diff --git a/Cargo.lock b/Cargo.lock
index 8fcefa97489..ee396cce26a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -343,9 +343,9 @@ dependencies = [
 
 [[package]]
 name = "itertools"
-version = "0.10.3"
+version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9a9d19fa1e79b6215ff29b9d6880b706147f16e9b1dbb1e4e5947b5b02bc5e3"
+checksum = "b1c173a5686ce8bfa551b3563d0c2170bf24ca44da99c7ca4bfdab5418c3fe57"
 dependencies = [
  "either",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 00e0ed37a84..032b9b54810 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -43,7 +43,7 @@ diff = "0.1"
 dirs = "4.0"
 getopts = "0.2"
 ignore = "0.4"
-itertools = "0.10"
+itertools = "0.11"
 lazy_static = "1.4"
 regex = "1.7"
 serde = { version = "1.0.160", features = ["derive"] }
diff --git a/Configurations.md b/Configurations.md
index c4680a3023f..51a06ffc09f 100644
--- a/Configurations.md
+++ b/Configurations.md
@@ -1111,7 +1111,7 @@ See also [`format_macro_bodies`](#format_macro_bodies).
 
 ## `format_macro_bodies`
 
-Format the bodies of macros.
+Format the bodies of declarative macro definitions.
 
 - **Default value**: `true`
 - **Possible values**: `true`, `false`
@@ -1261,12 +1261,20 @@ Control the case of the letters in hexadecimal literal values
 
 ## `hide_parse_errors`
 
-Do not show parse errors if the parser failed to parse files.
+This option is deprecated and has been renamed to `show_parse_errors` to avoid confusion around the double negative default of `hide_parse_errors=false`.
 
 - **Default value**: `false`
 - **Possible values**: `true`, `false`
 - **Stable**: No (tracking issue: [#3390](https://github.com/rust-lang/rustfmt/issues/3390))
 
+## `show_parse_errors`
+
+Show parse errors if the parser failed to parse files.
+
+- **Default value**: `true`
+- **Possible values**: `true`, `false`
+- **Stable**: No (tracking issue: [#5977](https://github.com/rust-lang/rustfmt/issues/5977))
+
 ## `ignore`
 
 Skip formatting files and directories that match the specified pattern.
diff --git a/rust-toolchain b/rust-toolchain
index 0057e2f370a..aa35a7f12d5 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2023-10-22"
+channel = "nightly-2023-12-28"
 components = ["llvm-tools", "rustc-dev"]
diff --git a/src/closures.rs b/src/closures.rs
index a09146e9592..5bf29441b54 100644
--- a/src/closures.rs
+++ b/src/closures.rs
@@ -29,7 +29,7 @@ pub(crate) fn rewrite_closure(
     binder: &ast::ClosureBinder,
     constness: ast::Const,
     capture: ast::CaptureBy,
-    is_async: &ast::Async,
+    coroutine_kind: &Option<ast::CoroutineKind>,
     movability: ast::Movability,
     fn_decl: &ast::FnDecl,
     body: &ast::Expr,
@@ -40,7 +40,16 @@ pub(crate) fn rewrite_closure(
     debug!("rewrite_closure {:?}", body);
 
     let (prefix, extra_offset) = rewrite_closure_fn_decl(
-        binder, constness, capture, is_async, movability, fn_decl, body, span, context, shape,
+        binder,
+        constness,
+        capture,
+        coroutine_kind,
+        movability,
+        fn_decl,
+        body,
+        span,
+        context,
+        shape,
     )?;
     // 1 = space between `|...|` and body.
     let body_shape = shape.offset_left(extra_offset)?;
@@ -188,7 +197,7 @@ fn rewrite_closure_expr(
     fn allow_multi_line(expr: &ast::Expr) -> bool {
         match expr.kind {
             ast::ExprKind::Match(..)
-            | ast::ExprKind::Async(..)
+            | ast::ExprKind::Gen(..)
             | ast::ExprKind::Block(..)
             | ast::ExprKind::TryBlock(..)
             | ast::ExprKind::Loop(..)
@@ -233,7 +242,7 @@ fn rewrite_closure_fn_decl(
     binder: &ast::ClosureBinder,
     constness: ast::Const,
     capture: ast::CaptureBy,
-    asyncness: &ast::Async,
+    coroutine_kind: &Option<ast::CoroutineKind>,
     movability: ast::Movability,
     fn_decl: &ast::FnDecl,
     body: &ast::Expr,
@@ -263,8 +272,13 @@ fn rewrite_closure_fn_decl(
     } else {
         ""
     };
-    let is_async = if asyncness.is_async() { "async " } else { "" };
-    let mover = if capture == ast::CaptureBy::Value {
+    let coro = match coroutine_kind {
+        Some(ast::CoroutineKind::Async { .. }) => "async ",
+        Some(ast::CoroutineKind::Gen { .. }) => "gen ",
+        Some(ast::CoroutineKind::AsyncGen { .. }) => "async gen ",
+        None => "",
+    };
+    let mover = if matches!(capture, ast::CaptureBy::Value { .. }) {
         "move "
     } else {
         ""
@@ -272,7 +286,7 @@ fn rewrite_closure_fn_decl(
     // 4 = "|| {".len(), which is overconservative when the closure consists of
     // a single expression.
     let nested_shape = shape
-        .shrink_left(binder.len() + const_.len() + immovable.len() + is_async.len() + mover.len())?
+        .shrink_left(binder.len() + const_.len() + immovable.len() + coro.len() + mover.len())?
         .sub_width(4)?;
 
     // 1 = |
@@ -310,7 +324,7 @@ fn rewrite_closure_fn_decl(
         .tactic(tactic)
         .preserve_newline(true);
     let list_str = write_list(&item_vec, &fmt)?;
-    let mut prefix = format!("{binder}{const_}{immovable}{is_async}{mover}|{list_str}|");
+    let mut prefix = format!("{binder}{const_}{immovable}{coro}{mover}|{list_str}|");
 
     if !ret_str.is_empty() {
         if prefix.contains('\n') {
@@ -339,7 +353,7 @@ pub(crate) fn rewrite_last_closure(
             ref binder,
             constness,
             capture_clause,
-            ref asyncness,
+            ref coroutine_kind,
             movability,
             ref fn_decl,
             ref body,
@@ -360,7 +374,7 @@ pub(crate) fn rewrite_last_closure(
             binder,
             constness,
             capture_clause,
-            asyncness,
+            coroutine_kind,
             movability,
             fn_decl,
             body,
@@ -434,7 +448,7 @@ fn is_block_closure_forced(context: &RewriteContext<'_>, expr: &ast::Expr) -> bo
 
 fn is_block_closure_forced_inner(expr: &ast::Expr, version: Version) -> bool {
     match expr.kind {
-        ast::ExprKind::If(..) | ast::ExprKind::While(..) | ast::ExprKind::ForLoop(..) => true,
+        ast::ExprKind::If(..) | ast::ExprKind::While(..) | ast::ExprKind::ForLoop { .. } => true,
         ast::ExprKind::Loop(..) if version == Version::Two => true,
         ast::ExprKind::AddrOf(_, _, ref expr)
         | ast::ExprKind::Try(ref expr)
@@ -459,7 +473,7 @@ fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool {
         | ast::ExprKind::Block(..)
         | ast::ExprKind::While(..)
         | ast::ExprKind::Loop(..)
-        | ast::ExprKind::ForLoop(..)
+        | ast::ExprKind::ForLoop { .. }
         | ast::ExprKind::TryBlock(..) => false,
         _ => true,
     }
diff --git a/src/comment.rs b/src/comment.rs
index 7da0f79bd09..44b3eb80aef 100644
--- a/src/comment.rs
+++ b/src/comment.rs
@@ -1,6 +1,6 @@
 // Formatting and tools for comments.
 
