4 files changed, 82 insertions, 13 deletions

diff --git a/crates/ra_fmt/src/lib.rs b/crates/ra_fmt/src/lib.rs
index 0b4ba1bbe..1a30b2b3a 100644
--- a/crates/ra_fmt/src/lib.rs
+++ b/crates/ra_fmt/src/lib.rs
@@ -57,18 +57,17 @@ pub fn extract_trivial_expression(block: &ast::BlockExpr) -> Option<ast::Expr> {
             return None;
         }
         return Some(expr);
-    } else {
-        // Unwrap `{ continue; }`
-        let (stmt,) = block.statements().next_tuple()?;
-        if let ast::Stmt::ExprStmt(expr_stmt) = stmt {
-            if has_anything_else(expr_stmt.syntax()) {
-                return None;
-            }
-            let expr = expr_stmt.expr()?;
-            match expr.syntax().kind() {
-                CONTINUE_EXPR | BREAK_EXPR | RETURN_EXPR => return Some(expr),
-                _ => (),
-            }
+    }
+    // Unwrap `{ continue; }`
+    let (stmt,) = block.statements().next_tuple()?;
+    if let ast::Stmt::ExprStmt(expr_stmt) = stmt {
+        if has_anything_else(expr_stmt.syntax()) {
+            return None;
+        }
+        let expr = expr_stmt.expr()?;
+        match expr.syntax().kind() {
+            CONTINUE_EXPR | BREAK_EXPR | RETURN_EXPR => return Some(expr),
+            _ => (),
         }
     }
     None
diff --git a/crates/ra_ide/src/join_lines.rs b/crates/ra_ide/src/join_lines.rs
index fde0bfa98..d0def7eaa 100644
--- a/crates/ra_ide/src/join_lines.rs
+++ b/crates/ra_ide/src/join_lines.rs
@@ -131,6 +131,9 @@ fn has_comma_after(node: &SyntaxNode) -> bool {
 fn join_single_expr_block(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
     let block = ast::Block::cast(token.parent())?;
     let block_expr = ast::BlockExpr::cast(block.syntax().parent()?)?;
+    if !block_expr.is_standalone() {
+        return None;
+    }
     let expr = extract_trivial_expression(&block_expr)?;
 
     let block_range = block_expr.syntax().text_range();
@@ -662,4 +665,67 @@ fn main() {
         ",
         )
     }
+
+    #[test]
+    fn join_lines_mandatory_blocks_block() {
+        check_join_lines(
+            r"
+<|>fn foo() {
+    92
+}
+        ",
+            r"
+<|>fn foo() { 92
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>if true {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>if true { 92
+    }
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>loop {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>loop { 92
+    }
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>unsafe {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>unsafe { 92
+    }
+}
+        ",
+        );
+    }
 }
diff --git a/crates/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 93aa3d45f..ecf74fd36 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -368,12 +368,15 @@ impl ast::BlockExpr {
     /// const FOO: () = { stand_alone };
     /// ```
     pub fn is_standalone(&self) -> bool {
+        if self.unsafe_token().is_some() || self.async_token().is_some() {
+            return false;
+        }
         let kind = match self.syntax().parent() {
             None => return true,
             Some(it) => it.kind(),
         };
         match kind {
-            FN_DEF | MATCH_ARM | IF_EXPR | WHILE_EXPR | LOOP_EXPR | TRY_BLOCK_EXPR => false,
+            FN_DEF | IF_EXPR | WHILE_EXPR | LOOP_EXPR | TRY_BLOCK_EXPR => false,
             _ => true,
         }
     }
diff --git a/crates/ra_syntax/src/ast/generated/nodes.rs b/crates/ra_syntax/src/ast/generated/nodes.rs
index 3b5e05af9..d2253d4af 100644
--- a/crates/ra_syntax/src/ast/generated/nodes.rs
+++ b/crates/ra_syntax/src/ast/generated/nodes.rs
@@ -554,6 +554,7 @@ impl ast::AttrsOwner for BlockExpr {}
 impl BlockExpr {
     pub fn label(&self) -> Option<Label> { support::child(&self.syntax) }
     pub fn unsafe_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![unsafe]) }
+    pub fn async_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![async]) }
     pub fn block(&self) -> Option<Block> { support::child(&self.syntax) }
 }