Merge pull request #384 from nrc/where-empty

Option for putting the where clause on the same line as the function …

src/config.rs

@@ -74,6 +74,8 @@ pub enum Density {
     Compressed,
     // Use more lines.
     Tall,
+    // Try to compress if the body is empty.
+    CompressedIfEmpty,
 }
 
 impl_enum_decodable!(Density, Compressed, Tall);
@@ -82,7 +84,7 @@ impl Density {
     pub fn to_list_tactic(self) -> ListTactic {
         match self {
             Density::Compressed => ListTactic::Mixed,
-            Density::Tall => ListTactic::HorizontalVertical,
+            Density::Tall | Density::CompressedIfEmpty => ListTactic::HorizontalVertical,
         }
     }
 }
@@ -267,7 +269,7 @@ impl Default for Config {
             fn_args_density: Density::Tall,
             fn_args_layout: StructLitStyle::Visual,
             fn_arg_indent: BlockIndentStyle::Visual,
-            where_density: Density::Tall,
+            where_density: Density::CompressedIfEmpty,
             where_indent: BlockIndentStyle::Tabbed,
             where_layout: ListTactic::Vertical,
             where_pred_indent: BlockIndentStyle::Visual,

src/items.rs

@@ -144,6 +144,7 @@ impl<'a> FmtVisitor<'a> {
                                                    abi::Abi::Rust,
                                                    ast::Visibility::Inherited,
                                                    span,
+                                                   false,
                                                    false);
 
                 match rewrite {
@@ -210,7 +211,8 @@ impl<'a> FmtVisitor<'a> {
                                                        abi,
                                                        vis,
                                                        span,
-                                                       newline_brace));
+                                                       newline_brace,
+                                                       true));
 
         if self.config.fn_brace_style != BraceStyle::AlwaysNextLine && !result.contains('\n') {
             newline_brace = false;
@@ -250,6 +252,7 @@ impl<'a> FmtVisitor<'a> {
                                                        sig.abi,
                                                        ast::Visibility::Inherited,
                                                        span,
+                                                       false,
                                                        false));
 
         // Re-attach semicolon
@@ -269,7 +272,8 @@ impl<'a> FmtVisitor<'a> {
                        abi: abi::Abi,
                        vis: ast::Visibility,
                        span: Span,
-                       newline_brace: bool)
+                       newline_brace: bool,
+                       has_body: bool)
                        -> Option<String> {
         // FIXME we'll lose any comments in between parts of the function decl, but anyone
         // who comments there probably deserves what they get.
@@ -407,7 +411,9 @@ impl<'a> FmtVisitor<'a> {
                                 (!result.contains('\n') ||
                                  self.config.fn_args_layout == StructLitStyle::Block)) ||
                                (self.config.fn_args_layout == StructLitStyle::Block &&
-                                ret_str.is_empty()) {
+                                ret_str.is_empty()) ||
+                               (self.config.where_density == Density::CompressedIfEmpty &&
+                                !has_body) {
             Density::Compressed
         } else {
             Density::Tall

tests/target/trait.rs

@@ -15,8 +15,7 @@ trait Foo {
 
     fn increment(&mut self, x: i32);
 
-    fn read(&mut self, x: BufReader<R> /* Used to be MemReader */)
-        where R: Read;
+    fn read(&mut self, x: BufReader<R> /* Used to be MemReader */) where R: Read;
 }
 
 pub trait WriteMessage {