Merge #10440

10440: Fix Clippy warnings and replace some `if let`s with `match` r=Veykril a=arzg

I decided to try fixing a bunch of Clippy warnings. I am aware of this project’s opinion of Clippy (I have read both [rust-lang/clippy#5537](https://github.com/rust-lang/rust-clippy/issues/5537) and [rust-analyzer/rowan#57 (comment)](https://github.com/rust-analyzer/rowan/pull/57#discussion_r415676159)), so I totally understand if part of or the entirety of this PR is rejected. In particular, I can see how the semicolons and `if let` vs `match` commits provide comparatively little benefit when compared to the ensuing churn.

I tried to separate each kind of change into its own commit to make it easier to discard certain changes. I also only applied Clippy suggestions where I thought they provided a definite improvement to the code (apart from semicolons, which is IMO more of a formatting/consistency question than a linting question). In the end I accumulated a list of 28 Clippy lints I ignored entirely.

Sidenote: I should really have asked about this on Zulip before going through all 1,555 `if let`s in the codebase to decide which ones definitely look better as `match` :P

Co-authored-by: Aramis Razzaghipour <aramisnoah@gmail.com>

crates/test_utils/src/assert_linear.rs

@@ -43,7 +43,7 @@ impl AssertLinear {
     }
 
     pub fn sample(&mut self, x: f64, y: f64) {
-        self.rounds.last_mut().unwrap().samples.push((x, y))
+        self.rounds.last_mut().unwrap().samples.push((x, y));
     }
 }
 
@@ -54,7 +54,7 @@ impl Drop for AssertLinear {
             for round in &self.rounds {
                 eprintln!("\n{}", round.plot);
             }
-            panic!("Doesn't look linear!")
+            panic!("Doesn't look linear!");
         }
     }
 }

crates/test_utils/src/fixture.rs

@@ -142,14 +142,14 @@ impl Fixture {
 
             if line.starts_with("//-") {
                 let meta = Fixture::parse_meta_line(line);
-                res.push(meta)
+                res.push(meta);
             } else {
                 if line.starts_with("// ")
                     && line.contains(':')
                     && !line.contains("::")
                     && line.chars().all(|it| !it.is_uppercase())
                 {
-                    panic!("looks like invalid metadata line: {:?}", line)
+                    panic!("looks like invalid metadata line: {:?}", line);
                 }
 
                 if let Some(entry) = res.last_mut() {
@@ -256,9 +256,9 @@ impl MiniCore {
         let line = line.strip_prefix("//- minicore:").unwrap().trim();
         for entry in line.split(", ") {
             if res.has_flag(entry) {
-                panic!("duplicate minicore flag: {:?}", entry)
+                panic!("duplicate minicore flag: {:?}", entry);
             }
-            res.activated_flags.push(entry.to_string())
+            res.activated_flags.push(entry.to_string());
         }
 
         res
@@ -310,7 +310,7 @@ impl MiniCore {
         // Fixed point loop to compute transitive closure of flags.
         loop {
             let mut changed = false;
-            for &(u, v) in implications.iter() {
+            for &(u, v) in &implications {
                 if self.has_flag(u) && !self.has_flag(v) {
                     self.activated_flags.push(v.to_string());
                     changed = true;
@@ -354,7 +354,7 @@ impl MiniCore {
             }
 
             if keep {
-                buf.push_str(line)
+                buf.push_str(line);
             }
             if line_region {
                 active_regions.pop().unwrap();

crates/test_utils/src/lib.rs

@@ -244,7 +244,7 @@ pub fn extract_annotations(text: &str) -> Vec<(TextRange, String)> {
 
                             range + line_start.1
                         };
-                        res.push((range, content))
+                        res.push((range, content));
                     }
                     LineAnnotation::Continuation { mut offset, content } => {
                         offset += annotation_offset;
@@ -301,7 +301,7 @@ fn extract_line_annotations(mut line: &str) -> Vec<LineAnnotation> {
         let mut file = false;
         if !continuation && content.starts_with("file") {
             file = true;
-            content = &content["file".len()..]
+            content = &content["file".len()..];
         }
 
         let content = content.trim().to_string();
@@ -371,7 +371,7 @@ fn main() {
 pub fn skip_slow_tests() -> bool {
     let should_skip = std::env::var("CI").is_err() && std::env::var("RUN_SLOW_TESTS").is_err();
     if should_skip {
-        eprintln!("ignoring slow test")
+        eprintln!("ignoring slow test");
     } else {
         let path = project_root().join("./target/.slow_tests_cookie");
         fs::write(&path, ".").unwrap();
@@ -432,7 +432,7 @@ pub fn bench(label: &'static str) -> impl Drop {
 
     impl Drop for Bencher {
         fn drop(&mut self) {
-            eprintln!("{}: {}", self.label, self.sw.elapsed())
+            eprintln!("{}: {}", self.label, self.sw.elapsed());
         }
     }