diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0cc3ab7485..d3a42c12ba 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -259,7 +259,7 @@ jobs:
             ~/.cargo/registry/index
             ~/.cargo/registry/cache
             ~/.cargo/git/db
-          key: 3-cargo-home-${{ matrix.os }}-${{ hashFiles('Cargo.lock') }}
+          key: 4-cargo-home-${{ matrix.os }}-${{ hashFiles('Cargo.lock') }}
 
       # In main branch, always creates fresh cache
       - name: Cache build output (main)
@@ -275,7 +275,7 @@ jobs:
             !./target/*/*.zip
             !./target/*/*.tar.gz
           key: |
-            3-cargo-target-${{ matrix.os }}-${{ matrix.profile }}-${{ github.sha }}
+            4-cargo-target-${{ matrix.os }}-${{ matrix.profile }}-${{ github.sha }}
 
       # Restore cache from the latest 'main' branch build.
       - name: Cache build output (PR)
@@ -291,7 +291,7 @@ jobs:
             !./target/*/*.tar.gz
           key: never_saved
           restore-keys: |
-            3-cargo-target-${{ matrix.os }}-${{ matrix.profile }}-
+            4-cargo-target-${{ matrix.os }}-${{ matrix.profile }}-
 
       # Don't save cache after building PRs or branches other than 'main'.
       - name: Skip save cache (PR)
diff --git a/Cargo.lock b/Cargo.lock
index a4e461dee3..f7a7e8cf6d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -773,7 +773,6 @@ dependencies = [
  "lspower",
  "nix",
  "notify",
- "num_cpus",
  "once_cell",
  "os_pipe",
  "percent-encoding",
diff --git a/cli/Cargo.toml b/cli/Cargo.toml
index 36a03c964c..b50efa09ef 100644
--- a/cli/Cargo.toml
+++ b/cli/Cargo.toml
@@ -75,7 +75,6 @@ libc = "=0.2.106"
 log = { version = "=0.4.14", features = ["serde"] }
 lspower = "=1.4.0"
 notify = "=5.0.0-pre.12"
-num_cpus = "=1.13.0"
 once_cell = "=1.9.0"
 percent-encoding = "=2.1.0"
 pin-project = "=1.0.8"
diff --git a/cli/cache.rs b/cli/cache.rs
index 8bd40fc8a4..586912495a 100644
--- a/cli/cache.rs
+++ b/cli/cache.rs
@@ -198,8 +198,7 @@ impl Cacher for FetchCacher {
       .disk_cache
       .get(&filename)
       .ok()
-      .map(|b| String::from_utf8(b).ok())
-      .flatten()
+      .and_then(|b| String::from_utf8(b).ok())
   }
 
   fn set(
diff --git a/cli/compat/esm_resolver.rs b/cli/compat/esm_resolver.rs
index 68824ab118..1ac12ca148 100644
--- a/cli/compat/esm_resolver.rs
+++ b/cli/compat/esm_resolver.rs
@@ -549,7 +549,7 @@ fn resolve_package_target_string(
 
   if invalid_segment_re.is_match(&subpath) {
     let request = if pattern {
-      match_.replace("*", &subpath)
+      match_.replace('*', &subpath)
     } else {
       format!("{}{}", match_, subpath)
     };
diff --git a/cli/compat/mod.rs b/cli/compat/mod.rs
index feeca2f4ae..0c30a58fc8 100644
--- a/cli/compat/mod.rs
+++ b/cli/compat/mod.rs
@@ -138,7 +138,7 @@ pub(crate) fn add_global_require(
 }
 
 fn escape_for_single_quote_string(text: &str) -> String {
-  text.replace(r"\", r"\\").replace("'", r"\'")
+  text.replace('\\', r"\\").replace('\'', r"\'")
 }
 
 pub fn setup_builtin_modules(
diff --git a/cli/config_file.rs b/cli/config_file.rs
index 3ca00b0f4c..205c789fbf 100644
--- a/cli/config_file.rs
+++ b/cli/config_file.rs
@@ -563,8 +563,7 @@ impl ConfigFile {
       .json
       .compiler_options
       .as_ref()
-      .map(|co| co.get("checkJs").map(|v| v.as_bool()).flatten())
-      .flatten()
+      .and_then(|co| co.get("checkJs").and_then(|v| v.as_bool()))
       .unwrap_or(false)
   }
 
