Fix clippy 1.62 (#771)

* clippy let_unit_value

error: this let-binding has unit value
   --> lib/segment/src/vector_storage/simple_vector_storage.rs:397:9
    |
397 | /         let _top_idx = match closest.get(0) {
398 | |             Some(scored_point) => {
399 | |                 assert_ne!(scored_point.idx, 2);
400 | |                 assert_eq!(&raw_res1[scored_point.idx as usize], scored_point);
...   |
404 | |             }
405 | |         };
    | |__________^
    |
    = note: `-D clippy::let-unit-value` implied by `-D warnings`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_unit_value
help: omit the `let` binding
    |
397 ~         match closest.get(0) {
398 +             Some(scored_point) => {
399 +                 assert_ne!(scored_point.idx, 2);
400 +                 assert_eq!(&raw_res1[scored_point.idx as usize], scored_point);
401 +             }
402 +             None => {

* clippy format_push_string

error: `format!(..)` appended to existing `String`
   --> src/main.rs:224:21
    |
224 |                     error.push_str(&format!("Deadlock #{}\n", i));
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::format-push-string` implied by `-D warnings`
    = help: consider using `write!` to avoid the extra allocation
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#format_push_string

error: `format!(..)` appended to existing `String`
   --> src/main.rs:226:25
    |
226 | /                         error.push_str(&format!(
227 | |                             "Thread Id {:#?}\n{:#?}\n",
228 | |                             t.thread_id(),
229 | |                             t.backtrace()
230 | |                         ));
    | |__________________________^
    |
    = help: consider using `write!` to avoid the extra allocation
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#format_push_string

error: could not compile `qdrant` due to 2 previous errors
warning: build failed, waiting for other jobs to finish...
error: could not compile `qdrant` due to 2 previous errors

lib/segment/src/vector_storage/simple_vector_storage.rs

@@ -394,7 +394,7 @@ mod tests {
 
         assert_eq!(raw_res1, raw_res2);
 
-        let _top_idx = match closest.get(0) {
+        match closest.get(0) {
             Some(scored_point) => {
                 assert_ne!(scored_point.idx, 2);
                 assert_eq!(&raw_res1[scored_point.idx as usize], scored_point);

src/main.rs

@@ -207,6 +207,7 @@ fn main() -> anyhow::Result<()> {
     #[cfg(feature = "service_debug")]
     {
         use parking_lot::deadlock;
+        use std::fmt::Write;
 
         const DEADLOCK_CHECK_PERIOD: Duration = Duration::from_secs(10);
 
@@ -221,13 +222,15 @@ fn main() -> anyhow::Result<()> {
 
                 let mut error = format!("{} deadlocks detected\n", deadlocks.len());
                 for (i, threads) in deadlocks.iter().enumerate() {
-                    error.push_str(&format!("Deadlock #{}\n", i));
+                    writeln!(error, "Deadlock #{}", i).expect("fail to writeln!");
                     for t in threads {
-                        error.push_str(&format!(
-                            "Thread Id {:#?}\n{:#?}\n",
+                        writeln!(
+                            error,
+                            "Thread Id {:#?}\n{:#?}",
                             t.thread_id(),
                             t.backtrace()
-                        ));
+                        )
+                        .expect("fail to writeln!");
                     }
                 }
                 log::error!("{}", error);