chore: fix clippy lints from nightly-2025-03-16 (#11273)

I like to run nightly clippy every so often to make our future rust
upgrades easier. Some notable changes:

* Prefer `next_back()` over `last()`. Generic iterators will implement
`last()` to run forward through the iterator until the end.

* Prefer `io::Error::other()`.

* Use implicit returns

One case where I haven't dealt with the issues is the now
[more-sensitive "large enum variant"
lint](rust-lang/rust-clippy#13833). I chose not
to take any decisions around it here, and simply marked them as allow
for now.

Author: conradludgate

compute_tools/src/catalog.rs

@@ -98,13 +98,15 @@ pub async fn get_database_schema(
         .kill_on_drop(true)
         .spawn()?;
 
-    let stdout = cmd.stdout.take().ok_or_else(|| {
-        std::io::Error::new(std::io::ErrorKind::Other, "Failed to capture stdout.")
-    })?;
+    let stdout = cmd
+        .stdout
+        .take()
+        .ok_or_else(|| std::io::Error::other("Failed to capture stdout."))?;
 
-    let stderr = cmd.stderr.take().ok_or_else(|| {
-        std::io::Error::new(std::io::ErrorKind::Other, "Failed to capture stderr.")
-    })?;
+    let stderr = cmd
+        .stderr
+        .take()
+        .ok_or_else(|| std::io::Error::other("Failed to capture stderr."))?;
 
     let mut stdout_reader = FramedRead::new(stdout, BytesCodec::new());
     let stderr_reader = BufReader::new(stderr);
@@ -128,8 +130,7 @@ pub async fn get_database_schema(
                 }
             });
 
-            return Err(SchemaDumpError::IO(std::io::Error::new(
-                std::io::ErrorKind::Other,
+            return Err(SchemaDumpError::IO(std::io::Error::other(
                 "failed to start pg_dump",
             )));
         }

control_plane/storcon_cli/src/main.rs

@@ -941,7 +941,7 @@ async fn main() -> anyhow::Result<()> {
             let mut node_to_fill_descs = Vec::new();
 
             for desc in node_descs {
-                let to_drain = nodes.iter().any(|id| *id == desc.id);
+                let to_drain = nodes.contains(&desc.id);
                 if to_drain {
                     node_to_drain_descs.push(desc);
                 } else {

libs/postgres_backend/src/lib.rs

@@ -5,7 +5,6 @@
 #![deny(unsafe_code)]
 #![deny(clippy::undocumented_unsafe_blocks)]
 use std::future::Future;
-use std::io::ErrorKind;
 use std::net::SocketAddr;
 use std::os::fd::{AsRawFd, RawFd};
 use std::pin::Pin;
@@ -227,7 +226,7 @@ impl<IO: AsyncRead + AsyncWrite + Unpin> MaybeWriteOnly<IO> {
         match self {
             MaybeWriteOnly::Full(framed) => framed.read_startup_message().await,
             MaybeWriteOnly::WriteOnly(_) => {
-                Err(io::Error::new(ErrorKind::Other, "reading from write only half").into())
+                Err(io::Error::other("reading from write only half").into())
             }
             MaybeWriteOnly::Broken => panic!("IO on invalid MaybeWriteOnly"),
         }
@@ -237,7 +236,7 @@ impl<IO: AsyncRead + AsyncWrite + Unpin> MaybeWriteOnly<IO> {
         match self {
             MaybeWriteOnly::Full(framed) => framed.read_message().await,
             MaybeWriteOnly::WriteOnly(_) => {
-                Err(io::Error::new(ErrorKind::Other, "reading from write only half").into())
+                Err(io::Error::other("reading from write only half").into())
             }
             MaybeWriteOnly::Broken => panic!("IO on invalid MaybeWriteOnly"),
         }
@@ -975,7 +974,7 @@ impl<IO: AsyncRead + AsyncWrite + Unpin> AsyncWrite for CopyDataWriter<'_, IO> {
             .write_message_noflush(&BeMessage::CopyData(buf))
             // write_message only writes to the buffer, so it can fail iff the
             // message is invaid, but CopyData can't be invalid.
-            .map_err(|_| io::Error::new(ErrorKind::Other, "failed to serialize CopyData"))?;
+            .map_err(|_| io::Error::other("failed to serialize CopyData"))?;
 
