From 7320daea4cac81602f6f75b0b446461fdc921710 Mon Sep 17 00:00:00 2001
From: Ashvin Arsakularatne <ashvin.arsakularatne@gmail.com>
Date: Thu, 15 Jul 2021 19:31:25 +0530
Subject: [PATCH 1/8] refactor: soft deprecate match_arm_blocks in favour of
 match_arm_wrapping (#4896)

Map `match_arm_blocks` option as `match_arm_wrapping` variants.
---
 src/config/config_type.rs | 24 +++++++++++++++++++++--
 src/config/mod.rs         | 11 +++++++++--
 src/config/options.rs     |  9 +++++++++
 src/matches.rs            | 40 +++++++++++++++++++++------------------
 4 files changed, 62 insertions(+), 22 deletions(-)

diff --git a/src/config/config_type.rs b/src/config/config_type.rs
index 7fc4486ddcd..5db0352107a 100644
--- a/src/config/config_type.rs
+++ b/src/config/config_type.rs
@@ -106,6 +106,7 @@ macro_rules! create_config {
                     | "chain_width" => self.0.set_heuristics(),
                     "license_template_path" => self.0.set_license_template(),
                     "merge_imports" => self.0.set_merge_imports(),
+                    "match_arm_blocks" => self.0.set_match_arm_blocks(),
                     &_ => (),
                 }
             }
@@ -166,6 +167,7 @@ macro_rules! create_config {
                 self.set_license_template();
                 self.set_ignore(dir);
                 self.set_merge_imports();
+                self.set_match_arm_blocks();
                 self
             }
 
@@ -249,14 +251,16 @@ macro_rules! create_config {
                     | "chain_width" => self.set_heuristics(),
                     "license_template_path" => self.set_license_template(),
                     "merge_imports" => self.set_merge_imports(),
+                    "match_arm_blocks" => self.set_match_arm_blocks(),
                     &_ => (),
                 }
             }
 
             #[allow(unreachable_pub)]
             pub fn is_hidden_option(name: &str) -> bool {
-                const HIDE_OPTIONS: [&str; 5] =
-                    ["verbose", "verbose_diff", "file_lines", "width_heuristics", "merge_imports"];
+                const HIDE_OPTIONS: [&str; 6] =
+                    ["verbose", "verbose_diff", "file_lines", "width_heuristics", "merge_imports",
+                    "match_arm_blocks"];
                 HIDE_OPTIONS.contains(&name)
             }
 
@@ -421,6 +425,22 @@ macro_rules! create_config {
                 }
             }
 
+            fn set_match_arm_blocks(&mut self) {
+                if self.was_set().match_arm_blocks() {
+                    eprintln!(
+                        "Warning: the `match_arm_blocks` option is deprecated. \
+                        Use `match_arm_wrapping` instead"
+                    );
+                    if !self.was_set().match_arm_wrapping() {
+                        self.match_arm_wrapping.2 = if self.match_arm_blocks() {
+                            MatchArmWrapping::Default
+                        } else {
+                            MatchArmWrapping::NoBlockFirstLine
+                        };
+                    }
+                }
+            }
+
             #[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/mod.rs b/src/config/mod.rs
index 8c04363b1fd..7c38f515f22 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -110,8 +110,9 @@ create_config! {
         "Align struct fields if their diffs fits within threshold";
     enum_discrim_align_threshold: usize, 0, false,
         "Align enum variants discrims, if their diffs fit within threshold";
-    match_arm_blocks: bool, true, false, "Wrap the body of arms in blocks when it does not fit on \
-        the same line with the pattern of arms";
+    match_arm_wrapping: MatchArmWrapping, MatchArmWrapping::Default, false,
+        "Wrap the body of match arms according to the given options";
+    match_arm_blocks: bool, true, false, "(deprecated: use match_arm_wrapping instead)";
     match_arm_leading_pipes: MatchArmLeadingPipe, MatchArmLeadingPipe::Never, true,
         "Determines whether leading pipes are emitted on match arms";
     force_multiline_blocks: bool, false, false,
@@ -426,6 +427,11 @@ mod test {
                 "Merge imports";
             merge_imports: bool, false, false, "(deprecated: use imports_granularity instead)";
 
+            // match_arm_blocks deprecation
+            match_arm_blocks: bool, true, false, "(deprecated: use match_arm_wrapping instead)";
+            match_arm_wrapping: MatchArmWrapping, MatchArmWrapping::Default, false,
+                "Wrap the body of match arms according to the given options";
+
             // Width Heuristics
             use_small_heuristics: Heuristics, Heuristics::Default, true,
                 "Whether to use different formatting for items and \
@@ -590,6 +596,7 @@ combine_control_expr = true
 overflow_delimited_expr = false
 struct_field_align_threshold = 0
 enum_discrim_align_threshold = 0
+match_arm_wrapping = "Default"
 match_arm_blocks = true
 match_arm_leading_pipes = "Never"
 force_multiline_blocks = false
diff --git a/src/config/options.rs b/src/config/options.rs
index 3b91021813c..6ab31eb33f7 100644
--- a/src/config/options.rs
+++ b/src/config/options.rs
@@ -442,3 +442,12 @@ pub enum MatchArmLeadingPipe {
     /// Preserve any existing leading pipes
     Preserve,
 }
+
+/// Controls wrapping for match arm bodies
+#[config_type]
+pub enum MatchArmWrapping {
+    /// Follow the Style Guide Prescription
+    Default,
+    /// Don't block wrap when the first line can't fit
+    NoBlockFirstLine,
+}
diff --git a/src/matches.rs b/src/matches.rs
index 140ec226c02..686729aba1d 100644
--- a/src/matches.rs
+++ b/src/matches.rs
@@ -7,7 +7,9 @@ use rustc_span::{BytePos, Span};
 
