From 094e687e42a19b747203fa1967d192c5384ef459 Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Tue, 9 Oct 2018 21:28:40 +0900
Subject: [PATCH 1/7] Remove an unsafe code

---
 src/visitor.rs | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/visitor.rs b/src/visitor.rs
index 30752826a85..7b952c20f52 100644
--- a/src/visitor.rs
+++ b/src/visitor.rs
@@ -792,13 +792,9 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
     where
         F: Fn(&RewriteContext) -> Option<String>,
     {
-        let result;
-        let macro_rewrite_failure = {
-            let context = self.get_context();
-            result = f(&context);
-            unsafe { *context.macro_rewrite_failure.as_ptr() }
-        };
-        self.macro_rewrite_failure |= macro_rewrite_failure;
+        let context = self.get_context();
+        let result = f(&context);
+        self.macro_rewrite_failure |= *context.macro_rewrite_failure.borrow();
         result
     }
 

From d55729987ff798b49838e5b5707cfca807b5b6b7 Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Tue, 9 Oct 2018 21:47:00 +0900
Subject: [PATCH 2/7] Use UnOp::to_string

---
 src/expr.rs | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/src/expr.rs b/src/expr.rs
index 752fb792899..48a493c8a74 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -1815,12 +1815,7 @@ fn rewrite_unary_op(
     shape: Shape,
 ) -> Option<String> {
     // For some reason, an UnOp is not spanned like BinOp!
-    let operator_str = match op {
-        ast::UnOp::Deref => "*",
-        ast::UnOp::Not => "!",
-        ast::UnOp::Neg => "-",
-    };
-    rewrite_unary_prefix(context, operator_str, expr, shape)
+    rewrite_unary_prefix(context, ast::UnOp::to_string(op), expr, shape)
 }
 
 fn rewrite_assignment(

From 751bcf5fa08ee5c5ba156e43c7f8327f7968b02f Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Mon, 15 Oct 2018 20:36:39 +0900
Subject: [PATCH 3/7] Clippy

---
 src/format-diff/main.rs |  2 +-
 src/items.rs            | 19 +++++++------------
 src/lists.rs            |  2 +-
 src/macros.rs           |  4 ++--
 src/overflow.rs         |  2 +-
 src/source_map.rs       | 12 +++++++-----
 src/utils.rs            |  2 +-
 src/visitor.rs          | 33 ++++++++++++++++-----------------
 8 files changed, 36 insertions(+), 40 deletions(-)

diff --git a/src/format-diff/main.rs b/src/format-diff/main.rs
index d509a4429b4..aacfa12d437 100644
--- a/src/format-diff/main.rs
+++ b/src/format-diff/main.rs
@@ -83,7 +83,7 @@ fn main() {
     );
 
     if let Err(e) = run(&opts) {
-        println!("{}", opts.usage(&format!("{}", e)));
+        println!("{}", opts.usage(&e.to_string()));
         process::exit(1);
     }
 }
diff --git a/src/items.rs b/src/items.rs
index 1673bffbce9..b35e8ea4587 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -1543,7 +1543,7 @@ pub fn rewrite_struct_field_prefix(
             rewrite_ident(context, name),
             type_annotation_spacing.0
         ),
-        None => format!("{}", vis),
+        None => vis.to_string(),
     })
 }
 
@@ -2004,18 +2004,13 @@ fn rewrite_fn_base(
         one_line_budget, multi_line_budget, arg_indent
     );
 
+    result.push('(');
     // Check if vertical layout was forced.
-    if one_line_budget == 0 {
-        if snuggle_angle_bracket {
-            result.push('(');
-        } else {
-            result.push_str("(");
-            if context.config.indent_style() == IndentStyle::Visual {
-                result.push_str(&arg_indent.to_string_with_newline(context.config));
-            }
-        }
-    } else {
-        result.push('(');
+    if one_line_budget == 0
+        && !snuggle_angle_bracket
+        && context.config.indent_style() == IndentStyle::Visual
+    {
+        result.push_str(&arg_indent.to_string_with_newline(context.config));
     }
 
