coroutines C error found.

[kuchaguangjie]

Describe the bug

coroutine_learn.v:

fn echo() {
	println("echo")
	$if is_coroutine ? {
		println("coroutine")
	}
}

fn main() {
	go echo()
}

run:

v -use-coroutines run ./coroutine_learn.v

output:

coroutines .so not found, downloading...
done!
================== C compilation error (from tcc): ==============
cc: /tmp/v_1000/coroutine_learn.01JJHGK3ZCB9N2GGW5VQ659HW9.tmp.c:5633: warning: implicit declaration of function 'delete_photon_work_pool'
cc: /mnt/star/program/vlang/v0.4.9/thirdparty/tcc/lib/libgc.a: error: 'GC_noop1_ptr' defined twice
cc: tcc: error: undefined symbol 'photon_thread_create_and_migrate_to_work_pool'
cc: tcc: error: undefined symbol 'delete_photon_work_pool'
... (the original output was 5 lines long, and was truncated to 4 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

Run the code above on ubuntu 24.04

Expected Behavior

no error

Current Behavior

error

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.9 801600c

Environment details (OS name and version, etc.)

V full version	V 0.4.9 d313355.801600c
OS	linux, Linux Mint 22
Processor	8 cpus, 64bit, little endian, Intel(R) Core(TM) i7-4720HQ CPU @ 2.60GHz
Memory	2.29GB/15.54GB
V executable	/mnt/star/program/vlang/v0.4.9/v
V last modified time	2025-01-26 14:38:08
V home dir	OK, value: /mnt/star/program/vlang/v0.4.9
VMODULES	OK, value: /home/eric/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /mnt/star/git_repos/vlearn/src/learn/coroutine
Git version	git version 2.43.0
V git status	weekly.2025.04-1-g801600c0
.git/config present	true
cc version	cc (Ubuntu 13.2.0-23ubuntu4) 13.2.0
gcc version	gcc (Ubuntu 13.2.0-23ubuntu4) 13.2.0
clang version	N/A
tcc version	tcc version 0.9.28rc 2024-07-31 HEAD@1cee0908 (x86_64 Linux)
tcc git status	N/A
emcc version	N/A
glibc version	ldd (Ubuntu GLIBC 2.39-0ubuntu8.3) 2.39

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[huly-for-github]

Connected to Huly®: V_0.6-22013

[kbkpbot]

This bug is because not #include "photonwrapper.h" . Workarounds for this bug :

1. import coroutines

import coroutines

fn echo() {
        println("echo")
        $if is_coroutine ? {
                println("coroutine")
        }
}

fn main() {
        go echo()
}

or

2. manually include the file:

#flag -I @VEXEROOT/thirdparty/photon
#flag @VEXEROOT/thirdparty/photon/photonwrapper.so
#include "photonwrapper.h"


fn echo() {
        println("echo")
        $if is_coroutine ? {
                println("coroutine")
        }
}

fn main() {
        go echo()
}

May require a patch for v, when detect used go keyword, include the "photonwrapper.h"

[kuchaguangjie]

photon
#flag @VEXEROOT/thirdparty/photon/photonwrapper.so

How to install photon and photonwrapper.so properly, on Linux?
Where is @VEXEROOT ?

[jorgeluismireles]

Where is @VEXEROOT ?

Is the base of V installation. You can see what thing does or try to do --use-coroutines argument around this code:
https://github.com/vlang/v/blob/master/vlib/v/pref/pref.v#L971. For linux the compiler tries to download .h and .so files using wget or curl...

What I noticed is that tcc does not understand #flag @VEXEROOT/thirdparty/photon/photonwrapper.so but instead needs -shared like this:

#flag -shared @VEXEROOT/thirdparty/photon/photonwrapper.so

I think tcc expects common format lxxx.so and seems that https://github.com/vlang/v/blob/master/vlib/coroutines/coroutines.c.v does not do it for tcc.

With -shared for tcc undefined symbols dissapear though, but for me, your code and the examples in got a Terminated by signal 11 (SIGSEGV) result.