use native external subcommand support instead of hand-rolled one

Dependencies

• [2] BQDE4VH6 Fixing the "empty subcommand" case
• [3] NV6OSWDH Fixing external subcommands
• [4] WXAFKN6J Do not call an external subcommand when the parsing of an existing subcommand fails
• [5] SFY4U6XE remove redundant conditional compilation
• [6] GURIBVW6 Fixing the pager
• [7] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).
• [8] RJMQSZER External commands
• [*] L4JXJHWX pijul/*: reorganize imports and remove extern crate

Change contents

• edit in pijul/src/main.rs at line 6
  [10.577]

  [4.84279]
  + use std::ffi::OsString;
• edit in pijul/src/main.rs at line 107
  [4.85867]

  [4.85867]
  +

  + #[clap(external_subcommand)]

  + ExternalSubcommand(Vec<OsString>),
• replacement in pijul/src/main.rs at line 183
  [4.88177]→[4.0:519](∅→∅),[4.519]→[4.190:200](∅→∅),[4.190]→[4.190:200](∅→∅),[4.419]→[4.88349:88355](∅→∅),[4.88349]→[4.88349:88355](∅→∅),[4.88355]→[4.0:27](∅→∅),[4.27]→[4.420:422](∅→∅)
  − match external_command() {

  − Ok(false) => {

  − let opts = Opts::parse();

  − if let Err(e) = run(opts).await {

  − writeln!(std::io::stderr(), "Error: {}", e).unwrap_or(());

  − std::process::exit(1);

  − }

  − }

  − Ok(true) => (),

  − Err((cmd, e)) => {

  − writeln!(

  − std::io::stderr(),

  − "Error while trying to run {:?}: {}",

  − cmd,

  − e

  − )

  − .unwrap_or(());

  − }

  − }

  − std::process::exit(0);

  − }
  [4.88177]

  [4.422]
  +

  + let opts = Opts::parse();
• replacement in pijul/src/main.rs at line 186
  [4.423]→[4.520:586](∅→∅),[4.586]→[4.487:551](∅→∅),[4.487]→[4.487:551](∅→∅),[4.551]→[4.587:642](∅→∅),[4.642]→[4.551:621](∅→∅),[4.551]→[4.551:621](∅→∅),[4.621]→[3.0:231](∅→∅),[3.231]→[4.792:854](∅→∅),[4.792]→[4.792:854](∅→∅),[4.854]→[4.621:748](∅→∅),[4.621]→[4.621:748](∅→∅),[4.748]→[2.0:56](∅→∅),[2.56]→[4.748:826](∅→∅),[4.748]→[4.748:826](∅→∅)
  − fn external_command() -> Result<bool, (String, std::io::Error)> {

  − let mut cmd = String::new();

  − let mut args = Vec::new();

  − use clap::IntoApp;

  − let app = Opts::into_app();

  − for arg in std::env::args().skip(1) {

  − if cmd.is_empty() {

  − if arg == "help"

  − || arg.starts_with("--")

  − || app

  − .get_subcommands()

  − .any(|sub| sub.get_name() == arg || sub.get_all_aliases().any(|al| al == arg))

  − {

  − return Ok(false);

  − }

  − cmd.push_str("pijul-");

  − cmd.push_str(&arg)

  − } else {

  − args.push(arg)

  − }

  − }

  − if cmd.is_empty() {

  − return Ok(false);

  − }

  − if let Err(e) = run_external_command(&cmd, &args) {

  − Err((cmd, e))
  [4.423]

  [4.826]
  + if let Err(e) = run(opts).await {

  + writeln!(std::io::stderr(), "Error: {}", e).unwrap_or(());

  + std::process::exit(1);
• replacement in pijul/src/main.rs at line 190
  [4.839]→[4.855:872](∅→∅)
  − Ok(true)
  [4.839]

  [4.854]
  + std::process::exit(0);
• replacement in pijul/src/main.rs at line 195
  [4.876]→[4.876:960](∅→∅)
  − fn run_external_command(cmd: &str, args: &[String]) -> Result<(), std::io::Error> {
  [4.876]

  [4.960]
  + fn run_external_command(mut command: Vec<OsString>) -> Result<(), std::io::Error> {

  + let args = command.split_off(1);

  + let cmd = &command[0];

  +
• replacement in pijul/src/main.rs at line 204
  [4.1082]→[4.1082:1166](∅→∅)
  − fn run_external_command(cmd: &str, args: &[String]) -> Result<(), std::io::Error> {
  [4.1082]

  [4.1166]
  + fn run_external_command(mut command: Vec<OsString>) -> Result<(), std::io::Error> {

  + let args = command.split_off(1);

  + let cmd = &command[0];

  +
• edit in pijul/src/main.rs at line 241
  [4.89705]

  [4.89705]
  + SubCommand::ExternalSubcommand(command) => Ok(run_external_command(command)?),