 use crate::comment::{combine_strs_with_missing_comments, rewrite_comment};
 use crate::config::lists::*;
-use crate::config::{Config, ControlBraceStyle, IndentStyle, MatchArmLeadingPipe, Version};
+use crate::config::{
+    Config, ControlBraceStyle, IndentStyle, MatchArmLeadingPipe, MatchArmWrapping, Version,
+};
 use crate::expr::{
     format_expr, is_empty_block, is_simple_block, is_unsafe_block, prefer_next_line, rewrite_cond,
     ExprType, RhsTactics,
@@ -413,26 +415,28 @@ fn rewrite_match_body(
         }
 
         let indent_str = shape.indent.to_string_with_newline(context.config);
-        let (body_prefix, body_suffix) =
-            if context.config.match_arm_blocks() && !context.inside_macro() {
-                let comma = if context.config.match_block_trailing_comma() {
-                    ","
+        let (body_prefix, body_suffix) = if context.config.match_arm_wrapping()
+            == MatchArmWrapping::Default
+            && !context.inside_macro()
+        {
+            let comma = if context.config.match_block_trailing_comma() {
+                ","
+            } else {
+                ""
+            };
+            let semicolon = if context.config.version() == Version::One {
+                ""
+            } else {
+                if semicolon_for_expr(context, body) {
+                    ";"
                 } else {
                     ""
-                };
-                let semicolon = if context.config.version() == Version::One {
-                    ""
-                } else {
-                    if semicolon_for_expr(context, body) {
-                        ";"
-                    } else {
-                        ""
-                    }
-                };
-                ("{", format!("{}{}}}{}", semicolon, indent_str, comma))
-            } else {
-                ("", String::from(","))
+                }
             };
+            ("{", format!("{}{}}}{}", semicolon, indent_str, comma))
+        } else {
+            ("", String::from(","))
+        };
 
         let block_sep = match context.config.control_brace_style() {
             ControlBraceStyle::AlwaysNextLine => format!("{}{}", alt_block_sep, body_prefix),

From 5c63ecdcb4c2562df9b0c5b906bf0d006981c6f5 Mon Sep 17 00:00:00 2001
From: Ashvin Arsakularatne <ashvin.arsakularatne@gmail.com>
Date: Thu, 15 Jul 2021 19:51:43 +0530
Subject: [PATCH 2/8] test: add tests for match_arm_blocks deprecation

---
 src/config/mod.rs | 68 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/src/config/mod.rs b/src/config/mod.rs
index 7c38f515f22..fd3c27237ca 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -730,6 +730,74 @@ make_backup = false
         }
     }
 
+    #[cfg(test)]
+    mod deprecated_option_match_arm_blocks {
+        use super::*;
+
+        #[test]
+        fn test_old_option_set() {
+            if !crate::is_nightly_channel!() {
+                return;
+            }
+            // Old option defaults to true - set it to false
+            let toml = r#"
+                unstable_features = true
+                match_arm_blocks = false
+            "#;
+            let config = Config::from_toml(toml, Path::new("")).unwrap();
+            assert_eq!(
+                config.match_arm_wrapping(),
+                MatchArmWrapping::NoBlockFirstLine
+            );
+        }
+
+        #[test]
+        fn test_both_set() {
+            if !crate::is_nightly_channel!() {
+                return;
+            }
+            let toml = r#"
+                unstable_features = true
+                match_arm_blocks = false
+                match_arm_wrapping = "Default"
+            "#;
+            let config = Config::from_toml(toml, Path::new("")).unwrap();
+            assert_eq!(config.match_arm_wrapping(), MatchArmWrapping::Default);
+        }
+
+        #[test]
+        fn test_new_overridden() {
+            if !crate::is_nightly_channel!() {
+                return;
+            }
+            let toml = r#"
+                unstable_features = true
+                merge_imports = false
+            "#;
+            let mut config = Config::from_toml(toml, Path::new("")).unwrap();
+            config.override_value("match_arm_wrapping", "Default");
+            assert_eq!(config.match_arm_wrapping(), MatchArmWrapping::Default);
+        }
+
+        #[test]
+        fn test_old_overridden() {
+            if !crate::is_nightly_channel!() {
+                return;
+            }
+            let toml = r#"
+                unstable_features = true
+                match_arm_wrapping = "NoBlockFirstLine"
+            "#;
+            let mut config = Config::from_toml(toml, Path::new("")).unwrap();
+            config.override_value("match_arm_blocks", "false");
+            // no effect: the new option always takes precedence
+            assert_eq!(
+                config.match_arm_wrapping(),
+                MatchArmWrapping::NoBlockFirstLine
+            );
+        }
+    }
+
     #[cfg(test)]
     mod use_small_heuristics {
         use super::*;

From 77193eb89f5cfafcf19a5730a95d8aea08dd1b64 Mon Sep 17 00:00:00 2001
From: Ashvin Arsakularatne <ashvin.arsakularatne@gmail.com>
Date: Tue, 20 Jul 2021 15:18:16 +0530
Subject: [PATCH 3/8] test: add tests for match_arm_wrapping

