feat(complete): Make '--shell' optional

clap_complete/src/dynamic/shells/mod.rs

@@ -192,7 +192,7 @@ impl CompleteCommand {
 pub struct CompleteArgs {
  /// Specify shell to complete for
  #[arg(long)]
- shell: Shell,
+ shell: Option<Shell>,
 
  /// Path to write completion-registration to
  #[arg(long, required = true)]
@@ -217,15 +217,21 @@ impl CompleteArgs {
  /// **Warning:** `stdout` should not be written to before or after this has run.
  pub fn try_complete(&self, cmd: &mut clap::Command) -> clap::error::Result<()> {
  debug!("CompleteCommand::try_complete: {self:?}");
+
+ let shell = self
+ .shell
+ .or_else(|| Shell::from_env())
+ .unwrap_or(Shell::Bash);
+
  if let Some(out_path) = self.register.as_deref() {
  let mut buf = Vec::new();
  let name = cmd.get_name();
  let bin = cmd.get_bin_name().unwrap_or_else(|| cmd.get_name());
- self.shell.write_registration(name, bin, bin, &mut buf)?;
+ shell.write_registration(name, bin, bin, &mut buf)?;
  if out_path == std::path::Path::new("-") {
  std::io::stdout().write_all(&buf)?;
  } else if out_path.is_dir() {
- let out_path = out_path.join(self.shell.file_name(name));
+ let out_path = out_path.join(shell.file_name(name));
  std::fs::write(out_path, buf)?;
  } else {
  std::fs::write(out_path, buf)?;
@@ -234,7 +240,7 @@ impl CompleteArgs {
  let current_dir = std::env::current_dir().ok();
 
  let mut buf = Vec::new();
- self.shell.write_complete(
+ shell.write_complete(
  cmd,
  self.comp_words.clone(),
  current_dir.as_deref(),