1 files changed, 42 insertions, 1 deletions

diff --git a/crates/libeditor/src/typing.rs b/crates/libeditor/src/typing.rs
index e7eba671f..060095f28 100644
--- a/crates/libeditor/src/typing.rs
+++ b/crates/libeditor/src/typing.rs
@@ -1,5 +1,8 @@
+use std::mem;
+
 use libsyntax2::{
-    TextUnit, TextRange, SyntaxNodeRef, File,
+    TextUnit, TextRange, SyntaxNodeRef, File, AstNode,
+    ast,
     algo::{
         walk::preorder,
         find_covering_node,
@@ -60,6 +63,9 @@ fn remove_newline(
     offset: TextUnit,
 ) {
     if node.kind() == WHITESPACE && node_text.bytes().filter(|&b| b == b'\n').count() == 1 {
+        if join_lambda_body(edit, node).is_some() {
+            return
+        }
         match (node.prev_sibling(), node.next_sibling()) {
             (Some(prev), Some(next)) => {
                 let range = TextRange::from_to(prev.range().start(), node.range().end());
@@ -91,6 +97,41 @@ fn remove_newline(
     );
 }
 
+fn join_lambda_body(
+    edit: &mut EditBuilder,
+    node: SyntaxNodeRef,
+) -> Option<()> {
+    let block = ast::Block::cast(node.parent()?)?;
+    let block_expr = ast::BlockExpr::cast(block.syntax().parent()?)?;
+    let _lambda = ast::LambdaExpr::cast(block_expr.syntax().parent()?)?;
+    let expr = single_expr(block)?;
+    edit.replace(
+        block_expr.syntax().range(),
+        expr.syntax().text(),
+    );
+    Some(())
+}
+
+fn single_expr(block: ast::Block) -> Option<ast::Expr> {
+    let mut res = None;
+    for child in block.syntax().children() {
+        if let Some(expr) = ast::Expr::cast(child) {
+            if expr.syntax().text().contains('\n') {
+                return None;
+            }
+            if mem::replace(&mut res, Some(expr)).is_some() {
+                return None;
+            }
+        } else {
+            match child.kind() {
+                WHITESPACE | L_CURLY | R_CURLY => (),
+                _ => return None,
+            }
+        }
+    }
+    res
+}
+
 fn compute_ws(left: SyntaxNodeRef, right: SyntaxNodeRef) -> &'static str {
     match left.kind() {
         L_PAREN | L_BRACK => return "",