Use a standalone error type for --find-links registry (#936)

crates/puffin-cli/src/commands/venv.rs

@@ -70,7 +70,7 @@ enum VenvError {
 
     #[error("Failed to resolve `--find-links` entry")]
     #[diagnostic(code(puffin::venv::flat_index))]
-    FlatIndexError(#[source] puffin_client::Error),
+    FlatIndexError(#[source] puffin_client::FlatIndexError),
 }
 
 /// Create a virtual environment.

crates/puffin-client/src/error.rs

@@ -1,15 +1,13 @@
-use std::io;
-
 use async_http_range_reader::AsyncHttpRangeReaderError;
 use async_zip::error::ZipError;
-use thiserror::Error;
 use url::Url;
 
-use crate::html;
 use distribution_filename::{WheelFilename, WheelFilenameError};
 use puffin_normalize::PackageName;
 
-#[derive(Debug, Error)]
+use crate::html;
+
+#[derive(Debug, thiserror::Error)]
 pub enum Error {
     /// An invalid URL was provided.
     #[error(transparent)]
@@ -72,10 +70,10 @@ pub enum Error {
     Zip(WheelFilename, #[source] ZipError),
 
     #[error("Failed to write to the client cache")]
-    CacheWrite(#[source] io::Error),
+    CacheWrite(#[source] std::io::Error),
 
     #[error(transparent)]
-    Io(#[from] io::Error),
+    Io(#[from] std::io::Error),
 
     #[error("Cache deserialization failed")]
     Decode(#[from] rmp_serde::decode::Error),
@@ -95,9 +93,6 @@ pub enum Error {
 
     #[error("Unsupported `Content-Type` \"{1}\" for {0}. Expected JSON or HTML.")]
     UnsupportedMediaType(Url, String),
-
-    #[error("Failed to read find links directory")]
-    FindLinks(#[source] io::Error),
 }
 
 impl Error {

crates/puffin-client/src/flat_index.rs

@@ -22,6 +22,15 @@ use pypi_types::Hashes;
 use crate::html::SimpleHtml;
 use crate::{Error, RegistryClient};
 
+#[derive(Debug, thiserror::Error)]
+pub enum FlatIndexError {
+    #[error("Failed to read `--find-links` directory: {0}")]
+    FindLinksDirectory(PathBuf, #[source] std::io::Error),
+
+    #[error("Failed to read `--find-links` URL: {0}")]
+    FindLinksUrl(Url, #[source] Error),
+}
+
 type FlatIndexEntry = (DistFilename, File, IndexUrl);
 
 /// A client for reading distributions from `--find-links` entries (either local directories or
@@ -43,15 +52,17 @@ impl<'a> FlatIndexClient<'a> {
     pub async fn fetch(
         &self,
         indexes: impl Iterator<Item = &FlatIndexLocation>,
-    ) -> Result<Vec<FlatIndexEntry>, Error> {
+    ) -> Result<Vec<FlatIndexEntry>, FlatIndexError> {
         let mut dists = Vec::new();
         // TODO(konstin): Parallelize reads over flat indexes.
         for flat_index in indexes {
             let index_dists = match flat_index {
-                FlatIndexLocation::Path(path) => {
-                    Self::read_from_directory(path).map_err(Error::FindLinks)?
-                }
-                FlatIndexLocation::Url(url) => self.read_from_url(url).await?,
+                FlatIndexLocation::Path(path) => Self::read_from_directory(path)
+                    .map_err(|err| FlatIndexError::FindLinksDirectory(path.clone(), err))?,
+                FlatIndexLocation::Url(url) => self
+                    .read_from_url(url)
+                    .await
+                    .map_err(|err| FlatIndexError::FindLinksUrl(url.clone(), err))?,
             };
             if index_dists.is_empty() {
                 warn!("No packages found in `--find-links` entry: {}", flat_index);

crates/puffin-client/src/lib.rs

@@ -1,6 +1,6 @@
 pub use cached_client::{CachedClient, CachedClientError, DataWithCachePolicy};
 pub use error::Error;
-pub use flat_index::{FlatDistributions, FlatIndex, FlatIndexClient};
+pub use flat_index::{FlatDistributions, FlatIndex, FlatIndexClient, FlatIndexError};
 pub use registry_client::{
     read_metadata_async, RegistryClient, RegistryClientBuilder, SimpleMetadata, VersionFiles,
 };