-use std::{self, borrow::Cow, iter};
+use std::{borrow::Cow, iter};
 
 use itertools::{multipeek, MultiPeek};
 use lazy_static::lazy_static;
@@ -173,10 +173,7 @@ pub(crate) fn combine_strs_with_missing_comments(
 ) -> Option<String> {
     trace!(
         "combine_strs_with_missing_comments `{}` `{}` {:?} {:?}",
-        prev_str,
-        next_str,
-        span,
-        shape
+        prev_str, next_str, span, shape
     );
 
     let mut result =
@@ -1847,7 +1844,6 @@ fn remove_comment_header(comment: &str) -> &str {
 #[cfg(test)]
 mod test {
     use super::*;
-    use crate::shape::{Indent, Shape};
 
     #[test]
     fn char_classes() {
diff --git a/src/config/config_type.rs b/src/config/config_type.rs
index feb452d7235..7551241fc00 100644
--- a/src/config/config_type.rs
+++ b/src/config/config_type.rs
@@ -129,6 +129,7 @@ macro_rules! create_config {
                     | "chain_width" => self.0.set_heuristics(),
                     "merge_imports" => self.0.set_merge_imports(),
                     "fn_args_layout" => self.0.set_fn_args_layout(),
+                    "hide_parse_errors" => self.0.set_hide_parse_errors(),
                     &_ => (),
                 }
             }
@@ -184,6 +185,7 @@ macro_rules! create_config {
                 self.set_ignore(dir);
                 self.set_merge_imports();
                 self.set_fn_args_layout();
+                self.set_hide_parse_errors();
                 self
             }
 
@@ -278,19 +280,21 @@ macro_rules! create_config {
                     | "chain_width" => self.set_heuristics(),
                     "merge_imports" => self.set_merge_imports(),
                     "fn_args_layout" => self.set_fn_args_layout(),
+                    "hide_parse_errors" => self.set_hide_parse_errors(),
                     &_ => (),
                 }
             }
 
             #[allow(unreachable_pub)]
             pub fn is_hidden_option(name: &str) -> bool {
-                const HIDE_OPTIONS: [&str; 6] = [
+                const HIDE_OPTIONS: [&str; 7] = [
                     "verbose",
                     "verbose_diff",
                     "file_lines",
                     "width_heuristics",
                     "merge_imports",
-                    "fn_args_layout"
+                    "fn_args_layout",
+                    "hide_parse_errors"
                 ];
                 HIDE_OPTIONS.contains(&name)
             }
@@ -461,6 +465,18 @@ macro_rules! create_config {
                 }
             }
 
+            fn set_hide_parse_errors(&mut self) {
+                if self.was_set().hide_parse_errors() {
+                    eprintln!(
+                        "Warning: the `hide_parse_errors` option is deprecated. \
+                        Use `show_parse_errors` instead"
+                    );
+                    if !self.was_set().show_parse_errors() {
+                        self.show_parse_errors.2 = self.hide_parse_errors();
+                    }
+                }
+            }
+
             #[allow(unreachable_pub)]
             /// Returns `true` if the config key was explicitly set and is the default value.
             pub fn is_default(&self, key: &str) -> bool {
diff --git a/src/config/file_lines.rs b/src/config/file_lines.rs
index e33fe9bb283..224864393d3 100644
--- a/src/config/file_lines.rs
+++ b/src/config/file_lines.rs
@@ -6,7 +6,7 @@ use std::path::PathBuf;
 use std::{cmp, fmt, iter, str};
 
 use rustc_data_structures::sync::Lrc;
-use rustc_span::{self, SourceFile};
+use rustc_span::SourceFile;
 use serde::{ser, Deserialize, Deserializer, Serialize, Serializer};
 use serde_json as json;
 use thiserror::Error;
diff --git a/src/config/mod.rs b/src/config/mod.rs
index 23f09e4d028..1139289880c 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -1,5 +1,4 @@
 use std::cell::Cell;
-use std::default::Default;
 use std::fs::File;
 use std::io::{Error, ErrorKind, Read};
 use std::path::{Path, PathBuf};
@@ -27,6 +26,7 @@ pub(crate) mod file_lines;
 #[allow(unreachable_pub)]
 pub(crate) mod lists;
 pub(crate) mod macro_names;
+pub(crate) mod style_edition;
 
 // This macro defines configuration options used in rustfmt. Each option
 // is defined as follows:
@@ -74,7 +74,7 @@ create_config! {
     format_strings: bool, false, false, "Format string literals where necessary";
     format_macro_matchers: bool, false, false,
         "Format the metavariable matching patterns in macros";
-    format_macro_bodies: bool, true, false, "Format the bodies of macros";
+    format_macro_bodies: bool, true, false, "Format the bodies of declarative macro definitions";
     skip_macro_invocations: MacroSelectors, MacroSelectors::default(), false,
         "Skip formatting the bodies of macros invoked with the following names.";
     hex_literal_case: HexLiteralCase, HexLiteralCase::Preserve, false,
@@ -172,7 +172,8 @@ create_config! {
             "Enables unstable features. Only available on nightly channel";
     disable_all_formatting: bool, false, true, "Don't reformat anything";
     skip_children: bool, false, false, "Don't reformat out of line modules";
-    hide_parse_errors: bool, false, false, "Hide errors from the parser";
+    hide_parse_errors: bool, false, false, "(deprecated: use show_parse_errors instead)";
+    show_parse_errors: bool, true, false, "Show errors from the parser (unstable)";
     error_on_line_overflow: bool, false, false, "Error if unable to get all lines within max_width";
     error_on_unformatted: bool, false, false,
         "Error if unable to get comments or string literals within max_width, \
@@ -207,6 +208,7 @@ impl PartialConfig {
         cloned.print_misformatted_file_names = None;
         cloned.merge_imports = None;
         cloned.fn_args_layout = None;
+        cloned.hide_parse_errors = None;
 
         ::toml::to_string(&cloned).map_err(ToTomlError)
     }
@@ -459,6 +461,13 @@ mod test {
             fn_params_layout: Density, Density::Tall, true,
                 "Control the layout of parameters in a function signatures.";
 
+            // hide_parse_errors renamed to show_parse_errors
+            hide_parse_errors: bool, false, false,
+                "(deprecated: use show_parse_errors instead)";
+            show_parse_errors: bool, true, false,
+                "Show errors from the parser (unstable)";
+
+
             // Width Heuristics
             use_small_heuristics: Heuristics, Heuristics::Default, true,
                 "Whether to use different formatting for items and \
@@ -685,7 +694,7 @@ required_version = "{}"
 unstable_features = false
 disable_all_formatting = false
 skip_children = false
-hide_parse_errors = false
+show_parse_errors = true
 error_on_line_overflow = false
 error_on_unformatted = false
 ignore = []
@@ -1021,7 +1030,6 @@ make_backup = false
     #[cfg(test)]
     mod partially_unstable_option {
         use super::mock::{Config, PartiallyUnstableOption};
-        use super::*;
 
