catch exceptions during flush and cal handler

include/spdlog/details/logger_impl.h

@@ -278,7 +278,18 @@ inline spdlog::log_err_handler spdlog::logger::error_handler()
 
 inline void spdlog::logger::flush()
 {
-    _flush();
+	try 
+	{
+		_flush();
+	}
+	catch (const std::exception &ex)
+	{
+		_err_handler(ex.what());
+	}
+	catch (...)
+	{
+		_err_handler("Unknown exception in logger during flush: " + _name);
+	}
 }
 
 inline void spdlog::logger::flush_on(level::level_enum log_level)

tests/errors.cpp

@@ -7,16 +7,20 @@
 
 class failing_sink : public spdlog::sinks::sink
 {
-    void log(const spdlog::details::log_msg &msg) override
+    void log(const spdlog::details::log_msg &) override
     {
         throw std::runtime_error("some error happened during log");
     }
 
-    void flush() override {}
+    void flush() override
+	{
+		throw std::runtime_error("some error happened during flush");
+	}
 };
 
 TEST_CASE("default_error_handler", "[errors]]")
 {
+	spdlog::drop_all();
     prepare_logdir();
     std::string filename = "logs/simple_log.txt";
 
@@ -40,11 +44,12 @@ struct custom_ex
 };
 TEST_CASE("custom_error_handler", "[errors]]")
 {
+	spdlog::drop_all();
     prepare_logdir();
     std::string filename = "logs/simple_log.txt";
     auto logger = spdlog::create<spdlog::sinks::simple_file_sink_mt>("logger", filename, true);
     logger->flush_on(spdlog::level::info);
-    logger->set_error_handler([=](const std::string &msg) { throw custom_ex(); });
+    logger->set_error_handler([=](const std::string &) { throw custom_ex(); });
     logger->info("Good message #1");
 #if !defined(SPDLOG_FMT_PRINTF)
     REQUIRE_THROWS_AS(logger->info("Bad format msg {} {}", "xxx"), custom_ex);
@@ -57,14 +62,23 @@ TEST_CASE("custom_error_handler", "[errors]]")
 
 TEST_CASE("default_error_handler2", "[errors]]")
 {
-
+	spdlog::drop_all();
     auto logger = spdlog::create<failing_sink>("failed_logger");
-    logger->set_error_handler([=](const std::string &msg) { throw custom_ex(); });
+    logger->set_error_handler([=](const std::string &) { throw custom_ex(); });
     REQUIRE_THROWS_AS(logger->info("Some message"), custom_ex);
 }
 
+TEST_CASE("flush_error_handler", "[errors]]")
+{
+	spdlog::drop_all();
+	auto logger = spdlog::create<failing_sink>("failed_logger");
+	logger->set_error_handler([=](const std::string &) { throw custom_ex(); });
+	REQUIRE_THROWS_AS(logger->flush(), custom_ex);
+}
+
 TEST_CASE("async_error_handler", "[errors]]")
 {
+	spdlog::drop_all();
     prepare_logdir();
     std::string err_msg("log failed with some msg");
 
@@ -72,7 +86,7 @@ TEST_CASE("async_error_handler", "[errors]]")
     {
         spdlog::init_thread_pool(128, 1);
         auto logger = spdlog::create_async_logger<spdlog::sinks::simple_file_sink_mt>("logger", filename, true);
-        logger->set_error_handler([=](const std::string &msg) {
+        logger->set_error_handler([=](const std::string &) {
             std::ofstream ofs("logs/custom_err.txt");
             if (!ofs)
                 throw std::runtime_error("Failed open logs/custom_err.txt");
@@ -95,12 +109,13 @@ TEST_CASE("async_error_handler", "[errors]]")
 // Make sure async error handler is executed
 TEST_CASE("async_error_handler2", "[errors]]")
 {
+	spdlog::drop_all();
     prepare_logdir();
     std::string err_msg("This is async handler error message");
     {
         spdlog::init_thread_pool(128, 1);
         auto logger = spdlog::create_async_logger<failing_sink>("failed_logger");
-        logger->set_error_handler([=](const std::string &msg) {
+        logger->set_error_handler([=](const std::string &) {
             std::ofstream ofs("logs/custom_err2.txt");
             if (!ofs)
                 throw std::runtime_error("Failed open logs/custom_err2.txt");