---
 tests/source/configs/match_arm_wrapping/default.rs  | 11 +++++++++++
 .../match_arm_wrapping/no_block_first_line.rs       | 11 +++++++++++
 tests/target/configs/match_arm_wrapping/default.rs  | 13 +++++++++++++
 .../match_arm_wrapping/no_block_first_line.rs       | 12 ++++++++++++
 4 files changed, 47 insertions(+)
 create mode 100644 tests/source/configs/match_arm_wrapping/default.rs
 create mode 100644 tests/source/configs/match_arm_wrapping/no_block_first_line.rs
 create mode 100644 tests/target/configs/match_arm_wrapping/default.rs
 create mode 100644 tests/target/configs/match_arm_wrapping/no_block_first_line.rs

diff --git a/tests/source/configs/match_arm_wrapping/default.rs b/tests/source/configs/match_arm_wrapping/default.rs
new file mode 100644
index 00000000000..03f29d373bc
--- /dev/null
+++ b/tests/source/configs/match_arm_wrapping/default.rs
@@ -0,0 +1,11 @@
+// rustfmt-match_arm_wrapping: Default
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        true => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        false => {
+            println!("{}", sit)
+        }
+    }
+}
diff --git a/tests/source/configs/match_arm_wrapping/no_block_first_line.rs b/tests/source/configs/match_arm_wrapping/no_block_first_line.rs
new file mode 100644
index 00000000000..25383169106
--- /dev/null
+++ b/tests/source/configs/match_arm_wrapping/no_block_first_line.rs
@@ -0,0 +1,11 @@
+// rustfmt-match_arm_wrapping: NoBlockFirstLine
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        true => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        false => {
+            println!("{}", sit)
+        }
+    }
+}
diff --git a/tests/target/configs/match_arm_wrapping/default.rs b/tests/target/configs/match_arm_wrapping/default.rs
new file mode 100644
index 00000000000..c1812ca1fb7
--- /dev/null
+++ b/tests/target/configs/match_arm_wrapping/default.rs
@@ -0,0 +1,13 @@
+// rustfmt-match_arm_wrapping: Default
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        true => {
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
+        }
+        false => {
+            println!("{}", sit)
+        }
+    }
+}
diff --git a/tests/target/configs/match_arm_wrapping/no_block_first_line.rs b/tests/target/configs/match_arm_wrapping/no_block_first_line.rs
new file mode 100644
index 00000000000..6d6aeb50539
--- /dev/null
+++ b/tests/target/configs/match_arm_wrapping/no_block_first_line.rs
@@ -0,0 +1,12 @@
+// rustfmt-match_arm_wrapping: NoBlockFirstLine
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        true =>
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        false => {
+            println!("{}", sit)
+        }
+    }
+}

From 14a4d02f876b4cb06c407244c3fcc7af5ea0ebd9 Mon Sep 17 00:00:00 2001
From: Ashvin Arsakularatne <ashvin.arsakularatne@gmail.com>
Date: Wed, 21 Jul 2021 15:05:00 +0530
Subject: [PATCH 4/8] feat: add Always option to match_arm_wrapping, with tests
 (#4896)

---
 src/config/options.rs                         |  2 +
 src/matches.rs                                | 41 ++++++++++---------
 .../configs/match_arm_wrapping/always.rs      | 18 ++++++++
 .../configs/match_arm_wrapping/always.rs      | 24 +++++++++++
 4 files changed, 65 insertions(+), 20 deletions(-)
 create mode 100644 tests/source/configs/match_arm_wrapping/always.rs
 create mode 100644 tests/target/configs/match_arm_wrapping/always.rs

diff --git a/src/config/options.rs b/src/config/options.rs
index 6ab31eb33f7..10c49977ef6 100644
--- a/src/config/options.rs
+++ b/src/config/options.rs
@@ -450,4 +450,6 @@ pub enum MatchArmWrapping {
     Default,
     /// Don't block wrap when the first line can't fit
     NoBlockFirstLine,
+    /// Always wrap match arms
+    Always,
 }
diff --git a/src/matches.rs b/src/matches.rs
index 686729aba1d..072c436def8 100644
--- a/src/matches.rs
+++ b/src/matches.rs
@@ -415,27 +415,23 @@ fn rewrite_match_body(
         }
 
         let indent_str = shape.indent.to_string_with_newline(context.config);
-        let (body_prefix, body_suffix) = if context.config.match_arm_wrapping()
-            == MatchArmWrapping::Default
-            && !context.inside_macro()
-        {
-            let comma = if context.config.match_block_trailing_comma() {
-                ","
-            } else {
-                ""
-            };
-            let semicolon = if context.config.version() == Version::One {
-                ""
-            } else {
-                if semicolon_for_expr(context, body) {
-                    ";"
+        let (body_prefix, body_suffix) = match context.config.match_arm_wrapping() {
+            MatchArmWrapping::Default | MatchArmWrapping::Always if !context.inside_macro() => {
+                let comma = if context.config.match_block_trailing_comma() {
+                    ","
                 } else {
                     ""
-                }
-            };
-            ("{", format!("{}{}}}{}", semicolon, indent_str, comma))
-        } else {
-            ("", String::from(","))
+                };
+
+                let semicolon = match context.config.version() {
+                    Version::One => "",
+                    _ if semicolon_for_expr(context, body) => ";",
+                    _ => "",
+                };
+
+                ("{", format!("{}{}}}{}", semicolon, indent_str, comma))
+            }
+            _ => ("", String::from(",")),
         };
 