         /// From the command line, we can override with a stable variant.
         #[test]
diff --git a/src/config/options.rs b/src/config/options.rs
index e37f4027e4a..e7fd2cfbd31 100644
--- a/src/config/options.rs
+++ b/src/config/options.rs
@@ -1,3 +1,5 @@
+#![allow(unused_imports)]
+
 use std::collections::{hash_set, HashSet};
 use std::fmt;
 use std::path::{Path, PathBuf};
@@ -468,3 +470,27 @@ pub enum MatchArmLeadingPipe {
     /// Preserve any existing leading pipes
     Preserve,
 }
+
+/// Defines the default values for each config according to [the style guide].
+/// rustfmt output may differ between style editions.
+///
+/// [the style guide]: https://doc.rust-lang.org/nightly/style-guide/
+#[config_type]
+pub enum StyleEdition {
+    #[value = "2015"]
+    #[doc_hint = "2015"]
+    /// [Edition 2015]()
+    Edition2015,
+    #[value = "2018"]
+    #[doc_hint = "2018"]
+    /// [Edition 2018]()
+    Edition2018,
+    #[value = "2021"]
+    #[doc_hint = "2021"]
+    /// [Edition 2021]()
+    Edition2021,
+    #[value = "2024"]
+    #[doc_hint = "2024"]
+    /// [Edition 2024]().
+    Edition2024,
+}
diff --git a/src/config/style_edition.rs b/src/config/style_edition.rs
new file mode 100644
index 00000000000..4dd5f0164fa
--- /dev/null
+++ b/src/config/style_edition.rs
@@ -0,0 +1,69 @@
+use crate::config::StyleEdition;
+
+/// Defines the default value for the given style edition
+pub(crate) trait StyleEditionDefault {
+    type ConfigType;
+    fn style_edition_default(style_edition: StyleEdition) -> Self::ConfigType;
+}
+
+/// macro to help implement `StyleEditionDefault` for config options
+#[macro_export]
+macro_rules! style_edition_default {
+    ($ty:ident, $config_ty:ty, _ => $default:expr) => {
+        impl $crate::config::style_edition::StyleEditionDefault for $ty {
+            type ConfigType = $config_ty;
+
+            fn style_edition_default(_: $crate::config::StyleEdition) -> Self::ConfigType {
+                $default
+            }
+        }
+    };
+    ($ty:ident, $config_ty:ty, Edition2024 => $default_2024:expr, _ => $default_2015:expr) => {
+        impl $crate::config::style_edition::StyleEditionDefault for $ty {
+            type ConfigType = $config_ty;
+
+            fn style_edition_default(
+                style_edition: $crate::config::StyleEdition,
+            ) -> Self::ConfigType {
+                match style_edition {
+                    $crate::config::StyleEdition::Edition2015
+                    | $crate::config::StyleEdition::Edition2018
+                    | $crate::config::StyleEdition::Edition2021 => $default_2015,
+                    $crate::config::StyleEdition::Edition2024 => $default_2024,
+                }
+            }
+        }
+    };
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::config::StyleEdition;
+
+    #[test]
+    fn test_impl_default_style_edition_struct_for_all_editions() {
+        struct Unit;
+        style_edition_default!(Unit, usize, _ => 100);
+
+        // regardless of the style edition used the value will always return 100
+        assert_eq!(Unit::style_edition_default(StyleEdition::Edition2015), 100);
+        assert_eq!(Unit::style_edition_default(StyleEdition::Edition2018), 100);
+        assert_eq!(Unit::style_edition_default(StyleEdition::Edition2021), 100);
+        assert_eq!(Unit::style_edition_default(StyleEdition::Edition2024), 100);
+    }
+
+    #[test]
+    fn test_impl_default_style_edition_for_old_and_new_editions() {
+        struct Unit;
+        style_edition_default!(Unit, usize, Edition2024 => 50, _ => 100);
+
+        // style edition 2015-2021 are all the same
+        assert_eq!(Unit::style_edition_default(StyleEdition::Edition2015), 100);
+        assert_eq!(Unit::style_edition_default(StyleEdition::Edition2018), 100);
+        assert_eq!(Unit::style_edition_default(StyleEdition::Edition2021), 100);
+
+        // style edition 2024
+        assert_eq!(Unit::style_edition_default(StyleEdition::Edition2024), 50);
+    }
+}
diff --git a/src/emitter/checkstyle.rs b/src/emitter/checkstyle.rs
index 56d6a0ed681..2a4a9dfce8e 100644
--- a/src/emitter/checkstyle.rs
+++ b/src/emitter/checkstyle.rs
@@ -1,7 +1,6 @@
 use self::xml::XmlEscaped;
 use super::*;
 use crate::rustfmt_diff::{make_diff, DiffLine, Mismatch};
-use std::io::{self, Write};
 
 mod xml;
 
diff --git a/src/emitter/diff.rs b/src/emitter/diff.rs
index 764cd136e01..0af19a7d0b2 100644
--- a/src/emitter/diff.rs
+++ b/src/emitter/diff.rs
@@ -51,8 +51,6 @@ impl Emitter for DiffEmitter {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::config::Config;
-    use crate::FileName;
     use std::path::PathBuf;
 
     #[test]
diff --git a/src/emitter/json.rs b/src/emitter/json.rs
index 5594196bed9..f47c3260a02 100644
--- a/src/emitter/json.rs
+++ b/src/emitter/json.rs
@@ -2,7 +2,6 @@ use super::*;
 use crate::rustfmt_diff::{make_diff, DiffLine, Mismatch};
 use serde::Serialize;
 use serde_json::to_string as to_json_string;
-use std::io::{self, Write};
 
 #[derive(Debug, Default)]
 pub(crate) struct JsonEmitter {
@@ -106,7 +105,6 @@ impl JsonEmitter {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::FileName;
     use std::path::PathBuf;
 
     #[test]
diff --git a/src/emitter/modified_lines.rs b/src/emitter/modified_lines.rs
index 94ff570a8a9..81f0a31b974 100644
--- a/src/emitter/modified_lines.rs
+++ b/src/emitter/modified_lines.rs
@@ -1,6 +1,5 @@
 use super::*;
 use crate::rustfmt_diff::{make_diff, ModifiedLines};
-use std::io::Write;
 
 #[derive(Debug, Default)]
 pub(crate) struct ModifiedLinesEmitter;
diff --git a/src/emitter/stdout.rs b/src/emitter/stdout.rs
index 0bbc7332dfe..0b635a28bf2 100644
--- a/src/emitter/stdout.rs
+++ b/src/emitter/stdout.rs
@@ -1,6 +1,5 @@
 use super::*;
 use crate::config::Verbosity;
-use std::io::Write;
 
