fix/issue-3101: fix the issue where mdc ignores SPDLOG_NO_TLS (#3184)

Co-authored-by: dyf <yufeng.duan@senscape.com.cn>

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 @@ private:
 
 // 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 @@ public:
         }
     }
 };
+#endif
 
 // Full info formatter
 // pattern: [%Y-%m-%d %H:%M:%S.%e] [%n] [%l] [%s:%#] %v
@@ -901,6 +907,7 @@ public:
             dest.push_back(' ');
         }
 
+#ifndef SPDLOG_NO_TLS
         // add mdc if present
         auto &mdc_map = mdc::get_context();
         if (!mdc_map.empty()) {
@@ -909,6 +916,7 @@ public:
             dest.push_back(']');
             dest.push_back(' ');
         }
+#endif
         // fmt_helper::append_string_view(msg.msg(), dest);
         fmt_helper::append_string_view(msg.payload, dest);
     }
@@ -916,7 +924,11 @@ public:
 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>();