Auto merge of #90680 - calebcartwright:rustfmt-sync, r=calebcartwright

sync rustfmt subtree

src/tools/rustfmt/.github/workflows/rustdoc_check.yml

@@ -0,0 +1,25 @@
+name: rustdoc check
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  rustdoc_check:
+    runs-on: ubuntu-latest
+    name: rustdoc check
+    steps:
+    - name: checkout
+      uses: actions/checkout@v2
+
+    - name: install rustup
+      run: |
+        curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs > rustup-init.sh
+        sh rustup-init.sh -y --default-toolchain none
+        rustup target add x86_64-unknown-linux-gnu
+
+    - name: document rustfmt
+      env:
+        RUSTDOCFLAGS: --document-private-items --enable-index-page --show-type-layout --generate-link-to-definition -Zunstable-options -Dwarnings
+      run: cargo doc -Zskip-rustdoc-fingerprint --no-deps -p rustfmt-nightly -p rustfmt-config_proc_macro

src/tools/rustfmt/Configurations.md

@@ -2062,7 +2062,7 @@ use sit;
 Controls the strategy for how imports are grouped together.
 
 - **Default value**: `Preserve`
-- **Possible values**: `Preserve`, `StdExternalCrate`
+- **Possible values**: `Preserve`, `StdExternalCrate`, `One`
 - **Stable**: No
 
 #### `Preserve` (default):
@@ -2108,6 +2108,23 @@ use super::update::convert_publish_payload;
 use crate::models::Event;
 ```
 
+#### `One`:
+
+Discard existing import groups, and create a single group for everything
+
+```rust
+use super::schema::{Context, Payload};
+use super::update::convert_publish_payload;
+use crate::models::Event;
+use alloc::alloc::Layout;
+use broker::database::PooledConnection;
+use chrono::Utc;
+use core::f32;
+use juniper::{FieldError, FieldResult};
+use std::sync::Arc;
+use uuid::Uuid;
+```
+
 ## `reorder_modules`
 
 Reorder `mod` declarations alphabetically in group.

src/tools/rustfmt/Contributing.md

@@ -59,7 +59,7 @@ example, the `issue-1111.rs` test file is configured by the file
 ## Debugging
 
 Some `rewrite_*` methods use the `debug!` macro for printing useful information.
-These messages can be printed by using the environment variable `RUST_LOG=rustfmt=DEBUG`.
+These messages can be printed by using the environment variable `RUSTFMT_LOG=rustfmt=DEBUG`.
 These traces can be helpful in understanding which part of the code was used
 and get a better grasp on the execution flow.
 

src/tools/rustfmt/README.md

@@ -47,7 +47,7 @@ cargo +nightly fmt
 
 ## Limitations
 
-Rustfmt tries to work on as much Rust code as possible, sometimes, the code
+Rustfmt tries to work on as much Rust code as possible. Sometimes, the code
 doesn't even need to compile! As we approach a 1.0 release we are also looking
 to limit areas of instability; in particular, post-1.0, the formatting of most
 code should not change as Rustfmt improves. However, there are some things that
@@ -102,6 +102,25 @@ read data from stdin. Alternatively, you can use `cargo fmt` to format all
 binary and library targets of your crate.
 
 You can run `rustfmt --help` for information about available arguments.
+The easiest way to run rustfmt against a project is with `cargo fmt`. `cargo fmt` works on both
+single-crate projects and [cargo workspaces](https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html).
+Please see `cargo fmt --help` for usage information.
+
+You can specify the path to your own `rustfmt` binary for cargo to use by setting the`RUSTFMT` 
+environment variable. This was added in v1.4.22, so you must have this version or newer to leverage this feature (`cargo fmt --version`)
+
+### Running `rustfmt` directly
+
+To format individual files or arbitrary codes from stdin, the `rustfmt` binary should be used. Some
+examples follow:
+
+- `rustfmt lib.rs main.rs` will format "lib.rs" and "main.rs" in place
+- `rustfmt` will read a code from stdin and write formatting to stdout
+  - `echo "fn     main() {}" | rustfmt` would emit "fn main() {}".
+
+For more information, including arguments and emit options, see `rustfmt --help`.
+
+### Verifying code is formatted
 
 When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not
 make any formatting changes to the input, and `1` if Rustfmt would make changes.
@@ -129,7 +148,7 @@ rustfmt to exit with an error code if the input is not formatted correctly.
 It will also print any found differences. (Older versions of Rustfmt don't
 support `--check`, use `--write-mode diff`).
 
-A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
+A minimal Travis setup could look like this (requires Rust 1.31.0 or greater):
 
 ```yaml
 language: rust

src/tools/rustfmt/appveyor.yml

@@ -1,8 +0,0 @@
-environment:
-  global:
-    PROJECT_NAME: rustfmt
-
-build: false
-
-test_script:
-  - echo Why does no one have access to delete me?

src/tools/rustfmt/intellij.md

@@ -3,19 +3,28 @@
 ## Installation
 
 - Install [CLion](https://www.jetbrains.com/clion/), [IntelliJ Ultimate or CE](https://www.jetbrains.com/idea/) through the direct download link or using the [JetBrains Toolbox](https://www.jetbrains.com/toolbox/).
-  CLion provides a built-in debugger interface but its not free like IntelliJ CE - which does not provide the debugger interface. (IntelliJ seems to lack the toolchain for that, see this discussion [intellij-rust/issues/535](https://github.com/intellij-rust/intellij-rust/issues/535))
+  CLion and IntelliJ Ultimate [provide a built-in debugger interface](https://github.com/intellij-rust/intellij-rust#compatible-ides) but they are not free like IntelliJ CE.
 
