Use an explicit flag to decide on whether to add brace compensation

src/closures.rs

@@ -131,7 +131,8 @@ fn rewrite_closure_with_block(
         rules: ast::BlockCheckMode::Default,
         span: body.span,
     };
-    rewrite_closure_block(&block, prefix, context, shape)
+    let block = ::expr::rewrite_block_with_visitor(context, "", &block, shape, true)?;
+    Some(format!("{} {}", prefix, block))
 }
 
 // Rewrite closure with a single expression without wrapping its body with block.

src/expr.rs

@@ -116,7 +116,7 @@ pub fn format_expr(
                         rw
                     } else {
                         let prefix = block_prefix(context, block, shape)?;
-                        rewrite_block_with_visitor(context, &prefix, block, shape)
+                        rewrite_block_with_visitor(context, &prefix, block, shape, false)
                     }
                 }
                 ExprType::SubExpression => block.rewrite(context, shape),
@@ -598,11 +598,12 @@ fn rewrite_single_line_block(
     None
 }
 
-fn rewrite_block_with_visitor(
+pub fn rewrite_block_with_visitor(
     context: &RewriteContext,
     prefix: &str,
     block: &ast::Block,
     shape: Shape,
+    is_dummy: bool,
 ) -> Option<String> {
     if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
         return rw;
@@ -620,7 +621,7 @@ fn rewrite_block_with_visitor(
         ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
     }
 
-    visitor.visit_block(block, None);
+    visitor.visit_block(block, None, is_dummy);
     Some(format!("{}{}", prefix, visitor.buffer))
 }
 
@@ -634,7 +635,7 @@ impl Rewrite for ast::Block {
 
         let prefix = block_prefix(context, self, shape)?;
 
-        let result = rewrite_block_with_visitor(context, &prefix, self, shape);
+        let result = rewrite_block_with_visitor(context, &prefix, self, shape, false);
         if let Some(ref result_str) = result {
             if result_str.lines().count() <= 3 {
                 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, self, shape) {
@@ -1064,7 +1065,8 @@ impl<'a> Rewrite for ControlFlow<'a> {
         };
         let mut block_context = context.clone();
         block_context.is_if_else_block = self.else_block.is_some();
-        let block_str = rewrite_block_with_visitor(&block_context, "", self.block, block_shape)?;
+        let block_str =
+            rewrite_block_with_visitor(&block_context, "", self.block, block_shape, false)?;
 
         let mut result = format!("{}{}", cond_str, block_str);
 

src/visitor.rs

@@ -90,7 +90,12 @@ impl<'a> FmtVisitor<'a> {
         }
     }
 
-    pub fn visit_block(&mut self, b: &ast::Block, inner_attrs: Option<&[ast::Attribute]>) {
+    pub fn visit_block(
+        &mut self,
+        b: &ast::Block,
+        inner_attrs: Option<&[ast::Attribute]>,
+        is_dummy: bool,
+    ) {
         debug!(
             "visit_block: {:?} {:?}",
             self.codemap.lookup_char_pos(b.span.lo()),
@@ -98,9 +103,7 @@ impl<'a> FmtVisitor<'a> {
         );
 
         // Check if this block has braces.
-        let snippet = self.snippet(b.span);
-        let has_braces = snippet.starts_with('{') || snippet.starts_with("unsafe");
-        let brace_compensation = if has_braces { BytePos(1) } else { BytePos(0) };
+        let brace_compensation = BytePos(if is_dummy { 0 } else { 1 });
 
         self.last_pos = self.last_pos + brace_compensation;
         self.block_indent = self.block_indent.block_indent(self.config);
@@ -272,7 +275,7 @@ impl<'a> FmtVisitor<'a> {
         }
 
         self.last_pos = source!(self, block.span).lo();
-        self.visit_block(block, inner_attrs)
+        self.visit_block(block, inner_attrs, false)
     }
 
     pub fn visit_item(&mut self, item: &ast::Item) {