diff --git a/src/attr.rs b/src/attr.rs
index a5982820e3de..76b66e9da809 100644
--- a/src/attr.rs
+++ b/src/attr.rs
@@ -451,7 +451,7 @@ impl Rewrite for [ast::Attribute] {
                         if next.is_doc_comment() {
                             let snippet = context.snippet(missing_span);
                             let (_, mlb) = has_newlines_before_after_comment(snippet);
-                            result.push_str(&mlb);
+                            result.push_str(mlb);
                         }
                     }
                     result.push('\n');
@@ -484,7 +484,7 @@ impl Rewrite for [ast::Attribute] {
                     if next.is_doc_comment() {
                         let snippet = context.snippet(missing_span);
                         let (_, mlb) = has_newlines_before_after_comment(snippet);
-                        result.push_str(&mlb);
+                        result.push_str(mlb);
                     }
                 }
                 result.push('\n');
diff --git a/src/attr/doc_comment.rs b/src/attr/doc_comment.rs
index c3dcb84c9488..f653a12a8afe 100644
--- a/src/attr/doc_comment.rs
+++ b/src/attr/doc_comment.rs
@@ -77,7 +77,7 @@ mod tests {
     ) {
         assert_eq!(
             expected_comment,
-            format!("{}", DocCommentFormatter::new(&literal, style))
+            format!("{}", DocCommentFormatter::new(literal, style))
         );
     }
 }
diff --git a/src/cargo-fmt/main.rs b/src/cargo-fmt/main.rs
index 1d423ac34919..759b21218c35 100644
--- a/src/cargo-fmt/main.rs
+++ b/src/cargo-fmt/main.rs
@@ -401,12 +401,12 @@ fn get_targets_root_only(
 
 fn get_targets_recursive(
     manifest_path: Option<&Path>,
-    mut targets: &mut BTreeSet<Target>,
+    targets: &mut BTreeSet<Target>,
     visited: &mut BTreeSet<String>,
 ) -> Result<(), io::Error> {
     let metadata = get_cargo_metadata(manifest_path)?;
     for package in &metadata.packages {
-        add_targets(&package.targets, &mut targets);
+        add_targets(&package.targets, targets);
 
         // Look for local dependencies using information available since cargo v1.51
         // It's theoretically possible someone could use a newer version of rustfmt with
@@ -427,7 +427,7 @@ fn get_targets_recursive(
                     .any(|p| p.manifest_path.eq(&manifest_path))
             {
                 visited.insert(dependency.name.to_owned());
-                get_targets_recursive(Some(&manifest_path), &mut targets, visited)?;
+                get_targets_recursive(Some(&manifest_path), targets, visited)?;
             }
         }
     }
diff --git a/src/chains.rs b/src/chains.rs
index 614638ea2abf..e26e24ec55ad 100644
--- a/src/chains.rs
+++ b/src/chains.rs
@@ -568,7 +568,7 @@ impl<'a> ChainFormatterShared<'a> {
         } else {
             self.rewrites
                 .iter()
-                .map(|rw| utils::unicode_str_width(&rw))
+                .map(|rw| utils::unicode_str_width(rw))
                 .sum()
         } + last.tries;
         let one_line_budget = if self.child_count == 1 {
@@ -673,7 +673,7 @@ impl<'a> ChainFormatterShared<'a> {
                 ChainItemKind::Comment(_, CommentPosition::Top) => result.push_str(&connector),
                 _ => result.push_str(&connector),
             }
-            result.push_str(&rewrite);
+            result.push_str(rewrite);
         }
 
         Some(result)
diff --git a/src/comment.rs b/src/comment.rs
index dc4f4516252b..a3cd0359e6ba 100644
--- a/src/comment.rs
+++ b/src/comment.rs
@@ -563,7 +563,7 @@ impl<'a> CommentRewrite<'a> {
             result.push_str(line);
             result.push_str(match iter.peek() {
                 Some(next_line) if next_line.is_empty() => sep.trim_end(),
-                Some(..) => &sep,
+                Some(..) => sep,
                 None => "",
             });
         }
@@ -622,7 +622,7 @@ impl<'a> CommentRewrite<'a> {
         let is_last = i == count_newlines(orig);
 