     // Skip `pub(crate)`.
diff --git a/src/lists.rs b/src/lists.rs
index 57f778896d3..92990fe9a17 100644
--- a/src/lists.rs
+++ b/src/lists.rs
@@ -50,7 +50,7 @@ impl<'a> ListFormatting<'a> {
             ends_with_newline: true,
             preserve_newline: false,
             nested: false,
-            config: config,
+            config,
         }
     }
 
diff --git a/src/macros.rs b/src/macros.rs
index dab27d8a073..1e668cf1d87 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -1073,7 +1073,7 @@ fn next_space(tok: &Token) -> SpaceState {
 /// when the macro is not an instance of try! (or parsing the inner expression
 /// failed).
 pub fn convert_try_mac(mac: &ast::Mac, context: &RewriteContext) -> Option<ast::Expr> {
-    if &format!("{}", mac.node.path) == "try" {
+    if &mac.node.path.to_string() == "try" {
         let ts: TokenStream = mac.node.tts.clone().into();
         let mut parser = new_parser_from_tts(context.parse_session, ts.trees().collect());
 
@@ -1491,5 +1491,5 @@ fn rewrite_macro_with_items(
     result.push_str(&shape.indent.to_string_with_newline(context.config));
     result.push_str(closer);
     result.push_str(trailing_semicolon);
-    return Some(result);
+    Some(result)
 }
diff --git a/src/overflow.rs b/src/overflow.rs
index fc1803b2ab6..053ce1b9212 100644
--- a/src/overflow.rs
+++ b/src/overflow.rs
@@ -425,7 +425,7 @@ impl<'a> Context<'a> {
                     _ => expr.rewrite(self.context, shape),
                 }
             }
-            item @ _ => item.rewrite(self.context, shape),
+            item => item.rewrite(self.context, shape),
         };
 
         if let Some(rewrite) = rewrite {
diff --git a/src/source_map.rs b/src/source_map.rs
index dee5e4f7601..ed081adcd86 100644
--- a/src/source_map.rs
+++ b/src/source_map.rs
@@ -51,11 +51,13 @@ impl<'a> SpanUtils for SnippetProvider<'a> {
     }
 
     fn span_before(&self, original: Span, needle: &str) -> BytePos {
-        self.opt_span_before(original, needle).expect(&format!(
-            "bad span: {}: {}",
-            needle,
-            self.span_to_snippet(original).unwrap()
-        ))
+        self.opt_span_before(original, needle).unwrap_or_else(|| {
+            panic!(
+                "bad span: {}: {}",
+                needle,
+                self.span_to_snippet(original).unwrap()
+            )
+        })
     }
 