         let block_sep = match context.config.control_brace_style() {
@@ -464,7 +460,10 @@ fn rewrite_match_body(
     let orig_body_shape = shape
         .offset_left(extra_offset(pats_str, shape) + 4)
         .and_then(|shape| shape.sub_width(comma.len()));
-    let orig_body = if forbid_same_line || !arrow_comment.is_empty() {
+    let orig_body = if forbid_same_line
+        || !arrow_comment.is_empty()
+        || (!is_block && context.config.match_arm_wrapping() == MatchArmWrapping::Always)
+    {
         None
     } else if let Some(body_shape) = orig_body_shape {
         let rewrite = nop_block_collapse(
@@ -485,6 +484,7 @@ fn rewrite_match_body(
     } else {
         None
     };
+
     let orig_budget = orig_body_shape.map_or(0, |shape| shape.width);
 
     // Try putting body on the next line and see if it looks better.
@@ -493,6 +493,7 @@ fn rewrite_match_body(
         format_expr(body, ExprType::Statement, context, next_line_body_shape),
         next_line_body_shape.width,
     );
+
     match (orig_body, next_line_body) {
         (Some(ref orig_str), Some(ref next_line_str))
             if prefer_next_line(orig_str, next_line_str, RhsTactics::Default) =>
diff --git a/tests/source/configs/match_arm_wrapping/always.rs b/tests/source/configs/match_arm_wrapping/always.rs
new file mode 100644
index 00000000000..ac51e4cef88
--- /dev/null
+++ b/tests/source/configs/match_arm_wrapping/always.rs
@@ -0,0 +1,18 @@
+// rustfmt-match_arm_wrapping: Always
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        1 => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2 => {
+            println!("{}", sit)
+        }
+        3 => panic!(),
+        4 => (),
+        y => {
+            // Some comment
+            let ipsum = y - 1;
+            println!("{}", ipsum);
+        }
+    }
+}
diff --git a/tests/target/configs/match_arm_wrapping/always.rs b/tests/target/configs/match_arm_wrapping/always.rs
new file mode 100644
index 00000000000..7f410121698
--- /dev/null
+++ b/tests/target/configs/match_arm_wrapping/always.rs
@@ -0,0 +1,24 @@
+// rustfmt-match_arm_wrapping: Always
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        1 => {
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
+        }
+        2 => {
+            println!("{}", sit)
+        }
+        3 => {
+            panic!()
+        }
+        4 => {
+            ()
+        }
+        y => {
+            // Some comment
+            let ipsum = y - 1;
+            println!("{}", ipsum);
+        }
+    }
+}

From 1ee0c72f2c2b25cb0595dc6c3c6a97c2bce914e3 Mon Sep 17 00:00:00 2001
From: Ashvin Arsakularatne <ashvin.arsakularatne@gmail.com>
Date: Thu, 22 Jul 2021 01:17:06 +0530
Subject: [PATCH 5/8] feat: add Preserve option to match_arm_wrapping (#4896)

---
 src/config/options.rs                         |  7 ++++--
 src/matches.rs                                |  7 +++++-
 .../configs/match_arm_wrapping/always.rs      | 14 ++++++------
 .../configs/match_arm_wrapping/preserve.rs    | 20 +++++++++++++++++
 .../configs/match_arm_wrapping/always.rs      | 14 ++++++------
 .../configs/match_arm_wrapping/preserve.rs    | 22 +++++++++++++++++++
 6 files changed, 67 insertions(+), 17 deletions(-)
 create mode 100644 tests/source/configs/match_arm_wrapping/preserve.rs
 create mode 100644 tests/target/configs/match_arm_wrapping/preserve.rs

diff --git a/src/config/options.rs b/src/config/options.rs
index 10c49977ef6..d58c8ed0f3b 100644
--- a/src/config/options.rs
+++ b/src/config/options.rs
@@ -448,8 +448,11 @@ pub enum MatchArmLeadingPipe {
 pub enum MatchArmWrapping {
     /// Follow the Style Guide Prescription
     Default,
-    /// Don't block wrap when the first line can't fit
+    /// Same as Default, except don't block wrap match arms when the opening line of its body
+    /// can't fit on the same line as the `=>`.
     NoBlockFirstLine,
-    /// Always wrap match arms
+    /// Always block wrap match arms
     Always,
+    /// Preserve the block wrapping on match arms
+    Preserve,
 }
diff --git a/src/matches.rs b/src/matches.rs
index 072c436def8..f9f2b5b0b07 100644
--- a/src/matches.rs
+++ b/src/matches.rs
@@ -326,6 +326,10 @@ fn flatten_arm_body<'a>(
             if let ast::ExprKind::Block(..) = expr.kind {
                 flatten_arm_body(context, expr, None)
             } else {
+                if context.config.match_arm_wrapping() == MatchArmWrapping::Preserve {
+                    return (false, body);
+                }
+
                 let cond_becomes_muti_line = opt_shape
                     .and_then(|shape| rewrite_cond(context, expr, shape))
                     .map_or(false, |cond| cond.contains('\n'));
@@ -416,7 +420,8 @@ fn rewrite_match_body(
 
