Auto merge of #15651 - rmehri01:15639_fix_inline_local_closure, r=lnicola

Fix inlining closures from local variables and functions

Previously, closures were not properly wrapped in parentheses for the `inline_local_variable` and `inline_call` assists, leading to the usages being incorrectly called:

```rust
fn main() {
    let $0f = || 2;
    let _ = f();
}
```

Now produces:

```rust
fn main() {
    let _ = (|| 2)();
}
```

Instead of:

```rust
fn main() {
    let _ = || 2();
}
```

Closes #15639

Author: bors

crates/ide-assists/src/handlers/inline_call.rs

@@ -481,8 +481,12 @@ fn inline(
     };
     body.reindent_to(original_indentation);
 
+    let no_stmts = body.statements().next().is_none();
     match body.tail_expr() {
-        Some(expr) if !is_async_fn && body.statements().next().is_none() => expr,
+        Some(expr) if matches!(expr, ast::Expr::ClosureExpr(_)) && no_stmts => {
+            make::expr_paren(expr).clone_for_update()
+        }
+        Some(expr) if !is_async_fn && no_stmts => expr,
         _ => match node
             .syntax()
             .parent()
@@ -1471,6 +1475,31 @@ fn main() {
         }
     });
 }
+"#,
+        );
+    }
+
+    #[test]
+    fn inline_call_closure_body() {
+        check_assist(
+            inline_call,
+            r#"
+fn f() -> impl Fn() -> i32 {
+    || 2
+}
+
+fn main() {
+    let _ = $0f()();
+}
+"#,
+            r#"
+fn f() -> impl Fn() -> i32 {
+    || 2
+}
+
+fn main() {
+    let _ = (|| 2)();
+}
 "#,
         );
     }

crates/ide-assists/src/handlers/inline_local_variable.rs

@@ -96,8 +96,7 @@ pub(crate) fn inline_local_variable(acc: &mut Assists, ctx: &AssistContext<'_>)
             );
             let parent = matches!(
                 usage_parent,
-                ast::Expr::CallExpr(_)
-                    | ast::Expr::TupleExpr(_)
+                ast::Expr::TupleExpr(_)
                     | ast::Expr::ArrayExpr(_)
                     | ast::Expr::ParenExpr(_)
                     | ast::Expr::ForExpr(_)
@@ -949,6 +948,24 @@ fn f() {
     let S$0 = S;
     S;
 }
+"#,
+        );
+    }
+
+    #[test]
+    fn test_inline_closure() {
+        check_assist(
+            inline_local_variable,
+            r#"
+fn main() {
+    let $0f = || 2;
+    let _ = f();
+}
+"#,
+            r#"
+fn main() {
+    let _ = (|| 2)();
+}
 "#,
         );
     }