diff --git a/cli/disk_cache.rs b/cli/disk_cache.rs
index d3d294c18b..349b786b7d 100644
--- a/cli/disk_cache.rs
+++ b/cli/disk_cache.rs
@@ -91,7 +91,7 @@ impl DiskCache {
               | Prefix::VerbatimUNC(server, share) => {
                 out.push("UNC");
                 let host = Host::parse(server.to_str().unwrap()).unwrap();
-                let host = host.to_string().replace(":", "_");
+                let host = host.to_string().replace(':', "_");
                 out.push(host);
                 out.push(share);
               }
diff --git a/cli/flags.rs b/cli/flags.rs
index ab8153c4ed..316425247c 100644
--- a/cli/flags.rs
+++ b/cli/flags.rs
@@ -2232,8 +2232,8 @@ fn test_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
     if let Some(value) = matches.value_of("jobs") {
       value.parse().unwrap()
     } else {
-      // TODO(caspervonb) drop the dependency on num_cpus when https://doc.rust-lang.org/std/thread/fn.available_concurrency.html becomes stable.
-      NonZeroUsize::new(num_cpus::get()).unwrap()
+      std::thread::available_parallelism()
+        .unwrap_or(NonZeroUsize::new(1).unwrap())
     }
   } else {
     NonZeroUsize::new(1).unwrap()
diff --git a/cli/lsp/cache.rs b/cli/lsp/cache.rs
index 8b2c85dec7..f94faa4192 100644
--- a/cli/lsp/cache.rs
+++ b/cli/lsp/cache.rs
@@ -61,13 +61,10 @@ impl CacheServer {
         .unwrap();
         let maybe_import_map_resolver =
           maybe_import_map.map(ImportMapResolver::new);
-        let maybe_jsx_resolver = maybe_config_file
-          .as_ref()
-          .map(|cf| {
-            cf.to_maybe_jsx_import_source_module()
-              .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
-          })
-          .flatten();
+        let maybe_jsx_resolver = maybe_config_file.as_ref().and_then(|cf| {
+          cf.to_maybe_jsx_import_source_module()
+            .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
+        });
         let maybe_resolver = if maybe_jsx_resolver.is_some() {
           maybe_jsx_resolver.as_ref().map(|jr| jr.as_resolver())
         } else {
@@ -76,8 +73,7 @@ impl CacheServer {
             .map(|im| im.as_resolver())
         };
         let maybe_imports = maybe_config_file
-          .map(|cf| cf.to_maybe_imports().ok())
-          .flatten()
+          .and_then(|cf| cf.to_maybe_imports().ok())
           .flatten();
         let mut cache = FetchCacher::new(
           ps.dir.gen_cache.clone(),
@@ -187,10 +183,9 @@ impl CacheMetadata {
     let version = self
       .cache
       .get_cache_filename(specifier)
-      .map(|ref path| calculate_fs_version(path))
-      .flatten();
+      .and_then(|ref path| calculate_fs_version(path));
     let metadata = self.metadata.lock().get(specifier).cloned();
-    if metadata.as_ref().map(|m| m.version.clone()).flatten() != version {
+    if metadata.as_ref().and_then(|m| m.version.clone()) != version {
       self.refresh(specifier).map(|m| m.values)
     } else {
       metadata.map(|m| m.values)
diff --git a/cli/lsp/diagnostics.rs b/cli/lsp/diagnostics.rs
index 39f7f1c489..8801af7225 100644
--- a/cli/lsp/diagnostics.rs
+++ b/cli/lsp/diagnostics.rs
@@ -538,8 +538,7 @@ async fn generate_ts_diagnostics(
     let version = snapshot
       .documents
       .get(&specifier)
-      .map(|d| d.maybe_lsp_version())
-      .flatten();
+      .and_then(|d| d.maybe_lsp_version());
     // check if the specifier is enabled again just in case TS returns us
     // diagnostics for a disabled specifier
     let ts_diagnostics = if config.specifier_enabled(&specifier) {
@@ -555,8 +554,7 @@ async fn generate_ts_diagnostics(
     let version = snapshot
       .documents
       .get(&specifier)
-      .map(|d| d.maybe_lsp_version())
-      .flatten();
+      .and_then(|d| d.maybe_lsp_version());
     diagnostics_vec.push((specifier, version, Vec::new()));
   }
   Ok(diagnostics_vec)
diff --git a/cli/lsp/documents.rs b/cli/lsp/documents.rs
index 9a302bb9ee..cc320db461 100644
--- a/cli/lsp/documents.rs
+++ b/cli/lsp/documents.rs
@@ -199,18 +199,17 @@ impl AssetOrDocument {
   ) -> Option<(String, deno_graph::Dependency, deno_graph::Range)> {
     self
       .document()
-      .map(|d| d.get_maybe_dependency(position))
-      .flatten()
+      .and_then(|d| d.get_maybe_dependency(position))
   }
 
   pub fn maybe_parsed_source(
     &self,
   ) -> Option<Result<deno_ast::ParsedSource, deno_graph::ModuleGraphError>> {
-    self.document().map(|d| d.maybe_parsed_source()).flatten()
+    self.document().and_then(|d| d.maybe_parsed_source())
   }
 
   pub fn document_lsp_version(&self) -> Option<i32> {
-    self.document().map(|d| d.maybe_lsp_version()).flatten()
+    self.document().and_then(|d| d.maybe_lsp_version())
   }
 }
 