         let indent_str = shape.indent.to_string_with_newline(context.config);
         let (body_prefix, body_suffix) = match context.config.match_arm_wrapping() {
-            MatchArmWrapping::Default | MatchArmWrapping::Always if !context.inside_macro() => {
+            MatchArmWrapping::NoBlockFirstLine => ("", String::from(",")),
+            _ if !context.inside_macro() => {
                 let comma = if context.config.match_block_trailing_comma() {
                     ","
                 } else {
diff --git a/tests/source/configs/match_arm_wrapping/always.rs b/tests/source/configs/match_arm_wrapping/always.rs
index ac51e4cef88..debb491f8b1 100644
--- a/tests/source/configs/match_arm_wrapping/always.rs
+++ b/tests/source/configs/match_arm_wrapping/always.rs
@@ -3,16 +3,16 @@
 
 fn main() {
     match lorem {
-        1 => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
-        2 => {
+        1000 => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2000 => {
             println!("{}", sit)
         }
-        3 => panic!(),
-        4 => (),
-        y => {
+        3000 => panic!(),
+        4000 => (),
+        ipsum => {
             // Some comment
-            let ipsum = y - 1;
-            println!("{}", ipsum);
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
         }
     }
 }
diff --git a/tests/source/configs/match_arm_wrapping/preserve.rs b/tests/source/configs/match_arm_wrapping/preserve.rs
new file mode 100644
index 00000000000..c1c387b3622
--- /dev/null
+++ b/tests/source/configs/match_arm_wrapping/preserve.rs
@@ -0,0 +1,20 @@
+// rustfmt-match_arm_wrapping: Preserve
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        1000 => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => {
+            ()
+        }
+        ipsum => {
+            // Some comment
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
+        }
+    }
+}
diff --git a/tests/target/configs/match_arm_wrapping/always.rs b/tests/target/configs/match_arm_wrapping/always.rs
index 7f410121698..571149692e9 100644
--- a/tests/target/configs/match_arm_wrapping/always.rs
+++ b/tests/target/configs/match_arm_wrapping/always.rs
@@ -3,22 +3,22 @@
 
 fn main() {
     match lorem {
-        1 => {
+        1000 => {
             foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
         }
-        2 => {
+        2000 => {
             println!("{}", sit)
         }
-        3 => {
+        3000 => {
             panic!()
         }
-        4 => {
+        4000 => {
             ()
         }
-        y => {
+        ipsum => {
             // Some comment
-            let ipsum = y - 1;
-            println!("{}", ipsum);
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
         }
     }
 }
diff --git a/tests/target/configs/match_arm_wrapping/preserve.rs b/tests/target/configs/match_arm_wrapping/preserve.rs
new file mode 100644
index 00000000000..75a5b1a9be3
--- /dev/null
+++ b/tests/target/configs/match_arm_wrapping/preserve.rs
@@ -0,0 +1,22 @@
+// rustfmt-match_arm_wrapping: Preserve
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        1000 => {
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
+        }
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => {
+            ()
+        }
+        ipsum => {
+            // Some comment
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
+        }
+    }
+}

From db129434bbf8fec5b27f38853a190665aaf5943c Mon Sep 17 00:00:00 2001
From: Ashvin Arsakularatne <ashvin.arsakularatne@gmail.com>
Date: Fri, 23 Jul 2021 03:37:58 +0530
Subject: [PATCH 6/8] feat: add FitEntireBody as new match_arm_wrapping option,
 and rename NoBlockFirstLine to FitFirstLine (#4896)

---
 src/config/config_type.rs |  2 +-
 src/config/mod.rs         | 12 +++---------
 src/config/options.rs     |  5 ++++-
 src/matches.rs            |  6 ++++--
 4 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/src/config/config_type.rs b/src/config/config_type.rs
index 5db0352107a..08134322439 100644
--- a/src/config/config_type.rs
+++ b/src/config/config_type.rs
@@ -435,7 +435,7 @@ macro_rules! create_config {
                         self.match_arm_wrapping.2 = if self.match_arm_blocks() {
                             MatchArmWrapping::Default
                         } else {
-                            MatchArmWrapping::NoBlockFirstLine
+                            MatchArmWrapping::FitFirstLine
                         };
                     }
                 }
diff --git a/src/config/mod.rs b/src/config/mod.rs
index fd3c27237ca..96469bd6d56 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -745,10 +745,7 @@ make_backup = false
                 match_arm_blocks = false
             "#;
             let config = Config::from_toml(toml, Path::new("")).unwrap();
-            assert_eq!(
-                config.match_arm_wrapping(),
-                MatchArmWrapping::NoBlockFirstLine
-            );
+            assert_eq!(config.match_arm_wrapping(), MatchArmWrapping::FitFirstLine);
         }
 
         #[test]
@@ -786,15 +783,12 @@ make_backup = false
             }
             let toml = r#"
                 unstable_features = true
-                match_arm_wrapping = "NoBlockFirstLine"
+                match_arm_wrapping = "FitFirstLine"
             "#;
             let mut config = Config::from_toml(toml, Path::new("")).unwrap();
             config.override_value("match_arm_blocks", "false");
             // no effect: the new option always takes precedence
-            assert_eq!(
-                config.match_arm_wrapping(),
-                MatchArmWrapping::NoBlockFirstLine
-            );
+            assert_eq!(config.match_arm_wrapping(), MatchArmWrapping::FitFirstLine);
         }
     }
 