-- Install the [Rust Plugin](https://intellij-rust.github.io/) by navigating to File -> Settings -> Plugins and press "Install JetBrains Plugin"
+- Install the [Rust Plugin](https://intellij-rust.github.io/) by navigating to File → Settings → Plugins and searching the plugin in the Marketplace
-  ![plugins](https://user-images.githubusercontent.com/1133787/47240861-f40af680-d3e9-11e8-9b82-cdd5c8d5f5b8.png)
+  ![plugins](https://user-images.githubusercontent.com/6505554/83944518-6f1e5c00-a81d-11ea-9c35-e16948811ba8.png)
 
-- Press "Install" on the rust plugin
+- Press "Install" on the Rust plugin
-  ![install rust](https://user-images.githubusercontent.com/1133787/47240803-c0c86780-d3e9-11e8-9265-22f735e4d7ed.png)
+  ![install rust](https://user-images.githubusercontent.com/6505554/83944533-82c9c280-a81d-11ea-86b3-ee2e31bc7d12.png)
   
 - Restart CLion/IntelliJ
 
 ## Configuration
 
-- Open the settings window (File -> Settings) and search for "reformat"
+### Run Rustfmt on save
+
+- Open Rustfmt settings (File → Settings → Languages & Frameworks → Rust → Rustfmt) and enable "Run rustfmt on Save"
+  ![run_rustfmt_on_save](https://user-images.githubusercontent.com/6505554/83944610-3468f380-a81e-11ea-9c34-0cbd18dd4969.png)
+
+- IntellJ uses autosave, so now your files will always be formatted according to rustfmt. Alternatively you can use Ctrl+S to reformat file manually
+
+### Bind shortcut to "Reformat File with Rustfmt" action
+
+- Open the settings window (File → Settings) and search for "reformat"
   ![keymap](https://user-images.githubusercontent.com/1133787/47240922-2ae10c80-d3ea-11e8-9d8f-c798d9749240.png)
 - Right-click on "Reformat File with Rustfmt" and assign a keyboard shortcut
 

src/tools/rustfmt/legacy-rustfmt.toml

@@ -1,2 +0,0 @@
-indent_style = "Visual"
-combine_control_expr = false

src/tools/rustfmt/rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2021-10-20"
+channel = "nightly-2021-11-08"
 components = ["rustc-dev"]

src/tools/rustfmt/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');

src/tools/rustfmt/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))
         );
     }
 }

src/tools/rustfmt/src/bin/main.rs

@@ -20,7 +20,7 @@ use crate::rustfmt::{
 };
 
 fn main() {
-    env_logger::init();
+    env_logger::Builder::from_env("RUSTFMT_LOG").init();
     let opts = make_opts();
 
     let exit_code = match execute(&opts) {

src/tools/rustfmt/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)?;
             }
         }
     }

src/tools/rustfmt/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)

src/tools/rustfmt/src/comment.rs

@@ -405,7 +405,7 @@ impl CodeBlockAttribute {
     /// attributes are valid rust attributes
     /// See <https://doc.rust-lang.org/rustdoc/print.html#attributes>
     fn new(attributes: &str) -> CodeBlockAttribute {
-        for attribute in attributes.split(",") {
+        for attribute in attributes.split(',') {
             match attribute.trim() {
                 "" | "rust" | "should_panic" | "no_run" | "edition2015" | "edition2018"
                 | "edition2021" => (),
@@ -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) {
+        } else if self.fmt.config.wrap_comments() && ItemizedBlock::is_itemized_line(line) {
-            let ib = ItemizedBlock::new(&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)
@@ -1384,7 +1384,7 @@ impl<'a> Iterator for LineClasses<'a> {
             None => unreachable!(),
         };
 
-        while let Some((kind, c)) = self.base.next() {
+        for (kind, c) in self.base.by_ref() {
             // needed to set the kind of the ending character on the last line
             self.kind = kind;
             if c == '\n' {
@@ -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("/*!")

src/tools/rustfmt/src/config/options.rs

@@ -20,7 +20,7 @@ pub enum NewlineStyle {
     Windows,
     /// Force CR (`\n).
     Unix,
-    /// `\r\n` in Windows, `\n`` on other platforms.
+    /// `\r\n` in Windows, `\n` on other platforms.
     Native,
 }
 
@@ -112,6 +112,8 @@ pub enum GroupImportsTactic {
     ///  2. other imports
     ///  3. `self` / `crate` / `super` imports
     StdExternalCrate,
+    /// Discard existing groups, and create a single group for everything
+    One,
 }
 
 #[config_type]

src/tools/rustfmt/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>"),
         ];

src/tools/rustfmt/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 {

src/tools/rustfmt/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())
 }
@@ -1207,11 +1207,11 @@ fn rewrite_int_lit(context: &RewriteContext<'_>, lit: &ast::Lit, shape: Shape) -
     let span = lit.span;
     let symbol = lit.token.symbol.as_str();
 
-    if symbol.starts_with("0x") {
+    if let Some(symbol_stripped) = symbol.strip_prefix("0x") {
         let hex_lit = match context.config.hex_literal_case() {
             HexLiteralCase::Preserve => None,
-            HexLiteralCase::Upper => Some(symbol[2..].to_ascii_uppercase()),
+            HexLiteralCase::Upper => Some(symbol_stripped.to_ascii_uppercase()),
-            HexLiteralCase::Lower => Some(symbol[2..].to_ascii_lowercase()),
+            HexLiteralCase::Lower => Some(symbol_stripped.to_ascii_lowercase()),
         };
         if let Some(hex_lit) = hex_lit {
             return wrap_str(
@@ -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)
     }
@@ -1962,6 +1962,9 @@ fn choose_rhs<R: Rewrite>(
     has_rhs_comment: bool,
 ) -> Option<String> {
     match orig_rhs {
+        Some(ref new_str) if new_str.is_empty() => {
+            return Some(String::new());
+        }
         Some(ref new_str)
             if !new_str.contains('\n') && unicode_str_width(new_str) <= shape.width =>
         {

src/tools/rustfmt/src/format-diff/main.rs

@@ -64,7 +64,7 @@ pub struct Opts {
 }
 
 fn main() {
-    env_logger::init();
+    env_logger::Builder::from_env("RUSTFMT_LOG").init();
     let opts = Opts::from_args();
     if let Err(e) = run(opts) {
         println!("{}", e);

src/tools/rustfmt/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,
         );
 

src/tools/rustfmt/src/git-rustfmt/main.rs

@@ -170,7 +170,7 @@ impl Config {
 }
 
 fn main() {
-    env_logger::init();
+    env_logger::Builder::from_env("RUSTFMT_LOG").init();
 
     let opts = make_opts();
     let matches = opts

src/tools/rustfmt/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() {

src/tools/rustfmt/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));
@@ -1127,12 +1127,24 @@ pub(crate) fn format_trait(
             }
         }
 