     fn opt_span_after(&self, original: Span, needle: &str) -> Option<BytePos> {
diff --git a/src/utils.rs b/src/utils.rs
index 7ef9254a482..2ff3b7e525a 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -45,7 +45,7 @@ pub fn is_same_visibility(a: &Visibility, b: &Visibility) -> bool {
         (
             VisibilityKind::Restricted { path: p, .. },
             VisibilityKind::Restricted { path: q, .. },
-        ) => format!("{}", p) == format!("{}", q),
+        ) => p.to_string() == q.to_string(),
         (VisibilityKind::Public, VisibilityKind::Public)
         | (VisibilityKind::Inherited, VisibilityKind::Inherited)
         | (
diff --git a/src/visitor.rs b/src/visitor.rs
index 7b952c20f52..63e2c6bdcac 100644
--- a/src/visitor.rs
+++ b/src/visitor.rs
@@ -112,7 +112,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                 if contains_skip(get_attrs_from_stmt(stmt)) {
                     self.push_skipped_with_span(stmt.span());
                 } else {
-                    let shape = self.shape().clone();
+                    let shape = self.shape();
                     let rewrite = self.with_context(|ctx| stmt.rewrite(&ctx, shape));
                     self.push_rewrite(stmt.span(), rewrite)
                 }
@@ -367,13 +367,13 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                 let where_span_end = snippet
                     .find_uncommented("{")
                     .map(|x| BytePos(x as u32) + source!(self, item.span).lo());
-                let block_indent = self.block_indent.clone();
+                let block_indent = self.block_indent;
                 let rw =
                     self.with_context(|ctx| format_impl(&ctx, item, block_indent, where_span_end));
                 self.push_rewrite(item.span, rw);
             }
             ast::ItemKind::Trait(..) => {
-                let block_indent = self.block_indent.clone();
+                let block_indent = self.block_indent;
                 let rw = self.with_context(|ctx| format_trait(&ctx, item, block_indent));
                 self.push_rewrite(item.span, rw);
             }
@@ -652,20 +652,19 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                         ErrorKind::DeprecatedAttr,
                     )],
                 );
-            } else if attr.path.segments[0].ident.to_string() == "rustfmt" {
-                if attr.path.segments.len() == 1
-                    || attr.path.segments[1].ident.to_string() != "skip"
-                {
-                    let file_name = self.source_map.span_to_filename(attr.span).into();
-                    self.report.append(
-                        file_name,
-                        vec![FormattingError::from_span(
-                            attr.span,
-                            &self.source_map,
-                            ErrorKind::BadAttr,
-                        )],
-                    );
-                }
+            } else if attr.path.segments[0].ident.to_string() == "rustfmt"
+                && (attr.path.segments.len() == 1
+                    || attr.path.segments[1].ident.to_string() != "skip")
+            {
+                let file_name = self.source_map.span_to_filename(attr.span).into();
+                self.report.append(
+                    file_name,
+                    vec![FormattingError::from_span(
+                        attr.span,
+                        &self.source_map,
+                        ErrorKind::BadAttr,
+                    )],
+                );
             }
         }
         if contains_skip(attrs) {

From 6380f885278e33ff058e01555538ced58c44dacf Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Wed, 10 Oct 2018 10:50:25 +0900
Subject: [PATCH 4/7] Cleanup

---
 src/missed_spans.rs | 18 ++----------------
 src/string.rs       |  4 ++--
 2 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/src/missed_spans.rs b/src/missed_spans.rs
index f2f2295a872..b7d73bbf0ba 100644
--- a/src/missed_spans.rs
+++ b/src/missed_spans.rs
@@ -120,7 +120,7 @@ impl<'a> FmtVisitor<'a> {
     }
 
     fn push_vertical_spaces(&mut self, mut newline_count: usize) {
-        let offset = self.count_trailing_newlines();
+        let offset = self.buffer.chars().rev().take_while(|c| *c == '\n').count();
         let newline_upper_bound = self.config.blank_lines_upper_bound() + 1;
         let newline_lower_bound = self.config.blank_lines_lower_bound() + 1;
 
@@ -142,16 +142,6 @@ impl<'a> FmtVisitor<'a> {
         self.push_str(&blank_lines);
     }
 
-    fn count_trailing_newlines(&self) -> usize {
-        let mut buf = &*self.buffer;
-        let mut result = 0;
-        while buf.ends_with('\n') {
-            buf = &buf[..buf.len() - 1];
-            result += 1;
-        }
-        result
-    }
-
     fn write_snippet<F>(&mut self, span: Span, process_last_snippet: F)
     where
         F: Fn(&mut FmtVisitor, &str, &str),
@@ -271,11 +261,7 @@ impl<'a> FmtVisitor<'a> {
 
         if let Some('/') = subslice.chars().nth(1) {
             // check that there are no contained block comments
-            if !subslice
-                .split('\n')
-                .map(|s| s.trim_left())
-                .any(|s| s.len() >= 2 && &s[0..2] == "/*")
-            {
+            if !subslice.lines().any(|s| s.trim_left().starts_with("/*")) {
                 // Add a newline after line comments
                 self.push_str("\n");
             }
diff --git a/src/string.rs b/src/string.rs
index ca063123e39..b70f9f0f12b 100644
--- a/src/string.rs
+++ b/src/string.rs
@@ -242,9 +242,9 @@ fn break_string(max_chars: usize, trim_end: bool, line_end: &str, input: &[&str]
         for (i, grapheme) in input[0..=index].iter().enumerate() {
             if is_line_feed(grapheme) {
                 if i <= index_minus_ws {
-                    let mut line = input[0..i].join("");
+                    let mut line = &input[0..i].join("")[..];
                     if trim_end {
-                        line = line.trim_right().to_string();
+                        line = line.trim_right();
                     }
                     return SnippetState::EndWithLineFeed(format!("{}\n", line), i + 1);
                 }