diff --git a/src/config/options.rs b/src/config/options.rs
index d58c8ed0f3b..ca80834c19a 100644
--- a/src/config/options.rs
+++ b/src/config/options.rs
@@ -450,9 +450,12 @@ pub enum MatchArmWrapping {
     Default,
     /// Same as Default, except don't block wrap match arms when the opening line of its body
     /// can't fit on the same line as the `=>`.
-    NoBlockFirstLine,
+    FitFirstLine,
     /// Always block wrap match arms
     Always,
     /// Preserve the block wrapping on match arms
     Preserve,
+    /// Same as Default, except wrap the match arm if the entire body cannot fit on the same line
+    /// as the `=>`.
+    FitEntireBody,
 }
diff --git a/src/matches.rs b/src/matches.rs
index f9f2b5b0b07..5a994f353d1 100644
--- a/src/matches.rs
+++ b/src/matches.rs
@@ -420,7 +420,7 @@ fn rewrite_match_body(
 
         let indent_str = shape.indent.to_string_with_newline(context.config);
         let (body_prefix, body_suffix) = match context.config.match_arm_wrapping() {
-            MatchArmWrapping::NoBlockFirstLine => ("", String::from(",")),
+            MatchArmWrapping::FitFirstLine => ("", String::from(",")),
             _ if !context.inside_macro() => {
                 let comma = if context.config.match_block_trailing_comma() {
                     ","
@@ -501,7 +501,9 @@ fn rewrite_match_body(
 
     match (orig_body, next_line_body) {
         (Some(ref orig_str), Some(ref next_line_str))
-            if prefer_next_line(orig_str, next_line_str, RhsTactics::Default) =>
+            if prefer_next_line(orig_str, next_line_str, RhsTactics::Default)
+                || (context.config.match_arm_wrapping() == MatchArmWrapping::FitEntireBody
+                    && orig_str.contains('\n')) =>
         {
             combine_next_line_body(next_line_str)
         }

From 310023b0402863d3db3869a1f3fe0416c4d873b5 Mon Sep 17 00:00:00 2001
From: Ashvin Arsakularatne <ashvin.arsakularatne@gmail.com>
Date: Fri, 23 Jul 2021 03:39:04 +0530
Subject: [PATCH 7/8] test: add tests for FitEntireBody, and make the tests for
 match_arm_wrapping consistent

---
 .../configs/match_arm_wrapping/always.rs      |  5 ++-
 .../configs/match_arm_wrapping/default.rs     | 14 +++++++--
 .../match_arm_wrapping/fit_entire_body.rs     | 21 +++++++++++++
 .../match_arm_wrapping/fit_first_line.rs      | 21 +++++++++++++
 .../match_arm_wrapping/no_block_first_line.rs | 11 -------
 .../configs/match_arm_wrapping/preserve.rs    |  1 +
 .../configs/match_arm_wrapping/always.rs      | 11 +++++++
 .../configs/match_arm_wrapping/default.rs     | 20 ++++++++++--
 .../match_arm_wrapping/fit_entire_body.rs     | 31 +++++++++++++++++++
 .../match_arm_wrapping/fit_first_line.rs      | 28 +++++++++++++++++
 .../match_arm_wrapping/no_block_first_line.rs | 12 -------
 .../configs/match_arm_wrapping/preserve.rs    |  9 ++++++
 12 files changed, 156 insertions(+), 28 deletions(-)
 create mode 100644 tests/source/configs/match_arm_wrapping/fit_entire_body.rs
 create mode 100644 tests/source/configs/match_arm_wrapping/fit_first_line.rs
 delete mode 100644 tests/source/configs/match_arm_wrapping/no_block_first_line.rs
 create mode 100644 tests/target/configs/match_arm_wrapping/fit_entire_body.rs
 create mode 100644 tests/target/configs/match_arm_wrapping/fit_first_line.rs
 delete mode 100644 tests/target/configs/match_arm_wrapping/no_block_first_line.rs

diff --git a/tests/source/configs/match_arm_wrapping/always.rs b/tests/source/configs/match_arm_wrapping/always.rs
index debb491f8b1..318e963164f 100644
--- a/tests/source/configs/match_arm_wrapping/always.rs
+++ b/tests/source/configs/match_arm_wrapping/always.rs
@@ -8,7 +8,10 @@ fn main() {
             println!("{}", sit)
         }
         3000 => panic!(),
-        4000 => (),
+        4000 => {
+            ()
+        }
+        5000 => this.a_very_long_function_name(foo, bar, bazz, fizz, another_argument, some_more_arguments, which_dont_fit),
         ipsum => {
             // Some comment
             let dolor = ipsum % 2;
diff --git a/tests/source/configs/match_arm_wrapping/default.rs b/tests/source/configs/match_arm_wrapping/default.rs
index 03f29d373bc..d004cc75f0e 100644
--- a/tests/source/configs/match_arm_wrapping/default.rs
+++ b/tests/source/configs/match_arm_wrapping/default.rs
@@ -3,9 +3,19 @@
 
