From b48274fd98b74c1fb28842d899aa0ee377d9f923 Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Fri, 9 Jul 2021 17:29:41 +0200
Subject: [PATCH] Use unreachable_unchecked in const_panic_fmt.

---
 library/core/src/panicking.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/library/core/src/panicking.rs b/library/core/src/panicking.rs
index 03398869466c..65267a417cb4 100644
--- a/library/core/src/panicking.rs
+++ b/library/core/src/panicking.rs
@@ -100,7 +100,10 @@ pub const fn const_panic_fmt(fmt: fmt::Arguments<'_>) -> ! {
     if let Some(msg) = fmt.as_str() {
         panic_str(msg);
     } else {
-        panic_str("???");
+        // SAFETY: This is only evaluated at compile time, which handles this
+        // fine (in case it turns out this branch turns out to be reachable
+        // somehow).
+        unsafe { crate::hint::unreachable_unchecked() };
     }
 }