+        let block_span = mk_sp(generics.where_clause.span.hi(), item.span.hi());
+        let snippet = context.snippet(block_span);
+        let open_pos = snippet.find_uncommented("{")? + 1;
+
         match context.config.brace_style() {
             _ if last_line_contains_single_line_comment(&result)
                 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
             {
                 result.push_str(&offset.to_string_with_newline(context.config));
             }
+            _ if context.config.empty_item_single_line()
+                && items.is_empty()
+                && !result.contains('\n')
+                && !contains_comment(&snippet[open_pos..]) =>
+            {
+                result.push_str(" {}");
+                return Some(result);
+            }
             BraceStyle::AlwaysNextLine => {
                 result.push_str(&offset.to_string_with_newline(context.config));
             }
@@ -1149,9 +1161,6 @@ pub(crate) fn format_trait(
         }
         result.push('{');
 
-        let block_span = mk_sp(generics.where_clause.span.hi(), item.span.hi());
-        let snippet = context.snippet(block_span);
-        let open_pos = snippet.find_uncommented("{")? + 1;
         let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
 
         if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
@@ -1181,18 +1190,6 @@ pub(crate) fn format_trait(
     }
 }
 
-struct OpaqueTypeBounds<'a> {
-    generic_bounds: &'a ast::GenericBounds,
-}
-
-impl<'a> Rewrite for OpaqueTypeBounds<'a> {
-    fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
-        self.generic_bounds
-            .rewrite(context, shape)
-            .map(|s| format!("impl {}", s))
-    }
-}
-
 pub(crate) struct TraitAliasBounds<'a> {
     generic_bounds: &'a ast::GenericBounds,
     generics: &'a ast::Generics,
@@ -1225,7 +1222,7 @@ 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))
@@ -1243,7 +1240,7 @@ 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 = ";"
@@ -1391,7 +1388,7 @@ 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))
     }
@@ -1514,17 +1511,84 @@ fn format_tuple_struct(
     Some(result)
 }
 
-pub(crate) fn rewrite_type<R: Rewrite>(
+pub(crate) enum ItemVisitorKind<'a> {
-    context: &RewriteContext<'_>,
+    Item(&'a ast::Item),
+    AssocTraitItem(&'a ast::AssocItem),
+    AssocImplItem(&'a ast::AssocItem),
+    ForeignItem(&'a ast::ForeignItem),
+}
+
+struct TyAliasRewriteInfo<'c, 'g>(
+    &'c RewriteContext<'c>,
+    Indent,
+    &'g ast::Generics,
+    symbol::Ident,
+    Span,
+);
+
+pub(crate) fn rewrite_type_alias<'a, 'b>(
+    ty_alias_kind: &ast::TyAlias,
+    context: &RewriteContext<'a>,
     indent: Indent,
-    ident: symbol::Ident,
+    visitor_kind: &ItemVisitorKind<'b>,
-    vis: &ast::Visibility,
-    generics: &ast::Generics,
-    generic_bounds_opt: Option<&ast::GenericBounds>,
-    rhs: Option<&R>,
     span: Span,
+) -> Option<String> {
+    use ItemVisitorKind::*;
+
+    let ast::TyAlias {
+        defaultness,
+        ref generics,
+        ref bounds,
+        ref ty,
+    } = *ty_alias_kind;
+    let ty_opt = ty.as_ref().map(|t| &**t);
+    let (ident, vis) = match visitor_kind {
+        Item(i) => (i.ident, &i.vis),
+        AssocTraitItem(i) | AssocImplItem(i) => (i.ident, &i.vis),
+        ForeignItem(i) => (i.ident, &i.vis),
+    };
+    let rw_info = &TyAliasRewriteInfo(context, indent, generics, ident, span);
+
+    // Type Aliases are formatted slightly differently depending on the context
+    // in which they appear, whether they are opaque, and whether they are associated.
+    // https://rustc-dev-guide.rust-lang.org/opaque-types-type-alias-impl-trait.html
+    // https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/items.md#type-aliases
+    match (visitor_kind, ty_opt) {
+        (Item(_), None) => {
+            let op_ty = OpaqueType { bounds };
+            rewrite_ty(rw_info, Some(bounds), Some(&op_ty), vis)
+        }
+        (Item(_), Some(ty)) => rewrite_ty(rw_info, Some(bounds), Some(&*ty), vis),
+        (AssocImplItem(_), _) => {
+            let result = if let Some(ast::Ty {
+                kind: ast::TyKind::ImplTrait(_, ref bounds),
+                ..
+            }) = ty_opt
+            {
+                let op_ty = OpaqueType { bounds };
+                rewrite_ty(rw_info, None, Some(&op_ty), &DEFAULT_VISIBILITY)
+            } else {
+                rewrite_ty(rw_info, None, ty.as_ref(), vis)
+            }?;
+            match defaultness {
+                ast::Defaultness::Default(..) => Some(format!("default {}", result)),
+                _ => Some(result),
+            }
+        }
+        (AssocTraitItem(_), _) | (ForeignItem(_), _) => {
+            rewrite_ty(rw_info, Some(bounds), ty.as_ref(), vis)
+        }
+    }
+}
+
+fn rewrite_ty<R: Rewrite>(
+    rw_info: &TyAliasRewriteInfo<'_, '_>,
+    generic_bounds_opt: Option<&ast::GenericBounds>,
+    rhs: Option<&R>,
+    vis: &ast::Visibility,
 ) -> Option<String> {
     let mut result = String::with_capacity(128);
+    let TyAliasRewriteInfo(context, indent, generics, ident, span) = *rw_info;
     result.push_str(&format!("{}type ", format_visibility(context, vis)));
     let ident_str = rewrite_ident(context, ident);
 
