Nixpkgs: weechat-matrix-bridge: fails to load with “undefined symbol: lua_objlen”

[bdesham]

Describe the bug

When running a version of Weechat that has the weechat-matrix-bridge script “built in,” Weechat gives the following errors on startup:

lua: loading script "/nix/store/962z42i4kxmb1r4bb75lfqbs5xdc122g-weechat-matrix-bridge-2018-11-19/share/matrix.lua"
lua: unable to execute file "/nix/store/962z42i4kxmb1r4bb75lfqbs5xdc122g-weechat-matrix-bridge-2018-11-19/share/matrix.lua"
lua: error: error loading module 'cjson' from file '/nix/store/962z42i4kxmb1r4bb75lfqbs5xdc122g-weechat-matrix-bridge-2018-11-19/lib/cjson.so':
/nix/store/962z42i4kxmb1r4bb75lfqbs5xdc122g-weechat-matrix-bridge-2018-11-19/lib/cjson.so: undefined symbol: lua_objlen

The Matrix features like /matrix ... are unavailable.

To Reproduce

1. Have a config.nix that looks like this:

   { pkgs }:

   {
   packageOverrides = pkgs: {
   myWeechat = pkgs.weechat.override {
   configure = { availablePlugins, ... }: {
   plugins = with availablePlugins; [ lua ];
   scripts = with pkgs.weechatScripts; [ weechat-matrix-bridge ];
   };
   };
   }

2. Install the customized weechat with nix-env -i -A nixpkgs.myWeechat

3. Run weechat

Expected behavior

Weechat launches and the Matrix script is loaded successfully.

Additional info

Running the customized version of Weechat and loading the script manually with /script load /nix/store/962z42i4kxmb1r4bb75lfqbs5xdc122g-weechat-matrix-bridge-2018-11-19/share/matrix.lua gives the same error message.

Metadata

• system: "x86_64-linux"
• host os: Linux 4.4.0-151-generic, Ubuntu, 16.04.6 LTS (Xenial Xerus)
• multi-user?: no
• sandbox: yes
• version: nix-env (Nix) 2.2.2
• channels(bdesham): "nixpkgs-19.09pre185473.31c38894c90"
• nixpkgs: /home/bdesham/.nix-defexpr/channels/nixpkgs

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute: weechat-matrix-bridge

[zimbatm]

maintainers: @ma27

[Ma27]

So, I can reproduce the bug on master (f99063f6a1c2ee14794c3d79d51a7d3a497bee83), however it appears to work fine on release-19.03, so you might want to use the weechatScripts.weechat-matrix-bridge from 19.03 as a temporary workaround.

Two additional things to note:

• The package doesn't support encryption of new Matrix rooms which is why I hardly use this anymore. I'm actually thinking about removing this entirely and look for alternatives in case they don't get to implement this.

• On master some internal stuff for the lua packages changed (including the cjson package for lua), I'm pretty certain that it's somehow related to this change, will try to investigate and provide a fix :)

[bdesham]

Yeah, I noticed that the README for weechat-matrix-protocol-script mentions https://github.com/poljar/weechat-matrix as an alternative. It seems like maybe the encryption support in that script is more fleshed out than in weechat-matrix-protocol-script. (It’s written in Python, though, and I’ve compiled my Weechat without Python because of #64167, so I haven’t tried to use it yet.)

[Ma27]

WeeChat can be built with Python using an expression like this:

weechat.override {
  configure = { availablePlugins }: {
    plugins = with availablePlugins; [
      python
    ];
  };
}

It would be awesome to get some feedback on how reliable this works, then we could actually deprecate this package :)

[Ma27]

@bdesham did you manage to take a look at the python-based matrix plugin? I'd still prefer to get rid of the current one :)

[vcunat]

lua_objlen: are you sure you got lua versions right in there? 5.2 language changelog:

Function lua_objlen was renamed lua_rawlen.

[bdesham]

@Ma27 I did take a look, but that plugin depends on the matrix-nio package, which we don’t have a derivation for yet. I haven’t looked into it any further yet.

[Ma27]

Have you also checked what @vcunat suggested? :)

[bdesham]

Sorry, I’m not sure what the suggestion was :-) If lua_objlen was removed, that would explain the error I got (lib/cjson.so: undefined symbol: lua_objlen), wouldn’t it? It seems like maybe the code in the plugin is just incompatible with the version of Lua that WeeChat is being built against in the latest Nixpkgs master.

[vcunat]

The suggestion I meant was to check what upstream says about lua compatibility and perhaps use that version of lua (if that doesn't collide with something else – I haven't looked). Or... this function rename should be easy to fix by itself, but there are much worse incompatibilities between the language versions.

[vcunat]

Oh, can you re-test after #67382? I see it was using luaffi linked against lua-5.1 and the rest linked against lua-5.2.

[bdesham]

It still doesn’t seem to work, unfortunately 😕 Following the steps in the original post gives the same error as before.

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