New configuration flag to warn that a variable is obsolete.

Part of 32404.

2 files changed, 12 insertions, 1 deletions

diff --git a/src/lib/conf/conftypes.h b/src/lib/conf/conftypes.h
index dfe51cfba1..bf748efbb7 100644
--- a/src/lib/conf/conftypes.h
+++ b/src/lib/conf/conftypes.h
@@ -183,12 +183,18 @@ typedef struct struct_magic_decl_t {
  * running.
  **/
 #define CFLG_IMMUTABLE (1u<<6)
+/**
+ * Flag to indicate that we should warn that an option or type is obsolete
+ * whenever the user tries to use it.
+ **/
+#define CFLG_WARN_OBSOLETE (1u<<7)
 
 /**
  * A group of flags that should be set on all obsolete options and types.
  **/
 #define CFLG_GROUP_OBSOLETE \
-  (CFLG_NOCOPY|CFLG_NOCMP|CFLG_NODUMP|CFLG_NOSET|CFLG_NOLIST)
+  (CFLG_NOCOPY|CFLG_NOCMP|CFLG_NODUMP|CFLG_NOSET|CFLG_NOLIST|\
+   CFLG_WARN_OBSOLETE)
 
 /** A variable allowed in the configuration file or on the command line. */
 typedef struct config_var_t {
diff --git a/src/lib/confmgt/confmgt.c b/src/lib/confmgt/confmgt.c
index a96c7f96bf..c72efa847c 100644
--- a/src/lib/confmgt/confmgt.c
+++ b/src/lib/confmgt/confmgt.c
@@ -657,6 +657,11 @@ config_assign_value(const config_mgr_t *mgr, void *options,
   tor_assert(!strcmp(c->key, var->cvar->member.name));
   void *object = config_mgr_get_obj_mutable(mgr, options, var->object_idx);
 
+  if (config_var_has_flag(var->cvar, CFLG_WARN_OBSOLETE)) {
+    log_warn(LD_GENERAL, "Skipping obsolete configuration option \"%s\".",
+             var->cvar->member.name);
+  }
+
   return struct_var_kvassign(object, c, msg, &var->cvar->member);
 }