 #[derive(Debug)]
 pub(crate) struct StdoutEmitter {
diff --git a/src/expr.rs b/src/expr.rs
index 7e537ad4fbd..3445733f1d3 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -3,7 +3,7 @@ use std::cmp::min;
 
 use itertools::Itertools;
 use rustc_ast::token::{Delimiter, Lit, LitKind};
-use rustc_ast::{ast, ptr, token};
+use rustc_ast::{ast, ptr, token, ForLoopKind};
 use rustc_span::{BytePos, Span};
 
 use crate::chains::rewrite_chain;
@@ -134,7 +134,7 @@ pub(crate) fn format_expr(
         }
         ast::ExprKind::Let(ref pat, ref expr, _span, _) => rewrite_let(context, shape, pat, expr),
         ast::ExprKind::If(..)
-        | ast::ExprKind::ForLoop(..)
+        | ast::ExprKind::ForLoop { .. }
         | ast::ExprKind::Loop(..)
         | ast::ExprKind::While(..) => to_control_flow(expr, expr_type)
             .and_then(|control_flow| control_flow.rewrite(context, shape)),
@@ -212,7 +212,7 @@ pub(crate) fn format_expr(
             &cl.binder,
             cl.constness,
             cl.capture_clause,
-            &cl.asyncness,
+            &cl.coroutine_kind,
             cl.movability,
             &cl.fn_decl,
             &cl.body,
@@ -367,15 +367,15 @@ pub(crate) fn format_expr(
                 ))
             }
         }
-        ast::ExprKind::Async(capture_by, ref block) => {
-            let mover = if capture_by == ast::CaptureBy::Value {
+        ast::ExprKind::Gen(capture_by, ref block, ref kind) => {
+            let mover = if matches!(capture_by, ast::CaptureBy::Value { .. }) {
                 "move "
             } else {
                 ""
             };
             if let rw @ Some(_) = rewrite_single_line_block(
                 context,
-                format!("async {mover}").as_str(),
+                format!("{kind} {mover}").as_str(),
                 block,
                 Some(&expr.attrs),
                 None,
@@ -386,7 +386,7 @@ pub(crate) fn format_expr(
                 // 6 = `async `
                 let budget = shape.width.saturating_sub(6);
                 Some(format!(
-                    "async {mover}{}",
+                    "{kind} {mover}{}",
                     rewrite_block(
                         block,
                         Some(&expr.attrs),
@@ -682,9 +682,15 @@ fn to_control_flow(expr: &ast::Expr, expr_type: ExprType) -> Option<ControlFlow<
                 expr.span,
             ))
         }
-        ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
-            Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
-        }
+        ast::ExprKind::ForLoop {
+            ref pat,
+            ref iter,
+            ref body,
+            label,
+            kind,
+        } => Some(ControlFlow::new_for(
+            pat, iter, body, label, expr.span, kind,
+        )),
         ast::ExprKind::Loop(ref block, label, _) => {
             Some(ControlFlow::new_loop(block, label, expr.span))
         }
@@ -771,6 +777,7 @@ impl<'a> ControlFlow<'a> {
         block: &'a ast::Block,
         label: Option<ast::Label>,
         span: Span,
+        kind: ForLoopKind,
     ) -> ControlFlow<'a> {
         ControlFlow {
             cond: Some(cond),
@@ -778,7 +785,10 @@ impl<'a> ControlFlow<'a> {
             else_block: None,
             label,
             pat: Some(pat),
-            keyword: "for",
+            keyword: match kind {
+                ForLoopKind::For => "for",
+                ForLoopKind::ForAwait => "for await",
+            },
             matcher: "",
             connector: " in",
             allow_single_line: false,
@@ -1421,14 +1431,14 @@ pub(crate) fn can_be_overflowed_expr(
                 || context.config.overflow_delimited_expr()
         }
         ast::ExprKind::If(..)
-        | ast::ExprKind::ForLoop(..)
+        | ast::ExprKind::ForLoop { .. }
         | ast::ExprKind::Loop(..)
         | ast::ExprKind::While(..) => {
             context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
         }
 
         // Handle always block-like expressions
-        ast::ExprKind::Async(..) | ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => true,
+        ast::ExprKind::Gen(..) | ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => true,
 
         // Handle `[]` and `{}`-like expressions
         ast::ExprKind::Array(..) | ast::ExprKind::Struct(..) => {
@@ -1990,7 +2000,7 @@ fn rewrite_unary_op(
     shape: Shape,
 ) -> Option<String> {
     // For some reason, an UnOp is not spanned like BinOp!
-    rewrite_unary_prefix(context, ast::UnOp::to_string(op), expr, shape)
+    rewrite_unary_prefix(context, op.as_str(), expr, shape)
 }
 
 pub(crate) enum RhsAssignKind<'ast> {
diff --git a/src/ignore_path.rs b/src/ignore_path.rs
index d955949496a..7b5697bec3e 100644
--- a/src/ignore_path.rs
+++ b/src/ignore_path.rs
@@ -1,4 +1,4 @@
-use ignore::{self, gitignore};
+use ignore::gitignore;
 
 use crate::config::{FileName, IgnoreList};
 
diff --git a/src/imports.rs b/src/imports.rs
index f8e7fa62890..09f6e752338 100644
--- a/src/imports.rs
+++ b/src/imports.rs
@@ -1102,7 +1102,6 @@ enum SharedPrefix {
 #[cfg(test)]
 mod test {
     use super::*;
-    use rustc_span::DUMMY_SP;
 
     // Parse the path part of an import. This parser is not robust and is only
     // suitable for use in a test harness.
diff --git a/src/items.rs b/src/items.rs
index 386fdcf9698..a6295384b99 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -287,7 +287,7 @@ pub(crate) struct FnSig<'a> {
     decl: &'a ast::FnDecl,
     generics: &'a ast::Generics,
     ext: ast::Extern,
-    is_async: Cow<'a, ast::Async>,
+    coroutine_kind: Cow<'a, Option<ast::CoroutineKind>>,
     constness: ast::Const,
     defaultness: ast::Defaultness,
     unsafety: ast::Unsafe,
@@ -302,7 +302,7 @@ impl<'a> FnSig<'a> {
     ) -> FnSig<'a> {
         FnSig {
             unsafety: method_sig.header.unsafety,
-            is_async: Cow::Borrowed(&method_sig.header.asyncness),
+            coroutine_kind: Cow::Borrowed(&method_sig.header.coroutine_kind),
             constness: method_sig.header.constness,
             defaultness: ast::Defaultness::Final,
             ext: method_sig.header.ext,
@@ -328,7 +328,7 @@ impl<'a> FnSig<'a> {
                 generics,
                 ext: fn_sig.header.ext,
                 constness: fn_sig.header.constness,
-                is_async: Cow::Borrowed(&fn_sig.header.asyncness),
+                coroutine_kind: Cow::Borrowed(&fn_sig.header.coroutine_kind),
                 defaultness,
                 unsafety: fn_sig.header.unsafety,
                 visibility: vis,
@@ -343,7 +343,8 @@ impl<'a> FnSig<'a> {
         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));
+        self.coroutine_kind
+            .map(|coroutine_kind| result.push_str(format_coro(&coroutine_kind)));
         result.push_str(format_unsafety(self.unsafety));
         result.push_str(&format_extern(
             self.ext,
@@ -665,7 +666,7 @@ impl<'a> FmtVisitor<'a> {
         let span = mk_sp(lo, field.span.lo());
 
