deprecate config_file + add warning

Probably not used at all - it was created for some purpose some 10 years
ago but perhaps never used outside our internal needs.

Author: MartinPulec

src/aja_common.hpp

@@ -43,9 +43,6 @@
 class CNTV2Card;
 
 #ifdef _MSC_VER
-#define bug_msg(x, ...) \
-        log_msg(x, __VA_ARGS__); \
-        log_msg(x, " Please report a bug if you reach here.\n")
 #define color_printf printf
 #undef LOG
 #include <iostream>

src/config_msvc.h

@@ -3,7 +3,7 @@
  * @author Martin Pulec     <pulec@cesnet.cz>
  */
 /*
- * Copyright (c) 2017-2025 CESNET, zájmové sdružení právnických osob
+ * Copyright (c) 2017-2026 CESNET, zájmové sdružení právnických osob
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -67,6 +67,10 @@
 #define aligned_malloc _aligned_malloc
 #define aligned_free _aligned_free
 
+#define bug_msg(log_level, ...) \
+        fprintf(stderr, __VA_ARGS__); \
+        fprintf(stderr, "Please report a bug if you reach here.\n")
+
 #endif // defined _MSC_VER
 
 #endif // defined CONFIG_MSVC_H

src/debug.h

@@ -120,7 +120,7 @@ bool parse_log_cfg(const char *conf_str,
 #if defined __MINGW32__
         __MINGW_GNU_PRINTF(2, 3)
         void bug_msg(int level, const char *format, ...);
-#else
+#elif !defined _MSC_VER
         void bug_msg(int level, const char *format, ...)
             __attribute__((format(printf, 2, 3)));
 #endif

src/utils/config_file.cpp

@@ -3,6 +3,10 @@
  * @author Martin Pulec     <pulec@cesnet.cz>
  *
  * @brief  Configuration file for UltraGrid
+ *
+ * @todo
+ * TOREMOVE: doesn't seem to be used anyhow - if noone objects to, remove
+ * after some time (perhaps after next release).
  */
 /*
  * Copyright (c) 2013-2026 CESNET, zájmové sdružení právnických osob
@@ -44,9 +48,12 @@
 #include <cstring>
 
 #include "config_msvc.h"
+#include "debug.h"
 #include "compat/strings.h" // for strlcpy
 
 
+#define MOD_NAME "[config_file] "
+
 using namespace std;
 
 struct config_file {
@@ -90,6 +97,9 @@ struct config_file *config_file_open(const char *name)
         if (f == NULL) {
                 return NULL;
         }
+        bug_msg(LOG_LEVEL_WARNING, MOD_NAME
+                "configuration file is deprecated and about to be removed in "
+                "future. Please let us know if using this feature. ");
         struct config_file *s = (struct config_file *) calloc(1, sizeof(struct config_file));
         s->f = f;
         strncpy(s->file_name, name, sizeof(s->file_name) - 1);