Fatal error running example app

[davidrupp]

MacBook Pro, 14-inch, Nov 2023, Apple M3 Max, Tahoe 26.2
Ruby 3.3.5 (via rbenv)
go version go1.25.5 darwin/arm64 (via Homebrew)

https://charm-ruby.dev/#getting-started -> "Your First TUI"

Running this app results in a stack trace from (I assume) the Go runtime; top frame:

runtime: g 17: unexpected return pc for _cgoexp_add47dcbfd29_lipgloss_new_style called from 0x1203f4f28
stack: frame={sp:0x14000076c20, fp:0x14000076e60} stack=[0x14000076000,0x14000077000)
0x0000014000076b20:  0x000000012755f590  0x0000014000076ba8 
0x0000014000076b30:  0x00000001274d2b4c <main.allocStyle+0x000000000000007c>  0x000000012753baa0 
0x0000014000076b40:  0x000000012755f590  0x0000014000076b68 
0x0000014000076b50:  0x00000001274d1f60 <main.getNextID+0x00000000000000e0>  0x0000000000000000 
0x0000014000076b60:  0x0000000000000000  0x0000014000076ba8 
0x0000014000076b70:  0x00000001274d2b2c <main.allocStyle+0x000000000000005c>  0x0000014000076ba8 
0x0000014000076b80:  0x00000001274d2b00 <main.allocStyle+0x0000000000000030>  0x0000000000000001 
0x0000014000076b90:  0x00000001274d1f90 <main.getNextID.deferwrap1+0x0000000000000000>  0x00000001276d4c38 
0x0000014000076ba0:  0x0000014000076b90  0x0000014000076c18 
0x0000014000076bb0:  0x00000001274dc320 <_cgoexp_add47dcbfd29_lipgloss_new_style+0x0000000000000050>  0x0000000000000000 
0x0000014000076bc0:  0x0000000000000000  0x0000000000000000 
0x0000014000076bd0:  0x0000000000000000  0x0000000000000000 
0x0000014000076be0:  0x0000000000000000  0x0000000000000001 
0x0000014000076bf0:  0x0000000000000001  0x00000001274d2bf0 <main.allocStyle.deferwrap1+0x0000000000000000> 
0x0000014000076c00:  0x00000001276d4ea0  0x0000014000076c18 
0x0000014000076c10:  0x0000014000076bf8  0x0000014000076e58 
0x0000014000076c20: <0x00000001203f4f28  0x00000001276ae320 
0x0000014000076c30:  0x0000000000000000  0x0000000000000000 
0x0000014000076c40:  0x0000000000000000  0x0000000000000000 
0x0000014000076c50:  0x0000000000000000  0x0000000000000000 
0x0000014000076c60:  0x0000000000000000  0x0000000000000000 
0x0000014000076c70:  0x0000000000000000  0x0000000000000000 
0x0000014000076c80:  0x0000000000000000  0x0000000000000000 
0x0000014000076c90:  0x0000000000000000  0x0000000000000000 
0x0000014000076ca0:  0x0000000000000000  0x0000000000000000 
0x0000014000076cb0:  0x0000000000000000  0x0000000000000000 
0x0000014000076cc0:  0x0000000000000000  0x0000000000000000 
0x0000014000076cd0:  0x0000000000000000  0x0000000000000000 
0x0000014000076ce0:  0x0000000000000000  0x0000000000000000 
0x0000014000076cf0:  0x0000000000000000  0x0000000000000000 
0x0000014000076d00:  0x0000000000000000  0x0000000000000000 
0x0000014000076d10:  0x0000000000000000  0x0000000000000000 
0x0000014000076d20:  0x0000000000000000  0x0000000000000000 
0x0000014000076d30:  0x0000000000000000  0x0000000000000000 
0x0000014000076d40:  0x0000000000000000  0x0000000000000000 
0x0000014000076d50:  0x0000000000000000  0x0000000000000000 
0x0000014000076d60:  0x0000000000000000  0x0000000000000000 
0x0000014000076d70:  0x0000000000000000  0x0000000000000000 
0x0000014000076d80:  0x0000000000000000  0x0000000000000000 
0x0000014000076d90:  0x0000000000000000  0x0000000000000000 
0x0000014000076da0:  0x0000000000000000  0x0000000000000000 
0x0000014000076db0:  0x0000000000000000  0x0000000000000000 
0x0000014000076dc0:  0x0000000000000000  0x0000000000000000 
0x0000014000076dd0:  0x0000000000000000  0x0000000000000000 
0x0000014000076de0:  0x0000000000000000  0x0000000000000000 
0x0000014000076df0:  0x0000000000000000  0x0000000000000000 
0x0000014000076e00:  0x0000000000000000  0x0000000000000000 
0x0000014000076e10:  0x0000000000000000  0x0000000000000000 
0x0000014000076e20:  0x0000000000000000  0x0000000000000000 
0x0000014000076e30:  0x0000000000000000  0x0000000000000000 
0x0000014000076e40:  0x0000000000000000  0x0000000000000000 
0x0000014000076e50:  0x00000001203f4d80  0x0000014000076f28 
0x0000014000076e60: >0x00000001203f4c84  0x000000016f9f21e8 
0x0000014000076e70:  0x0000000120459a28  0x0000014000076ea8 
0x0000014000076e80:  0x0000000000000000  0x0000000000000000 
0x0000014000076e90:  0x0100000000000000  0x0000000000000000 
0x0000014000076ea0:  0x0000000000000000  0x000000012042ff00 
0x0000014000076eb0:  0x0202014000076e97  0x0000014000076f28 
0x0000014000076ec0:  0x00000001203f4c50  0x00000001274dc2d0 <_cgoexp_add47dcbfd29_lipgloss_new_style+0x0000000000000000> 
0x0000014000076ed0:  0x0000000200000003  0x0000014000002700 
0x0000014000076ee0:  0x0000014000076ec8  0x0000014000002700 
0x0000014000076ef0:  0x00000001203f4fc0  0x0000014000076eb5 
0x0000014000076f00:  0x000000016f9f4000  0x0000000000000000 
0x0000014000076f10:  0x0000000000000000  0x0000000000000000 
0x0000014000076f20:  0x0000014000076ef0  0x0000014000076f78 
0x0000014000076f30:  0x0000000120462aac  0x00000001274dc2d0 <_cgoexp_add47dcbfd29_lipgloss_new_style+0x0000000000000000> 
0x0000014000076f40:  0x000000016f9f21e8  0x0000000000000000 
0x0000014000076f50:  0x0000000120460db4  0x0000000000000000 
fatal error: unknown caller pc

