From d52d13bffcc952e003aca074d2f87bdc757ea828 Mon Sep 17 00:00:00 2001
From: Anthony Van Herrewege <anthony@anthonyvh.com>
Date: Thu, 8 Aug 2024 00:56:47 +0200
Subject: [PATCH] Improve compile-time formatting

---
 include/fmt/format.h | 20 +++++++++++---------
 test/compile-test.cc |  1 +
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index 99596a1305fb..254dce18ba59 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1003,7 +1003,7 @@ template <typename Char, size_t N> struct fixed_string {
   }
   Char data[N] = {};
 };
-#endif
+#endif  // FMT_USE_NONTYPE_TEMPLATE_ARGS
 
 // Converts a compile-time string to basic_string_view.
 template <typename Char, size_t N>
@@ -3912,19 +3912,21 @@ template <typename T, typename Char>
 struct formatter<T, Char, enable_if_t<detail::has_format_as<T>::value>>
     : formatter<detail::format_as_t<T>, Char> {
   template <typename FormatContext>
-  auto format(const T& value, FormatContext& ctx) const -> decltype(ctx.out()) {
+  FMT_CONSTEXPR auto format(const T& value, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
     auto&& val = format_as(value);  // Make an lvalue reference for format.
     return formatter<detail::format_as_t<T>, Char>::format(val, ctx);
   }
 };
 
-#define FMT_FORMAT_AS(Type, Base)                                              \
-  template <typename Char>                                                     \
-  struct formatter<Type, Char> : formatter<Base, Char> {                       \
-    template <typename FormatContext>                                          \
-    auto format(Type value, FormatContext& ctx) const -> decltype(ctx.out()) { \
-      return formatter<Base, Char>::format(value, ctx);                        \
-    }                                                                          \
+#define FMT_FORMAT_AS(Type, Base)                                   \
+  template <typename Char>                                          \
+  struct formatter<Type, Char> : formatter<Base, Char> {            \
+    template <typename FormatContext>                               \
+    FMT_CONSTEXPR auto format(Type value, FormatContext& ctx) const \
+        -> decltype(ctx.out()) {                                    \
+      return formatter<Base, Char>::format(value, ctx);             \
+    }                                                               \
   }
 
 FMT_FORMAT_AS(signed char, int);
diff --git a/test/compile-test.cc b/test/compile-test.cc
index 5ba3edea2ebf..99006910ff71 100644
--- a/test/compile-test.cc
+++ b/test/compile-test.cc
@@ -334,6 +334,7 @@ TEST(compile_time_formatting_test, integer) {
   EXPECT_EQ("0X4A", test_format<5>(FMT_COMPILE("{:#X}"), 0x4a));
 
   EXPECT_EQ("   42", test_format<6>(FMT_COMPILE("{:5}"), 42));
+  EXPECT_EQ("   42", test_format<6>(FMT_COMPILE("{:5}"), 42l));
   EXPECT_EQ("   42", test_format<6>(FMT_COMPILE("{:5}"), 42ll));
   EXPECT_EQ("   42", test_format<6>(FMT_COMPILE("{:5}"), 42ull));