C error. mut type cast of unwrapped interface

[phcreery]

Describe the bug

src/message/message.v

module message

pub struct Message {
pub mut:
	text string = 'Init'
	m2   ?&Message
}

pub fn (mut m Message) update_text(new_text string) {
	m.text = new_text
}

pub fn (mut m Message) update_ext_text(new_text string) {
	m.m2?.text = new_text
}

src/main.v

module main

import time
import message

// Build this example with `v -live .`

type LocalMessageType = message.Message

interface IMessage {
mut:
	text string
	update_text(new_text string)
}

struct App {
mut:
	message &IMessage
}

pub fn (mut m LocalMessageType) update_text_externally(new_text string) {
	m.text = new_text
}

@[live]
fn print_message(mut mdef IMessage) {
	if mut mdef is message.Message {
		// mut m := LocalMessageType(*mdef) // works. with -live: Unhandled Exception 0xC0000005
		// mut m := &LocalMessageType(mdef) // works, warning. with -live: Unhandled Exception 0xC0000005
		mut m := LocalMessageType(mdef) // does not work, C compilation error

		dump(mdef)
		dump(*mdef)
		dump(m)

		m.update_text('Updated within')
		m.update_ext_text('Updated ext')
		m.update_text_externally('Updated externally')
		println('${m.text}, ${m.m2?.text}')
	}
}

fn main() {
	for {
		mut m2 := &message.Message{
			text: 'Init External'
		}
		mut mdef := &message.Message{
			text: 'Init'
			m2:   m2
		}
		mut app := &App{
			message: mdef
		}
		print_message(mut app.message)
		time.sleep(500 * time.millisecond)
	}
}

> v run .      
INFO: compile with `v -live . `, if you want to use the @[live] function main.print_message .
================== C compilation error (from tcc): ==============
cc: C:/Users/phcre/AppData/Local/Temp/v_0/vtests.01JDYPQX81M8CS5V5Q38G0PNJC.tmp.c:7803: warning: implicit declaration of function 'tcc_backtrace'
cc: C:/Users/phcre/AppData/Local/Temp/v_0/vtests.01JDYPQX81M8CS5V5Q38G0PNJC.tmp.c:17195: error: cannot convert 'struct src__message__Message *' to 'struct src__message__Message'
... (the original output was 3 lines long, and was truncated to 2 lines)
=================================================================
(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 .

Reproduction Steps

Type cast an unwrapped interface

Expected Behavior

A checker warning

Current Behavior

C compile error

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.8 5092626.e4d24e8

Environment details (OS name and version, etc.)

> v doctor
V full version: V 0.4.8 5092626.e4d24e8
OS: windows, Microsoft Windows 10 Pro v19045 64-bit
Processor: 8 cpus, 64bit, little endian, 

getwd: C:\Users\phcre\Documents\v\vtests
vexe: C:\Users\phcre\Documents\v\v\v.exe
vexe mtime: 2024-11-24 01:17:49

vroot: OK, value: C:\Users\phcre\Documents\v\v
VMODULES: OK, value: C:\Users\phcre\.vmodules
VTMP: OK, value: C:\Users\phcre\AppData\Local\Temp\v_0

Git version: git version 2.24.1.windows.2
Git vroot status: weekly.2024.37-553-ge4d24e89 (40 commit(s) behind V master)
.git/config present: true

CC version: cc (Rev6, Built by MSYS2 project) 13.1.0
emcc version: emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.44 (bec42dac7873903d09d713963e34020c22a8bd2d)
thirdparty/tcc status: thirdparty-windows-amd64 b425ac82

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_{Huly®: V_0.6-21458}