         if let Some(ref mut ib) = self.item_block {
-            if ib.add_line(&line) {
+            if ib.add_line(line) {
                 return false;
             }
             self.is_prev_line_multi_line = false;
@@ -684,8 +684,8 @@ impl<'a> CommentRewrite<'a> {
         self.item_block = None;
         if let Some(stripped) = line.strip_prefix("```") {
             self.code_block_attr = Some(CodeBlockAttribute::new(stripped))
-        } else if self.fmt.config.wrap_comments() && ItemizedBlock::is_itemized_line(&line) {
-            let ib = ItemizedBlock::new(&line);
+        } else if self.fmt.config.wrap_comments() && ItemizedBlock::is_itemized_line(line) {
+            let ib = ItemizedBlock::new(line);
             self.item_block = Some(ib);
             return false;
         }
@@ -941,7 +941,7 @@ fn left_trim_comment_line<'a>(line: &'a str, style: &CommentStyle<'_>) -> (&'a s
     {
         (&line[4..], true)
     } else if let CommentStyle::Custom(opener) = *style {
-        if let Some(ref stripped) = line.strip_prefix(opener) {
+        if let Some(stripped) = line.strip_prefix(opener) {
             (stripped, true)
         } else {
             (&line[opener.trim_end().len()..], false)
@@ -1570,7 +1570,7 @@ pub(crate) fn recover_comment_removed(
                 context.parse_sess.span_to_filename(span),
                 vec![FormattingError::from_span(
                     span,
-                    &context.parse_sess,
+                    context.parse_sess,
                     ErrorKind::LostComment,
                 )],
             );
@@ -1675,7 +1675,7 @@ impl<'a> Iterator for CommentReducer<'a> {
 fn remove_comment_header(comment: &str) -> &str {
     if comment.starts_with("///") || comment.starts_with("//!") {
         &comment[3..]
-    } else if let Some(ref stripped) = comment.strip_prefix("//") {
+    } else if let Some(stripped) = comment.strip_prefix("//") {
         stripped
     } else if (comment.starts_with("/**") && !comment.starts_with("/**/"))
         || comment.starts_with("/*!")
diff --git a/src/emitter/checkstyle.rs b/src/emitter/checkstyle.rs
index 4448214f3ff2..76f2527db3da 100644
--- a/src/emitter/checkstyle.rs
+++ b/src/emitter/checkstyle.rs
@@ -121,7 +121,7 @@ mod tests {
             format!(r#"<file name="{}">"#, bin_file),
             format!(
                 r#"<error line="2" severity="warning" message="Should be `{}`" />"#,
-                XmlEscaped(&r#"    println!("Hello, world!");"#),
+                XmlEscaped(r#"    println!("Hello, world!");"#),
             ),
             String::from("</file>"),
         ];
@@ -129,7 +129,7 @@ mod tests {
             format!(r#"<file name="{}">"#, lib_file),
             format!(
                 r#"<error line="2" severity="warning" message="Should be `{}`" />"#,
-                XmlEscaped(&r#"    println!("Greetings!");"#),
+                XmlEscaped(r#"    println!("Greetings!");"#),
             ),
             String::from("</file>"),
         ];
diff --git a/src/emitter/diff.rs b/src/emitter/diff.rs
index 2fbbfedb566d..7264ad8bbf36 100644
--- a/src/emitter/diff.rs
+++ b/src/emitter/diff.rs
@@ -23,7 +23,7 @@ impl Emitter for DiffEmitter {
         }: FormattedFile<'_>,
     ) -> Result<EmitterResult, io::Error> {
         const CONTEXT_SIZE: usize = 3;
-        let mismatch = make_diff(&original_text, formatted_text, CONTEXT_SIZE);
+        let mismatch = make_diff(original_text, formatted_text, CONTEXT_SIZE);
         let has_diff = !mismatch.is_empty();
 
         if has_diff {
diff --git a/src/expr.rs b/src/expr.rs
index 7f1dd363f937..c67c14b19852 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -257,7 +257,7 @@ pub(crate) fn format_expr(
                         }
                         _ => false,
                     },
-                    ast::ExprKind::Unary(_, ref expr) => needs_space_before_range(context, &expr),
+                    ast::ExprKind::Unary(_, ref expr) => needs_space_before_range(context, expr),
                     _ => false,
                 }
             }
@@ -423,7 +423,7 @@ fn rewrite_empty_block(
     prefix: &str,
     shape: Shape,
 ) -> Option<String> {
-    if block_has_statements(&block) {
+    if block_has_statements(block) {
         return None;
     }
 
@@ -1148,7 +1148,7 @@ pub(crate) fn is_empty_block(
     block: &ast::Block,
     attrs: Option<&[ast::Attribute]>,
 ) -> bool {
-    !block_has_statements(&block)
+    !block_has_statements(block)
         && !block_contains_comment(context, block)
         && attrs.map_or(true, |a| inner_attributes(a).is_empty())
 }
@@ -1621,7 +1621,7 @@ fn rewrite_struct_lit<'a>(
     };
 
     let fields_str =
-        wrap_struct_field(context, &attrs, &fields_str, shape, v_shape, one_line_width)?;
+        wrap_struct_field(context, attrs, &fields_str, shape, v_shape, one_line_width)?;
     Some(format!("{} {{{}}}", path_str, fields_str))
 