@@ -1612,28 +1676,6 @@ pub(crate) fn rewrite_type<R: Rewrite>(
     }
 }
 
-pub(crate) fn rewrite_opaque_type(
-    context: &RewriteContext<'_>,
-    indent: Indent,
-    ident: symbol::Ident,
-    generic_bounds: &ast::GenericBounds,
-    generics: &ast::Generics,
-    vis: &ast::Visibility,
-    span: Span,
-) -> Option<String> {
-    let opaque_type_bounds = OpaqueTypeBounds { generic_bounds };
-    rewrite_type(
-        context,
-        indent,
-        ident,
-        vis,
-        generics,
-        Some(generic_bounds),
-        Some(&opaque_type_bounds),
-        span,
-    )
-}
-
 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
     (
         if config.space_before_colon() { " " } else { "" },
@@ -1871,42 +1913,6 @@ impl<'a> Rewrite for OpaqueType<'a> {
     }
 }
 
-pub(crate) fn rewrite_impl_type(
-    ident: symbol::Ident,
-    vis: &ast::Visibility,
-    defaultness: ast::Defaultness,
-    ty_opt: Option<&ptr::P<ast::Ty>>,
-    generics: &ast::Generics,
-    context: &RewriteContext<'_>,
-    indent: Indent,
-    span: Span,
-) -> Option<String> {
-    // Opaque type
-    let result = if let Some(rustc_ast::ast::Ty {
-        kind: ast::TyKind::ImplTrait(_, ref bounds),
-        ..
-    }) = ty_opt.map(|t| &**t)
-    {
-        rewrite_type(
-            context,
-            indent,
-            ident,
-            &DEFAULT_VISIBILITY,
-            generics,
-            None,
-            Some(&OpaqueType { bounds }),
-            span,
-        )
-    } else {
-        rewrite_type(context, indent, ident, vis, generics, None, ty_opt, span)
-    }?;
-
-    match defaultness {
-        ast::Defaultness::Default(..) => Some(format!("default {}", result)),
-        _ => Some(result),
-    }
-}
-
 impl Rewrite for ast::FnRetTy {
     fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
         match *self {
@@ -2071,7 +2077,7 @@ fn rewrite_explicit_self(
                     )?;
                     Some(combine_strs_with_missing_comments(
                         context,
-                        &param_attrs,
+                        param_attrs,
                         &format!("&{} {}self", lifetime_str, mut_str),
                         span,
                         shape,
@@ -2080,7 +2086,7 @@ fn rewrite_explicit_self(
                 }
                 None => Some(combine_strs_with_missing_comments(
                     context,
-                    &param_attrs,
+                    param_attrs,
                     &format!("&{}self", mut_str),
                     span,
                     shape,
@@ -2096,7 +2102,7 @@ fn rewrite_explicit_self(
 
             Some(combine_strs_with_missing_comments(
                 context,
-                &param_attrs,
+                param_attrs,
                 &format!("{}self: {}", format_mutability(mutability), type_str),
                 span,
                 shape,
@@ -2105,7 +2111,7 @@ 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,
@@ -2231,7 +2237,7 @@ 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
@@ -2989,7 +2995,7 @@ 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();
@@ -3010,7 +3016,7 @@ fn format_header(
         }
     }
 
-    result.push_str(&rewrite_ident(context, ident));
+    result.push_str(rewrite_ident(context, ident));
 
     result
 }
@@ -3177,23 +3183,9 @@ impl Rewrite for ast::ForeignItem {
                 // 1 = ;
                 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
             }
-            ast::ForeignItemKind::TyAlias(ref ty_alias_kind) => {
+            ast::ForeignItemKind::TyAlias(ref ty_alias) => {
-                let ast::TyAlias {
+                let (kind, span) = (&ItemVisitorKind::ForeignItem(&self), self.span);
-                    ref generics,
+                rewrite_type_alias(ty_alias, context, shape.indent, kind, span)
-                    ref bounds,
-                    ref ty,
-                    ..
-                } = **ty_alias_kind;
-                rewrite_type(
-                    &context,
-                    shape.indent,
-                    self.ident,
-                    &self.vis,
-                    generics,
-                    Some(bounds),
-                    ty.as_ref(),
-                    self.span,
-                )
             }
             ast::ForeignItemKind::MacCall(ref mac) => {
                 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
@@ -3243,7 +3235,7 @@ fn rewrite_attrs(
     combine_strs_with_missing_comments(
         context,
         &attrs_str,
-        &item_str,
+        item_str,
         missed_span,
         shape,
         allow_extend,

src/tools/rustfmt/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(())
     }
 }

src/tools/rustfmt/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 {

src/tools/rustfmt/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());

src/tools/rustfmt/src/matches.rs

@@ -168,7 +168,7 @@ fn collect_beginning_verts(
         .map(|a| {
             context
                 .snippet(a.pat.span)
-                .starts_with("|")
+                .starts_with('|')
                 .then(|| a.pat.span().lo())
         })
         .collect()
@@ -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(body_str);
-            result.push_str(&comma);
+            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)
     };

src/tools/rustfmt/src/modules.rs

@@ -16,7 +16,7 @@ use crate::syntux::parser::{
     Directory, DirectoryOwnership, ModError, ModulePathSuccess, Parser, ParserError,
 };
 use crate::syntux::session::ParseSess;
-use crate::utils::contains_skip;
+use crate::utils::{contains_skip, mk_sp};
 
 mod visitor;
 
@@ -135,10 +135,12 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
             self.visit_mod_from_ast(&krate.items)?;
         }
 