         Poll::Ready(Ok(buf.len()))
     }

libs/postgres_backend/tests/simple_select.rs

@@ -85,8 +85,8 @@ static KEY: Lazy<rustls::pki_types::PrivateKeyDer<'static>> = Lazy::new(|| {
 
 static CERT: Lazy<rustls::pki_types::CertificateDer<'static>> = Lazy::new(|| {
     let mut cursor = Cursor::new(include_bytes!("cert.pem"));
-    let cert = rustls_pemfile::certs(&mut cursor).next().unwrap().unwrap();
-    cert
+
+    rustls_pemfile::certs(&mut cursor).next().unwrap().unwrap()
 });
 
 // test that basic select with ssl works

libs/pq_proto/src/framed.rs

@@ -35,7 +35,7 @@ impl ConnectionError {
     pub fn into_io_error(self) -> io::Error {
         match self {
             ConnectionError::Io(io) => io,
-            ConnectionError::Protocol(pe) => io::Error::new(io::ErrorKind::Other, pe.to_string()),
+            ConnectionError::Protocol(pe) => io::Error::other(pe.to_string()),
         }
     }
 }

libs/pq_proto/src/lib.rs

@@ -257,7 +257,7 @@ pub enum ProtocolError {
 impl ProtocolError {
     /// Proxy stream.rs uses only io::Error; provide it.
     pub fn into_io_error(self) -> io::Error {
-        io::Error::new(io::ErrorKind::Other, self.to_string())
+        io::Error::other(self.to_string())
     }
 }
 

libs/proxy/postgres-protocol2/src/authentication/sasl.rs

@@ -212,7 +212,7 @@ impl ScramSha256 {
                     password,
                     channel_binding,
                 } => (nonce, password, channel_binding),
-                _ => return Err(io::Error::new(io::ErrorKind::Other, "invalid SCRAM state")),
+                _ => return Err(io::Error::other("invalid SCRAM state")),
             };
 
         let message =
@@ -291,7 +291,7 @@ impl ScramSha256 {
                 server_key,
                 auth_message,
             } => (server_key, auth_message),
-            _ => return Err(io::Error::new(io::ErrorKind::Other, "invalid SCRAM state")),
+            _ => return Err(io::Error::other("invalid SCRAM state")),
         };
 
         let message =
@@ -301,10 +301,7 @@ impl ScramSha256 {
 
         let verifier = match parsed {
             ServerFinalMessage::Error(e) => {
-                return Err(io::Error::new(
-                    io::ErrorKind::Other,
-                    format!("SCRAM error: {}", e),
-                ));
+                return Err(io::Error::other(format!("SCRAM error: {}", e)));
             }
             ServerFinalMessage::Verifier(verifier) => verifier,
         };

libs/remote_storage/src/azure_blob.rs

@@ -801,8 +801,7 @@ where
             // that support needs to be hacked in.
             //
             // including {self:?} into the message would be useful, but unsure how to unproject.
-            _ => std::task::Poll::Ready(Err(std::io::Error::new(
-                std::io::ErrorKind::Other,
+            _ => std::task::Poll::Ready(Err(std::io::Error::other(
                 "cloned or initial values cannot be read",
             ))),
         }
@@ -855,7 +854,7 @@ where
         };
         Err(azure_core::error::Error::new(
             azure_core::error::ErrorKind::Io,
-            std::io::Error::new(std::io::ErrorKind::Other, msg),
+            std::io::Error::other(msg),
         ))
     }
 

libs/utils/src/crashsafe.rs

@@ -81,12 +81,9 @@ pub fn path_with_suffix_extension(
 }
 
 pub fn fsync_file_and_parent(file_path: &Utf8Path) -> io::Result<()> {
-    let parent = file_path.parent().ok_or_else(|| {
-        io::Error::new(
-            io::ErrorKind::Other,
-            format!("File {file_path:?} has no parent"),
-        )
-    })?;
+    let parent = file_path
+        .parent()
+        .ok_or_else(|| io::Error::other(format!("File {file_path:?} has no parent")))?;
 
     fsync(file_path)?;
     fsync(parent)?;

pageserver/src/http/routes.rs

@@ -3381,11 +3381,11 @@ async fn put_tenant_timeline_import_basebackup(
 
         let broker_client = state.broker_client.clone();
 
