rhg-files: make signature of `display_files` more flexible

This allows the callers to use any error type that converts to `CommandError`
instead of a particular concrete type.

rust/rhg/src/commands/files.rs

@@ -1,110 +1,112 b''
 use crate::error::CommandError;
 use crate::ui::Ui;
 use crate::utils::path_utils::RelativizePaths;
 use clap::Arg;
-use hg::errors::HgError;
 use hg::operations::list_rev_tracked_files;
 use hg::repo::Repo;
 use hg::utils::filter_map_results;
 use hg::utils::hg_path::HgPath;
 use rayon::prelude::*;
 
 pub const HELP_TEXT: &str = "
 List tracked files.
 
 Returns 0 on success.
 ";
 
 pub fn args() -> clap::Command {
     clap::command!("files")
         .arg(
             Arg::new("rev")
                 .help("search the repository as it is in REV")
                 .short('r')
                 .long("revision")
                 .value_name("REV"),
         )
         .about(HELP_TEXT)
 }
 
 pub fn run(invocation: &crate::CliInvocation) -> Result<(), CommandError> {
     let relative = invocation.config.get(b"ui", b"relative-paths");
     if relative.is_some() {
         return Err(CommandError::unsupported(
             "non-default ui.relative-paths",
         ));
     }
 
     let rev = invocation.subcommand_args.get_one::<String>("rev");
 
     let repo = invocation.repo?;
 
     // It seems better if this check is removed: this would correspond to
     // automatically enabling the extension if the repo requires it.
     // However we need this check to be in sync with vanilla hg so hg tests
     // pass.
     if repo.has_sparse()
         && invocation.config.get(b"extensions", b"sparse").is_none()
     {
         return Err(CommandError::unsupported(
             "repo is using sparse, but sparse extension is not enabled",
         ));
     }
 
     if let Some(rev) = rev {
         if repo.has_narrow() {
             return Err(CommandError::unsupported(
                 "rhg files -r <rev> is not supported in narrow clones",
             ));
         }
         let files = list_rev_tracked_files(repo, rev)
             .map_err(|e| (e, rev.as_ref()))?;
         display_files(invocation.ui, repo, files.iter())
     } else {
         // The dirstate always reflects the sparse narrowspec, so if
         // we only have sparse without narrow all is fine.
         // If we have narrow, then [hg files] needs to check if
         // the store narrowspec is in sync with the one of the dirstate,
         // so we can't support that without explicit code.
         if repo.has_narrow() {
             return Err(CommandError::unsupported(
                 "rhg files is not supported in narrow clones",
             ));
         }
         let dirstate = repo.dirstate_map()?;
         let files_res: Result<Vec<_>, _> =
             filter_map_results(dirstate.iter(), |(path, entry)| {
                 Ok(if entry.tracked() { Some(path) } else { None })
             })
             .collect();
 
         let mut files = files_res?;
         files.par_sort_unstable();
 
         display_files(invocation.ui, repo, files.into_iter().map(Ok))
     }
 }
 
-fn display_files<'a>(
+fn display_files<'a, E>(
     ui: &Ui,
     repo: &Repo,
-    files: impl IntoIterator<Item = Result<&'a HgPath, HgError>>,
-) -> Result<(), CommandError> {
+    files: impl IntoIterator<Item = Result<&'a HgPath, E>>,
+) -> Result<(), CommandError>
+where
+    CommandError: From<E>,
+{
     let mut stdout = ui.stdout_buffer();
     let mut any = false;
 
     let relativize = RelativizePaths::new(repo)?;
     for result in files {
         let path = result?;
         stdout.write_all(&relativize.relativize(path))?;
         stdout.write_all(b"\n")?;
         any = true;
     }
 
     stdout.flush()?;
     if any {
         Ok(())
     } else {
         Err(CommandError::Unsuccessful)
     }
 }