x.json2 decode result wrong value about field order

[kitech]

Describe the bug

Code: https://play.vlang.io/p/b188f6719d

import x.json2

struct Foo {
	id  string  @[required]
    title string @[required]
}

s1 := '{"id":"sss","title":"ttt","thumb":[{ "url":"i1.jpg","id":"000"}]}'
s2 := '{"title":"ttt","thumb":[{ "url":"i1.jpg","id":"000"}],"id":"sss"}'

f1 := json2.decode[Foo](s1) !
f2 := json2.decode[Foo](s2) !

println('${f1.id} ${f2.id}')

Reproduction Steps

click run

Expected Behavior

output should be:
sss sss

Current Behavior

Output:

000 sss

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.5.0 2332ecf

Environment details (OS name and version, etc.)

|V full version      |V 0.5.0 2332ecff4811b8c97dfda8e825170e9397962519
|:-------------------|:-------------------
|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              |0.59GB/2.02GB
|                    |
|V executable        |/home/admin/v/v
|V last modified time|2026-02-02 10:25:33
|                    |
|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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[jorgeluismireles]

Seems duplicated issue #25390 . The problem is with a field name appearing more than once and when appears second time as member inside another field not defined in V:

import x.json2

struct Foo {
	repeated string
}

s := '{"repeated":"old","not_used":{"repeated":"new"}}'
f := json2.decode[Foo](s)!

assert f.repeated == 'old'

https://play.vlang.io/p/173d5eaa6c

Above assertion should pass but fails:

code.v:10:NaN: fn main.main: assert f.repeated == 'old'
   left value: f.repeated = new
  right value: 'old' = old
V panic: Assertion failed...

Field repeated has value old in json, but also not_used.repeated exists with value new which replaces old.

[jorgeluismireles]

In this issue the repeated fields have the same type and the value is replaced incorrectly. In the "duplicated" issue case the repeated fields were from different types and the error was different (it should not be), but seems the same problem with a repeated field after all.