         let variant_body = match field.data {
-            ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
+            ast::VariantData::Tuple(..) | ast::VariantData::Struct { .. } => format_struct(
                 &context,
                 &StructParts::from_variant(field, &context),
                 self.block_indent,
@@ -1093,7 +1094,7 @@ fn enum_variant_span(variant: &ast::Variant, context: &RewriteContext<'_>) -> Sp
     if let Some(ref anon_const) = variant.disr_expr {
         let span_before_consts = variant.span.until(anon_const.value.span);
         let hi = match &variant.data {
-            Struct(..) => context
+            Struct { .. } => context
                 .snippet_provider
                 .span_after_last(span_before_consts, "}"),
             Tuple(..) => context
@@ -1113,12 +1114,12 @@ fn format_struct(
     offset: Indent,
     one_line_width: Option<usize>,
 ) -> Option<String> {
-    match *struct_parts.def {
+    match struct_parts.def {
         ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
-        ast::VariantData::Tuple(ref fields, _) => {
+        ast::VariantData::Tuple(fields, _) => {
             format_tuple_struct(context, struct_parts, fields, offset)
         }
-        ast::VariantData::Struct(ref fields, _) => {
+        ast::VariantData::Struct { fields, .. } => {
             format_struct_struct(context, struct_parts, fields, offset, one_line_width)
         }
     }
diff --git a/src/lib.rs b/src/lib.rs
index 8800e200fa4..400d3fe6dce 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -304,7 +304,7 @@ fn format_snippet(snippet: &str, config: &Config, is_macro_def: bool) -> Option<
         let mut out: Vec<u8> = Vec::with_capacity(snippet.len() * 2);
         config.set().emit_mode(config::EmitMode::Stdout);
         config.set().verbose(Verbosity::Quiet);
-        config.set().hide_parse_errors(true);
+        config.set().show_parse_errors(false);
         if is_macro_def {
             config.set().error_on_unformatted(true);
         }
diff --git a/src/macros.rs b/src/macros.rs
index 76553466e48..86694089fd6 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -708,7 +708,7 @@ struct MacroArgParser {
 fn last_tok(tt: &TokenTree) -> Token {
     match *tt {
         TokenTree::Token(ref t, _) => t.clone(),
-        TokenTree::Delimited(delim_span, delim, _) => Token {
+        TokenTree::Delimited(delim_span, _, delim, _) => Token {
             kind: TokenKind::CloseDelim(delim),
             span: delim_span.close,
         },
@@ -925,7 +925,7 @@ impl MacroArgParser {
                     self.add_meta_variable(&mut iter)?;
                 }
                 TokenTree::Token(ref t, _) => self.update_buffer(t),
-                &TokenTree::Delimited(_delimited_span, delimited, ref tts) => {
+                &TokenTree::Delimited(_dspan, _spacing, delimited, ref tts) => {
                     if !self.buf.is_empty() {
                         if next_space(&self.last_tok.kind) == SpaceState::Always {
                             self.add_separator();
@@ -1167,7 +1167,7 @@ impl<'a> MacroParser<'a> {
         let tok = self.toks.next()?;
         let (lo, args_paren_kind) = match tok {
             TokenTree::Token(..) => return None,
-            &TokenTree::Delimited(delimited_span, d, _) => (delimited_span.open.lo(), d),
+            &TokenTree::Delimited(delimited_span, _, d, _) => (delimited_span.open.lo(), d),
         };
         let args = TokenStream::new(vec![tok.clone()]);
         match self.toks.next()? {
@@ -1269,7 +1269,7 @@ impl MacroBranch {
         let has_block_body = old_body.starts_with('{');
 
         let mut config = context.config.clone();
-        config.set().hide_parse_errors(true);
+        config.set().show_parse_errors(false);
 
         result += " {";
 
diff --git a/src/matches.rs b/src/matches.rs
index 45f8bd90206..72386f0a097 100644
--- a/src/matches.rs
+++ b/src/matches.rs
@@ -223,7 +223,7 @@ fn rewrite_match_arm(
 ) -> Option<String> {
     let (missing_span, attrs_str) = if !arm.attrs.is_empty() {
         if contains_skip(&arm.attrs) {
-            let (_, body) = flatten_arm_body(context, &arm.body, None);
+            let (_, body) = flatten_arm_body(context, arm.body.as_deref()?, None);
             // `arm.span()` does not include trailing comma, add it manually.
             return Some(format!(
                 "{}{}",
@@ -246,7 +246,7 @@ fn rewrite_match_arm(
     };
 
     // Patterns
-    let pat_shape = match &arm.body.kind {
+    let pat_shape = match &arm.body.as_ref()?.kind {
         ast::ExprKind::Block(_, Some(label)) => {
             // Some block with a label ` => 'label: {`
             // 7 = ` => : {`
@@ -280,10 +280,10 @@ fn rewrite_match_arm(
         false,
     )?;
 
-    let arrow_span = mk_sp(arm.pat.span.hi(), arm.body.span().lo());
+    let arrow_span = mk_sp(arm.pat.span.hi(), arm.body.as_ref()?.span().lo());
     rewrite_match_body(
         context,
-        &arm.body,
+        arm.body.as_ref()?,
         &lhs_str,
         shape,
         guard_str.contains('\n'),
@@ -591,7 +591,7 @@ fn can_flatten_block_around_this(body: &ast::Expr) -> bool {
         ast::ExprKind::If(..) => false,
         // We do not allow collapsing a block around expression with condition
         // to avoid it being cluttered with match arm.
-        ast::ExprKind::ForLoop(..) | ast::ExprKind::While(..) => false,
+        ast::ExprKind::ForLoop { .. } | ast::ExprKind::While(..) => false,
         ast::ExprKind::Loop(..)
         | ast::ExprKind::Match(..)
         | ast::ExprKind::Block(..)
diff --git a/src/overflow.rs b/src/overflow.rs
index d81bf24dbd1..2f9705ec943 100644
--- a/src/overflow.rs
+++ b/src/overflow.rs
@@ -8,8 +8,8 @@ use rustc_ast::{ast, ptr};
 use rustc_span::Span;
 
 use crate::closures;
-use crate::config::lists::*;
 use crate::config::Version;
+use crate::config::{lists::*, Config};
 use crate::expr::{
     can_be_overflowed_expr, is_every_expr_simple, is_method_call, is_nested_call, is_simple_expr,
     rewrite_cond,
@@ -60,6 +60,13 @@ const SPECIAL_CASE_MACROS: &[(&str, usize)] = &[
     ("debug_assert_ne!", 2),
 ];
 
+/// Additional special case macros for version 2; these are separated to avoid breaking changes in
+/// version 1.
+const SPECIAL_CASE_MACROS_V2: &[(&str, usize)] = &[
+    // From the `log` crate.
+    ("trace!", 0),
+];
+
 const SPECIAL_CASE_ATTR: &[(&str, usize)] = &[
     // From the `failure` crate.
     ("fail", 0),
@@ -182,12 +189,17 @@ impl<'a> OverflowableItem<'a> {
         }
     }
 
