Generic function compilation problem

[get200]

V version: V 0.4.10 22c327f, press to see full `v doctor` output

V full version	V 0.4.10 22c327f
OS	windows, Microsoft Windows 11 专业版 Insider Preview 26200 64-bit
Processor	24 cpus, 64bit, little endian, AMD Ryzen 9 5900X 12-Core Processor
Memory	47.94GB/63.91GB
V executable	D:\v\v\v.exe
V last modified time	2025-05-24 15:59:38
V home dir	OK, value: D:\v\v
VMODULES	OK, value: C:\Users\Administrator.vmodules
VTMP	OK, value: C:\Users\Administrator\AppData\Local\Temp\v_0
Current working dir	OK, value: E:\2025\v\v_test
Git version	git version 2.46.0.windows.1
V git status	weekly.2022.48-5473-g22c327fe-dirty
.git/config present	true
cc version	cc (Rev5, Built by MSYS2 project) 13.2.0
gcc version	gcc (Rev5, Built by MSYS2 project) 13.2.0
clang version	clang version 18.1.6
msvc version	N/A
tcc version	tcc version 0.9.27 (x86_64 Windows)
tcc git status	thirdparty-windows-amd64 b425ac82
emcc version	N/A
glibc version	N/A

What did you do?
./v -g -o vdbg cmd/v && ./vdbg main.v && E:\2025\v\v_test\main.exe

module main

struct Demo[T] {
mut:
	val T
}

type DemoType = int | []DemoType

fn main() {
	decode[Demo[DemoType]]()
	decode[Demo[[]DemoType]]()
}

fn decode[T]() {
	mut typ := T{}
	typ.val = decode_x(typ.val)
}

fn decode_x[T](_ T) T {
	mut field := T{}
	$if T is int {
		field = 0
	} $else $if T is $array {
		field = []DemoType{}
	}
	return field
}

What did you see?

================== C compilation error (from tcc): ==============
cc: C:/Users/Administrator/AppData/Local/Temp/v_0/main.01JW2KG3VWJ79PK76PNFD0DGE2.tmp.c:537: warning: WINVER redefined
cc: C:/Users/Administrator/AppData/Local/Temp/v_0/main.01JW2KG3VWJ79PK76PNFD0DGE2.tmp.c:5859: error: cannot convert 'struct main__DemoType' to 'struct array'
=================================================================
(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 .

VV_LOCAL_SYMBOL void main__decode_T_main__Demo_T_main__DemoType(void) {
	main__Demo_T_main__DemoType typ = ((main__Demo_T_main__DemoType){.val = (main__DemoType){._int=HEAP(int, (0)),._typ=8},});
	typ.val = main__decode_x_T_Array_main__DemoType(typ.val);  // <----- The same function name was generated as a result
}
VV_LOCAL_SYMBOL void main__decode_T_main__Demo_T_Array_main__DemoType(void) {
	main__Demo_T_Array_main__DemoType typ = ((main__Demo_T_Array_main__DemoType){.val = __new_array(0, 0, sizeof(main__DemoType)),});
	typ.val = main__decode_x_T_Array_main__DemoType(typ.val);  // <----- The same function name was generated as a result
}

What did you expect to see?

Compiled successfully

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[huly-for-github]

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