3 files changed, 15 insertions, 1 deletions
diff --git a/src/debug.cpp b/src/debug.cpp
index 39c695e03..cfcb0ee8b 100644
--- a/src/debug.cpp
+++ b/src/debug.cpp
@@ -103,7 +103,7 @@ char *DumpDebugFacilityNames(char *buf, char *last)
  * @param dbg Debug category.
  * @param buf Text line to output.
  */
-static void debug_print(const char *dbg, const char *buf)
+void debug_print(const char *dbg, const char *buf)
 {
 	if (_debug_socket != INVALID_SOCKET) {
 		char buf2[1024 + 32];
diff --git a/src/debug.h b/src/debug.h
index 29a7114aa..8923e706b 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -12,6 +12,7 @@
 
 #include "cpu.h"
 #include <chrono>
+#include "3rdparty/fmt/format.h"
 
 /* Debugging messages policy:
  * These should be the severities used for direct DEBUG() calls
@@ -27,6 +28,16 @@
  * 6.. - extremely detailed spamming
  */
 
+void debug_print(const char *dbg, const char *buf);
+
+/**
+ * Ouptut a line of debugging information.
+ * @param name The category of debug information.
+ * @param level The maximum debug level this message should be shown at. When the debug level for this category is set lower, then the message will not be shown.
+ * @param format_string The formatting string of the message.
+ */
+#define Debug(name, level, format_string, ...) if ((level) == 0 || _debug_ ## name ## _level >= (level)) debug_print(#name, fmt::format(FMT_STRING(format_string), ## __VA_ARGS__).c_str())
+
 /**
  * Output a line of debugging information.
  * @param name Category
diff --git a/src/stdafx.h b/src/stdafx.h
index e593344bf..effd57cae 100644
--- a/src/stdafx.h
+++ b/src/stdafx.h
@@ -425,6 +425,9 @@ static_assert(SIZE_MAX >= UINT32_MAX);
 #	define unlikely(x) (x)
 #endif /* __GNUC__ || __clang__ */
 
+/* For the FMT library we only want to use the headers, not link to some library. */
+#define FMT_HEADER_ONLY
+
 void NORETURN CDECL usererror(const char *str, ...) WARN_FORMAT(1, 2);
 void NORETURN CDECL error(const char *str, ...) WARN_FORMAT(1, 2);
 #define NOT_REACHED() error("NOT_REACHED triggered at line %i of %s", __LINE__, __FILE__)