rust-clippy: refactor complex type

This makes reading the signature a bit less tiring.

rust/hg-core/src/operations/cat.rs

@@ -1,114 +1,117 b''
 // list_tracked_files.rs
 //
 // Copyright 2020 Antoine Cezar <[e-mail]>
 //
 // This software may be used and distributed according to the terms of the
 // GNU General Public License version 2 or any later version.
 
 use crate::repo::Repo;
 use crate::revlog::revlog::RevlogError;
 use crate::revlog::Node;
 
 use crate::utils::hg_path::HgPath;
 
 use crate::errors::HgError;
 use crate::manifest::Manifest;
 use crate::manifest::ManifestEntry;
 use itertools::put_back;
 use itertools::PutBack;
 use std::cmp::Ordering;
 
 pub struct CatOutput<'a> {
     /// Whether any file in the manifest matched the paths given as CLI
     /// arguments
     pub found_any: bool,
     /// The contents of matching files, in manifest order
     pub results: Vec<(&'a HgPath, Vec<u8>)>,
     /// Which of the CLI arguments did not match any manifest file
     pub missing: Vec<&'a HgPath>,
     /// The node ID that the given revset was resolved to
     pub node: Node,
 }
 
 // Find an item in an iterator over a sorted collection.
 fn find_item<'a>(
     i: &mut PutBack<impl Iterator<Item = Result<ManifestEntry<'a>, HgError>>>,
     needle: &HgPath,
 ) -> Result<Option<Node>, HgError> {
     loop {
         match i.next() {
             None => return Ok(None),
             Some(result) => {
                 let entry = result?;
                 match needle.as_bytes().cmp(entry.path.as_bytes()) {
                     Ordering::Less => {
                         i.put_back(Ok(entry));
                         return Ok(None);
                     }
                     Ordering::Greater => continue,
                     Ordering::Equal => return Ok(Some(entry.node_id()?)),
                 }
             }
         }
     }
 }
 
+// Tuple of (missing, found) paths in the manifest
+type ManifestQueryResponse<'a> = (Vec<(&'a HgPath, Node)>, Vec<&'a HgPath>);
+
 fn find_files_in_manifest<'query>(
     manifest: &Manifest,
     query: impl Iterator<Item = &'query HgPath>,
-) -> Result<(Vec<(&'query HgPath, Node)>, Vec<&'query HgPath>), HgError> {
+) -> Result<ManifestQueryResponse<'query>, HgError> {
     let mut manifest = put_back(manifest.iter());
     let mut res = vec![];
     let mut missing = vec![];
 
     for file in query {
         match find_item(&mut manifest, file)? {
             None => missing.push(file),
             Some(item) => res.push((file, item)),
         }
     }
     return Ok((res, missing));
 }
 
 /// Output the given revision of files
 ///
 /// * `root`: Repository root
 /// * `rev`: The revision to cat the files from.
 /// * `files`: The files to output.
 pub fn cat<'a>(
     repo: &Repo,
     revset: &str,
     mut files: Vec<&'a HgPath>,
 ) -> Result<CatOutput<'a>, RevlogError> {
     let rev = crate::revset::resolve_single(revset, repo)?;
     let manifest = repo.manifest_for_rev(rev)?;
     let node = *repo
         .changelog()?
         .node_from_rev(rev)
         .expect("should succeed when repo.manifest did");
     let mut results: Vec<(&'a HgPath, Vec<u8>)> = vec![];
     let mut found_any = false;
 
     files.sort_unstable();
 
     let (found, missing) = find_files_in_manifest(
         &manifest,
         files.into_iter().map(|f| f.as_ref()),
     )?;
 
     for (file_path, file_node) in found {
         found_any = true;
         let file_log = repo.filelog(file_path)?;
         results.push((
             file_path,
             file_log.data_for_node(file_node)?.into_file_data()?,
         ));
     }
 
     Ok(CatOutput {
         found_any,
         results,
         missing,
         node,
     })
 }