     // FIXME if context.config.indent_style() == Visual, but we run out
@@ -1888,7 +1888,7 @@ pub(crate) fn rewrite_assign_rhs_expr<R: Rewrite>(
     shape: Shape,
     rhs_tactics: RhsTactics,
 ) -> Option<String> {
-    let last_line_width = last_line_width(&lhs).saturating_sub(if lhs.contains('\n') {
+    let last_line_width = last_line_width(lhs).saturating_sub(if lhs.contains('\n') {
         shape.indent.width()
     } else {
         0
@@ -1947,7 +1947,7 @@ pub(crate) fn rewrite_assign_rhs_with_comments<S: Into<String>, R: Rewrite>(
 
     if contains_comment {
         let rhs = rhs.trim_start();
-        combine_strs_with_missing_comments(context, &lhs, &rhs, between_span, shape, allow_extend)
+        combine_strs_with_missing_comments(context, &lhs, rhs, between_span, shape, allow_extend)
     } else {
         Some(lhs + &rhs)
     }
diff --git a/src/formatting.rs b/src/formatting.rs
index 9ef47b887cad..7d0facb8f12c 100644
--- a/src/formatting.rs
+++ b/src/formatting.rs
@@ -155,7 +155,7 @@ impl<'a, T: FormatHandler + 'a> FormatContext<'a, T> {
         let snippet_provider = self.parse_session.snippet_provider(module.span);
         let mut visitor = FmtVisitor::from_parse_sess(
             &self.parse_session,
-            &self.config,
+            self.config,
             &snippet_provider,
             self.report.clone(),
         );
@@ -180,7 +180,7 @@ impl<'a, T: FormatHandler + 'a> FormatContext<'a, T> {
             &mut visitor.buffer,
             &path,
             &visitor.skipped_range.borrow(),
-            &self.config,
+            self.config,
             &self.report,
         );
 
diff --git a/src/imports.rs b/src/imports.rs
index 5ac799366894..40e0d06f99df 100644
--- a/src/imports.rs
+++ b/src/imports.rs
@@ -275,7 +275,7 @@ impl UseTree {
         shape: Shape,
     ) -> Option<String> {
         let vis = self.visibility.as_ref().map_or(Cow::from(""), |vis| {
-            crate::utils::format_visibility(context, &vis)
+            crate::utils::format_visibility(context, vis)
         });
         let use_str = self
             .rewrite(context, shape.offset_left(vis.len())?)
@@ -929,7 +929,7 @@ impl Rewrite for UseTree {
     fn rewrite(&self, context: &RewriteContext<'_>, mut shape: Shape) -> Option<String> {
         let mut result = String::with_capacity(256);
         let mut iter = self.path.iter().peekable();
-        while let Some(ref segment) = iter.next() {
+        while let Some(segment) = iter.next() {
             let segment_str = segment.rewrite(context, shape)?;
             result.push_str(&segment_str);
             if iter.peek().is_some() {
diff --git a/src/items.rs b/src/items.rs
index 1cb1a2701c36..1c7899b3ac3b 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -226,7 +226,7 @@ impl<'a> FnSig<'a> {
     fn to_str(&self, context: &RewriteContext<'_>) -> String {
         let mut result = String::with_capacity(128);
         // Vis defaultness constness unsafety abi.
-        result.push_str(&*format_visibility(context, &self.visibility));
+        result.push_str(&*format_visibility(context, self.visibility));
         result.push_str(format_defaultness(self.defaultness));
         result.push_str(format_constness(self.constness));
         result.push_str(format_async(&self.is_async));
@@ -1220,7 +1220,7 @@ impl<'a> Rewrite for TraitAliasBounds<'a> {
         } else if fits_single_line {
             Cow::from(" ")
         } else {
-            shape.indent.to_string_with_newline(&context.config)
+            shape.indent.to_string_with_newline(context.config)
         };
 