@@ -347,8 +346,7 @@ impl Document {
         .0
         .maybe_language_id
         .as_ref()
-        .map(|li| li.as_headers())
-        .flatten();
+        .and_then(|li| li.as_headers());
       let parser = SourceParser::default();
       Some(deno_graph::parse_module(
         &self.0.specifier,
@@ -865,8 +863,7 @@ impl Documents {
     } else {
       let mut file_system_docs = self.file_system_docs.lock();
       let fs_version = get_document_path(&self.cache, &specifier)
-        .map(|path| calculate_fs_version(&path))
-        .flatten();
+        .and_then(|path| calculate_fs_version(&path));
       let file_system_doc = file_system_docs.docs.get(&specifier);
       if file_system_doc.map(|d| d.fs_version().to_string()) != fs_version {
         // attempt to update the file on the file system
@@ -1009,12 +1006,10 @@ impl Documents {
   ) {
     // TODO(@kitsonk) update resolved dependencies?
     self.maybe_import_map = maybe_import_map.map(ImportMapResolver::new);
-    self.maybe_jsx_resolver = maybe_config_file
-      .map(|cf| {
-        cf.to_maybe_jsx_import_source_module()
-          .map(|im| JsxResolver::new(im, self.maybe_import_map.clone()))
-      })
-      .flatten();
+    self.maybe_jsx_resolver = maybe_config_file.and_then(|cf| {
+      cf.to_maybe_jsx_import_source_module()
+        .map(|im| JsxResolver::new(im, self.maybe_import_map.clone()))
+    });
     self.imports = Arc::new(
       if let Some(Ok(Some(imports))) =
         maybe_config_file.map(|cf| cf.to_maybe_imports())
@@ -1094,14 +1089,12 @@ impl Documents {
     specifier: &ModuleSpecifier,
   ) -> Option<(ModuleSpecifier, MediaType)> {
     let doc = self.get(specifier)?;
-    let maybe_module = doc.maybe_module().map(|r| r.as_ref().ok()).flatten();
-    let maybe_types_dependency = maybe_module
-      .map(|m| {
-        m.maybe_types_dependency
-          .as_ref()
-          .map(|(_, resolved)| resolved.clone())
-      })
-      .flatten();
+    let maybe_module = doc.maybe_module().and_then(|r| r.as_ref().ok());
+    let maybe_types_dependency = maybe_module.and_then(|m| {
+      m.maybe_types_dependency
+        .as_ref()
+        .map(|(_, resolved)| resolved.clone())
+    });
     if let Some(Resolved::Ok { specifier, .. }) = maybe_types_dependency {
       self.resolve_dependency(&specifier)
     } else {
diff --git a/cli/lsp/language_server.rs b/cli/lsp/language_server.rs
index e4dd8b3d6a..05b6fcc03f 100644
--- a/cli/lsp/language_server.rs
+++ b/cli/lsp/language_server.rs
@@ -833,8 +833,7 @@ impl Inner {
         params
           .settings
           .as_object()
-          .map(|settings| settings.get(SETTINGS_SECTION))
-          .flatten()
+          .and_then(|settings| settings.get(SETTINGS_SECTION))
           .cloned()
       };
 