+        let snippet_provider = self.parse_sess.snippet_provider(krate.span);
+
         self.file_map.insert(
             root_filename,
             Module::new(
-                krate.span,
+                mk_sp(snippet_provider.start_pos(), snippet_provider.end_pos()),
                 None,
                 Cow::Borrowed(&krate.items),
                 Cow::Borrowed(&krate.attrs),
@@ -197,7 +199,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
     /// Visit modules from AST.
     fn visit_mod_from_ast(
         &mut self,
-        items: &'ast Vec<rustc_ast::ptr::P<ast::Item>>,
+        items: &'ast [rustc_ast::ptr::P<ast::Item>],
     ) -> Result<(), ModuleResolutionError> {
         for item in items {
             if is_cfg_if(item) {
@@ -290,7 +292,7 @@ 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)
             }
@@ -317,9 +319,11 @@ 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(ast::ModKind::Loaded(items, _, _))), _) | (_, Cow::Owned(items)) => {
+                self.visit_mod_outside_ast(items)
             }
-            (Some(Cow::Owned(..)), Cow::Owned(items)) => self.visit_mod_outside_ast(items),
             (_, _) => Ok(()),
         }
     }

src/tools/rustfmt/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.

src/tools/rustfmt/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)?,

src/tools/rustfmt/src/patterns.rs

@@ -456,11 +456,11 @@ fn rewrite_tuple_pat(
     context: &RewriteContext<'_>,
     shape: Shape,
 ) -> Option<String> {
-    let mut pat_vec: Vec<_> = pats.iter().map(|x| TuplePatField::Pat(x)).collect();
+    if pats.is_empty() {
-
-    if pat_vec.is_empty() {
         return Some(format!("{}()", path_str.unwrap_or_default()));
     }
+    let mut pat_vec: Vec<_> = pats.iter().map(TuplePatField::Pat).collect();
+
     let wildcard_suffix_len = count_wildcard_suffix_len(context, &pat_vec, span, shape);
     let (pat_vec, span) = if context.config.condense_wildcard_suffixes() && wildcard_suffix_len >= 2
     {
@@ -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,

src/tools/rustfmt/src/reorder.rs

@@ -118,7 +118,9 @@ fn rewrite_reorderable_or_regroupable_items(
             };
 
             let mut regrouped_items = match context.config.group_imports() {
-                GroupImportsTactic::Preserve => vec![normalized_items],
+                GroupImportsTactic::Preserve | GroupImportsTactic::One => {
+                    vec![normalized_items]
+                }
                 GroupImportsTactic::StdExternalCrate => group_imports(normalized_items),
             };
 

src/tools/rustfmt/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) => {
@@ -125,18 +125,12 @@ impl<'a> Parser<'a> {
             }
         }));
         match result {
-            Ok(Some(m)) => {
+            Ok(Some(m)) if !sess.has_errors() => Ok(m),
-                if !sess.has_errors() {
+            Ok(Some(m)) if sess.can_reset_errors() => {
-                    return Ok(m);
-                }
-
-                if sess.can_reset_errors() {
                 sess.reset_errors();
-                    return Ok(m);
+                Ok(m)
             }
-                Err(ParserError::ParseError)
+            Ok(_) => Err(ParserError::ParseError),
-            }
-            Ok(None) => Err(ParserError::ParseError),
             Err(..) if path.exists() => Err(ParserError::ParseError),
             Err(_) => Err(ParserError::ParsePanicError),
         }

src/tools/rustfmt/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) {

src/tools/rustfmt/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),

src/tools/rustfmt/src/test/mod_resolver.rs

@@ -5,21 +5,39 @@ use super::read_config;
 
 use crate::{FileName, Input, Session};
 
-#[test]
+fn verify_mod_resolution(input_file_name: &str, exp_misformatted_files: &[&str]) {
-fn nested_out_of_line_mods_loaded() {
+    let input_file = PathBuf::from(input_file_name);
-    // See also https://github.com/rust-lang/rustfmt/issues/4874
-    let filename = "tests/mod-resolver/issue-4874/main.rs";
-    let input_file = PathBuf::from(filename);
     let config = read_config(&input_file);
     let mut session = Session::<io::Stdout>::new(config, None);
     let report = session
-        .format(Input::File(filename.into()))
+        .format(Input::File(input_file_name.into()))
         .expect("Should not have had any execution errors");
     let errors_by_file = &report.internal.borrow().0;
-    assert!(errors_by_file.contains_key(&FileName::Real(PathBuf::from(
+    for exp_file in exp_misformatted_files {
-        "tests/mod-resolver/issue-4874/bar/baz.rs",
+        assert!(errors_by_file.contains_key(&FileName::Real(PathBuf::from(exp_file))));
-    ))));
+    }
-    assert!(errors_by_file.contains_key(&FileName::Real(PathBuf::from(
+}
-        "tests/mod-resolver/issue-4874/foo/qux.rs",
+
-    ))));
+#[test]
+fn nested_out_of_line_mods_loaded() {
+    // See also https://github.com/rust-lang/rustfmt/issues/4874
+    verify_mod_resolution(
+        "tests/mod-resolver/issue-4874/main.rs",
+        &[
+            "tests/mod-resolver/issue-4874/bar/baz.rs",
+            "tests/mod-resolver/issue-4874/foo/qux.rs",
+        ],
+    );
+}
+
+#[test]
+fn out_of_line_nested_inline_within_out_of_line() {
+    // See also https://github.com/rust-lang/rustfmt/issues/5063
+    verify_mod_resolution(
+        "tests/mod-resolver/issue-5063/main.rs",
+        &[
+            "tests/mod-resolver/issue-5063/foo/bar/baz.rs",
+            "tests/mod-resolver/issue-5063/foo.rs",
+        ],
+    );
 }

src/tools/rustfmt/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);
                 }
 

src/tools/rustfmt/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())
         );
     }