-        let mut body = StreamReader::new(request.into_body().map(|res| {
-            res.map_err(|error| {
-                std::io::Error::new(std::io::ErrorKind::Other, anyhow::anyhow!(error))
-            })
-        }));
+        let mut body = StreamReader::new(
+            request
+                .into_body()
+                .map(|res| res.map_err(|error| std::io::Error::other(anyhow::anyhow!(error)))),
+        );
 
         tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;
 
@@ -3459,7 +3459,7 @@ async fn put_tenant_timeline_import_wal(
 
         let mut body = StreamReader::new(request.into_body().map(|res| {
             res.map_err(|error| {
-                std::io::Error::new(std::io::ErrorKind::Other, anyhow::anyhow!(error))
+                std::io::Error::other( anyhow::anyhow!(error))
             })
         }));
 

pageserver/src/tenant.rs

@@ -920,6 +920,7 @@ enum StartCreatingTimelineResult {
     Idempotent(Arc<Timeline>),
 }
 
+#[allow(clippy::large_enum_variant, reason = "TODO")]
 enum TimelineInitAndSyncResult {
     ReadyToActivate(Arc<Timeline>),
     NeedsSpawnImportPgdata(TimelineInitAndSyncNeedsSpawnImportPgdata),
@@ -1006,6 +1007,7 @@ enum CreateTimelineCause {
     Delete,
 }
 
+#[allow(clippy::large_enum_variant, reason = "TODO")]
 enum LoadTimelineCause {
     Attach,
     Unoffload,
@@ -4399,10 +4401,7 @@ impl Tenant {
         .to_string();
 
         fail::fail_point!("tenant-config-before-write", |_| {
-            Err(std::io::Error::new(
-                std::io::ErrorKind::Other,
-                "tenant-config-before-write",
-            ))
+            Err(std::io::Error::other("tenant-config-before-write"))
         });
 
         // Convert the config to a toml file.

pageserver/src/tenant/blob_io.rs

@@ -15,7 +15,7 @@
 //! len >= 128: 1CCCXXXX XXXXXXXX XXXXXXXX XXXXXXXX
 //!
 use std::cmp::min;
-use std::io::{Error, ErrorKind};
+use std::io::Error;
 
 use async_compression::Level;
 use bytes::{BufMut, BytesMut};
@@ -331,10 +331,7 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
                     return (
                         (
                             io_buf.slice_len(),
-                            Err(Error::new(
-                                ErrorKind::Other,
-                                format!("blob too large ({len} bytes)"),
-                            )),
+                            Err(Error::other(format!("blob too large ({len} bytes)"))),
                         ),
                         srcbuf,
                     );

pageserver/src/tenant/block_io.rs

@@ -216,12 +216,8 @@ impl<'a> FileBlockReader<'a> {
         match cache
             .read_immutable_buf(self.file_id, blknum, ctx)
             .await
-            .map_err(|e| {
-                std::io::Error::new(
-                    std::io::ErrorKind::Other,
-                    format!("Failed to read immutable buf: {e:#}"),
-                )
-            })? {
+            .map_err(|e| std::io::Error::other(format!("Failed to read immutable buf: {e:#}")))?
+        {
             ReadBufResult::Found(guard) => Ok(guard.into()),
             ReadBufResult::NotFound(write_guard) => {
                 // Read the page from disk into the buffer

pageserver/src/tenant/storage_layer/batch_split_writer.rs

@@ -366,7 +366,7 @@ impl SplitDeltaLayerWriter {
                 )
                 .await?;
                 let (start_key, prev_delta_writer) =
-                    std::mem::replace(&mut self.inner, Some((key, next_delta_writer))).unwrap();
+                    self.inner.replace((key, next_delta_writer)).unwrap();
                 self.batches.add_unfinished_delta_writer(
                     prev_delta_writer,
                     start_key..key,

pageserver/src/tenant/storage_layer/inmemory_layer/vectored_dio_read.rs

@@ -766,7 +766,7 @@ mod tests {
                     rand::Rng::fill(&mut rand::thread_rng(), &mut dst_slice[len..]); // to discover bugs
                     Ok((dst, len))
                 }
-                Err(e) => Err(std::io::Error::new(std::io::ErrorKind::Other, e)),
+                Err(e) => Err(std::io::Error::other(e)),
             }
         }
     }

