From 0166f455f6681144a18553d2ea0cda8946bff019 Mon Sep 17 00:00:00 2001
From: prlw1 <prlw1@cam.ac.uk>
Date: Mon, 19 Feb 2024 18:19:39 +0000
Subject: [PATCH] std.h c++23 build fix (#3856)

Add ::value to is_formattable<...> as per suggestion by @vitaut in
https://github.com/fmtlib/fmt/issues/3854
---
 include/fmt/std.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/fmt/std.h b/include/fmt/std.h
index ff96a9525f23..12e15d3ecb51 100644
--- a/include/fmt/std.h
+++ b/include/fmt/std.h
@@ -269,9 +269,9 @@ FMT_BEGIN_NAMESPACE
 
 FMT_EXPORT
 template <typename T, typename E, typename Char>
-struct formatter<
-    std::expected<T, E>, Char,
-    std::enable_if_t<is_formattable<T, Char> && is_formattable<E, Char>>> {
+struct formatter<std::expected<T, E>, Char,
+                 std::enable_if_t<is_formattable<T, Char>::value &&
+                                  is_formattable<E, Char>::value>> {
   template <typename ParseContext>
   FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
     return ctx.begin();