From a2fd48e039c9f1cdfc7e4b7e8d0c601ae558dbee Mon Sep 17 00:00:00 2001
From: SnapperTT <4939563+SnapperTT@users.noreply.github.com>
Date: Thu, 25 Sep 2025 03:30:41 +0930
Subject: [PATCH] Make FMT_USE_CONSTEVAL optional #4545 (#4546)

---
 include/fmt/base.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/fmt/base.h b/include/fmt/base.h
index a1ddd537..4b687a8f 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -114,7 +114,9 @@
 #endif
 
 // Detect consteval, C++20 constexpr extensions and std::is_constant_evaluated.
-#if !defined(__cpp_lib_is_constant_evaluated)
+#ifdef FMT_USE_CONSTEVAL
+// Use the provided definition.
+#elif !defined(__cpp_lib_is_constant_evaluated)
 #  define FMT_USE_CONSTEVAL 0
 #elif FMT_CPLUSPLUS < 201709L
 #  define FMT_USE_CONSTEVAL 0