src/tools/rustfmt/src/visitor.rs

@@ -12,8 +12,7 @@ use crate::config::{BraceStyle, Config};
 use crate::coverage::transform_missing_snippet;
 use crate::items::{
     format_impl, format_trait, format_trait_alias, is_mod_decl, is_use_item, rewrite_extern_crate,
-    rewrite_impl_type, rewrite_opaque_type, rewrite_type, FnBraceStyle, FnSig, StaticParts,
+    rewrite_type_alias, FnBraceStyle, FnSig, ItemVisitorKind, StaticParts, StructParts,
-    StructParts,
 };
 use crate::macros::{macro_style, rewrite_macro, rewrite_macro_def, MacroPosition};
 use crate::modules::Module;
@@ -164,7 +163,7 @@ 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 +272,9 @@ 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 +438,7 @@ 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 +487,12 @@ 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) => {
@@ -568,40 +567,9 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                         self.push_rewrite(item.span, rewrite);
                     }
                 }
-                ast::ItemKind::TyAlias(ref alias_kind) => {
+                ast::ItemKind::TyAlias(ref ty_alias) => {
-                    let ast::TyAlias {
+                    use ItemVisitorKind::Item;
-                        ref generics,
+                    self.visit_ty_alias_kind(ty_alias, &Item(&item), item.span);
-                        ref bounds,
-                        ref ty,
-                        ..
-                    } = **alias_kind;
-                    match ty {
-                        Some(ty) => {
-                            let rewrite = rewrite_type(
-                                &self.get_context(),
-                                self.block_indent,
-                                item.ident,
-                                &item.vis,
-                                generics,
-                                Some(bounds),
-                                Some(&*ty),
-                                item.span,
-                            );
-                            self.push_rewrite(item.span, rewrite);
-                        }
-                        None => {
-                            let rewrite = rewrite_opaque_type(
-                                &self.get_context(),
-                                self.block_indent,
-                                item.ident,
-                                bounds,
-                                generics,
-                                &item.vis,
-                                item.span,
-                            );
-                            self.push_rewrite(item.span, rewrite);
-                        }
-                    }
                 }
                 ast::ItemKind::GlobalAsm(..) => {
                     let snippet = Some(self.snippet(item.span).to_owned());
@@ -624,18 +592,46 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
         self.skip_context = skip_context_saved;
     }
 
-    pub(crate) fn visit_trait_item(&mut self, ti: &ast::AssocItem) {
+    fn visit_ty_alias_kind(
-        skip_out_of_file_lines_range_visitor!(self, ti.span);
+        &mut self,
+        ty_kind: &ast::TyAlias,
+        visitor_kind: &ItemVisitorKind<'_>,
+        span: Span,
+    ) {
+        let rewrite = rewrite_type_alias(
+            ty_kind,
+            &self.get_context(),
+            self.block_indent,
+            visitor_kind,
+            span,
+        );
+        self.push_rewrite(span, rewrite);
+    }
 
-        if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
+    fn visit_assoc_item(&mut self, visitor_kind: &ItemVisitorKind<'_>) {
-            self.push_skipped_with_span(ti.attrs.as_slice(), ti.span(), ti.span());
+        use ItemVisitorKind::*;
+        // TODO(calebcartwright): Not sure the skip spans are correct
+        let (ai, skip_span, assoc_ctxt) = match visitor_kind {
+            AssocTraitItem(ai) => (*ai, ai.span(), visit::AssocCtxt::Trait),
+            AssocImplItem(ai) => (*ai, ai.span, visit::AssocCtxt::Impl),
+            _ => unreachable!(),
+        };
+        skip_out_of_file_lines_range_visitor!(self, ai.span);
+
+        if self.visit_attrs(&ai.attrs, ast::AttrStyle::Outer) {
+            self.push_skipped_with_span(&ai.attrs.as_slice(), skip_span, skip_span);
             return;
         }
 
         // TODO(calebcartwright): consider enabling box_patterns feature gate
-        match ti.kind {
+        match (&ai.kind, visitor_kind) {
-            ast::AssocItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
+            (ast::AssocItemKind::Const(..), AssocTraitItem(_)) => {
-            ast::AssocItemKind::Fn(ref fn_kind) => {
+                self.visit_static(&StaticParts::from_trait_item(&ai))
+            }
+            (ast::AssocItemKind::Const(..), AssocImplItem(_)) => {
+                self.visit_static(&StaticParts::from_impl_item(&ai))
+            }
+            (ast::AssocItemKind::Fn(ref fn_kind), _) => {
                 let ast::Fn {
                     defaultness,
                     ref sig,
@@ -643,108 +639,39 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                     ref body,
                 } = **fn_kind;
                 if let Some(ref body) = body {
-                    let inner_attrs = inner_attributes(&ti.attrs);
+                    let inner_attrs = inner_attributes(&ai.attrs);
-                    let fn_ctxt = visit::FnCtxt::Assoc(visit::AssocCtxt::Trait);
+                    let fn_ctxt = visit::FnCtxt::Assoc(assoc_ctxt);
                     self.visit_fn(
-                        visit::FnKind::Fn(fn_ctxt, ti.ident, sig, &ti.vis, Some(body)),
+                        visit::FnKind::Fn(fn_ctxt, ai.ident, sig, &ai.vis, Some(body)),
                         generics,
                         &sig.decl,
-                        ti.span,
+                        ai.span,
                         defaultness,
                         Some(&inner_attrs),
                     );
                 } else {
                     let indent = self.block_indent;
                     let rewrite =
-                        self.rewrite_required_fn(indent, ti.ident, sig, &ti.vis, generics, ti.span);
+                        self.rewrite_required_fn(indent, ai.ident, sig, &ai.vis, generics, ai.span);
-                    self.push_rewrite(ti.span, rewrite);
+                    self.push_rewrite(ai.span, rewrite);
                 }
             }
-            ast::AssocItemKind::TyAlias(ref ty_alias_kind) => {
+            (ast::AssocItemKind::TyAlias(ref ty_alias), _) => {
-                let ast::TyAlias {
+                self.visit_ty_alias_kind(ty_alias, visitor_kind, ai.span);
-                    ref generics,
-                    ref bounds,
-                    ref ty,
-                    ..
-                } = **ty_alias_kind;
-                let rewrite = rewrite_type(
-                    &self.get_context(),
-                    self.block_indent,
-                    ti.ident,
-                    &ti.vis,
-                    generics,
-                    Some(bounds),
-                    ty.as_ref(),
-                    ti.span,
-                );
-                self.push_rewrite(ti.span, rewrite);
             }
-            ast::AssocItemKind::MacCall(ref mac) => {
+            (ast::AssocItemKind::MacCall(ref mac), _) => {
-                self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
+                self.visit_mac(mac, Some(ai.ident), MacroPosition::Item);
+            }
+            _ => unreachable!(),
         }
     }
+
+    pub(crate) fn visit_trait_item(&mut self, ti: &ast::AssocItem) {
+        self.visit_assoc_item(&ItemVisitorKind::AssocTraitItem(ti));
     }
 