-    fn special_cases(&self) -> &'static [(&'static str, usize)] {
-        match self {
+    fn special_cases(&self, config: &Config) -> impl Iterator<Item = &(&'static str, usize)> {
+        let base_cases = match self {
             OverflowableItem::MacroArg(..) => SPECIAL_CASE_MACROS,
             OverflowableItem::NestedMetaItem(..) => SPECIAL_CASE_ATTR,
             _ => &[],
-        }
+        };
+        let additional_cases = match (self, config.version()) {
+            (OverflowableItem::MacroArg(..), Version::Two) => SPECIAL_CASE_MACROS_V2,
+            _ => &[],
+        };
+        base_cases.iter().chain(additional_cases)
     }
 }
 
@@ -409,7 +421,7 @@ impl<'a> Context<'a> {
                     // When overflowing the expressions which consists of a control flow
                     // expression, avoid condition to use multi line.
                     ast::ExprKind::If(..)
-                    | ast::ExprKind::ForLoop(..)
+                    | ast::ExprKind::ForLoop { .. }
                     | ast::ExprKind::Loop(..)
                     | ast::ExprKind::While(..)
                     | ast::ExprKind::Match(..) => {
@@ -551,7 +563,7 @@ impl<'a> Context<'a> {
 
                     if tactic == DefinitiveListTactic::Vertical {
                         if let Some((all_simple, num_args_before)) =
-                            maybe_get_args_offset(self.ident, &self.items)
+                            maybe_get_args_offset(self.ident, &self.items, &self.context.config)
                         {
                             let one_line = all_simple
                                 && definitive_tactic(
@@ -771,11 +783,11 @@ fn no_long_items(list: &[ListItem], short_array_element_width_threshold: usize)
 pub(crate) fn maybe_get_args_offset(
     callee_str: &str,
     args: &[OverflowableItem<'_>],
+    config: &Config,
 ) -> Option<(bool, usize)> {
     if let Some(&(_, num_args_before)) = args
         .get(0)?
-        .special_cases()
-        .iter()
+        .special_cases(config)
         .find(|&&(s, _)| s == callee_str)
     {
         let all_simple = args.len() > num_args_before
diff --git a/src/pairs.rs b/src/pairs.rs
index 07c05193739..bfc2ffed383 100644
--- a/src/pairs.rs
+++ b/src/pairs.rs
@@ -339,7 +339,7 @@ impl FlattenPair for ast::Expr {
                     if let Some(pop) = stack.pop() {
                         match pop.kind {
                             ast::ExprKind::Binary(op, _, ref rhs) => {
-                                separators.push(op.node.to_string());
+                                separators.push(op.node.as_str());
                                 node = rhs;
                             }
                             _ => unreachable!(),
diff --git a/src/parse/macros/cfg_if.rs b/src/parse/macros/cfg_if.rs
index cbc4c90b8f9..bafef7b0f46 100644
--- a/src/parse/macros/cfg_if.rs
+++ b/src/parse/macros/cfg_if.rs
@@ -67,7 +67,7 @@ fn parse_cfg_if_inner<'a>(
                 Ok(None) => continue,
                 Err(err) => {
                     err.cancel();
-                    parser.sess.span_diagnostic.reset_err_count();
+                    parser.sess.dcx.reset_err_count();
                     return Err(
                         "Expected item inside cfg_if block, but failed to parse it as an item",
                     );
diff --git a/src/parse/macros/lazy_static.rs b/src/parse/macros/lazy_static.rs
index a8c2feec453..8b1dc6694d6 100644
--- a/src/parse/macros/lazy_static.rs
+++ b/src/parse/macros/lazy_static.rs
@@ -16,8 +16,8 @@ pub(crate) fn parse_lazy_static(
         ($method:ident $(,)* $($arg:expr),* $(,)*) => {
             match parser.$method($($arg,)*) {
                 Ok(val) => {
-                    if parser.sess.span_diagnostic.has_errors().is_some() {
-                        parser.sess.span_diagnostic.reset_err_count();
+                    if parser.sess.dcx.has_errors().is_some() {
+                        parser.sess.dcx.reset_err_count();
                         return None;
                     } else {
                         val
@@ -25,7 +25,7 @@ pub(crate) fn parse_lazy_static(
                 }
                 Err(err) => {
                     err.cancel();
-                    parser.sess.span_diagnostic.reset_err_count();
+                    parser.sess.dcx.reset_err_count();
                     return None;
                 }
             }
diff --git a/src/parse/macros/mod.rs b/src/parse/macros/mod.rs
index 7a802f7a88e..2dd2622174f 100644
--- a/src/parse/macros/mod.rs
+++ b/src/parse/macros/mod.rs
@@ -28,8 +28,8 @@ fn parse_macro_arg<'a, 'b: 'a>(parser: &'a mut Parser<'b>) -> Option<MacroArg> {
             let mut cloned_parser = (*parser).clone();
             match $parser(&mut cloned_parser) {
                 Ok(x) => {
-                    if parser.sess.span_diagnostic.has_errors().is_some() {
-                        parser.sess.span_diagnostic.reset_err_count();
+                    if parser.sess.dcx.has_errors().is_some() {
+                        parser.sess.dcx.reset_err_count();
                     } else {
                         // Parsing succeeded.
                         *parser = cloned_parser;
@@ -38,7 +38,7 @@ fn parse_macro_arg<'a, 'b: 'a>(parser: &'a mut Parser<'b>) -> Option<MacroArg> {
                 }
                 Err(e) => {
                     e.cancel();
-                    parser.sess.span_diagnostic.reset_err_count();
+                    parser.sess.dcx.reset_err_count();
                 }
             }
         };
diff --git a/src/parse/session.rs b/src/parse/session.rs
index 0573df9de2f..646d2d132a8 100644
--- a/src/parse/session.rs
+++ b/src/parse/session.rs
@@ -4,7 +4,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use rustc_data_structures::sync::{IntoDynSyncSend, Lrc};
 use rustc_errors::emitter::{DynEmitter, Emitter, EmitterWriter};
 use rustc_errors::translation::Translate;
-use rustc_errors::{ColorConfig, Diagnostic, Handler, Level as DiagnosticLevel};
+use rustc_errors::{ColorConfig, DiagCtxt, Diagnostic, Level as DiagnosticLevel};
 use rustc_session::parse::ParseSess as RawParseSess;
 use rustc_span::{
     source_map::{FilePathMapping, SourceMap},
@@ -118,13 +118,13 @@ impl From<Color> for ColorConfig {
     }
 }
 
-fn default_handler(
+fn default_dcx(
     source_map: Lrc<SourceMap>,
     ignore_path_set: Lrc<IgnorePathSet>,
     can_reset: Lrc<AtomicBool>,
-    hide_parse_errors: bool,
+    show_parse_errors: bool,
     color: Color,
-) -> Handler {
+) -> DiagCtxt {
     let supports_color = term::stderr().map_or(false, |term| term.supports_color());
     let emit_color = if supports_color {
         ColorConfig::from(color)
@@ -132,7 +132,7 @@ fn default_handler(
         ColorConfig::Never
     };
 