From 6fb188bd43840f4a99c6a4b4cdbdb21ccf3304e7 Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Mon, 15 Oct 2018 21:10:34 +0900
Subject: [PATCH 5/7] Use concat() instead of join("")

---
 src/string.rs | 28 ++++++++--------------------
 1 file changed, 8 insertions(+), 20 deletions(-)

diff --git a/src/string.rs b/src/string.rs
index b70f9f0f12b..d45f15a1c9b 100644
--- a/src/string.rs
+++ b/src/string.rs
@@ -172,7 +172,7 @@ fn detect_url(s: &[&str], index: usize) -> Option<usize> {
     if s.len() < start + 8 {
         return None;
     }
-    let prefix = s[start..start + 8].join("");
+    let prefix = s[start..start + 8].concat();
     if prefix.starts_with("https://")
         || prefix.starts_with("http://")
         || prefix.starts_with("ftp://")
@@ -242,7 +242,7 @@ fn break_string(max_chars: usize, trim_end: bool, line_end: &str, input: &[&str]
         for (i, grapheme) in input[0..=index].iter().enumerate() {
             if is_line_feed(grapheme) {
                 if i <= index_minus_ws {
-                    let mut line = &input[0..i].join("")[..];
+                    let mut line = &input[0..i].concat()[..];
                     if trim_end {
                         line = line.trim_right();
                     }
@@ -256,7 +256,7 @@ fn break_string(max_chars: usize, trim_end: bool, line_end: &str, input: &[&str]
         for (i, grapheme) in input[index + 1..].iter().enumerate() {
             if !trim_end && is_line_feed(grapheme) {
                 return SnippetState::EndWithLineFeed(
-                    input[0..=index + 1 + i].join("").to_string(),
+                    input[0..=index + 1 + i].concat(),
                     index + 2 + i,
                 );
             } else if not_whitespace_except_line_feed(grapheme) {
@@ -266,15 +266,9 @@ fn break_string(max_chars: usize, trim_end: bool, line_end: &str, input: &[&str]
         }
 
         if trim_end {
-            SnippetState::LineEnd(
-                input[0..=index_minus_ws].join("").to_string(),
-                index_plus_ws + 1,
-            )
+            SnippetState::LineEnd(input[0..=index_minus_ws].concat(), index_plus_ws + 1)
         } else {
-            SnippetState::LineEnd(
-                input[0..=index_plus_ws].join("").to_string(),
-                index_plus_ws + 1,
-            )
+            SnippetState::LineEnd(input[0..=index_plus_ws].concat(), index_plus_ws + 1)
         }
     };
 
@@ -297,15 +291,9 @@ fn break_string(max_chars: usize, trim_end: bool, line_end: &str, input: &[&str]
             .position(|grapheme| not_whitespace_except_line_feed(grapheme))
             .unwrap_or(0);
         return if trim_end {
-            SnippetState::LineEnd(
-                input[..=url_index_end].join("").to_string(),
-                index_plus_ws + 1,
-            )
+            SnippetState::LineEnd(input[..=url_index_end].concat(), index_plus_ws + 1)
         } else {
-            return SnippetState::LineEnd(
-                input[..=index_plus_ws].join("").to_string(),
-                index_plus_ws + 1,
-            );
+            return SnippetState::LineEnd(input[..=index_plus_ws].concat(), index_plus_ws + 1);
         };
     }
     match input[0..max_chars]
@@ -330,7 +318,7 @@ fn break_string(max_chars: usize, trim_end: bool, line_end: &str, input: &[&str]
                 // A boundary was found after the line limit
                 Some(index) => break_at(max_chars + index),
                 // No boundary to the right, the input cannot be broken
-                None => SnippetState::EndOfInput(input.join("").to_string()),
+                None => SnippetState::EndOfInput(input.concat()),
             },
         },
     }