@@ -1037,8 +1036,7 @@ impl Inner {
     {
       let dep_maybe_types_dependency = dep
         .get_code()
-        .map(|s| self.documents.get(s))
-        .flatten()
+        .and_then(|s| self.documents.get(s))
         .map(|d| d.maybe_types_dependency());
       let value = match (dep.maybe_code.is_none(), dep.maybe_type.is_none(), &dep_maybe_types_dependency) {
         (false, false, None) => format!(
@@ -1204,7 +1202,7 @@ impl Inner {
               &specifier,
               diagnostic,
               asset_or_doc.document().map(|d| d.text_info()),
-              asset_or_doc.maybe_parsed_source().map(|r| r.ok()).flatten(),
+              asset_or_doc.maybe_parsed_source().and_then(|r| r.ok()),
             )
             .map_err(|err| {
               error!("Unable to fix lint error: {}", err);
@@ -1388,8 +1386,7 @@ impl Inner {
         error!("Error getting code lenses for \"{}\": {}", specifier, err);
         LspError::internal_error()
       })?;
-    let parsed_source =
-      asset_or_doc.maybe_parsed_source().map(|r| r.ok()).flatten();
+    let parsed_source = asset_or_doc.maybe_parsed_source().and_then(|r| r.ok());
     let line_index = asset_or_doc.line_index();
     let code_lenses = code_lens::collect(
       &specifier,
@@ -1463,8 +1460,7 @@ impl Inner {
     if let Some(document_highlights) = maybe_document_highlights {
       let result = document_highlights
         .into_iter()
-        .map(|dh| dh.to_highlight(line_index.clone()))
-        .flatten()
+        .flat_map(|dh| dh.to_highlight(line_index.clone()))
         .collect();
       self.performance.measure(mark);
       Ok(Some(result))
diff --git a/cli/lsp/tsc.rs b/cli/lsp/tsc.rs
index f2d733e6fb..a0f2008a4e 100644
--- a/cli/lsp/tsc.rs
+++ b/cli/lsp/tsc.rs
@@ -1402,9 +1402,7 @@ impl FileTextChanges {
     ops.push(lsp::DocumentChangeOperation::Edit(lsp::TextDocumentEdit {
       text_document: lsp::OptionalVersionedTextDocumentIdentifier {
         uri: specifier.clone(),
-        version: maybe_asset_or_document
-          .map(|d| d.document_lsp_version())
-          .flatten(),
+        version: maybe_asset_or_document.and_then(|d| d.document_lsp_version()),
       },
       edits,
     }));
@@ -2064,7 +2062,7 @@ impl CompletionEntry {
           return Some(insert_text.clone());
         }
       } else {
-        return Some(self.name.replace("#", ""));
+        return Some(self.name.replace('#', ""));
       }
     }
 
diff --git a/cli/main.rs b/cli/main.rs
index 597845daed..f5c1b78d33 100644
--- a/cli/main.rs
+++ b/cli/main.rs
@@ -146,7 +146,9 @@ fn create_web_worker_callback(ps: ProcState) -> Arc<CreateWebWorkerCb> {
       bootstrap: BootstrapOptions {
         args: ps.flags.argv.clone(),
         apply_source_maps: true,
-        cpu_count: num_cpus::get(),
+        cpu_count: std::thread::available_parallelism()
+          .map(|p| p.get())
+          .unwrap_or(1),
         debug_flag: ps
           .flags
           .log_level
@@ -247,7 +249,9 @@ pub fn create_main_worker(
     bootstrap: BootstrapOptions {
       apply_source_maps: true,
       args: ps.flags.argv.clone(),
-      cpu_count: num_cpus::get(),
+      cpu_count: std::thread::available_parallelism()
+        .map(|p| p.get())
+        .unwrap_or(1),
       debug_flag: ps.flags.log_level.map_or(false, |l| l == log::Level::Debug),
       enable_testing_features: ps.flags.enable_testing_features,
       location: ps.flags.location.clone(),
@@ -477,14 +481,10 @@ async fn info_command(
     let maybe_locker = lockfile::as_maybe_locker(ps.lockfile.clone());
     let maybe_import_map_resolver =
       ps.maybe_import_map.clone().map(ImportMapResolver::new);
-    let maybe_jsx_resolver = ps
-      .maybe_config_file
-      .as_ref()
-      .map(|cf| {
-        cf.to_maybe_jsx_import_source_module()
-          .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
-      })
-      .flatten();
+    let maybe_jsx_resolver = ps.maybe_config_file.as_ref().and_then(|cf| {
+      cf.to_maybe_jsx_import_source_module()
+        .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
+    });
     let maybe_resolver = if maybe_jsx_resolver.is_some() {
       maybe_jsx_resolver.as_ref().map(|jr| jr.as_resolver())
     } else {
@@ -649,14 +649,10 @@ async fn create_graph_and_maybe_check(
   };
   let maybe_import_map_resolver =
     ps.maybe_import_map.clone().map(ImportMapResolver::new);
-  let maybe_jsx_resolver = ps
-    .maybe_config_file
-    .as_ref()
-    .map(|cf| {
-      cf.to_maybe_jsx_import_source_module()
-        .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
-    })
-    .flatten();
+  let maybe_jsx_resolver = ps.maybe_config_file.as_ref().and_then(|cf| {
+    cf.to_maybe_jsx_import_source_module()
+      .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
+  });
   let maybe_resolver = if maybe_jsx_resolver.is_some() {
     maybe_jsx_resolver.as_ref().map(|jr| jr.as_resolver())
   } else {
@@ -802,10 +798,7 @@ async fn bundle_command(
         .specifiers()
         .iter()
         .filter_map(|(_, r)| {
-          r.as_ref()
-            .ok()
-            .map(|(s, _, _)| s.to_file_path().ok())
-            .flatten()
+          r.as_ref().ok().and_then(|(s, _, _)| s.to_file_path().ok())
         })
         .collect();
 