[jeffmcfadden]

@davidrupp I ran into this as well. The Go bindings in the pre-built binaries seem to have been compiled against Go 1.23, and you (and I) are running 1.25.

I was able to get playing by re-compiling the gems locally and messing about with them that way.

I'm sure there's a good long-term solution here, but if you just want to experiment, give that a try.

[davidrupp]

@jeffmcfadden Thanks for the suggestion. I also tried downgrading to go@1.23 and got what looks like the same error. I'll keep poking at it.

[marcoroth]

Hey @davidrupp and @jeffmcfadden, thanks for reporting!

Sadly, this is one of the current limitations I pointed out in the blog post, but I still wanted to get these gems out there so we, as a community, can build these gems out and make them better.

From what I can tell, it only happens when you require two Charm Ruby gems that have a Go Native extension. It seems to have to do with the way Goroutines work and the order the gems are require'd.

I'm new to Go and the distribution of Go binaries. It seems to be an issue that these two gems weren't compiled on the same machine with the exact same setup, and that trips up the Goroutines and its assumptions about how things are setup.

If anyone has experience with this, I would be really happy about any feedback. Maybe it would also be better to use another approach to build Go Native Extensions, as the current approach of doing Go library → cgo shared library → Ruby C extension → Ruby seems a bit fragile for distribution, as we can see here.

The only other solution I have in mind is to create one big shared gem that has the go extension, and then all the other gems on top of it can stay in pure Ruby. With that, these native extensions wouldn't conflict with each other.

[pusewicz]

Can the gems be compiled on the target (user) machine instead when installing?

[mperham]

I'm getting a similar error, also on Go 1.25.5.

I wonder if Go is a poor choice for a native extension and something like Rust and Ratatui (https://ratatui.rs) would be a better choice, long-term. Ruby bindings were just published last week.

https://kerrick.blog/posts/2025/ratatui-bindings-for-ruby/

[esmarkowski]

I was so looking forward to playing with these! @marcoroth Thanks for making them.

I'm getting the same error as above also and noticed there wasn't a bundle exec rake compile as stated in the docs.

I'd be happy with one big gem!

[swerner]

I'm running into the same issue. I'm also new to Go, but started doing some digging with Claude.

It looks like this issue also means that if you use any other gems with Go extensions, you'd also run into a segfault, since what's happening is that we're creating multiple Go runtimes within the same process.

One option to fix this (and avoid breaking other Go-wrapper gems) could be to create a separate charm-go gem that runs Go as a subprocess. The Charm gems with native extensions would become pure Ruby and communicate with the single Go process.

I've been working with Claude on a detailed architecture doc for this if you'd be interested in seeing it @marcoroth?

[esmarkowski]

@swerner lol. I went down the same path https://github.com/esmarkowski/charm-native

I can get all of the demos to work across all the gems now.

[swerner]

@esmarkowski I explored this path a bit (and again, I'm really new to Go so I'm trusting AI quite a bit on this) - this approach solves the multiple charm gems with Go extension issue, wouldn't we still run into an issue if we wanted to use a different, non-Charm Go-based Gem? I know there aren't a ton out there so maybe this isn't an important concern for now...but definitely a landmine to be aware of...