From 6c964fd0303041066381204328d4368b5c29d3f7 Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Mon, 15 Oct 2018 21:20:03 +0900
Subject: [PATCH 6/7] Reduce allocations

---
 src/comment.rs            | 6 +++---
 src/config/config_type.rs | 2 +-
 src/items.rs              | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/comment.rs b/src/comment.rs
index 0f2409be1c6..561989a1a11 100644
--- a/src/comment.rs
+++ b/src/comment.rs
@@ -764,12 +764,12 @@ fn trim_custom_comment_prefix(s: &str) -> String {
                 // due to comment wrapping, a line that was originaly behind `#` is split over
                 // multiple lines, which needs then to be prefixed with a `#`
                 if !orig.trim_left().starts_with("# ") {
-                    format!("# {}", orig)
+                    Cow::from(format!("# {}", orig))
                 } else {
-                    orig.to_string()
+                    Cow::from(orig)
                 }
             } else {
-                line.to_string()
+                Cow::from(line)
             }
         })
         .collect::<Vec<_>>()
diff --git a/src/config/config_type.rs b/src/config/config_type.rs
index edd6ae5634f..291a59e1055 100644
--- a/src/config/config_type.rs
+++ b/src/config/config_type.rs
@@ -112,7 +112,7 @@ macro_rules! create_config {
                 cloned.width_heuristics = None;
 
                 ::toml::to_string(&cloned)
-                    .map_err(|e| format!("Could not output config: {}", e.to_string()))
+                    .map_err(|e| format!("Could not output config: {}", e))
             }
         }
 
diff --git a/src/items.rs b/src/items.rs
index b35e8ea4587..19caafbfb82 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -779,7 +779,7 @@ pub fn format_impl(
             let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
 
             result.push_str(&inner_indent_str);
-            result.push_str(visitor.buffer.to_string().trim());
+            result.push_str(visitor.buffer.trim());
             result.push_str(&outer_indent_str);
         } else if need_newline || !context.config.empty_item_single_line() {
             result.push_str(&sep);
@@ -1137,7 +1137,7 @@ pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent)
             let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
 
             result.push_str(&inner_indent_str);
-            result.push_str(visitor.buffer.to_string().trim());
+            result.push_str(visitor.buffer.trim());
             result.push_str(&outer_indent_str);
         } else if result.contains('\n') {
             result.push_str(&outer_indent_str);

From e64a6d371b498ad2187ec4937c144b1bf83d0659 Mon Sep 17 00:00:00 2001
From: Shotaro Yamada <sinkuu@sinkuu.xyz>
Date: Mon, 15 Oct 2018 23:50:01 +0900
Subject: [PATCH 7/7] Cargo.lock

---
 Cargo.lock | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index be908dac466..53890b57fe1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -67,6 +67,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "bytecount"
 version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "simd 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
 
 [[package]]
 name = "byteorder"
@@ -674,6 +677,11 @@ dependencies = [
  "serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "simd"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "smallvec"
 version = "0.6.5"
@@ -918,6 +926,7 @@ dependencies = [
 "checksum serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)" = "84257ccd054dc351472528c8587b4de2dbf0dc0fe2e634030c1a90bfdacebaa9"
 "checksum serde_derive 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)" = "31569d901045afbff7a9479f793177fe9259819aff10ab4f89ef69bbc5f567fe"
 "checksum serde_json 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)" = "43344e7ce05d0d8280c5940cabb4964bea626aa58b1ec0e8c73fa2a8512a38ce"
+"checksum simd 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "0048b17eb9577ac545c61d85c3559b41dfb4cbea41c9bd9ca6a4f73ff05fda84"
 "checksum smallvec 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)" = "153ffa32fd170e9944f7e0838edf824a754ec4c1fc64746fcc9fe1f8fa602e5d"
 "checksum stable_deref_trait 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "dba1a27d3efae4351c8051072d619e3ade2820635c3958d826bfea39d59b54c8"
 "checksum syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)" = "261ae9ecaa397c42b960649561949d69311f08eeaea86a65696e6e46517cf741"