 fn main() {
     match lorem {
-        true => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
-        false => {
+        1000 => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2000 => {
             println!("{}", sit)
         }
+        3000 => panic!(),
+        4000 => {
+            ()
+        }
+        5000 => this.a_very_long_function_name(foo, bar, bazz, fizz, another_argument, some_more_arguments, which_dont_fit),
+        ipsum => {
+            // Some comment
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
+        }
     }
 }
diff --git a/tests/source/configs/match_arm_wrapping/fit_entire_body.rs b/tests/source/configs/match_arm_wrapping/fit_entire_body.rs
new file mode 100644
index 00000000000..91f8da4ae22
--- /dev/null
+++ b/tests/source/configs/match_arm_wrapping/fit_entire_body.rs
@@ -0,0 +1,21 @@
+// rustfmt-match_arm_wrapping: FitEntireBody
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        1000 => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => {
+            ()
+        }
+        5000 => this.a_very_long_function_name(foo, bar, bazz, fizz, another_argument, some_more_arguments, which_dont_fit),
+        ipsum => {
+            // Some comment
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
+        }
+    }
+}
diff --git a/tests/source/configs/match_arm_wrapping/fit_first_line.rs b/tests/source/configs/match_arm_wrapping/fit_first_line.rs
new file mode 100644
index 00000000000..5142f73bdd8
--- /dev/null
+++ b/tests/source/configs/match_arm_wrapping/fit_first_line.rs
@@ -0,0 +1,21 @@
+// rustfmt-match_arm_wrapping: FitFirstLine
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        1000 => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => { 
+            ()
+        }
+        5000 => this.a_very_long_function_name(foo, bar, bazz, fizz, another_argument, some_more_arguments, which_dont_fit),
+        ipsum => {
+            // Some comment
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
+        }
+    }
+}
diff --git a/tests/source/configs/match_arm_wrapping/no_block_first_line.rs b/tests/source/configs/match_arm_wrapping/no_block_first_line.rs
deleted file mode 100644
index 25383169106..00000000000
--- a/tests/source/configs/match_arm_wrapping/no_block_first_line.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-// rustfmt-match_arm_wrapping: NoBlockFirstLine
-// Wrap match-arms
-
-fn main() {
-    match lorem {
-        true => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
-        false => {
-            println!("{}", sit)
-        }
-    }
-}
diff --git a/tests/source/configs/match_arm_wrapping/preserve.rs b/tests/source/configs/match_arm_wrapping/preserve.rs
index c1c387b3622..642272c1619 100644
--- a/tests/source/configs/match_arm_wrapping/preserve.rs
+++ b/tests/source/configs/match_arm_wrapping/preserve.rs
@@ -11,6 +11,7 @@ fn main() {
         4000 => {
             ()
         }
+        5000 => this.a_very_long_function_name(foo, bar, bazz, fizz, another_argument, some_more_arguments, which_dont_fit),
         ipsum => {
             // Some comment
             let dolor = ipsum % 2;
diff --git a/tests/target/configs/match_arm_wrapping/always.rs b/tests/target/configs/match_arm_wrapping/always.rs
index 571149692e9..a7c56796f0f 100644
--- a/tests/target/configs/match_arm_wrapping/always.rs
+++ b/tests/target/configs/match_arm_wrapping/always.rs
@@ -15,6 +15,17 @@ fn main() {
         4000 => {
             ()
         }
+        5000 => {
+            this.a_very_long_function_name(
+                foo,
+                bar,
+                bazz,
+                fizz,
+                another_argument,
+                some_more_arguments,
+                which_dont_fit,
+            )
+        }
         ipsum => {
             // Some comment
             let dolor = ipsum % 2;
diff --git a/tests/target/configs/match_arm_wrapping/default.rs b/tests/target/configs/match_arm_wrapping/default.rs
index c1812ca1fb7..7867da97f06 100644
--- a/tests/target/configs/match_arm_wrapping/default.rs
+++ b/tests/target/configs/match_arm_wrapping/default.rs
@@ -3,11 +3,27 @@
 
 fn main() {
     match lorem {
-        true => {
+        1000 => {
             foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
         }
-        false => {
+        2000 => {
             println!("{}", sit)
         }
+        3000 => panic!(),
+        4000 => (),
+        5000 => this.a_very_long_function_name(
+            foo,
+            bar,
+            bazz,
+            fizz,
+            another_argument,
+            some_more_arguments,
+            which_dont_fit,
+        ),
+        ipsum => {
+            // Some comment
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
+        }
     }
 }
diff --git a/tests/target/configs/match_arm_wrapping/fit_entire_body.rs b/tests/target/configs/match_arm_wrapping/fit_entire_body.rs
new file mode 100644
index 00000000000..e9ce3944887
--- /dev/null
+++ b/tests/target/configs/match_arm_wrapping/fit_entire_body.rs
@@ -0,0 +1,31 @@
+// rustfmt-match_arm_wrapping: FitEntireBody
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        1000 => {
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
+        }
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => (),
+        5000 => {
+            this.a_very_long_function_name(
+                foo,
+                bar,
+                bazz,
+                fizz,
+                another_argument,
+                some_more_arguments,
+                which_dont_fit,
+            )
+        }
+        ipsum => {
+            // Some comment
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
+        }
+    }
+}
diff --git a/tests/target/configs/match_arm_wrapping/fit_first_line.rs b/tests/target/configs/match_arm_wrapping/fit_first_line.rs
new file mode 100644
index 00000000000..ceebc7371da
--- /dev/null
+++ b/tests/target/configs/match_arm_wrapping/fit_first_line.rs
@@ -0,0 +1,28 @@
+// rustfmt-match_arm_wrapping: FitFirstLine
+// Wrap match-arms
+
+fn main() {
+    match lorem {
+        1000 =>
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => (),
+        5000 => this.a_very_long_function_name(
+            foo,
+            bar,
+            bazz,
+            fizz,
+            another_argument,
+            some_more_arguments,
+            which_dont_fit,
+        ),
+        ipsum => {
+            // Some comment
+            let dolor = ipsum % 2;
+            println!("{}", dolor);
+        }
+    }
+}
diff --git a/tests/target/configs/match_arm_wrapping/no_block_first_line.rs b/tests/target/configs/match_arm_wrapping/no_block_first_line.rs
deleted file mode 100644
index 6d6aeb50539..00000000000
--- a/tests/target/configs/match_arm_wrapping/no_block_first_line.rs
+++ /dev/null
@@ -1,12 +0,0 @@
-// rustfmt-match_arm_wrapping: NoBlockFirstLine
-// Wrap match-arms
-
-fn main() {
-    match lorem {
-        true =>
-            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
-        false => {
-            println!("{}", sit)
-        }
-    }
-}
diff --git a/tests/target/configs/match_arm_wrapping/preserve.rs b/tests/target/configs/match_arm_wrapping/preserve.rs
index 75a5b1a9be3..9a5199df2cf 100644
--- a/tests/target/configs/match_arm_wrapping/preserve.rs
+++ b/tests/target/configs/match_arm_wrapping/preserve.rs
@@ -13,6 +13,15 @@ fn main() {
         4000 => {
             ()
         }
+        5000 => this.a_very_long_function_name(
+            foo,
+            bar,
+            bazz,
+            fizz,
+            another_argument,
+            some_more_arguments,
+            which_dont_fit,
+        ),
         ipsum => {
             // Some comment
             let dolor = ipsum % 2;