-    let emitter = if hide_parse_errors {
+    let emitter = if !show_parse_errors {
         silent_emitter()
     } else {
         let fallback_bundle = rustc_errors::fallback_fluent_bundle(
@@ -141,7 +141,7 @@ fn default_handler(
         );
         Box::new(EmitterWriter::stderr(emit_color, fallback_bundle).sm(Some(source_map.clone())))
     };
-    Handler::with_emitter(Box::new(SilentOnIgnoredFilesEmitter {
+    DiagCtxt::with_emitter(Box::new(SilentOnIgnoredFilesEmitter {
         has_non_ignorable_parser_errors: false,
         source_map,
         emitter,
@@ -159,14 +159,14 @@ impl ParseSess {
         let source_map = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let can_reset_errors = Lrc::new(AtomicBool::new(false));
 
-        let handler = default_handler(
+        let dcx = default_dcx(
             Lrc::clone(&source_map),
             Lrc::clone(&ignore_path_set),
             Lrc::clone(&can_reset_errors),
-            config.hide_parse_errors(),
+            config.show_parse_errors(),
             config.color(),
         );
-        let parse_sess = RawParseSess::with_span_handler(handler, source_map);
+        let parse_sess = RawParseSess::with_dcx(dcx, source_map);
 
         Ok(ParseSess {
             parse_sess,
@@ -218,7 +218,7 @@ impl ParseSess {
     }
 
     pub(crate) fn set_silent_emitter(&mut self) {
-        self.parse_sess.span_diagnostic = Handler::with_emitter(silent_emitter());
+        self.parse_sess.dcx = DiagCtxt::with_emitter(silent_emitter());
     }
 
     pub(crate) fn span_to_filename(&self, span: Span) -> FileName {
@@ -284,10 +284,8 @@ impl ParseSess {
 // Methods that should be restricted within the parse module.
 impl ParseSess {
     pub(super) fn emit_diagnostics(&self, diagnostics: Vec<Diagnostic>) {
-        for mut diagnostic in diagnostics {
-            self.parse_sess
-                .span_diagnostic
-                .emit_diagnostic(&mut diagnostic);
+        for diagnostic in diagnostics {
+            self.parse_sess.dcx.emit_diagnostic(diagnostic);
         }
     }
 
@@ -296,11 +294,11 @@ impl ParseSess {
     }
 
     pub(super) fn has_errors(&self) -> bool {
-        self.parse_sess.span_diagnostic.has_errors().is_some()
+        self.parse_sess.dcx.has_errors().is_some()
     }
 
     pub(super) fn reset_errors(&self) {
-        self.parse_sess.span_diagnostic.reset_err_count();
+        self.parse_sess.dcx.reset_err_count();
     }
 }
 
@@ -372,7 +370,7 @@ mod tests {
 
         fn build_diagnostic(level: DiagnosticLevel, span: Option<MultiSpan>) -> Diagnostic {
             let mut diag = Diagnostic::new(level, "");
-            diag.message.clear();
+            diag.messages.clear();
             if let Some(span) = span {
                 diag.span = span;
             }
diff --git a/src/patterns.rs b/src/patterns.rs
index 33f3b4b8a21..0fa6edaa5d7 100644
--- a/src/patterns.rs
+++ b/src/patterns.rs
@@ -40,7 +40,9 @@ pub(crate) fn is_short_pattern(pat: &ast::Pat, pat_str: &str) -> bool {
 
 fn is_short_pattern_inner(pat: &ast::Pat) -> bool {
     match pat.kind {
-        ast::PatKind::Rest | ast::PatKind::Wild | ast::PatKind::Lit(_) => true,
+        ast::PatKind::Rest | ast::PatKind::Never | ast::PatKind::Wild | ast::PatKind::Lit(_) => {
+            true
+        }
         ast::PatKind::Ident(_, _, ref pat) => pat.is_none(),
         ast::PatKind::Struct(..)
         | ast::PatKind::MacCall(..)
@@ -193,6 +195,7 @@ impl Rewrite for Pat {
                     None
                 }
             }
+            PatKind::Never => None,
             PatKind::Range(ref lhs, ref rhs, ref end_kind) => {
                 let infix = match end_kind.node {
                     RangeEnd::Included(RangeSyntax::DotDotDot) => "...",
@@ -256,9 +259,15 @@ impl Rewrite for Pat {
                 None,
                 None,
             ),
-            PatKind::Struct(ref qself, ref path, ref fields, ellipsis) => {
-                rewrite_struct_pat(qself, path, fields, ellipsis, self.span, context, shape)
-            }
+            PatKind::Struct(ref qself, ref path, ref fields, rest) => rewrite_struct_pat(
+                qself,
+                path,
+                fields,
+                rest == ast::PatFieldsRest::Rest,
+                self.span,
+                context,
+                shape,
+            ),
             PatKind::MacCall(ref mac) => {
                 rewrite_macro(mac, None, context, shape, MacroPosition::Pat)
             }
diff --git a/src/reorder.rs b/src/reorder.rs
index 3bddf4c1b6a..3e14f9f1272 100644
--- a/src/reorder.rs
+++ b/src/reorder.rs
@@ -6,7 +6,7 @@
 
 // FIXME(#2455): Reorder trait items.
 
-use std::cmp::{Ord, Ordering};
+use std::cmp::Ordering;
 
 use rustc_ast::{ast, attr};
 use rustc_span::{symbol::sym, Span};
diff --git a/src/spanned.rs b/src/spanned.rs
index 2136cfeae1a..5960b144499 100644
--- a/src/spanned.rs
+++ b/src/spanned.rs
@@ -97,7 +97,12 @@ impl Spanned for ast::Arm {
         } else {
             self.attrs[0].span.lo()
         };
-        span_with_attrs_lo_hi!(self, lo, self.body.span.hi())
+        let hi = if let Some(body) = &self.body {
+            body.span.hi()
+        } else {
+            self.pat.span.hi()
+        };
+        span_with_attrs_lo_hi!(self, lo, hi)
     }
 }
 
diff --git a/src/types.rs b/src/types.rs
index 127aff913e3..cd2582e66be 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -1,4 +1,3 @@
-use std::iter::ExactSizeIterator;
 use std::ops::Deref;
 
