diff --git a/compiler/rustc_expand/src/config.rs b/compiler/rustc_expand/src/config.rs
index 38c099fa4f59c..1b123520961a6 100644
--- a/compiler/rustc_expand/src/config.rs
+++ b/compiler/rustc_expand/src/config.rs
@@ -171,7 +171,7 @@ fn get_features(
             }
 
             if let Some(allowed) = sess.opts.debugging_opts.allow_features.as_ref() {
-                if allowed.iter().find(|&f| name.as_str() == *f).is_none() {
+                if allowed.iter().all(|f| name.as_str() != *f) {
                     struct_span_err!(
                         span_handler,
                         mi.span(),
diff --git a/compiler/rustc_middle/src/mir/interpret/allocation.rs b/compiler/rustc_middle/src/mir/interpret/allocation.rs
index b6358f9929448..a36c9b6ed7304 100644
--- a/compiler/rustc_middle/src/mir/interpret/allocation.rs
+++ b/compiler/rustc_middle/src/mir/interpret/allocation.rs
@@ -1004,13 +1004,13 @@ impl<Tag: Copy, Extra> Allocation<Tag, Extra> {
     /// Checks that a range of bytes is initialized. If not, returns the `InvalidUninitBytes`
     /// error which will report the first range of bytes which is uninitialized.
     fn check_init(&self, range: AllocRange) -> AllocResult {
-        self.is_init(range).or_else(|idx_range| {
-            Err(AllocError::InvalidUninitBytes(Some(UninitBytesAccess {
+        self.is_init(range).map_err(|idx_range| {
+            AllocError::InvalidUninitBytes(Some(UninitBytesAccess {
                 access_offset: range.start,
                 access_size: range.size,
                 uninit_offset: idx_range.start,
                 uninit_size: idx_range.end - idx_range.start, // `Size` subtraction
-            })))
+            }))
         })
     }
 
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index e3970038a33b0..05675e086d777 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -1837,7 +1837,7 @@ crate fn show_candidates(
                 .skip(1)
                 .all(|(_, descr, _)| descr == descr_first)
             {
-                format!("{}", descr_first)
+                descr_first.to_string()
             } else {
                 "item".to_string()
             };
diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index 9f2e282fce1c3..c46439b851050 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -765,7 +765,7 @@ crate fn find_testable_code<T: doctest::Tester>(
                 // If there are characters between the preceding line ending and
                 // this code block, `str::lines` will return an additional line,
                 // which we subtract here.
-                if nb_lines != 0 && !&doc[prev_offset..offset.start].ends_with("\n") {
+                if nb_lines != 0 && !&doc[prev_offset..offset.start].ends_with('\n') {
                     nb_lines -= 1;
                 }
                 let line = tests.get_line() + nb_lines + 1;
diff --git a/src/librustdoc/visit_ast.rs b/src/librustdoc/visit_ast.rs
index 36b1a14f6c1ea..b13ab64011dc1 100644
--- a/src/librustdoc/visit_ast.rs
+++ b/src/librustdoc/visit_ast.rs
@@ -113,11 +113,9 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     .unwrap_or(&[])
                     .iter()
                     .filter_map(|attr| {
-                        Some(
-                            Cfg::parse(attr.meta_item()?)
-                                .map_err(|e| self.cx.sess().diagnostic().span_err(e.span, e.msg))
-                                .ok()?,
-                        )
+                        Cfg::parse(attr.meta_item()?)
+                            .map_err(|e| self.cx.sess().diagnostic().span_err(e.span, e.msg))
+                            .ok()
                     })
                     .collect::<Vec<_>>()
             })