From 9b8f44cdaea3677731fc83c15f8ee4681cbc4470 Mon Sep 17 00:00:00 2001
From: Jack Lloyd <jack@randombit.net>
Date: Wed, 10 Apr 2024 09:27:53 -0400
Subject: [PATCH] New approach for checked_cast
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Co-authored-by: René Meusel <github@renemeusel.de>
---
 src/lib/utils/int_utils.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/lib/utils/int_utils.h b/src/lib/utils/int_utils.h
index 95b31e16db5..2c943f4d402 100644
--- a/src/lib/utils/int_utils.h
+++ b/src/lib/utils/int_utils.h
@@ -9,6 +9,7 @@
 
 #include <botan/concepts.h>
 #include <botan/types.h>
+#include <limits>
 #include <optional>
 
 namespace Botan {
@@ -46,13 +47,12 @@ constexpr inline std::optional<T> checked_mul(T a, T b) {
    return r;
 }
 
-template <std::unsigned_integral T, std::unsigned_integral RT>
-std::optional<RT> checked_cast(T input) {
-   const RT cast = static_cast<RT>(input);
-   if(static_cast<T>(cast) != input) {
+template <std::unsigned_integral ReturnT>
+constexpr inline std::optional<ReturnT> checked_cast(std::unsigned_integral auto input) {
+   if(std::numeric_limits<ReturnT>::max() < input) {
       return {};
    }
-   return cast;
+   return static_cast<ReturnT>(input);
 }
 
 }  // namespace Botan