pageserver/src/tenant/storage_layer/merge_iterator.rs

@@ -59,6 +59,7 @@ impl LayerIterRef<'_> {
 /// 1. Unified iterator for image and delta layers.
 /// 2. `Ord` for use in [`MergeIterator::heap`] (for the k-merge).
 /// 3. Lazy creation of the real delta/image iterator.
+#[allow(clippy::large_enum_variant, reason = "TODO")]
 pub(crate) enum IteratorWrapper<'a> {
     NotLoaded {
         ctx: &'a RequestContext,

pageserver/src/tenant/timeline.rs

@@ -1039,6 +1039,7 @@ pub(crate) enum ShutdownMode {
     Hard,
 }
 
+#[allow(clippy::large_enum_variant, reason = "TODO")]
 enum ImageLayerCreationOutcome {
     /// We generated an image layer
     Generated {

pageserver/src/tenant/upload_queue.rs

@@ -302,6 +302,7 @@ pub struct UploadQueueStoppedDeletable {
     pub(super) deleted_at: SetDeletedFlagProgress,
 }
 
+#[allow(clippy::large_enum_variant, reason = "TODO")]
 pub enum UploadQueueStopped {
     Deletable(UploadQueueStoppedDeletable),
     Uninitialized,

proxy/src/cancellation.rs

@@ -425,12 +425,7 @@ impl CancelClosure {
             &mut mk_tls,
             &self.hostname,
         )
-        .map_err(|e| {
-            CancelError::IO(std::io::Error::new(
-                std::io::ErrorKind::Other,
-                e.to_string(),
-            ))
-        })?;
+        .map_err(|e| CancelError::IO(std::io::Error::other(e.to_string())))?;
 
         self.cancel_token.cancel_query_raw(socket, tls).await?;
         debug!("query was cancelled");

proxy/src/proxy/tests/mod.rs

@@ -568,7 +568,7 @@ fn helper_create_cached_node_info(cache: &'static NodeInfoCache) -> CachedNodeIn
 fn helper_create_connect_info(
     mechanism: &TestConnectMechanism,
 ) -> auth::Backend<'static, ComputeCredentials> {
-    let user_info = auth::Backend::ControlPlane(
+    auth::Backend::ControlPlane(
         MaybeOwned::Owned(ControlPlaneClient::Test(Box::new(mechanism.clone()))),
         ComputeCredentials {
             info: ComputeUserInfo {
@@ -578,8 +578,7 @@ fn helper_create_connect_info(
             },
             keys: ComputeCredentialKeys::Password("password".into()),
         },
-    );
-    user_info
+    )
 }
 
 fn config() -> ComputeConfig {

proxy/src/serverless/conn_pool_lib.rs

@@ -47,6 +47,7 @@ impl ConnInfo {
 }
 
 #[derive(Clone)]
+#[allow(clippy::large_enum_variant, reason = "TODO")]
 pub(crate) enum ClientDataEnum {
     Remote(ClientDataRemote),
     Local(ClientDataLocal),

safekeeper/src/timeline.rs

@@ -138,6 +138,7 @@ impl Drop for WriteGuardSharedState<'_> {
 /// Usually it holds SafeKeeper, but it also supports offloaded timeline state. In this
 /// case, SafeKeeper is not available (because WAL is not present on disk) and all
 /// operations can be done only with control file.
+#[allow(clippy::large_enum_variant, reason = "TODO")]
 pub enum StateSK {
     Loaded(SafeKeeper<control_file::FileStorage, wal_storage::PhysicalStorage>),
     Offloaded(Box<TimelineState<control_file::FileStorage>>),

safekeeper/src/timeline_eviction.rs

@@ -35,7 +35,7 @@ impl Manager {
         next_event: &Option<tokio::time::Instant>,
         state: &StateSnapshot,
     ) -> bool {
-        let ready = self.backup_task.is_none()
+        self.backup_task.is_none()
             && self.recovery_task.is_none()
             && self.wal_removal_task.is_none()
             && self.partial_backup_task.is_none()
@@ -61,8 +61,7 @@ impl Manager {
                 .unwrap()
                 .flush_lsn
                 .segment_number(self.wal_seg_size)
-                == self.last_removed_segno + 1;
-        ready
+                == self.last_removed_segno + 1
     }
 
     /// Evict the timeline to remote storage. Returns whether the eviction was successful.