cleanup(scm-diff-editor): use thiserror for errors

It's a pain to refer to the separate `Display` implementation. The original reason was probably to avoid bloating library dependencies, but `scm-diff-editor` is no longer part of the `scm-record` library, so no need to separate them.

scm-diff-editor/Cargo.toml

@@ -16,9 +16,10 @@ rust-version = "1.74"
 clap = { version = "4.5", features = ["derive"] }
 diffy = "0.3"
 scm-record = { version = "0.3", path = "../scm-record" }
-sha1 = "0.10"
+sha1 = "0.10"
+thiserror = "1.0.61"
 tracing = "0.1.40"
-walkdir =  "2.5"
+walkdir = "2.5"
 
 [dev-dependencies]
 insta = "1.39"

scm-diff-editor/src/lib.rs

@@ -14,13 +14,12 @@ pub mod testing;
 
 use std::borrow::Cow;
 use std::collections::BTreeSet;
-use std::error;
-use std::fmt::Display;
 use std::io;
 use std::path::{Path, PathBuf, StripPrefixError};
 
 use clap::Parser;
 use scm_record::{File, FileMode, RecordError, RecordState, SelectedContents};
+use thiserror::Error;
 
 /// Render a partial commit selector for use as a difftool or mergetool.
 ///
@@ -65,108 +64,52 @@ pub struct Opts {
  pub output: Option<PathBuf>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Error)]
 #[allow(missing_docs)]
 pub enum Error {
+ #[error("aborted by user")]
  Cancelled,
+
+ #[error("dry run, not writing any files")]
  DryRun,
- WalkDir {
- source: walkdir::Error,
- },
+
+ #[error("walking directory: {source}")]
+ WalkDir { source: walkdir::Error },
+
+ #[error("stripping directory prefix {root} from {path}: {source}")]
  StripPrefix {
  root: PathBuf,
  path: PathBuf,
  source: StripPrefixError,
  },
- ReadFile {
-  path: PathBuf,
-   source: io::Error,
- },
- RemoveFile {
-  path: PathBuf,
- source: io::Error,
- },
+
+ #[error("reading file {path}: {source}")]
+ ReadFile { path: PathBuf, source: io::Error },
+
+ #[error("removing file {path}: {source}")]
+ RemoveFile { path: PathBuf, source: io::Error },
+
+ #[error("copying file {old_path} to {new_path}: {source}")]
  CopyFile {
  old_path: PathBuf,
  new_path: PathBuf,
  source: io::Error,
  },
- CreateDirAll {
- path: PathBuf,
- source: io::Error,
- },
- WriteFile {
- path: PathBuf,
- source: io::Error,
- },
- MissingMergeFile {
- path: PathBuf,
- },
- BinaryMergeFile {
- path: PathBuf,
- },
- Record {
- source: RecordError,
- },
-}
 
-impl error::Error for Error {}
+ #[error("creating directory {path}: {source}")]
+ CreateDirAll { path: PathBuf, source: io::Error },
 
-impl Display for Error {
- fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- match self {
- Error::Cancelled => {
- write!(f, "aborted by user")
- }
- Error::DryRun => {
- write!(f, "dry run, not writing any files")
- }
- Error::WalkDir { source } => {
- write!(f, "walking directory: {source}")
- }
- Error::StripPrefix { root, path, source } => {
- write!(
- f,
- "stripping directory prefix {} from {}: {source}",
- root.display(),
- path.display()
- )
- }
- Error::ReadFile { path, source } => {
- write!(f, "reading file {}: {source}", path.display())
- }
- Error::RemoveFile { path, source } => {
- write!(f, "removing file {}: {source}", path.display())
- }
- Error::CopyFile {
- old_path,
- new_path,
- source,
- } => {
- write!(
- f,
- "copying file {} to {}: {source}",
- old_path.display(),
- new_path.display()
- )
- }
- Error::CreateDirAll { path, source } => {
- write!(f, "creating directory {}: {source}", path.display())
- }
- Error::WriteFile { path, source } => {
- write!(f, "writing file {}: {source}", path.display())
- }
- Error::MissingMergeFile { path } => {
- write!(f, "file did not exist: {}", path.display())
- }
- Error::BinaryMergeFile { path } => {
- write!(f, "file was not text: {}", path.display())
- }
- Error::Record { source } => {
- write!(f, "recording changes: {source}")
- }
- }
- }
+ #[error("writing file {path}: {source}")]
+ WriteFile { path: PathBuf, source: io::Error },
+
+ #[error("file did not exist: {path}")]
+ MissingMergeFile { path: PathBuf },
+
+ #[error("file was not text: {path}")]
+ BinaryMergeFile { path: PathBuf },
+
+ #[error("recording changes: {source}")]
+ Record { source: RecordError },
 }
 
 /// Result type.