Require braces when a closure has an explicit return type. This is a

[breaking-change]: instead of a closure like `|| -> i32 22`, prefer `||
-> i32 { 22 }`.

Fixes #23420.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 07303ba51ff..b58c121c5fd 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -1777,7 +1777,12 @@ impl<'a> State<'a> {
                 try!(self.print_fn_block_args(&**decl));
                 try!(space(&mut self.s));
 
-                if !body.stmts.is_empty() || !body.expr.is_some() {
+                let default_return = match decl.output {
+                    ast::DefaultReturn(..) => true,
+                    _ => false
+                };
+
+                if !default_return || !body.stmts.is_empty() || body.expr.is_none() {
                     try!(self.print_block_unclosed(&**body));
                 } else {
                     // we extract the block, so as not to create another set of boxes