backward compatibility with fmt version < 8

bench/async_bench.cpp

@@ -103,12 +103,11 @@ int main(int argc, char *argv[])
 
         auto slot_size = sizeof(spdlog::details::async_msg);
         spdlog::info("-------------------------------------------------");
-        spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Messages     : {:L}", howmany));
-        spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Threads      : {:L}", threads));
-        spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Queue        : {:L} slots", queue_size));
-        spdlog::info(fmt::format(
-            std::locale("en_US.UTF-8"), "Queue memory : {:L} x {:L} = {:L} KB ", queue_size, slot_size, (queue_size * slot_size) / 1024));
-        spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Total iters  : {:L}", iters));
+        spdlog::info("Messages     : {:L}", howmany);
+        spdlog::info("Threads      : {:L}", threads);
+        spdlog::info("Queue        : {:L} slots", queue_size);
+        spdlog::info("Queue memory : {:L} x {:L} = {:L} KB ", queue_size, slot_size, (queue_size * slot_size) / 1024);
+        spdlog::info("Total iters  : {:L}", iters);
         spdlog::info("-------------------------------------------------");
 
         const char *filename = "logs/basic_async.log";
@@ -181,5 +180,5 @@ void bench_mt(int howmany, std::shared_ptr<spdlog::logger> logger, int thread_co
 
     auto delta = high_resolution_clock::now() - start;
     auto delta_d = duration_cast<duration<double>>(delta).count();
-    spdlog::info(fmt::format(std::locale("en_US.UTF-8"), "Elapsed: {} secs\t {:L}/sec", delta_d, int(howmany / delta_d)));
+    spdlog::info("Elapsed: {} secs\t {:L}/sec", delta_d, int(howmany / delta_d));
 }

include/spdlog/common.h

@@ -35,8 +35,14 @@
 
 #include <spdlog/fmt/fmt.h>
 
-#if defined(SPDLOG_WCHAR_FILENAMES) || defined(SPDLOG_WCHAR_TO_UTF8_SUPPORT)
-#    include <spdlog/fmt/xchar.h>
+// backward compatibility with fmt versions older than 8
+#if FMT_VERSION >= 80000
+#    define SPDLOG_FMT_RUNTIME(format_string) fmt::runtime(format_string)
+#    if defined(SPDLOG_WCHAR_FILENAMES) || defined(SPDLOG_WCHAR_TO_UTF8_SUPPORT)
+#        include <spdlog/fmt/xchar.h>
+#    endif
+#else
+#    define SPDLOG_FMT_RUNTIME(format_string) format_string
 #endif
 
 // visual studio upto 2013 does not support noexcept nor constexpr

include/spdlog/logger.h

@@ -341,7 +341,7 @@ protected:
         SPDLOG_TRY
         {
             memory_buf_t buf;
-            fmt::format_to(std::back_inserter(buf), fmt::runtime(fmt), std::forward<Args>(args)...);
+            fmt::format_to(std::back_inserter(buf), SPDLOG_FMT_RUNTIME(fmt), std::forward<Args>(args)...);
             details::log_msg log_msg(loc, name_, lvl, string_view_t(buf.data(), buf.size()));
             log_it_(log_msg, log_enabled, traceback_enabled);
         }

include/spdlog/sinks/daily_file_sink.h

@@ -53,7 +53,7 @@ struct daily_filename_format_calculator
 #if defined(_MSC_VER) && defined(SPDLOG_WCHAR_FILENAMES) // for some reason msvc doesnt allow fmt::runtime(..) with wchar here
         return fmt::format(fmt_filename, now_tm);
 #else
-        return fmt::format(fmt::runtime(fmt_filename), now_tm);
+        return fmt::format(SPDLOG_FMT_RUNTIME(fmt_filename), now_tm);
 #endif
     }
 };