file_util: move PathError and its helper trait from repo module

It's generally useful in order to attach context to io::Error.

lib/src/file_util.rs

@@ -13,10 +13,32 @@
 // limitations under the License.
 
 use std::fs::File;
-use std::iter;
 use std::path::{Component, Path, PathBuf};
+use std::{io, iter};
 
 use tempfile::{NamedTempFile, PersistError};
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+#[error("Cannot access {path}")]
+pub struct PathError {
+    pub path: PathBuf,
+    #[source]
+    pub error: io::Error,
+}
+
+pub(crate) trait IoResultExt<T> {
+    fn context(self, path: impl AsRef<Path>) -> Result<T, PathError>;
+}
+
+impl<T> IoResultExt<T> for io::Result<T> {
+    fn context(self, path: impl AsRef<Path>) -> Result<T, PathError> {
+        self.map_err(|error| PathError {
+            path: path.as_ref().to_path_buf(),
+            error,
+        })
+    }
+}
 
 /// Turns the given `to` path into relative path starting from the `from` path.
 ///

lib/src/repo.rs

@@ -31,6 +31,7 @@ use crate::commit::Commit;
 use crate::commit_builder::CommitBuilder;
 use crate::default_index_store::DefaultIndexStore;
 use crate::default_submodule_store::DefaultSubmoduleStore;
+use crate::file_util::{IoResultExt as _, PathError};
 use crate::git_backend::GitBackend;
 use crate::index::{HexPrefix, Index, IndexStore, MutableIndex, PrefixResolution, ReadonlyIndex};
 use crate::local_backend::LocalBackend;
@@ -1306,27 +1307,6 @@ pub enum CheckOutCommitError {
     EditCommit(#[from] EditCommitError),
 }
 
-#[derive(Debug, Error)]
-#[error("Cannot access {path}")]
-pub struct PathError {
-    pub path: PathBuf,
-    #[source]
-    pub error: io::Error,
-}
-
-pub(crate) trait IoResultExt<T> {
-    fn context(self, path: impl AsRef<Path>) -> Result<T, PathError>;
-}
-
-impl<T> IoResultExt<T> for io::Result<T> {
-    fn context(self, path: impl AsRef<Path>) -> Result<T, PathError> {
-        self.map_err(|error| PathError {
-            path: path.as_ref().to_path_buf(),
-            error,
-        })
-    }
-}
-
 mod dirty_cell {
     use std::cell::{Cell, RefCell};
 

lib/src/workspace.rs

@@ -20,14 +20,15 @@ use std::sync::Arc;
 use thiserror::Error;
 
 use crate::backend::{Backend, BackendError};
+use crate::file_util::{IoResultExt as _, PathError};
 use crate::git_backend::GitBackend;
 use crate::index::IndexStore;
 use crate::local_backend::LocalBackend;
 use crate::op_heads_store::OpHeadsStore;
 use crate::op_store::{OpStore, WorkspaceId};
 use crate::repo::{
-    CheckOutCommitError, IoResultExt, PathError, ReadonlyRepo, Repo, RepoInitError, RepoLoader,
-    StoreFactories, StoreLoadError,
+    CheckOutCommitError, ReadonlyRepo, Repo, RepoInitError, RepoLoader, StoreFactories,
+    StoreLoadError,
 };
 use crate::settings::UserSettings;
 use crate::submodule_store::SubmoduleStore;