fix/issue-3101: fix the issue where mdc ignores SPDLOG_NO_TLS

example/example.cpp

@@ -382,7 +382,9 @@ void replace_default_logger_example() {
 // Mapped Diagnostic Context (MDC) is a map that stores key-value pairs (string values) in thread local storage.
 // Each thread maintains its own MDC, which loggers use to append diagnostic information to log outputs.
 // Note: it is not supported in asynchronous mode due to its reliance on thread-local storage.
-#include "spdlog/mdc.h"
+
+#ifndef SPDLOG_NO_TLS
+    #include "spdlog/mdc.h"
 void mdc_example()
 {
     spdlog::mdc::put("key1", "value1");
@@ -391,3 +393,8 @@ void mdc_example()
     spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [%&] %v");
     spdlog::info("Some log message with context");
 }
+#else
+void mdc_example() {
+    // if TLS feature is disabled
+}
+#endif

include/spdlog/mdc.h

@@ -3,6 +3,10 @@
 
 #pragma once
 
+#if defined(SPDLOG_NO_TLS)
+    #error "This header requires thread local storage support. Please do not define SPDLOG_NO_TLS."
+#endif
+
 #include <map>
 #include <string>
 

include/spdlog/pattern_formatter-inl.h

@@ -10,7 +10,11 @@
 #include <spdlog/details/fmt_helper.h>
 #include <spdlog/details/log_msg.h>
 #include <spdlog/details/os.h>
-#include <spdlog/mdc.h>
+
+#ifndef SPDLOG_NO_TLS
+    #include <spdlog/mdc.h>
+#endif
+
 #include <spdlog/fmt/fmt.h>
 #include <spdlog/formatter.h>
 
@@ -786,6 +790,7 @@ class elapsed_formatter final : public flag_formatter {
 
 // Class for formatting Mapped Diagnostic Context (MDC) in log messages.
 // Example: [logger-name] [info] [mdc_key_1:mdc_value_1 mdc_key_2:mdc_value_2] some message
+#ifndef SPDLOG_NO_TLS
 template <typename ScopedPadder>
 class mdc_formatter : public flag_formatter {
 public:
@@ -824,6 +829,7 @@ class mdc_formatter : public flag_formatter {
         }
     }
 };
+#endif
 
 // Full info formatter
 // pattern: [%Y-%m-%d %H:%M:%S.%e] [%n] [%l] [%s:%#] %v
@@ -901,6 +907,7 @@ class full_formatter final : public flag_formatter {
             dest.push_back(' ');
         }
 
+#ifndef SPDLOG_NO_TLS
         // add mdc if present
         auto &mdc_map = mdc::get_context();
         if (!mdc_map.empty()) {
@@ -909,14 +916,19 @@ class full_formatter final : public flag_formatter {
             dest.push_back(']');
             dest.push_back(' ');
         }
+#endif
         // fmt_helper::append_string_view(msg.msg(), dest);
         fmt_helper::append_string_view(msg.payload, dest);
     }
 
 private:
     std::chrono::seconds cache_timestamp_{0};
     memory_buf_t cached_datetime_;
+
+#ifndef SPDLOG_NO_TLS
     mdc_formatter<null_scoped_padder> mdc_formatter_{padding_info{}};
+#endif
+
 };
 
 }  // namespace details
@@ -1211,9 +1223,11 @@ SPDLOG_INLINE void pattern_formatter::handle_flag_(char flag, details::padding_i
                     padding));
             break;
 
+#ifndef SPDLOG_NO_TLS  // mdc formatter requires TLS support
         case ('&'):
             formatters_.push_back(details::make_unique<details::mdc_formatter<Padder>>(padding));
             break;
+#endif
 
         default:  // Unknown flag appears as is
             auto unknown_flag = details::make_unique<details::aggregate_formatter>();

tests/includes.h

@@ -26,7 +26,11 @@
 #include "spdlog/spdlog.h"
 #include "spdlog/async.h"
 #include "spdlog/details/fmt_helper.h"
-#include "spdlog/mdc.h"
+
+#ifndef SPDLOG_NO_TLS
+    #include "spdlog/mdc.h"
+#endif
+
 #include "spdlog/sinks/basic_file_sink.h"
 #include "spdlog/sinks/daily_file_sink.h"
 #include "spdlog/sinks/null_sink.h"

tests/test_pattern_formatter.cpp

@@ -501,6 +501,7 @@ TEST_CASE("override need_localtime", "[pattern_formatter]") {
     }
 }
 
+#ifndef SPDLOG_NO_TLS
 TEST_CASE("mdc formatter test-1", "[pattern_formatter]") {
     spdlog::mdc::put("mdc_key_1", "mdc_value_1");
     spdlog::mdc::put("mdc_key_2", "mdc_value_2");
@@ -628,3 +629,4 @@ TEST_CASE("mdc empty", "[pattern_formatter]") {
 
     SECTION("Tear down") { spdlog::mdc::clear(); }
 }
+#endif