         Some(format!("{}{}{}", generic_bounds_str, space, where_str))
@@ -1238,7 +1238,7 @@ pub(crate) fn format_trait_alias(
     let alias = rewrite_ident(context, ident);
     // 6 = "trait ", 2 = " ="
     let g_shape = shape.offset_left(6)?.sub_width(2)?;
-    let generics_str = rewrite_generics(context, &alias, generics, g_shape)?;
+    let generics_str = rewrite_generics(context, alias, generics, g_shape)?;
     let vis_str = format_visibility(context, vis);
     let lhs = format!("{}trait {} =", vis_str, generics_str);
     // 1 = ";"
@@ -1386,7 +1386,7 @@ fn format_empty_struct_or_tuple(
     closer: &str,
 ) {
     // 3 = " {}" or "();"
-    let used_width = last_line_used_width(&result, offset.width()) + 3;
+    let used_width = last_line_used_width(result, offset.width()) + 3;
     if used_width > context.config.max_width() {
         result.push_str(&offset.to_string_with_newline(context.config))
     }
@@ -2066,7 +2066,7 @@ fn rewrite_explicit_self(
                     )?;
                     Some(combine_strs_with_missing_comments(
                         context,
-                        &param_attrs,
+                        param_attrs,
                         &format!("&{} {}self", lifetime_str, mut_str),
                         span,
                         shape,
@@ -2075,7 +2075,7 @@ fn rewrite_explicit_self(
                 }
                 None => Some(combine_strs_with_missing_comments(
                     context,
-                    &param_attrs,
+                    param_attrs,
                     &format!("&{}self", mut_str),
                     span,
                     shape,
@@ -2091,7 +2091,7 @@ fn rewrite_explicit_self(
 
             Some(combine_strs_with_missing_comments(
                 context,
-                &param_attrs,
+                param_attrs,
                 &format!("{}self: {}", format_mutability(mutability), type_str),
                 span,
                 shape,
@@ -2100,7 +2100,7 @@ fn rewrite_explicit_self(
         }
         ast::SelfKind::Value(mutability) => Some(combine_strs_with_missing_comments(
             context,
-            &param_attrs,
+            param_attrs,
             &format!("{}self", format_mutability(mutability)),
             span,
             shape,
@@ -2226,7 +2226,7 @@ fn rewrite_fn_base(
     }
 
     // Skip `pub(crate)`.
-    let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
+    let lo_after_visibility = get_bytepos_after_visibility(fn_sig.visibility, span);
     // A conservative estimation, the goal is to be over all parens in generics
     let params_start = fn_sig
         .generics
@@ -2984,7 +2984,7 @@ fn format_header(
     let mut result = String::with_capacity(128);
     let shape = Shape::indented(offset, context.config);
 
-    result.push_str(&format_visibility(context, vis).trim());
+    result.push_str(format_visibility(context, vis).trim());
 
     // Check for a missing comment between the visibility and the item name.
     let after_vis = vis.span.hi();
@@ -3005,7 +3005,7 @@ fn format_header(
         }
     }
 
-    result.push_str(&rewrite_ident(context, ident));
+    result.push_str(rewrite_ident(context, ident));
 
     result
 }
@@ -3133,7 +3133,7 @@ impl Rewrite for ast::ForeignItem {
                     let inner_attrs = inner_attributes(&self.attrs);
                     let fn_ctxt = visit::FnCtxt::Foreign;
                     visitor.visit_fn(
-                        visit::FnKind::Fn(fn_ctxt, self.ident, &fn_sig, &self.vis, Some(body)),
+                        visit::FnKind::Fn(fn_ctxt, self.ident, fn_sig, &self.vis, Some(body)),
                         generics,
                         &fn_sig.decl,
                         self.span,
@@ -3146,7 +3146,7 @@ impl Rewrite for ast::ForeignItem {
                         context,
                         shape.indent,
                         self.ident,
-                        &FnSig::from_method_sig(&fn_sig, generics, &self.vis),
+                        &FnSig::from_method_sig(fn_sig, generics, &self.vis),
                         span,
                         FnBraceStyle::None,
                     )
@@ -3171,7 +3171,7 @@ impl Rewrite for ast::ForeignItem {
                 let ast::TyAliasKind(_, ref generics, ref generic_bounds, ref type_default) =
                     **ty_alias_kind;
                 rewrite_type(
-                    &context,
+                    context,
                     shape.indent,
                     self.ident,
                     &self.vis,
@@ -3229,7 +3229,7 @@ fn rewrite_attrs(
     combine_strs_with_missing_comments(
         context,
         &attrs_str,
-        &item_str,
+        item_str,
         missed_span,
         shape,
         allow_extend,
diff --git a/src/lib.rs b/src/lib.rs
index 47a7b9d4dbe3..792a1080f0e9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -283,7 +283,7 @@ impl FormatReport {
         writeln!(
             t,
             "{}",
-            FormatReportFormatterBuilder::new(&self)
+            FormatReportFormatterBuilder::new(self)
                 .enable_colors(true)
                 .build()
         )?;
@@ -297,7 +297,7 @@ impl FormatReport {
 impl fmt::Display for FormatReport {
     // Prints all the formatting errors.
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        write!(fmt, "{}", FormatReportFormatterBuilder::new(&self).build())?;
+        write!(fmt, "{}", FormatReportFormatterBuilder::new(self).build())?;
         Ok(())
     }
 }
diff --git a/src/lists.rs b/src/lists.rs
index c04b47876169..d341ec8e6b0e 100644
--- a/src/lists.rs
+++ b/src/lists.rs
@@ -386,7 +386,7 @@ where
                         result.push('\n');
                         result.push_str(indent_str);
                         // This is the width of the item (without comments).
-                        line_len = item.item.as_ref().map_or(0, |s| unicode_str_width(&s));
+                        line_len = item.item.as_ref().map_or(0, |s| unicode_str_width(s));
                     }
                 } else {
                     result.push(' ')
@@ -820,7 +820,7 @@ where
 pub(crate) fn total_item_width(item: &ListItem) -> usize {
     comment_len(item.pre_comment.as_ref().map(|x| &(*x)[..]))
         + comment_len(item.post_comment.as_ref().map(|x| &(*x)[..]))
-        + item.item.as_ref().map_or(0, |s| unicode_str_width(&s))
+        + item.item.as_ref().map_or(0, |s| unicode_str_width(s))
 }
 
