Continue to respect `--find-links` with `--no-index` (#931)

Like `pip`, we should allow `--find-links` with `--no-index`.

crates/distribution-types/src/index_url.rs

@@ -137,11 +137,10 @@ impl IndexLocations {
         no_index: bool,
     ) -> Self {
         if no_index {
-            // TODO(charlie): Warn if the user passes in arguments here alongside `--no-index`.
             Self {
                 index: None,
                 extra_index: Vec::new(),
-                flat_index: Vec::new(),
+                flat_index,
             }
         } else {
             Self {
@@ -154,14 +153,17 @@ impl IndexLocations {
 }
 
 impl<'a> IndexLocations {
+    /// Return an iterator over the [`IndexUrl`] entries.
     pub fn indexes(&'a self) -> impl Iterator<Item = &'a IndexUrl> + 'a {
         self.index.iter().chain(self.extra_index.iter())
     }
 
+    /// Return an iterator over the [`FlatIndexLocation`] entries.
     pub fn flat_indexes(&'a self) -> impl Iterator<Item = &'a FlatIndexLocation> + 'a {
         self.flat_index.iter()
     }
 
+    /// Clone the index locations into a [`IndexUrls`] instance.
     pub fn index_urls(&'a self) -> IndexUrls {
         IndexUrls {
             index: self.index.clone(),
@@ -190,10 +192,12 @@ impl Default for IndexUrls {
 }
 
 impl<'a> IndexUrls {
+    /// Return an iterator over the [`IndexUrl`] entries.
     pub fn indexes(&'a self) -> impl Iterator<Item = &'a IndexUrl> + 'a {
         self.index.iter().chain(self.extra_index.iter())
     }
 
+    /// Return `true` if no index is configured.
     pub fn no_index(&self) -> bool {
         self.index.is_none() && self.extra_index.is_empty()
     }

crates/puffin-cli/src/main.rs

@@ -252,7 +252,8 @@ struct PipSyncArgs {
     #[clap(long)]
     find_links: Vec<FlatIndexLocation>,
 
-    /// Ignore the package index, instead relying on local archives and caches.
+    /// Ignore the registry index (e.g., PyPI), instead relying on local caches and `--find-links`
+    /// directories and URLs.
     #[clap(long, conflicts_with = "index_url", conflicts_with = "extra_index_url")]
     no_index: bool,
 

crates/puffin-cli/tests/pip_compile.rs

@@ -3089,8 +3089,7 @@ fn find_links_directory() -> Result<()> {
     Ok(())
 }
 
-/// Compile using `--find-links` with a URL by resolving `tqdm` from the `PyTorch` wheels index,
-/// and pointing `--index-url` to the test `PyPI` (which doesn't have `tqdm`).
+/// Compile using `--find-links` with a URL by resolving `tqdm` from the `PyTorch` wheels index.
 #[test]
 fn find_links_url() -> Result<()> {
     let temp_dir = TempDir::new()?;
@@ -3106,8 +3105,7 @@ fn find_links_url() -> Result<()> {
         assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
             .arg("pip-compile")
             .arg("requirements.in")
-            .arg("--index-url")
-            .arg("https://test.pypi.org/simple")
+            .arg("--no-index")
             .arg("--find-links")
             .arg("https://download.pytorch.org/whl/torch_stable.html")
             .arg("--cache-dir")
@@ -3120,7 +3118,7 @@ fn find_links_url() -> Result<()> {
         exit_code: 0
         ----- stdout -----
         # This file was autogenerated by Puffin v0.0.1 via the following command:
-        #    puffin pip-compile requirements.in --index-url https://test.pypi.org/simple --find-links https://download.pytorch.org/whl/torch_stable.html --cache-dir [CACHE_DIR]
+        #    puffin pip-compile requirements.in --no-index --find-links https://download.pytorch.org/whl/torch_stable.html --cache-dir [CACHE_DIR]
         tqdm==4.64.1
 
         ----- stderr -----

crates/puffin-client/src/registry_client.rs

@@ -265,10 +265,6 @@ impl RegistryClient {
         file: &File,
         url: &Url,
     ) -> Result<Metadata21, Error> {
-        if self.index_urls.no_index() {
-            return Err(Error::NoIndex(file.filename.clone()));
-        }
-
         // If the metadata file is available at its own url (PEP 658), download it from there.
         let filename = WheelFilename::from_str(&file.filename)?;
         if file
@@ -314,10 +310,6 @@ impl RegistryClient {
         url: &'data Url,
         cache_shard: WheelCache<'data>,
     ) -> Result<Metadata21, Error> {
-        if self.index_urls.no_index() {
-            return Err(Error::NoIndex(url.to_string()));
-        }
-
         let cache_entry = self.cache.entry(
             CacheBucket::Wheels,
             cache_shard.remote_wheel_dir(filename.name.as_ref()),
@@ -380,10 +372,6 @@ impl RegistryClient {
         &self,
         url: &Url,
     ) -> Result<Box<dyn futures::AsyncRead + Unpin + Send + Sync>, Error> {
-        if self.index_urls.no_index() {
-            return Err(Error::NoIndex(url.to_string()));
-        }
-
         Ok(Box::new(
             self.client
                 .uncached()

crates/puffin-resolver/src/resolver/provider.rs

@@ -100,7 +100,10 @@ impl<'a, Context: BuildContext + Send + Sync> ResolverProvider
                     self.exclude_newer.as_ref(),
                     self.flat_index.get(package_name).cloned(),
                 )),
-                Err(err @ puffin_client::Error::PackageNotFound(_)) => {
+                Err(
+                    err @ (puffin_client::Error::PackageNotFound(_)
+                    | puffin_client::Error::NoIndex(_)),
+                ) => {
                     if let Some(flat_index) = self.flat_index.get(package_name).cloned() {
                         Ok(VersionMap::from(flat_index))
                     } else {