From 52ed89ae8c264d8885bfda4f79033289db459c02 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Thu, 28 May 2020 10:31:38 +0200
Subject: [PATCH] from_u32_unchecked: check validity when debug assertions are
 enabled

---
 src/libcore/char/convert.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libcore/char/convert.rs b/src/libcore/char/convert.rs
index 315020bac585..87c56c4b0a10 100644
--- a/src/libcore/char/convert.rs
+++ b/src/libcore/char/convert.rs
@@ -99,7 +99,7 @@ pub fn from_u32(i: u32) -> Option<char> {
 #[inline]
 #[stable(feature = "char_from_unchecked", since = "1.5.0")]
 pub unsafe fn from_u32_unchecked(i: u32) -> char {
-    transmute(i)
+    if cfg!(debug_assertions) { char::from_u32(i).unwrap() } else { transmute(i) }
 }
 
 #[stable(feature = "char_convert", since = "1.13.0")]
@@ -218,7 +218,7 @@ impl TryFrom<u32> for char {
             Err(CharTryFromError(()))
         } else {
             // SAFETY: checked that it's a legal unicode value
-            Ok(unsafe { from_u32_unchecked(i) })
+            Ok(unsafe { transmute(i) })
         }
     }
 }