 fn comment_len(comment: Option<&str>) -> usize {
diff --git a/src/macros.rs b/src/macros.rs
index 927187dfd8a2..ef747638e33e 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -186,7 +186,7 @@ fn return_macro_parse_failure_fallback(
         })
         .unwrap_or(false);
     if is_like_block_indent_style {
-        return trim_left_preserve_layout(context.snippet(span), indent, &context.config);
+        return trim_left_preserve_layout(context.snippet(span), indent, context.config);
     }
 
     context.skipped_range.borrow_mut().push((
@@ -437,7 +437,7 @@ fn rewrite_macro_inner(
             // the `macro_name!` and `{ /* macro_body */ }` but skip modifying
             // anything in between the braces (for now).
             let snippet = context.snippet(mac.span()).trim_start_matches(|c| c != '{');
-            match trim_left_preserve_layout(snippet, shape.indent, &context.config) {
+            match trim_left_preserve_layout(snippet, shape.indent, context.config) {
                 Some(macro_body) => Some(format!("{} {}", macro_name, macro_body)),
                 None => Some(format!("{} {}", macro_name, snippet)),
             }
@@ -901,7 +901,7 @@ impl MacroArgParser {
                     break;
                 }
                 TokenTree::Token(ref t) => {
-                    buffer.push_str(&pprust::token_to_string(&t));
+                    buffer.push_str(&pprust::token_to_string(t));
                 }
                 _ => return None,
             }
@@ -1045,7 +1045,7 @@ fn wrap_macro_args_inner(
     let mut iter = args.iter().peekable();
     let indent_str = shape.indent.to_string_with_newline(context.config);
 
-    while let Some(ref arg) = iter.next() {
+    while let Some(arg) = iter.next() {
         result.push_str(&arg.rewrite(context, shape, use_multiple_lines)?);
 
         if use_multiple_lines
@@ -1055,7 +1055,7 @@ fn wrap_macro_args_inner(
                 result.pop();
             }
             result.push_str(&indent_str);
-        } else if let Some(ref next_arg) = iter.peek() {
+        } else if let Some(next_arg) = iter.peek() {
             let space_before_dollar =
                 !arg.kind.ends_with_space() && next_arg.kind.starts_with_dollar();
             let space_before_brace = next_arg.kind.starts_with_brace();
@@ -1370,7 +1370,7 @@ impl MacroBranch {
                     {
                         s += &indent_str;
                     }
-                    (s + l + "\n", indent_next_line(kind, &l, &config))
+                    (s + l + "\n", indent_next_line(kind, l, &config))
                 },
             )
             .0;
@@ -1514,11 +1514,11 @@ fn rewrite_macro_with_items(
             MacroArg::Item(item) => item,
             _ => return None,
         };
-        visitor.visit_item(&item);
+        visitor.visit_item(item);
     }
 
     let mut result = String::with_capacity(256);
-    result.push_str(&macro_name);
+    result.push_str(macro_name);
     result.push_str(opener);
     result.push_str(&visitor.block_indent.to_string_with_newline(context.config));
     result.push_str(visitor.buffer.trim());
diff --git a/src/matches.rs b/src/matches.rs
index 5a6ed0ec06e5..25b953ef4257 100644
--- a/src/matches.rs
+++ b/src/matches.rs
@@ -319,7 +319,7 @@ fn flatten_arm_body<'a>(
     let can_extend =
         |expr| !context.config.force_multiline_blocks() && can_flatten_block_around_this(expr);
 