@@ -1003,14 +996,10 @@ async fn run_with_watch(flags: Flags, script: String) -> Result<i32, AnyError> {
       };
       let maybe_import_map_resolver =
         ps.maybe_import_map.clone().map(ImportMapResolver::new);
-      let maybe_jsx_resolver = ps
-        .maybe_config_file
-        .as_ref()
-        .map(|cf| {
-          cf.to_maybe_jsx_import_source_module()
-            .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
-        })
-        .flatten();
+      let maybe_jsx_resolver = ps.maybe_config_file.as_ref().and_then(|cf| {
+        cf.to_maybe_jsx_import_source_module()
+          .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
+      });
       let maybe_resolver = if maybe_jsx_resolver.is_some() {
         maybe_jsx_resolver.as_ref().map(|jr| jr.as_resolver())
       } else {
@@ -1041,10 +1030,7 @@ async fn run_with_watch(flags: Flags, script: String) -> Result<i32, AnyError> {
         .specifiers()
         .iter()
         .filter_map(|(_, r)| {
-          r.as_ref()
-            .ok()
-            .map(|(s, _, _)| s.to_file_path().ok())
-            .flatten()
+          r.as_ref().ok().and_then(|(s, _, _)| s.to_file_path().ok())
         })
         .collect();
 
diff --git a/cli/proc_state.rs b/cli/proc_state.rs
index 12bdd3149c..fee9e747e7 100644
--- a/cli/proc_state.rs
+++ b/cli/proc_state.rs
@@ -190,13 +190,10 @@ impl ProcState {
     );
     let maybe_import_map_resolver =
       maybe_import_map.clone().map(ImportMapResolver::new);
-    let maybe_jsx_resolver = maybe_config_file
-      .as_ref()
-      .map(|cf| {
-        cf.to_maybe_jsx_import_source_module()
-          .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
-      })
-      .flatten();
+    let maybe_jsx_resolver = maybe_config_file.as_ref().and_then(|cf| {
+      cf.to_maybe_jsx_import_source_module()
+        .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
+    });
     let maybe_resolver: Option<
       Arc<dyn deno_graph::source::Resolver + Send + Sync>,
     > = if flags.compat {
diff --git a/cli/standalone.rs b/cli/standalone.rs
index b7c026cece..bd7bef8acb 100644
--- a/cli/standalone.rs
+++ b/cli/standalone.rs
@@ -269,7 +269,9 @@ pub async fn run(
     bootstrap: BootstrapOptions {
       apply_source_maps: false,
       args: metadata.argv,
-      cpu_count: num_cpus::get(),
+      cpu_count: std::thread::available_parallelism()
+        .map(|p| p.get())
+        .unwrap_or(1),
       debug_flag: metadata.log_level.map_or(false, |l| l == log::Level::Debug),
       enable_testing_features: false,
       location: metadata.location,
diff --git a/cli/tools/coverage/mod.rs b/cli/tools/coverage/mod.rs
index 35001db1e9..26f36adaec 100644
--- a/cli/tools/coverage/mod.rs
+++ b/cli/tools/coverage/mod.rs
@@ -312,7 +312,7 @@ fn generate_coverage_report(
       let mut found_lines = line_counts
         .iter()
         .enumerate()
-        .map(|(index, count)| {
+        .flat_map(|(index, count)| {
           // get all the mappings from this destination line to a different src line
           let mut results = source_map
             .tokens()
@@ -324,7 +324,6 @@ fn generate_coverage_report(
           results.dedup_by_key(|(index, _)| *index);
           results.into_iter()
         })
-        .flatten()
         .collect::<Vec<(usize, i64)>>();
 
       found_lines.sort_unstable_by_key(|(index, _)| *index);
@@ -400,8 +399,7 @@ impl CoverageReporter for LcovCoverageReporter {
       .url
       .to_file_path()
       .ok()
-      .map(|p| p.to_str().map(|p| p.to_string()))
-      .flatten()
+      .and_then(|p| p.to_str().map(|p| p.to_string()))
       .unwrap_or_else(|| coverage_report.url.to_string());
     writeln!(out_writer, "SF:{}", file_path)?;
 