     pub(crate) fn visit_impl_item(&mut self, ii: &ast::AssocItem) {
-        skip_out_of_file_lines_range_visitor!(self, ii.span);
+        self.visit_assoc_item(&ItemVisitorKind::AssocImplItem(ii));
-
-        if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
-            self.push_skipped_with_span(ii.attrs.as_slice(), ii.span, ii.span);
-            return;
-        }
-
-        match ii.kind {
-            ast::AssocItemKind::Fn(ref fn_kind) => {
-                let ast::Fn {
-                    defaultness,
-                    ref sig,
-                    ref generics,
-                    ref body,
-                } = **fn_kind;
-                if let Some(ref body) = body {
-                    let inner_attrs = inner_attributes(&ii.attrs);
-                    let fn_ctxt = visit::FnCtxt::Assoc(visit::AssocCtxt::Impl);
-                    self.visit_fn(
-                        visit::FnKind::Fn(fn_ctxt, ii.ident, sig, &ii.vis, Some(body)),
-                        generics,
-                        &sig.decl,
-                        ii.span,
-                        defaultness,
-                        Some(&inner_attrs),
-                    );
-                } else {
-                    let indent = self.block_indent;
-                    let rewrite =
-                        self.rewrite_required_fn(indent, ii.ident, sig, &ii.vis, generics, ii.span);
-                    self.push_rewrite(ii.span, rewrite);
-                }
-            }
-            ast::AssocItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
-            ast::AssocItemKind::TyAlias(ref ty_alias_kind) => {
-                let ast::TyAlias {
-                    defaultness,
-                    ref generics,
-                    ref ty,
-                    ..
-                } = **ty_alias_kind;
-                self.push_rewrite(
-                    ii.span,
-                    rewrite_impl_type(
-                        ii.ident,
-                        &ii.vis,
-                        defaultness,
-                        ty.as_ref(),
-                        &generics,
-                        &self.get_context(),
-                        self.block_indent,
-                        ii.span,
-                    ),
-                );
-            }
-            ast::AssocItemKind::MacCall(ref mac) => {
-                self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
-            }
-        }
     }
 
     fn visit_mac(&mut self, mac: &ast::MacCall, ident: Option<symbol::Ident>, pos: MacroPosition) {
@@ -921,7 +848,7 @@ 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) {

src/tools/rustfmt/tests/mod-resolver/issue-5063/foo.rs

@@ -0,0 +1,2 @@
+mod bar {
+        mod baz;}

src/tools/rustfmt/tests/mod-resolver/issue-5063/foo/bar/baz.rs

@@ -0,0 +1 @@
+fn    baz()    {       }

src/tools/rustfmt/tests/mod-resolver/issue-5063/main.rs

@@ -0,0 +1,5 @@
+fn main() {
+    println!("Hello, world!");
+}
+
+mod foo;

src/tools/rustfmt/tests/source/configs/group_imports/One-merge_imports.rs

@@ -0,0 +1,17 @@
+// rustfmt-group_imports: One
+// rustfmt-imports_granularity: Crate
+use chrono::Utc;
+use super::update::convert_publish_payload;
+
+use juniper::{FieldError, FieldResult};
+use uuid::Uuid;
+use alloc::alloc::Layout;
+
+use std::sync::Arc;
+use alloc::vec::Vec;
+
+use broker::database::PooledConnection;
+
+use super::schema::{Context, Payload};
+use core::f32;
+use crate::models::Event;

src/tools/rustfmt/tests/source/configs/group_imports/One-nested.rs

@@ -0,0 +1,7 @@
+// rustfmt-group_imports: One
+mod test {
+    use crate::foo::bar;
+
+    use std::path;
+    use crate::foo::bar2;
+}

src/tools/rustfmt/tests/source/configs/group_imports/One-no_reorder.rs

@@ -0,0 +1,16 @@
+// rustfmt-group_imports: One
+// rustfmt-reorder_imports: false
+use chrono::Utc;
+use super::update::convert_publish_payload;
+
+use juniper::{FieldError, FieldResult};
+use uuid::Uuid;
+use alloc::alloc::Layout;
+
+use std::sync::Arc;
+
+use broker::database::PooledConnection;
+
+use super::schema::{Context, Payload};
+use core::f32;
+use crate::models::Event;

src/tools/rustfmt/tests/source/configs/group_imports/One.rs

@@ -0,0 +1,15 @@
+// rustfmt-group_imports: One
+use chrono::Utc;
+use super::update::convert_publish_payload;
+
+use juniper::{FieldError, FieldResult};
+use uuid::Uuid;
+use alloc::alloc::Layout;
+
+use std::sync::Arc;
+
+use broker::database::PooledConnection;
+
+use super::schema::{Context, Payload};
+use core::f32;
+use crate::models::Event;

