Better command line documentation

src/main.rs

@@ -26,15 +26,18 @@ pub struct SessionData {
 
 #[derive(clap::Parser)]
 struct Cli {
+    /// Override path to the bot's configuration file
     #[arg(long, short = 'c')]
     config: Option<PathBuf>,
     #[command(subcommand)]
-    sub: Option<Subcommand>,
+    sub: Subcommand,
 }
 
 #[derive(clap::Subcommand, Debug)]
 enum Subcommand {
     Setup(setup::Setup),
+    /// Run the bot
+    Run,
 }
 
 /// Returns the default path to the bot's configuration file.
@@ -106,13 +109,12 @@ async fn main() -> Result<()> {
 
     let args = Cli::parse();
 
-    #[allow(clippy::single_match_else)]
     match args.sub {
-        Some(Subcommand::Setup(setup)) => {
+        Subcommand::Setup(setup) => {
             setup::setup(setup).await?;
             Ok(())
         }
-        None => {
+        Subcommand::Run => {
             let config_path = if let Some(config) = args.config {
                 config
             } else {

src/setup.rs

@@ -7,9 +7,13 @@ use tokio::io::AsyncBufReadExt;
 
 use crate::SessionData;
 
+/// Perform first-time setup using password login
 #[derive(Args, Debug)]
 pub(crate) struct Setup {
+    /// The bot's matrix username, e.g. `@mybot:myhomeserver.example`
     username: Box<UserId>,
+    /// An optional homeserver base URL. Will attempt to auto-detect if not
+    /// specified.
     #[arg(long, short = 's')]
     homeserver_url: Option<String>,
 }