diff --git a/cli/tools/fmt.rs b/cli/tools/fmt.rs
index 45cf69b864..4fba9ea13d 100644
--- a/cli/tools/fmt.rs
+++ b/cli/tools/fmt.rs
@@ -234,7 +234,7 @@ pub fn format_file(
   file_text: &str,
   fmt_options: FmtOptionsConfig,
 ) -> Result<String, AnyError> {
-  let ext = get_extension(file_path).unwrap_or_else(String::new);
+  let ext = get_extension(file_path).unwrap_or_default();
   if matches!(
     ext.as_str(),
     "md" | "mkd" | "mkdn" | "mdwn" | "mdown" | "markdown"
@@ -589,8 +589,7 @@ where
   let mut errors = join_results.into_iter().filter_map(|join_result| {
     join_result
       .ok()
-      .map(|handle_result| handle_result.err())
-      .flatten()
+      .and_then(|handle_result| handle_result.err())
   });
 
   if let Some(e) = errors.next() {
diff --git a/cli/tools/installer.rs b/cli/tools/installer.rs
index 4cbbb7cf51..8318c72bf7 100644
--- a/cli/tools/installer.rs
+++ b/cli/tools/installer.rs
@@ -56,7 +56,7 @@ fn generate_executable_file(shim_data: &ShimData) -> Result<(), AnyError> {
     "% generated by deno install %\n@deno {} %*\n",
     args
       .iter()
-      .map(|arg| arg.replace("%", "%%"))
+      .map(|arg| arg.replace('%', "%%"))
       .collect::<Vec<_>>()
       .join(" ")
   );
@@ -646,7 +646,7 @@ mod tests {
     let bin_dir = temp_dir.path().join("bin");
     std::fs::create_dir(&bin_dir).unwrap();
     let original_install_root = env::var_os("DENO_INSTALL_ROOT");
-    env::set_var("DENO_INSTALL_ROOT", temp_dir.path().to_path_buf());
+    env::set_var("DENO_INSTALL_ROOT", temp_dir.path());
 
     let shim_data = resolve_shim_data(
       &Flags::default(),
@@ -876,7 +876,7 @@ mod tests {
 
     let config_file_name = "echo_test.tsconfig.json";
 
-    let file_path = bin_dir.join(config_file_name.to_string());
+    let file_path = bin_dir.join(config_file_name);
     assert!(file_path.exists());
     let content = fs::read_to_string(file_path).unwrap();
     assert!(content == "{}");
diff --git a/cli/tools/repl/editor.rs b/cli/tools/repl/editor.rs
index ea62bd49ff..825934b5ec 100644
--- a/cli/tools/repl/editor.rs
+++ b/cli/tools/repl/editor.rs
@@ -70,7 +70,7 @@ impl EditorHelper {
 
     self
       .get_object_expr_properties(object_expr)
-      .unwrap_or_else(Vec::new)
+      .unwrap_or_default()
   }
 
   fn get_expression_type(&self, expr: &str) -> Option<String> {
diff --git a/cli/tools/test.rs b/cli/tools/test.rs
index 101dcb6b6a..97a7ddf4f2 100644
--- a/cli/tools/test.rs
+++ b/cli/tools/test.rs
@@ -1082,14 +1082,10 @@ pub async fn run_tests_with_watch(
 
     let maybe_import_map_resolver =
       ps.maybe_import_map.clone().map(ImportMapResolver::new);
-    let maybe_jsx_resolver = ps
-      .maybe_config_file
-      .as_ref()
-      .map(|cf| {
-        cf.to_maybe_jsx_import_source_module()
-          .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
-      })
-      .flatten();
+    let maybe_jsx_resolver = ps.maybe_config_file.as_ref().and_then(|cf| {
+      cf.to_maybe_jsx_import_source_module()
+        .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
+    });
     let maybe_locker = lockfile::as_maybe_locker(ps.lockfile.clone());
     let maybe_imports = ps
       .maybe_config_file
diff --git a/cli/tools/upgrade.rs b/cli/tools/upgrade.rs
index e82d51a6e1..dfcb871d1c 100644
--- a/cli/tools/upgrade.rs
+++ b/cli/tools/upgrade.rs
@@ -151,7 +151,7 @@ async fn get_latest_release_version(
     .await?;
   let version = res.url().path_segments().unwrap().last().unwrap();
 
