Fix rust-lang#5662

Author: xldenis

Configurations.md

@@ -573,7 +573,6 @@ impl Lorem {
 
 See also [`brace_style`](#brace_style), [`control_brace_style`](#control_brace_style).
 
-
 ## `enum_discrim_align_threshold`
 
 The maximum length of enum variant having discriminant, that gets vertically aligned with others.
@@ -620,6 +619,74 @@ enum Bar {
 }
 ```
 
+## `enum_variant_layout`
+
+Control the layout of enum variants.
+
+- **Default value**: `"Tall"`
+- **Possible values**: `"Compressed"`, `"Tall"`, `"Vertical"`
+- **Stable**: No
+
+#### `"Tall"` (default):
+
+```rust
+enum MyType {
+    A {
+        field1: bool,
+        field2: bool,
+    },
+    #[something]
+    B {
+        field1: bool,
+        field2: bool,
+    },
+}
+
+enum T {
+    A { fieldA: T },
+    B { fieldB: U },
+}
+```
+
+#### `"Compressed"`
+
+```rust
+enum MyType {
+    A { field1: bool, field2: bool },
+    #[something]
+    B { field1: bool, field2: bool },
+}
+
+enum T {
+    A { fieldA: T },
+    B { fieldB: U },
+}
+```
+
+#### `"Vertical"`
+
+```rust
+enum MyType {
+    A {
+        field1: bool,
+        field2: bool,
+    },
+    #[something]
+    B {
+        field1: bool,
+        field2: bool,
+    },
+}
+
+enum T {
+    A {
+        fieldA: T,
+    },
+    B {
+        fieldB: U,
+    },
+}
+```
 
 ## `error_on_line_overflow`
 

src/config/mod.rs

@@ -148,6 +148,8 @@ create_config! {
         "Write an item and its attribute on the same line \
         if their combined width is below a threshold";
     format_generated_files: bool, true, false, "Format generated files";
+    enum_variant_layout: Density, Density::Tall, false,
+        "Control the layout of enum variants";
 
     // Options that can change the source code beyond whitespace/blocks (somewhat linty things)
     merge_derives: bool, true, true, "Merge multiple `#[derive(...)]` into a single one";
@@ -667,6 +669,7 @@ edition = "2015"
 version = "One"
 inline_attribute_width = 0
 format_generated_files = true
+enum_variant_layout = "Tall"
 merge_derives = true
 use_try_shorthand = false
 use_field_init_shorthand = false

src/items.rs

@@ -14,13 +14,15 @@ use crate::comment::{
     recover_comment_removed, recover_missing_comment_in_span, rewrite_missing_comment,
     FindUncommented,
 };
-use crate::config::lists::*;
+use crate::config::{lists::*, Density};
 use crate::config::{BraceStyle, Config, IndentStyle, Version};
 use crate::expr::{
     is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
     rewrite_assign_rhs_with_comments, RhsAssignKind, RhsTactics,
 };
-use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
+use crate::lists::{
+    definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator,
+};
 use crate::macros::{rewrite_macro, MacroPosition};
 use crate::overflow;
 use crate::rewrite::{Rewrite, RewriteContext};
@@ -515,11 +517,32 @@ impl<'a> FmtVisitor<'a> {
         };
         let mut items: Vec<_> = itemize_list_with(self.config.struct_variant_width());
 
+        let is_multiline_variant = |item: &ListItem| {
+            item.inner_as_ref()
+                .lines()
+                .skip_while(|l| {
+                    if self.config.enum_variant_layout() == Density::Compressed {
+                        l.trim_start().starts_with("#") || l.trim_start().starts_with("///")
+                    } else {
+                        false
+                    }
+                })
+                .count()
+                > 1
+        };
+
         // If one of the variants use multiple lines, use multi-lined formatting for all variants.
-        let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
-        let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
-        if has_multiline_variant && has_single_line_variant {
-            items = itemize_list_with(0);
+        let has_multiline_variant = items.iter().any(|item| is_multiline_variant(item));
+        let has_single_line_variant = items
+            .iter()
+            .any(|item| item.inner_as_ref().lines().count() == 1);
+
+        match self.config.enum_variant_layout() {
+            Density::Vertical => items = itemize_list_with(0),
+            Density::Tall if has_multiline_variant && has_single_line_variant => {
+                items = itemize_list_with(0)
+            }
+            _ => {}
         }
 
         let shape = self.shape().sub_width(2)?;

tests/source/configs/enum_variant_layout/compressed.rs

@@ -0,0 +1,20 @@
+// rustfmt-enum_variant_layout: Compressed
+
+pub enum MultiAndSingleLine {
+    A { field1: () },
+    #[attr]
+    B { field1 : (), field2: (), },
+}
+
+enum SingleLine {
+    A { field: () },
+    B { test: () },
+}
+
+enum MyType {
+    A { field1: bool, field2: bool },
+    B { field1: bool, field2: bool },
+    /// OMG a comment
+    C { field1: bool, field2: bool },
+    D { field1: bool, field2: bool },
+}

tests/source/configs/enum_variant_layout/tall.rs

@@ -0,0 +1,12 @@
+// rustfmt-enum_variant_layout: Tall
+
+pub enum MultiAndSingleLine {
+    A { field1: () },
+    #[attr]
+    B { field1 : (), field2: (), },
+}
+
+enum SingleLine {
+    A { field: () },
+    B { test: () },
+}

tests/source/configs/enum_variant_layout/vertical.rs

@@ -0,0 +1,12 @@
+// rustfmt-enum_variant_layout: Vertical
+
+pub enum MultiAndSingleLine {
+    A { field1: () },
+    #[attr]
+    B { field1: (), field2: (), },
+}
+
+enum SingleLine {
+    A { field: () },
+    B { test: () },
+}

tests/target/configs/enum_variant_layout/compressed.rs

@@ -0,0 +1,20 @@
+// rustfmt-enum_variant_layout: Compressed
+
+pub enum MultiAndSingleLine {
+    A { field1: () },
+    #[attr]
+    B { field1: (), field2: () },
+}
+
+enum SingleLine {
+    A { field: () },
+    B { test: () },
+}
+
+enum MyType {
+    A { field1: bool, field2: bool },
+    B { field1: bool, field2: bool },
+    /// OMG a comment
+    C { field1: bool, field2: bool },
+    D { field1: bool, field2: bool },
+}

tests/target/configs/enum_variant_layout/tall.rs

@@ -0,0 +1,17 @@
+// rustfmt-enum_variant_layout: Tall
+
+pub enum MultiAndSingleLine {
+    A {
+        field1: (),
+    },
+    #[attr]
+    B {
+        field1: (),
+        field2: (),
+    },
+}
+
+enum SingleLine {
+    A { field: () },
+    B { test: () },
+}

tests/target/configs/enum_variant_layout/vertical.rs

@@ -0,0 +1,21 @@
+// rustfmt-enum_variant_layout: Vertical
+
+pub enum MultiAndSingleLine {
+    A {
+        field1: (),
+    },
+    #[attr]
+    B {
+        field1: (),
+        field2: (),
+    },
+}
+
+enum SingleLine {
+    A {
+        field: (),
+    },
+    B {
+        test: (),
+    },
+}