From 88148a9960e22aef865fc7ece6e1c96512df382a Mon Sep 17 00:00:00 2001
From: Mike Lothian <mike@fireburn.co.uk>
Date: Thu, 18 Sep 2025 01:16:13 +0100
Subject: [PATCH] fmt: Replace removed locale-based format overloads for fmt >=
 12

`fmt::format(std::locale, ...)` was removed in fmt 12, causing link errors
when building with newer versions. Update `Movie.cpp` and `State.cpp` to
conditionally use `std::ostringstream` + `std::put_time` when building
against fmt >= 12, while keeping the existing locale-aware fmt calls for
fmt 11.

This ensures Dolphin builds cleanly with both fmt 11 and 12 while
retaining localized time output.
---
 Source/Core/Core/Movie.cpp | 9 ++++++++-
 Source/Core/Core/State.cpp | 8 +++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/Source/Core/Core/Movie.cpp b/Source/Core/Core/Movie.cpp
index aee5e4707a6..30e419560a5 100644
--- a/Source/Core/Core/Movie.cpp
+++ b/Source/Core/Core/Movie.cpp
@@ -159,8 +159,15 @@ std::string MovieManager::GetRTCDisplay() const
   const time_t current_time = CEXIIPL::GetEmulatedTime(m_system, CEXIIPL::UNIX_EPOCH);
   const tm gm_time = fmt::gmtime(current_time);
 
-  // Use current locale for formatting time, as fmt is locale-agnostic by default.
+#if FMT_VERSION < 120000  // fmt < 12 still supports locale overload
   return fmt::format(std::locale{""}, "Date/Time: {:%c}", gm_time);
+#else
+  // fmt >= 12: no locale overload, fall back to standard library
+  std::ostringstream oss;
+  oss.imbue(std::locale(""));
+  oss << "Date/Time: " << std::put_time(&gm_time, "%c");
+  return oss.str();
+#endif
 }
 
 // NOTE: GPU Thread
diff --git a/Source/Core/Core/State.cpp b/Source/Core/Core/State.cpp
index ffd811bd6c7..0bcbac1fc9a 100644
--- a/Source/Core/Core/State.cpp
+++ b/Source/Core/Core/State.cpp
@@ -285,8 +285,14 @@ static std::string SystemTimeAsDoubleToString(double time)
   if (!local_time)
     return "";
 
-  // fmt is locale agnostic by default, so explicitly use current locale.
+#if FMT_VERSION < 120000  // fmt < 12 still supports locale overload
   return fmt::format(std::locale{""}, "{:%x %X}", *local_time);
+#else
+  std::ostringstream oss;
+  oss.imbue(std::locale(""));
+  oss << std::put_time(&*local_time, "%x %X");
+  return oss.str();
+#endif
 }
 
 static std::string MakeStateFilename(int number);