-  Ok(version.replace("v", ""))
+  Ok(version.replace('v', ""))
 }
 
 async fn get_latest_canary_version(
diff --git a/cli/tools/vendor/mod.rs b/cli/tools/vendor/mod.rs
index eb9c91071b..3a5455aae6 100644
--- a/cli/tools/vendor/mod.rs
+++ b/cli/tools/vendor/mod.rs
@@ -137,14 +137,10 @@ async fn create_graph(
   };
   let maybe_import_map_resolver =
     ps.maybe_import_map.clone().map(ImportMapResolver::new);
-  let maybe_jsx_resolver = ps
-    .maybe_config_file
-    .as_ref()
-    .map(|cf| {
-      cf.to_maybe_jsx_import_source_module()
-        .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
-    })
-    .flatten();
+  let maybe_jsx_resolver = ps.maybe_config_file.as_ref().and_then(|cf| {
+    cf.to_maybe_jsx_import_source_module()
+      .map(|im| JsxResolver::new(im, maybe_import_map_resolver.clone()))
+  });
   let maybe_resolver = if maybe_jsx_resolver.is_some() {
     maybe_jsx_resolver.as_ref().map(|jr| jr.as_resolver())
   } else {
diff --git a/cli/tools/vendor/test.rs b/cli/tools/vendor/test.rs
index b37e2b3b0b..7f4c18fca3 100644
--- a/cli/tools/vendor/test.rs
+++ b/cli/tools/vendor/test.rs
@@ -223,7 +223,7 @@ fn make_path(text: &str) -> PathBuf {
   // a cross platform path here
   assert!(text.starts_with('/'));
   if cfg!(windows) {
-    PathBuf::from(format!("C:{}", text.replace("/", "\\")))
+    PathBuf::from(format!("C:{}", text.replace('/', "\\")))
   } else {
     PathBuf::from(text)
   }
diff --git a/cli/tsc.rs b/cli/tsc.rs
index b679b049e7..9500aae74d 100644
--- a/cli/tsc.rs
+++ b/cli/tsc.rs
@@ -737,7 +737,7 @@ mod tests {
         .to_string()
         .replace(":///", "_")
         .replace("://", "_")
-        .replace("/", "-");
+        .replace('/', "-");
       let source_path = self.fixtures.join(specifier_text);
       let response = fs::read_to_string(&source_path)
         .map(|c| {
diff --git a/core/async_cancel.rs b/core/async_cancel.rs
index 4c1cded0e1..e8f25136cf 100644
--- a/core/async_cancel.rs
+++ b/core/async_cancel.rs
@@ -460,18 +460,18 @@ mod internal {
     /// must refer to a head (`CancelHandle`) node.
     fn cancel(&mut self) {
       let mut head_nn = NonNull::from(self);
-      let mut item_nn;
 
       // Mark the head node as canceled.
-      match replace(unsafe { head_nn.as_mut() }, NodeInner::Canceled) {
-        NodeInner::Linked {
-          kind: NodeKind::Head { .. },
-          next: next_nn,
-          ..
-        } => item_nn = next_nn,
-        NodeInner::Unlinked | NodeInner::Canceled => return,
-        _ => unreachable!(),
-      };
+      let mut item_nn =
+        match replace(unsafe { head_nn.as_mut() }, NodeInner::Canceled) {
+          NodeInner::Linked {
+            kind: NodeKind::Head { .. },
+            next: next_nn,
+            ..
+          } => next_nn,
+          NodeInner::Unlinked | NodeInner::Canceled => return,
+          _ => unreachable!(),
+        };
 
       // Cancel all item nodes in the chain, waking each stored `Waker`.
       while item_nn != head_nn {
diff --git a/core/module_specifier.rs b/core/module_specifier.rs
index d09c4afb58..ecdebbd74a 100644
--- a/core/module_specifier.rs
+++ b/core/module_specifier.rs
@@ -397,7 +397,7 @@ mod tests {
       // Relative local path.
       let expected_url = format!(
         "file:///{}/tests/006_url_imports.ts",
-        cwd_str.replace("\\", "/")
+        cwd_str.replace('\\', "/")
       );
       tests.extend(vec![
         (r"tests/006_url_imports.ts", expected_url.to_string()),
diff --git a/runtime/ops/web_worker/sync_fetch.rs b/runtime/ops/web_worker/sync_fetch.rs
index 9f146b67e7..76791ded58 100644
--- a/runtime/ops/web_worker/sync_fetch.rs
+++ b/runtime/ops/web_worker/sync_fetch.rs
@@ -16,7 +16,7 @@ use tokio::task::JoinHandle;
 
 // TODO(andreubotella) Properly parse the MIME type
 fn mime_type_essence(mime_type: &str) -> String {
-  let essence = match mime_type.split_once(";") {
+  let essence = match mime_type.split_once(';') {
     Some((essence, _)) => essence,
     None => mime_type,
   };
diff --git a/runtime/permissions.rs b/runtime/permissions.rs
index 7e18fe217f..c4a9d144f9 100644
--- a/runtime/permissions.rs
+++ b/runtime/permissions.rs
@@ -2220,7 +2220,7 @@ mod tests {
     ];
 
     for (host, port) in domain_tests {
-      assert!(!perms.net.check(&(host, Some(port))).is_ok());
+      assert!(perms.net.check(&(host, Some(port))).is_err());
     }
   }
 
