From 06e4ff4d61f44d7e239e02256829ecf1e5598657 Mon Sep 17 00:00:00 2001
From: Jon Gjengset <jon@thesquareplanet.com>
Date: Fri, 27 Sep 2019 17:15:17 -0400
Subject: Scope format! temporaries

This places the temporaries that `format!` generates to refer to its
arguments (through `&dyn Trait`) in a short-lived scope surrounding just
the invocation of `format!`. This enables `format!` to be used in
generators without the temporaries preventing the generator from being
`Send` (due to `dyn Trait` not being `Sync`).

See rust-lang/rust#64477 for details.
---
 src/liballoc/macros.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'src/liballoc')

diff --git a/src/liballoc/macros.rs b/src/liballoc/macros.rs
index 2f2cdc39c63..422d3486f92 100644
--- a/src/liballoc/macros.rs
+++ b/src/liballoc/macros.rs
@@ -98,5 +98,8 @@ macro_rules! vec {
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
 macro_rules! format {
-    ($($arg:tt)*) => ($crate::fmt::format($crate::__export::format_args!($($arg)*)))
+    ($($arg:tt)*) => {{
+        let res = $crate::fmt::format($crate::__export::format_args!($($arg)*));
+        res
+    }}
 }
-- 
cgit 1.4.1-3-g733a5