 use rustc_ast::ast::{self, FnRetTy, Mutability, Term};
@@ -538,28 +537,19 @@ impl Rewrite for ast::Lifetime {
 impl Rewrite for ast::GenericBound {
     fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
         match *self {
-            ast::GenericBound::Trait(ref poly_trait_ref, trait_bound_modifier) => {
+            ast::GenericBound::Trait(ref poly_trait_ref, modifiers) => {
                 let snippet = context.snippet(self.span());
                 let has_paren = snippet.starts_with('(') && snippet.ends_with(')');
-                let rewrite = match trait_bound_modifier {
-                    ast::TraitBoundModifier::None => poly_trait_ref.rewrite(context, shape),
-                    ast::TraitBoundModifier::Maybe => poly_trait_ref
-                        .rewrite(context, shape.offset_left(1)?)
-                        .map(|s| format!("?{}", s)),
-                    ast::TraitBoundModifier::MaybeConst => poly_trait_ref
-                        .rewrite(context, shape.offset_left(7)?)
-                        .map(|s| format!("~const {}", s)),
-                    ast::TraitBoundModifier::MaybeConstMaybe => poly_trait_ref
-                        .rewrite(context, shape.offset_left(8)?)
-                        .map(|s| format!("~const ?{}", s)),
-                    ast::TraitBoundModifier::Negative => poly_trait_ref
-                        .rewrite(context, shape.offset_left(1)?)
-                        .map(|s| format!("!{}", s)),
-                    ast::TraitBoundModifier::MaybeConstNegative => poly_trait_ref
-                        .rewrite(context, shape.offset_left(8)?)
-                        .map(|s| format!("~const !{}", s)),
-                };
-                rewrite.map(|s| if has_paren { format!("({})", s) } else { s })
+                let mut constness = modifiers.constness.as_str().to_string();
+                if !constness.is_empty() {
+                    constness.push(' ');
+                }
+                let polarity = modifiers.polarity.as_str();
+                let shape = shape.offset_left(constness.len() + polarity.len())?;
+                poly_trait_ref
+                    .rewrite(context, shape)
+                    .map(|s| format!("{constness}{polarity}{s}"))
+                    .map(|s| if has_paren { format!("({})", s) } else { s })
             }
             ast::GenericBound::Outlives(ref lifetime) => lifetime.rewrite(context, shape),
         }
diff --git a/src/utils.rs b/src/utils.rs
index 79a759d68ce..642b6603b1e 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -75,10 +75,11 @@ pub(crate) fn format_visibility(
 }
 
 #[inline]
-pub(crate) fn format_async(is_async: &ast::Async) -> &'static str {
-    match is_async {
-        ast::Async::Yes { .. } => "async ",
-        ast::Async::No => "",
+pub(crate) fn format_coro(coroutine_kind: &ast::CoroutineKind) -> &'static str {
+    match coroutine_kind {
+        ast::CoroutineKind::Async { .. } => "async ",
+        ast::CoroutineKind::Gen { .. } => "gen ",
+        ast::CoroutineKind::AsyncGen { .. } => "async gen ",
     }
 }
 
@@ -294,7 +295,7 @@ pub(crate) fn semicolon_for_stmt(
 ) -> bool {
     match stmt.kind {
         ast::StmtKind::Semi(ref expr) => match expr.kind {
-            ast::ExprKind::While(..) | ast::ExprKind::Loop(..) | ast::ExprKind::ForLoop(..) => {
+            ast::ExprKind::While(..) | ast::ExprKind::Loop(..) | ast::ExprKind::ForLoop { .. } => {
                 false
             }
             ast::ExprKind::Break(..) | ast::ExprKind::Continue(..) | ast::ExprKind::Ret(..) => {
@@ -473,9 +474,9 @@ pub(crate) fn is_block_expr(context: &RewriteContext<'_>, expr: &ast::Expr, repr
         | ast::ExprKind::If(..)
         | ast::ExprKind::Block(..)
         | ast::ExprKind::ConstBlock(..)
-        | ast::ExprKind::Async(..)
+        | ast::ExprKind::Gen(..)
         | ast::ExprKind::Loop(..)
-        | ast::ExprKind::ForLoop(..)
+        | ast::ExprKind::ForLoop { .. }
         | ast::ExprKind::TryBlock(..)
         | ast::ExprKind::Match(..) => repr.contains('\n'),
         ast::ExprKind::Paren(ref expr)
diff --git a/tests/source/issue-2927-2.rs b/tests/source/issue-2927-2.rs
index d87761fdc9c..07afef38cf5 100644
--- a/tests/source/issue-2927-2.rs
+++ b/tests/source/issue-2927-2.rs
@@ -1,5 +1,5 @@
 // rustfmt-edition: 2015
-#![feature(rust_2018_preview, uniform_paths)]
+#![feature(uniform_paths)]
 use futures::prelude::*;
 use http_03::cli::Cli;
 use hyper::{service::service_fn_ok, Body, Response, Server};
diff --git a/tests/source/issue-2927.rs b/tests/source/issue-2927.rs
index a7df32084f3..c7ec7bb0855 100644
--- a/tests/source/issue-2927.rs
+++ b/tests/source/issue-2927.rs
@@ -1,5 +1,5 @@
 // rustfmt-edition: 2018
-#![feature(rust_2018_preview, uniform_paths)]
+#![feature(uniform_paths)]
 use futures::prelude::*;
 use http_03::cli::Cli;
 use hyper::{service::service_fn_ok, Body, Response, Server};
diff --git a/tests/source/issue-5987/two.rs b/tests/source/issue-5987/two.rs
new file mode 100644
index 00000000000..e20026b5565
--- /dev/null
+++ b/tests/source/issue-5987/two.rs
@@ -0,0 +1,13 @@
+// rustfmt-version: Two
+
+fn main() {
+    trace!(
+        "get some longer length in here yes yes {} {}",
+        "hello",
+        "world"
+    );
+    debug!(
+        "get some longer length in here yes yes {} {}",
+        "hello", "world"
+    );
+}
diff --git a/tests/target/issue-2927-2.rs b/tests/target/issue-2927-2.rs
index e895783ba8b..46e0bf0e989 100644
--- a/tests/target/issue-2927-2.rs
+++ b/tests/target/issue-2927-2.rs
@@ -1,5 +1,5 @@
 // rustfmt-edition: 2015
-#![feature(rust_2018_preview, uniform_paths)]
+#![feature(uniform_paths)]
 use futures::prelude::*;
 use http_03::cli::Cli;
 use hyper::{service::service_fn_ok, Body, Response, Server};
diff --git a/tests/target/issue-2927.rs b/tests/target/issue-2927.rs
index 3267be28d7b..56afc2d3e40 100644
--- a/tests/target/issue-2927.rs
+++ b/tests/target/issue-2927.rs
@@ -1,5 +1,5 @@
 // rustfmt-edition: 2018
-#![feature(rust_2018_preview, uniform_paths)]
+#![feature(uniform_paths)]
 use ::log::{error, info, log};
 use futures::prelude::*;
 use http_03::cli::Cli;
diff --git a/tests/target/issue-5987/one.rs b/tests/target/issue-5987/one.rs
new file mode 100644
index 00000000000..3c995ed28ba
--- /dev/null
+++ b/tests/target/issue-5987/one.rs
@@ -0,0 +1,13 @@
+// rustfmt-version: One
+
+fn main() {
+    trace!(
+        "get some longer length in here yes yes {} {}",
+        "hello",
+        "world"
+    );
+    debug!(
+        "get some longer length in here yes yes {} {}",
+        "hello", "world"
+    );
+}
diff --git a/tests/target/issue-5987/two.rs b/tests/target/issue-5987/two.rs
new file mode 100644
index 00000000000..8fd92fc179e
--- /dev/null
+++ b/tests/target/issue-5987/two.rs
@@ -0,0 +1,12 @@
+// rustfmt-version: Two
+
+fn main() {
+    trace!(
+        "get some longer length in here yes yes {} {}",
+        "hello", "world"
+    );
+    debug!(
+        "get some longer length in here yes yes {} {}",
+        "hello", "world"
+    );
+}