From 3a262bd9c9ab9af5ad79d28c52cfaa3085d0a3de Mon Sep 17 00:00:00 2001
From: Ashvin Arsakularatne <ashvin.arsakularatne@gmail.com>
Date: Wed, 28 Jul 2021 01:09:25 +0530
Subject: [PATCH 8/8] doc: add configuration snippets for match_arm_wrapping
 options

---
 Configurations.md | 179 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 179 insertions(+)

diff --git a/Configurations.md b/Configurations.md
index d2e5613eba9..c480703bff8 100644
--- a/Configurations.md
+++ b/Configurations.md
@@ -1604,6 +1604,185 @@ fn foo() {
 }
 ```
 
+## `match_arm_wrapping`
+
+Controls when to block wrap match arm bodies.
+
+- **Default value**: `"Default"`
+- **Possible values**: `"Default"`, `"FitFirstLine"`, `"FitEntireBody"`, `"Always"`, `"Preserve`
+- **Stable**: No (tracking issue: #4896)
+
+### Example
+
+#### Original code
+
+```rust
+#![rustfmt::skip]
+
+fn main() {
+    match lorem {
+        1000 => foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => {
+            ()
+        }
+        5000 => this.a_very_long_function_name(foo, bar, bazz, fizz, another_argument, some_more_arguments, which_dont_fit),
+    }
+}
+```
+
+#### `"Default"` (default):
+
+The default block wrapping settings, as described in the Style Guide.
+
+```rust
+fn main() {
+    match lorem {
+        1000 => {
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
+        }
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => (),
+        5000 => this.a_very_long_function_name(
+            foo,
+            bar,
+            bazz,
+            fizz,
+            another_argument,
+            some_more_arguments,
+            which_dont_fit,
+        ),
+    }
+}
+```
+
+#### `"FitFirstLine"`:
+
+Same as the default, except don't block wrap match arms when the opening line of its body can't fit on the same line as the `=>`.
+
+```rust
+fn main() {
+    match lorem {
+        1000 =>
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x),
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => (),
+        5000 => this.a_very_long_function_name(
+            foo,
+            bar,
+            bazz,
+            fizz,
+            another_argument,
+            some_more_arguments,
+            which_dont_fit,
+        ),
+    }
+}
+```
+
+#### `"Always"`:
+
+Always block wrap match arm bodies.
+
+```rust
+fn main() {
+    match lorem {
+        1000 => {
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
+        }
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => {
+            panic!()
+        }
+        4000 => {
+            ()
+        }
+        5000 => {
+            this.a_very_long_function_name(
+                foo,
+                bar,
+                bazz,
+                fizz,
+                another_argument,
+                some_more_arguments,
+                which_dont_fit,
+            )
+        }
+    }
+}
+```
+
+#### `"Preserve"`:
+
+Preserve block wrapping on match arm bodies if the developer originally had the body wrapped.
+
+```rust
+fn main() {
+    match lorem {
+        1000 => {
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
+        }
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => {
+            ()
+        }
+        5000 => this.a_very_long_function_name(
+            foo,
+            bar,
+            bazz,
+            fizz,
+            another_argument,
+            some_more_arguments,
+            which_dont_fit,
+        ),
+    }
+}
+```
+
+#### `"FitEntireBody"`:
+
+Same as default, except block wrap the match arm if the entire body cannot fit on the same line as the `=>`.
+
+```rust
+fn main() {
+    match lorem {
+        1000 => {
+            foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo(x)
+        }
+        2000 => {
+            println!("{}", sit)
+        }
+        3000 => panic!(),
+        4000 => (),
+        5000 => {
+            this.a_very_long_function_name(
+                foo,
+                bar,
+                bazz,
+                fizz,
+                another_argument,
+                some_more_arguments,
+                which_dont_fit,
+            )
+        }
+    }
+}
+```
+
 ## `match_block_trailing_comma`
 
 Put a trailing comma after a block based match arm (non-block arms are not affected)