-    if let Some(ref block) = block_can_be_flattened(context, body) {
+    if let Some(block) = block_can_be_flattened(context, body) {
         if let ast::StmtKind::Expr(ref expr) = block.stmts[0].kind {
             if let ast::ExprKind::Block(..) = expr.kind {
                 flatten_arm_body(context, expr, None)
@@ -393,7 +393,7 @@ fn rewrite_match_body(
         if comment_str.is_empty() {
             String::new()
         } else {
-            rewrite_comment(comment_str, false, shape, &context.config)?
+            rewrite_comment(comment_str, false, shape, context.config)?
         }
     };
 
@@ -408,8 +408,8 @@ fn rewrite_match_body(
                 result.push_str(&arrow_comment);
             }
             result.push_str(&nested_indent_str);
-            result.push_str(&body_str);
-            result.push_str(&comma);
+            result.push_str(body_str);
+            result.push_str(comma);
             return Some(result);
         }
 
@@ -451,7 +451,7 @@ fn rewrite_match_body(
             result.push_str(&arrow_comment);
         }
         result.push_str(&block_sep);
-        result.push_str(&body_str);
+        result.push_str(body_str);
         result.push_str(&body_suffix);
         Some(result)
     };
diff --git a/src/modules.rs b/src/modules.rs
index ded34d9032f9..b0c1604a6027 100644
--- a/src/modules.rs
+++ b/src/modules.rs
@@ -290,7 +290,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
                 };
                 self.visit_sub_mod_after_directory_update(sub_mod, Some(directory))
             }
-            SubModKind::Internal(ref item) => {
+            SubModKind::Internal(item) => {
                 self.push_inline_mod_directory(item.ident, &item.attrs);
                 self.visit_sub_mod_after_directory_update(sub_mod, None)
             }
@@ -317,7 +317,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
         }
         match (sub_mod.ast_mod_kind, sub_mod.items) {
             (Some(Cow::Borrowed(ast::ModKind::Loaded(items, _, _))), _) => {
-                self.visit_mod_from_ast(&items)
+                self.visit_mod_from_ast(items)
             }
             (Some(Cow::Owned(..)), Cow::Owned(items)) => self.visit_mod_outside_ast(items),
             (_, _) => Ok(()),
diff --git a/src/overflow.rs b/src/overflow.rs
index ac24181c7805..3475f5c378cd 100644
--- a/src/overflow.rs
+++ b/src/overflow.rs
@@ -394,7 +394,7 @@ impl<'a> Context<'a> {
     ) -> Option<String> {
         let last_item = self.last_item()?;
         let rewrite = match last_item {
-            OverflowableItem::Expr(ref expr) => {
+            OverflowableItem::Expr(expr) => {
                 match expr.kind {
                     // When overflowing the closure which consists of a single control flow
                     // expression, force to use block if its condition uses multi line.
diff --git a/src/pairs.rs b/src/pairs.rs
index 0f3d5e8f878b..d1c75126ea4a 100644
--- a/src/pairs.rs
+++ b/src/pairs.rs
@@ -55,11 +55,11 @@ fn rewrite_pairs_one_line<T: Rewrite>(
 
     for ((_, rewrite), s) in list.list.iter().zip(list.separators.iter()) {
         if let Some(rewrite) = rewrite {
-            if !is_single_line(&rewrite) || result.len() > shape.width {
+            if !is_single_line(rewrite) || result.len() > shape.width {
                 return None;
             }
 
-            result.push_str(&rewrite);
+            result.push_str(rewrite);
             result.push(' ');
             result.push_str(s);
             result.push(' ');
@@ -94,18 +94,18 @@ fn rewrite_pairs_multiline<T: Rewrite>(
     shape: Shape,
     context: &RewriteContext<'_>,
 ) -> Option<String> {
-    let rhs_offset = shape.rhs_overhead(&context.config);
+    let rhs_offset = shape.rhs_overhead(context.config);
     let nested_shape = (match context.config.indent_style() {
         IndentStyle::Visual => shape.visual_indent(0),
         IndentStyle::Block => shape.block_indent(context.config.tab_spaces()),
     })
-    .with_max_width(&context.config)
+    .with_max_width(context.config)
     .sub_width(rhs_offset)?;
 
     let indent_str = nested_shape.indent.to_string_with_newline(context.config);
     let mut result = String::new();
 
