Add overflow_closures and overflow_match_arms opts

overflow_closures = true:
    result.and_then(|maybe_value| match maybe_value {
        None => ...,
        Some(value) => ...,
    })

overflow_closures = false:
    result.and_then(|maybe_value| {
        match maybe_value {
            None => ...,
            Some(value) => ...,
        }
    })

overflow_match_arms = true:
    match lorem {
        None => if ipsum {
            println!("Hello World");
        },
        Some(dolor) => ...,
    }

overflow_match_arms = false:
    match lorem {
        None => {
            if ipsum {
                println!("Hello World");
            }
        }
        Some(dolor) => ...,
    }

Configurations.md

@@ -1206,6 +1206,64 @@ fn dolor() -> usize {}
 fn adipiscing() -> usize {}
 ```
 
+## `overflow_closures`
+
+Allow overflow on closures
+
+- **Default value**: `true`
+- **Possible values**: `true`, `false`
+
+#### `true`:
+
+```rust
+result.and_then(|maybe_value| match maybe_value {
+    None => ...,
+    Some(value) => ...,
+})
+```
+
+#### `false`:
+
+```rust
+result.and_then(|maybe_value| {
+    match maybe_value {
+        None => ...,
+        Some(value) => ...,
+    }
+})
+```
+
+## `overflow_match_arms`
+
+Allow overflow on match arms
+
+- **Default value**: `true`
+- **Possible values**: `true`, `false`
+
+#### `true`:
+
+```rust
+match lorem {
+    None => if ipsum {
+        println!("Hello World");
+    },
+    Some(dolor) => ...,
+}
+```
+
+#### `false`:
+
+```rust
+match lorem {
+    None => {
+        if ipsum {
+            println!("Hello World");
+        }
+    }
+    Some(dolor) => ...,
+}
+```
+
 ## `reorder_imported_names`
 
 Reorder lists of names in import statements alphabetically

src/config.rs

@@ -609,6 +609,8 @@ create_config! {
                                              threshold.";
     remove_blank_lines_at_start_or_end_of_block: bool, true,
         "Remove blank lines at start or end of a block";
+    overflow_match_arms: bool, true, "Allow overflow on match arms.";
+    overflow_closures: bool, true, "Allow overflow on closures.";
 }
 
 #[cfg(test)]

src/expr.rs

@@ -688,6 +688,13 @@ fn rewrite_closure_expr(
     if classify::expr_requires_semi_to_be_stmt(left_most_sub_expr(expr)) {
         rewrite = and_one_line(rewrite);
     }
+    rewrite = rewrite.and_then(|rw| {
+        if !context.config.overflow_closures() && rw.contains('\n') {
+            None
+        } else {
+            Some(rw)
+        }
+    });
     rewrite.map(|rw| format!("{} {}", prefix, rw))
 }
 
@@ -1697,12 +1704,18 @@ fn rewrite_match_body(
             if !is_unsafe_block(block) && is_simple_block(block, context.codemap) =>
         {
             if let ast::StmtKind::Expr(ref expr) = block.stmts[0].node {
-                (expr.can_be_overflowed(context, 1), &**expr)
+                (
+                    context.config.overflow_match_arms() && expr.can_be_overflowed(context, 1),
+                    &**expr,
+                )
             } else {
                 (false, &**body)
             }
         }
-        _ => (body.can_be_overflowed(context, 1), &**body),
+        _ => (
+            context.config.overflow_match_arms() && body.can_be_overflowed(context, 1),
+            &**body,
+        ),
     };
 
     let comma = arm_comma(&context.config, body);

tests/source/configs-overflow_match_arms-false.rs

@@ -0,0 +1,11 @@
+// rustfmt-overflow_match_arms: false
+// Overflowing match arms
+
+fn main() {
+    match lorem {
+        Lorem::Ipsum => if ipsum {
+            println!("dolor");
+        },
+        Lorem::Dolor => println!("amet"),
+    }
+}

tests/source/configs-overflow_match_arms-true.rs

@@ -0,0 +1,13 @@
+// rustfmt-overflow_match_arms: true
+// Overflowing match arms
+
+fn main() {
+    match lorem {
+        Lorem::Ipsum => {
+            if ipsum {
+                println!("dolor");
+            }
+        }
+        Lorem::Dolor => println!("amet"),
+    }
+}

tests/target/configs-overflow_match_arms-false.rs

@@ -0,0 +1,13 @@
+// rustfmt-overflow_match_arms: false
+// Overflowing match arms
+
+fn main() {
+    match lorem {
+        Lorem::Ipsum => {
+            if ipsum {
+                println!("dolor");
+            }
+        }
+        Lorem::Dolor => println!("amet"),
+    }
+}

tests/target/configs-overflow_match_arms-true.rs

@@ -0,0 +1,11 @@
+// rustfmt-overflow_match_arms: true
+// Overflowing match arms
+
+fn main() {
+    match lorem {
+        Lorem::Ipsum => if ipsum {
+            println!("dolor");
+        },
+        Lorem::Dolor => println!("amet"),
+    }
+}