Currently a work in progress. Me and a couple friends use it daily, so it's usable, but may have the occasional bug.
The makefile should give enough information for build commands. Here's the essentials:
cd weechat-discord # or wherever you cloned it
cargo build --release
This will produce a shared object called target/release/libweecord.so. Place it in your weechat plugins directory, which is probably located at ~/.weechat/plugins (may need to be created)
The Makefile has a tiny bit of automation that helps with development:
make # (same as make all) just runs that `cargo build --release` command, produces weecord.so
make install # builds and copies the .so to ~/.weechat/plugins, creating the dir if required
make run # installs and runs `weechat -a` (-a means "don't autoconnect to servers")
Maybe important note: The previous version of this project, written in Go, used to get really upset when the .so was modified during the same weechat session, even if unloaded. When developing, make sure to completely quit weechat when updating the .so, just to be sure (otherwise you might get a SIGSEGV and hard crash).
Due to some idiocracy on Discord's part, you will need to obtain a login token. The wonderful tip by the Discord devs on how to do that, though, doesn't work: for me, and only for chromium, I went into inspector (ctrl+shift+i, because Discord also decided to do the wonderful thing of ripping out right-click menus), Application tab, Local Storage on left, discordapp.com, token entry.
Set that token (make sure to remove the quotes if you copied them in!):
/discord token 123456789ABCDEF
Then, connect:
/discord connect
Note you may also have to adjust a few settings for best use:
weechat.completion.default_template -> append "|%(weecord_completion)"
weechat.bar.status.items -> replace buffer_name with buffer_short_name
plugins.var.python.go.short_name -> on (if you use go.py)
buffers.look.short_names -> on (if you use buffers.pl)