    created_at time.Time
}

data_all := [Users{
    id: '123'
    created_at : time.now()
}, Users{
    id: 'asd'
    created_at : time.now()
}]



mut result := []map[string]?Any{}
for raw in data_all {
    mut data := map[string]?Any{}
    data['id'] = raw.id
    data['time'] = raw.created_at
    result << data
}

println(result)

msg := json.encode(result)
println(msg)

Expected Behavior

like this:

[{'id': Any('123'), 'time': Any(2025-04-09 23:35:48)}, {'id': Any('asd'), 'time': Any(2025-04-09 23:35:48)}]
[{"id":"123","time":{"_type":"Time","value":1744241748}},{"id":"asd","time":{"_type":"Time","value":1744241748}}]

Current Behavior

[root_cn@archlinux json_null]$ v test_none.v -cg
/tmp/v_1000/test_none.01JRDKHSCE9ZJ2EKMDKRKYCFSX.tmp.c:2551: error: cannot convert 'struct main__Any' to 'struct _option_main__Any'
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 .
[root_cn@archlinux json_null]$ v test_none.v -show-c-output
======== Output of the C Compiler (/mnt/d/file/vlang/v/thirdparty/tcc/tcc.exe) ========
/tmp/v_1000/test_none.01JRDKJEY77SZTADGV5TDTXSPQ.tmp.c:2545: error: cannot convert 'struct main__Any' to 'struct _option_main__Any'
=======================================================================================
======== Output of the C Compiler (cc) ========
/tmp/v_1000/test_none.01JRDKJEY77SZTADGV5TDTXSPQ.tmp.c: In function ‘json__decode__option_main__Any’:
/tmp/v_1000/test_none.01JRDKJEY77SZTADGV5TDTXSPQ.tmp.c:2545:39: error: incompatible types when assigning to type ‘_option_main__Any’ from type ‘main__Any’
 2545 |                                 res = time__Time_to_sumtype_main__Any(&_t6);
      |                                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
===============================================

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.10 55b16fb

Environment details (OS name and version, etc.)

in linux:

|V full version      |V 0.4.10 f7f89b3c3c6ce0fc71f8a1ca2f85e00f318a1ff6.55b16fb
|:-------------------|:-------------------
|OS                  |linux, Linux version 4.4.0-19041-Microsoft (Microsoft@Microsoft.com) (gcc version 5.4.0 (GCC) ) #4355-Microsoft Thu Apr 12 17:37:00 PST 2024 (VM) (WSL)
|Processor           |8 cpus, 64bit, little endian, 11th Gen Intel(R) Core(TM) i5-1130G7 @ 1.10GHz
|Memory              |7.19GB/15.79GB
|                    |
|V executable        |/mnt/d/file/vlang/v/v
|V last modified time|2025-04-09 15:43:13
|                    |
|V home dir          |OK, value: /mnt/d/file/vlang/v
|VMODULES            |OK, value: /home/root_cn/.vmodules
|VTMP                |OK, value: /tmp/v_1000
|Current working dir |OK, value: /mnt/d/file/vlang/test/json_null
|                    |
|Git version         |git version 2.49.0
|V git status        |weekly.2025.13-75-g55b16fbd
|.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 2025-02-13 HEAD@f8bd136d (x86_64 Linux)
|tcc git status      |thirdparty-linux-amd64 696c1d84
|emcc version        |N/A
|glibc version       |ldd (GNU libc) 2.41

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[huly-for-github]

Connected to Huly®: V_0.6-22563

[CryingN]

I found that giving up none can solve many problems, but if we consider not introducing c in v as much as possible, should we reconstruct it?

import json
import time

type Any = time.Time | []map[string]Any

struct Users {
mut:
    test         Any
}

data_all := [Users{
    test : time.now()
}, Users{
    test : C.NULL
}]

mut result := []map[string]Any{}
for raw in data_all {
    mut data := map[string]Any{}
    data['test'] = raw.test
    result << data
}

println(result)

msg := json.encode(result)
println(msg)

[spytheman]

I found that giving up none can solve many problems

No, C errors for pure V code should be fixed - they are always a symptom of a compiler bug.

[spytheman]

I know that it could be tempting to change your model as a workaround, but then such bugs can persist, while with filing them, in time they decrease as we fix them.