src/tools/rustfmt/tests/source/empty-item-single-line-false.rs

@@ -0,0 +1,46 @@
+// rustfmt-brace_style: AlwaysNextLine
+// rustfmt-empty_item_single_line: false
+
+fn function()
+{
+
+}
+
+struct Struct
+{
+
+}
+
+enum Enum
+{
+
+}
+
+trait Trait
+{
+
+}
+
+impl<T> Trait for T
+{
+
+}
+
+trait Trait2<T>
+where
+    T: Copy + Display + Write + Read + FromStr, {}
+
+trait Trait3<T>
+where
+    T: Something
+        + SomethingElse
+        + Sync
+        + Send
+        + Display
+        + Debug
+        + Copy
+        + Hash
+        + Debug
+        + Display
+        + Write
+        + Read, {}

src/tools/rustfmt/tests/source/item-brace-style-always-next-line.rs

@@ -27,3 +27,38 @@ mod M {
 
     struct D<T> where T: Copy {}
 }
+
+
+fn function()
+{
+
+}
+
+trait Trait
+{
+
+}
+
+impl<T> Trait for T
+{
+
+}
+
+trait Trait2<T>
+where
+    T: Copy + Display + Write + Read + FromStr, {}
+
+trait Trait3<T>
+where
+    T: Something
+        + SomethingElse
+        + Sync
+        + Send
+        + Display
+        + Debug
+        + Copy
+        + Hash
+        + Debug
+        + Display
+        + Write
+        + Read, {}

src/tools/rustfmt/tests/target/configs/group_imports/One-merge_imports.rs

@@ -0,0 +1,14 @@
+// rustfmt-group_imports: One
+// rustfmt-imports_granularity: Crate
+use super::{
+    schema::{Context, Payload},
+    update::convert_publish_payload,
+};
+use crate::models::Event;
+use alloc::{alloc::Layout, vec::Vec};
+use broker::database::PooledConnection;
+use chrono::Utc;
+use core::f32;
+use juniper::{FieldError, FieldResult};
+use std::sync::Arc;
+use uuid::Uuid;

src/tools/rustfmt/tests/target/configs/group_imports/One-nested.rs

@@ -0,0 +1,6 @@
+// rustfmt-group_imports: One
+mod test {
+    use crate::foo::bar;
+    use crate::foo::bar2;
+    use std::path;
+}

src/tools/rustfmt/tests/target/configs/group_imports/One-no_reorder.rs

@@ -0,0 +1,12 @@
+// rustfmt-group_imports: One
+// rustfmt-reorder_imports: false
+use chrono::Utc;
+use super::update::convert_publish_payload;
+use juniper::{FieldError, FieldResult};
+use uuid::Uuid;
+use alloc::alloc::Layout;
+use std::sync::Arc;
+use broker::database::PooledConnection;
+use super::schema::{Context, Payload};
+use core::f32;
+use crate::models::Event;

src/tools/rustfmt/tests/target/configs/group_imports/One.rs

@@ -0,0 +1,11 @@
+// rustfmt-group_imports: One
+use super::schema::{Context, Payload};
+use super::update::convert_publish_payload;
+use crate::models::Event;
+use alloc::alloc::Layout;
+use broker::database::PooledConnection;
+use chrono::Utc;
+use core::f32;
+use juniper::{FieldError, FieldResult};
+use std::sync::Arc;
+use uuid::Uuid;

src/tools/rustfmt/tests/target/empty-item-single-line-false.rs

@@ -0,0 +1,41 @@
+// rustfmt-brace_style: AlwaysNextLine
+// rustfmt-empty_item_single_line: false
+
+fn function()
+{
+}
+
+struct Struct {}
+
+enum Enum {}
+
+trait Trait
+{
+}
+
+impl<T> Trait for T
+{
+}
+
+trait Trait2<T>
+where
+    T: Copy + Display + Write + Read + FromStr,
+{
+}
+
+trait Trait3<T>
+where
+    T: Something
+        + SomethingElse
+        + Sync
+        + Send
+        + Display
+        + Debug
+        + Copy
+        + Hash
+        + Debug
+        + Display
+        + Write
+        + Read,
+{
+}

src/tools/rustfmt/tests/target/issue-5012/trailing_comma_always.rs

@@ -0,0 +1,8 @@
+// rustfmt-trailing_comma: Always
+
+pub struct Matrix<T, const R: usize, const C: usize,>
+where
+    [T; R * C]:,
+{
+    contents: [T; R * C],
+}

src/tools/rustfmt/tests/target/issue-5012/trailing_comma_never.rs

@@ -0,0 +1,8 @@
+// rustfmt-trailing_comma: Never
+
+pub struct Matrix<T, const R: usize, const C: usize>
+where
+    [T; R * C]:
+{
+    contents: [T; R * C]
+}

src/tools/rustfmt/tests/target/issue-5033/minimum_example.rs

@@ -0,0 +1,8 @@
+// leading comment
+
+#![rustfmt::skip]
+fn main() {
+    println!("main"); // commented
+}
+
+// post comment

src/tools/rustfmt/tests/target/issue-5033/nested_modules.rs

@@ -0,0 +1,11 @@
+#![rustfmt::skip]
+
+mod a {
+    mod b {
+
+    }
+
+    // trailing comment b
+}
+
+// trailing comment a

src/tools/rustfmt/tests/target/issue_4850.rs

@@ -0,0 +1,4 @@
+impl ThisIsALongStructNameToPushTheWhereToWrapLolololol where
+    [(); this_is_a_long_const_function_name()]:
+{
+}

src/tools/rustfmt/tests/target/item-brace-style-always-next-line.rs

@@ -40,3 +40,32 @@ mod M
     where
         T: Copy, {}
 }
+
+fn function() {}
+
+trait Trait {}
+
+impl<T> Trait for T {}
+
+trait Trait2<T>
+where
+    T: Copy + Display + Write + Read + FromStr,
+{
+}
+
+trait Trait3<T>
+where
+    T: Something
+        + SomethingElse
+        + Sync
+        + Send
+        + Display
+        + Debug
+        + Copy
+        + Hash
+        + Debug
+        + Display
+        + Write
+        + Read,
+{
+}