From 63aa484046af419784c19e187916c41c0bd55404 Mon Sep 17 00:00:00 2001
From: Martin von Zweigbergk <martinvonz@google.com>
Date: Sun, 22 Jan 2023 21:38:06 -0800
Subject: [PATCH] repo: add a specific error type for
 `MutableRepo::check_out()`

---
 lib/src/repo.rs      | 15 ++++++++++++---
 lib/src/workspace.rs |  8 +++++---
 src/cli_util.rs      | 10 ++++++++--
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/lib/src/repo.rs b/lib/src/repo.rs
index 96490f2e3..7b5b2a607 100644
--- a/lib/src/repo.rs
+++ b/lib/src/repo.rs
@@ -746,7 +746,7 @@ impl MutableRepo {
         workspace_id: WorkspaceId,
         settings: &UserSettings,
         commit: &Commit,
-    ) -> BackendResult<Commit> {
+    ) -> Result<Commit, CheckOutCommitError> {
         let wc_commit = self
             .new_commit(
                 settings,
@@ -754,7 +754,7 @@ impl MutableRepo {
                 commit.tree_id().clone(),
             )
             .write()?;
-        self.edit(workspace_id, &wc_commit).unwrap();
+        self.edit(workspace_id, &wc_commit)?;
         Ok(wc_commit)
     }
 
@@ -1101,7 +1101,7 @@ impl MutableRepo {
 }
 
 /// Error from attempts to check out the root commit for editing
-#[derive(Debug, Copy, Clone, Error)]
+#[derive(Debug, Error)]
 #[error("Cannot rewrite the root commit")]
 pub struct RewriteRootCommit;
 
@@ -1112,6 +1112,15 @@ pub enum EditCommitError {
     RewriteRootCommit,
 }
 
+/// Error from attempts to check out a commit
+#[derive(Debug, Error)]
+pub enum CheckOutCommitError {
+    #[error("Failed to create new working-copy commit: {0}")]
+    CreateCommit(#[from] BackendError),
+    #[error("Failed to edit commit: {0}")]
+    EditCommit(#[from] EditCommitError),
+}
+
 #[derive(Debug, Error)]
 #[error("Cannot access {path}")]
 pub struct PathError {
diff --git a/lib/src/workspace.rs b/lib/src/workspace.rs
index 10930cab7..a57dc993f 100644
--- a/lib/src/workspace.rs
+++ b/lib/src/workspace.rs
@@ -19,13 +19,15 @@ use std::sync::Arc;
 
 use thiserror::Error;
 
-use crate::backend::{Backend, BackendError};
+use crate::backend::Backend;
 use crate::git_backend::GitBackend;
 use crate::local_backend::LocalBackend;
 use crate::op_heads_store::OpHeadsStore;
 use crate::op_store::{self, OpStore, OperationMetadata, WorkspaceId};
 use crate::operation::Operation;
-use crate::repo::{IoResultExt, PathError, ReadonlyRepo, RepoLoader, StoreFactories};
+use crate::repo::{
+    CheckOutCommitError, IoResultExt, PathError, ReadonlyRepo, RepoLoader, StoreFactories,
+};
 use crate::settings::UserSettings;
 use crate::working_copy::WorkingCopy;
 
@@ -36,7 +38,7 @@ pub enum WorkspaceInitError {
     #[error("Repo path could not be interpreted as Unicode text")]
     NonUnicodePath,
     #[error(transparent)]
-    BackendError(#[from] BackendError),
+    CheckOutCommit(#[from] CheckOutCommitError),
     #[error(transparent)]
     Path(#[from] PathError),
 }
diff --git a/src/cli_util.rs b/src/cli_util.rs
index aecd3162a..e7e11b9fd 100644
--- a/src/cli_util.rs
+++ b/src/cli_util.rs
@@ -37,8 +37,8 @@ use jujutsu_lib::op_heads_store::{self, OpHeadResolutionError, OpHeadsStore};
 use jujutsu_lib::op_store::{OpStore, OpStoreError, OperationId, WorkspaceId};
 use jujutsu_lib::operation::Operation;
 use jujutsu_lib::repo::{
-    EditCommitError, MutableRepo, ReadonlyRepo, RepoLoader, RepoRef, RewriteRootCommit,
-    StoreFactories,
+    CheckOutCommitError, EditCommitError, MutableRepo, ReadonlyRepo, RepoLoader, RepoRef,
+    RewriteRootCommit, StoreFactories,
 };
 use jujutsu_lib::repo_path::{FsPathParseError, RepoPath};
 use jujutsu_lib::revset::{
@@ -124,6 +124,12 @@ impl From<EditCommitError> for CommandError {
     }
 }
 
+impl From<CheckOutCommitError> for CommandError {
+    fn from(err: CheckOutCommitError) -> Self {
+        CommandError::InternalError(format!("Failed to check out a commit: {err}"))
+    }
+}
+
 impl From<BackendError> for CommandError {
     fn from(err: BackendError) -> Self {
         user_error(format!("Unexpected error from backend: {err}"))