-    result.push_str(&list.list[0].1.as_ref()?);
+    result.push_str(list.list[0].1.as_ref()?);
 
     for ((e, default_rw), s) in list.list[1..].iter().zip(list.separators.iter()) {
         // The following test checks if we should keep two subexprs on the same
@@ -144,7 +144,7 @@ fn rewrite_pairs_multiline<T: Rewrite>(
             }
         }
 
-        result.push_str(&default_rw.as_ref()?);
+        result.push_str(default_rw.as_ref()?);
     }
     Some(result)
 }
@@ -264,12 +264,12 @@ impl FlattenPair for ast::Expr {
                 return node.rewrite(context, shape);
             }
             let nested_overhead = sep + 1;
-            let rhs_offset = shape.rhs_overhead(&context.config);
+            let rhs_offset = shape.rhs_overhead(context.config);
             let nested_shape = (match context.config.indent_style() {
                 IndentStyle::Visual => shape.visual_indent(0),
                 IndentStyle::Block => shape.block_indent(context.config.tab_spaces()),
             })
-            .with_max_width(&context.config)
+            .with_max_width(context.config)
             .sub_width(rhs_offset)?;
             let default_shape = match context.config.binop_separator() {
                 SeparatorPlace::Back => nested_shape.sub_width(nested_overhead)?,
diff --git a/src/patterns.rs b/src/patterns.rs
index ba8d8024a970..2676c6473556 100644
--- a/src/patterns.rs
+++ b/src/patterns.rs
@@ -482,7 +482,7 @@ fn rewrite_tuple_pat(
     let path_str = path_str.unwrap_or_default();
 
     overflow::rewrite_with_parens(
-        &context,
+        context,
         &path_str,
         pat_vec.iter(),
         shape,
diff --git a/src/syntux/parser.rs b/src/syntux/parser.rs
index b5fe4335dd33..14b92238cfa6 100644
--- a/src/syntux/parser.rs
+++ b/src/syntux/parser.rs
@@ -112,7 +112,7 @@ impl<'a> Parser<'a> {
         span: Span,
     ) -> Result<(Vec<ast::Attribute>, Vec<ptr::P<ast::Item>>, Span), ParserError> {
         let result = catch_unwind(AssertUnwindSafe(|| {
-            let mut parser = new_parser_from_file(sess.inner(), &path, Some(span));
+            let mut parser = new_parser_from_file(sess.inner(), path, Some(span));
             match parser.parse_mod(&TokenKind::Eof) {
                 Ok(result) => Some(result),
                 Err(mut e) => {
diff --git a/src/syntux/session.rs b/src/syntux/session.rs
index 946c076d9f2d..cdb4893d443b 100644
--- a/src/syntux/session.rs
+++ b/src/syntux/session.rs
@@ -164,7 +164,7 @@ impl ParseSess {
     }
 
     pub(crate) fn ignore_file(&self, path: &FileName) -> bool {
-        self.ignore_path_set.as_ref().is_match(&path)
+        self.ignore_path_set.as_ref().is_match(path)
     }
 
     pub(crate) fn set_silent_emitter(&mut self) {
diff --git a/src/test/mod.rs b/src/test/mod.rs
index 48d61289a9b8..e2620508c340 100644
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@@ -535,9 +535,9 @@ fn check_files(files: Vec<PathBuf>, opt_config: &Option<PathBuf>) -> (Vec<Format
 
         debug!("Testing '{}'...", file_name.display());
 
-        match idempotent_check(&file_name, &opt_config) {
+        match idempotent_check(&file_name, opt_config) {
             Ok(ref report) if report.has_warnings() => {
-                print!("{}", FormatReportFormatterBuilder::new(&report).build());
+                print!("{}", FormatReportFormatterBuilder::new(report).build());
                 fails += 1;
             }
             Ok(report) => reports.push(report),
diff --git a/src/types.rs b/src/types.rs
index 62c05ba078c5..9ea90c5e46dd 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -728,7 +728,7 @@ impl Rewrite for ast::Ty {
                     result = combine_strs_with_missing_comments(
                         context,
                         result.trim_end(),
-                        &mt.ty.rewrite(&context, shape)?,
+                        &mt.ty.rewrite(context, shape)?,
                         before_ty_span,
                         shape,
                         true,
@@ -738,7 +738,7 @@ impl Rewrite for ast::Ty {
                     let budget = shape.width.checked_sub(used_width)?;
                     let ty_str = mt
                         .ty
-                        .rewrite(&context, Shape::legacy(budget, shape.indent + used_width))?;
+                        .rewrite(context, Shape::legacy(budget, shape.indent + used_width))?;
                     result.push_str(&ty_str);
                 }
 