@@ -2396,13 +2396,13 @@ mod tests {
       assert_eq!(perms2.net.query::<&str>(None), PermissionState::Prompt);
       assert_eq!(perms2.net.query(Some(&("127.0.0.1", Some(8000)))), PermissionState::Granted);
       assert_eq!(perms1.env.query(None), PermissionState::Granted);
-      assert_eq!(perms1.env.query(Some(&"HOME".to_string())), PermissionState::Granted);
+      assert_eq!(perms1.env.query(Some("HOME")), PermissionState::Granted);
       assert_eq!(perms2.env.query(None), PermissionState::Prompt);
-      assert_eq!(perms2.env.query(Some(&"HOME".to_string())), PermissionState::Granted);
+      assert_eq!(perms2.env.query(Some("HOME")), PermissionState::Granted);
       assert_eq!(perms1.run.query(None), PermissionState::Granted);
-      assert_eq!(perms1.run.query(Some(&"deno".to_string())), PermissionState::Granted);
+      assert_eq!(perms1.run.query(Some("deno")), PermissionState::Granted);
       assert_eq!(perms2.run.query(None), PermissionState::Prompt);
-      assert_eq!(perms2.run.query(Some(&"deno".to_string())), PermissionState::Granted);
+      assert_eq!(perms2.run.query(Some("deno")), PermissionState::Granted);
       assert_eq!(perms1.ffi.query(None), PermissionState::Granted);
       assert_eq!(perms1.ffi.query(Some(Path::new("deno"))), PermissionState::Granted);
       assert_eq!(perms2.ffi.query(None), PermissionState::Prompt);
@@ -2433,15 +2433,15 @@ mod tests {
       prompt_value.set(false);
       assert_eq!(perms.net.request(Some(&("127.0.0.1", Some(8000)))), PermissionState::Granted);
       prompt_value.set(true);
-      assert_eq!(perms.env.request(Some(&"HOME".to_string())), PermissionState::Granted);
+      assert_eq!(perms.env.request(Some("HOME")), PermissionState::Granted);
       assert_eq!(perms.env.query(None), PermissionState::Prompt);
       prompt_value.set(false);
-      assert_eq!(perms.env.request(Some(&"HOME".to_string())), PermissionState::Granted);
+      assert_eq!(perms.env.request(Some("HOME")), PermissionState::Granted);
       prompt_value.set(true);
-      assert_eq!(perms.run.request(Some(&"deno".to_string())), PermissionState::Granted);
+      assert_eq!(perms.run.request(Some("deno")), PermissionState::Granted);
       assert_eq!(perms.run.query(None), PermissionState::Prompt);
       prompt_value.set(false);
-      assert_eq!(perms.run.request(Some(&"deno".to_string())), PermissionState::Granted);
+      assert_eq!(perms.run.request(Some("deno")), PermissionState::Granted);
       prompt_value.set(true);
       assert_eq!(perms.ffi.request(Some(Path::new("deno"))), PermissionState::Granted);
       assert_eq!(perms.ffi.query(None), PermissionState::Prompt);
@@ -2506,8 +2506,8 @@ mod tests {
       assert_eq!(perms.net.revoke(Some(&("127.0.0.1", Some(9000)))), PermissionState::Prompt);
       assert_eq!(perms.net.query(Some(&("127.0.0.1", None))), PermissionState::Prompt);
       assert_eq!(perms.net.query(Some(&("127.0.0.1", Some(8000)))), PermissionState::Granted);
-      assert_eq!(perms.env.revoke(Some(&"HOME".to_string())), PermissionState::Prompt);
-      assert_eq!(perms.run.revoke(Some(&"deno".to_string())), PermissionState::Prompt);
+      assert_eq!(perms.env.revoke(Some("HOME")), PermissionState::Prompt);
+      assert_eq!(perms.run.revoke(Some("deno")), PermissionState::Prompt);
       assert_eq!(perms.ffi.revoke(Some(Path::new("deno"))), PermissionState::Prompt);
       assert_eq!(perms.hrtime.revoke(), PermissionState::Denied);
     };
@@ -2641,10 +2641,7 @@ mod tests {
     assert!(perms.env.check("HOME").is_ok());
     assert!(perms.env.check("hOmE").is_ok());
 
-    assert_eq!(
-      perms.env.revoke(Some(&"HomE".to_string())),
-      PermissionState::Prompt
-    );
+    assert_eq!(perms.env.revoke(Some("HomE")), PermissionState::Prompt);
   }
 
   #[test]
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 89378c52de..60883f424c 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,2 +1,2 @@
 [toolchain]
-channel = "1.58.1"
+channel = "1.59.0"