fix(cli): surface clap's --help instead of erroring on native subcommands

crates/mergify-cli/src/main.rs

@@ -145,6 +145,20 @@ fn looks_native(argv: &[String]) -> bool {
     })
 }
 
+/// Did clap exit on `--help` / `-h` / `--version`? Those return a
+/// special `Err` whose `kind()` is `DisplayHelp` /
+/// `DisplayHelpOnMissingArgumentOrSubcommand` / `DisplayVersion`;
+/// callers should always honor them and exit (printing the help /
+/// version) instead of falling through to the Python shim or
+/// surfacing them as argument errors.
+fn is_help_or_version(err: &clap::Error) -> bool {
+    matches!(
+        err.kind(),
+        clap::error::ErrorKind::DisplayHelp
+            | clap::error::ErrorKind::DisplayHelpOnMissingArgumentOrSubcommand
+    )
+}
+
 /// Try to recognize the invocation as a native command.
 ///
 /// Returns ``None`` when the argv doesn't look like a native
@@ -163,13 +177,23 @@ fn looks_native(argv: &[String]) -> bool {
 /// — the corresponding exit code is the one chosen by the command
 /// implementation (typically [`mergify_core::ExitCode::Configuration`]
 /// = 8), not 2.
+#[allow(clippy::too_many_lines)] // mostly mechanical match arms
 fn detect_native(argv: &[String]) -> Option<NativeCommand> {
     let looks_native = looks_native(argv);
 
     let parsed = match CliRoot::try_parse_from(
         std::iter::once("mergify".to_string()).chain(argv.iter().cloned()),
     ) {
         Ok(parsed) => parsed,
+        Err(err) if is_help_or_version(&err) => {
+            // ``--help`` (or implicit help on a subcommand group)
+            // is always handled natively by clap — even when
+            // ``looks_native`` is false. Otherwise we'd fall
+            // through to the Python shim's help, which no longer
+            // lists Rust-native subcommands. ``err.exit()`` prints
+            // to stdout and calls ``process::exit(0)``.
+            err.exit()
+        }
         Err(err) if looks_native => {
             // Native intent + clap rejection = surface clap's error
             // and exit. ``err.exit()`` prints to stderr and calls
@@ -370,7 +394,7 @@ fn run_native(cmd: NativeCommand) -> ExitCode {
 
 #[derive(Parser)]
 #[command(name = "mergify", disable_help_subcommand = true)]
-#[command(disable_version_flag = true, disable_help_flag = true)]
+#[command(disable_version_flag = true)]
 struct CliRoot {
     #[command(subcommand)]
     command: Subcommands,

crates/mergify-queue/src/status.rs

@@ -367,7 +367,7 @@ fn print_waiting_prs(
         if let Some(queued_at) = &pr.queued_at {
             let rel = relative_time(queued_at, now, false);
             if !rel.is_empty() {
-                write!(w, "  {D}queued {rel}{R}", D = theme.dim, R = theme.reset,)?;
+                write!(w, "  {D}queued {rel}{R}", D = theme.dim, R = theme.reset)?;
             }
         }
         if let Some(eta) = &pr.estimated_merge_at {

crates/mergify-tui/src/theme.rs

@@ -132,7 +132,7 @@ mod tests {
 
     #[test]
     fn fg_respects_enabled_flag() {
-        assert_eq!(format!("{}", Theme::new(false).fg(AnsiColor::Red)), "",);
+        assert_eq!(format!("{}", Theme::new(false).fg(AnsiColor::Red)), "");
         assert!(!format!("{}", Theme::new(true).fg(AnsiColor::Red)).is_empty());
     }
 }