diff --git a/src/utils.rs b/src/utils.rs
index 29e1e070d411..3a8713c5bdb0 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -42,7 +42,7 @@ pub(crate) fn is_same_visibility(a: &Visibility, b: &Visibility) -> bool {
         (
             VisibilityKind::Restricted { path: p, .. },
             VisibilityKind::Restricted { path: q, .. },
-        ) => pprust::path_to_string(&p) == pprust::path_to_string(&q),
+        ) => pprust::path_to_string(p) == pprust::path_to_string(q),
         (VisibilityKind::Public, VisibilityKind::Public)
         | (VisibilityKind::Inherited, VisibilityKind::Inherited)
         | (
@@ -689,7 +689,7 @@ mod test {
     #[test]
     fn test_remove_trailing_white_spaces() {
         let s = "    r#\"\n        test\n    \"#";
-        assert_eq!(remove_trailing_white_spaces(&s), s);
+        assert_eq!(remove_trailing_white_spaces(s), s);
     }
 
     #[test]
@@ -698,7 +698,7 @@ mod test {
         let config = Config::default();
         let indent = Indent::new(4, 0);
         assert_eq!(
-            trim_left_preserve_layout(&s, indent, &config),
+            trim_left_preserve_layout(s, indent, &config),
             Some("aaa\n    bbb\n    ccc".to_string())
         );
     }
diff --git a/src/visitor.rs b/src/visitor.rs
index d854d90b40b6..c37e1cb10117 100644
--- a/src/visitor.rs
+++ b/src/visitor.rs
@@ -164,7 +164,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                     );
                 } else {
                     let shape = self.shape();
-                    let rewrite = self.with_context(|ctx| stmt.rewrite(&ctx, shape));
+                    let rewrite = self.with_context(|ctx| stmt.rewrite(ctx, shape));
                     self.push_rewrite(stmt.span(), rewrite)
                 }
             }
@@ -273,9 +273,9 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
 
         let comment_snippet = self.snippet(span);
 
-        let align_to_right = if unindent_comment && contains_comment(&comment_snippet) {
+        let align_to_right = if unindent_comment && contains_comment(comment_snippet) {
             let first_lines = comment_snippet.splitn(2, '/').next().unwrap_or("");
-            last_line_width(first_lines) > last_line_width(&comment_snippet)
+            last_line_width(first_lines) > last_line_width(comment_snippet)
         } else {
             false
         };
@@ -439,7 +439,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
         let filtered_attrs;
         let mut attrs = &item.attrs;
         let skip_context_saved = self.skip_context.clone();
-        self.skip_context.update_with_attrs(&attrs);
+        self.skip_context.update_with_attrs(attrs);
 
         let should_visit_node_again = match item.kind {
             // For use/extern crate items, skip rewriting attributes but check for a skip attribute.
@@ -488,12 +488,12 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                 ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
                 ast::ItemKind::Impl { .. } => {
                     let block_indent = self.block_indent;
-                    let rw = self.with_context(|ctx| format_impl(&ctx, item, block_indent));
+                    let rw = self.with_context(|ctx| format_impl(ctx, item, block_indent));
                     self.push_rewrite(item.span, rw);
                 }
                 ast::ItemKind::Trait(..) => {
                     let block_indent = self.block_indent;
-                    let rw = self.with_context(|ctx| format_trait(&ctx, item, block_indent));
+                    let rw = self.with_context(|ctx| format_trait(ctx, item, block_indent));
                     self.push_rewrite(item.span, rw);
                 }
                 ast::ItemKind::TraitAlias(ref generics, ref generic_bounds) => {
@@ -552,7 +552,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                             visit::FnKind::Fn(
                                 fn_ctxt,
                                 item.ident,
-                                &fn_signature,
+                                fn_signature,
                                 &item.vis,
                                 Some(body),
                             ),
@@ -567,7 +567,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                         let rewrite = self.rewrite_required_fn(
                             indent,
                             item.ident,
-                            &fn_signature,
+                            fn_signature,
                             &item.vis,
                             generics,
                             item.span,
@@ -718,7 +718,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                         &ii.vis,
                         defaultness,
                         ty.as_ref(),
-                        &generics,
+                        generics,
                         &self.get_context(),
                         self.block_indent,
                         ii.span,
@@ -905,7 +905,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
     }
 
     fn walk_mod_items(&mut self, items: &[rustc_ast::ptr::P<ast::Item>]) {
-        self.visit_items_with_reordering(&ptr_vec_to_ref_vec(&items));
+        self.visit_items_with_reordering(&ptr_vec_to_ref_vec(items));
     }
 
     fn walk_stmts(&mut self, stmts: &[Stmt<'_>], include_current_empty_semi: bool) {