MDEV-36484 Atomic DDL: Assertion `!param->got_error' failed upon unsuccessful multi-RENAME TABLE

When executing an atomic sequence of RENAME operations, such as:
    RENAME TABLE t1 TO t2, t3 TO t4, ...
any failure in the sequence triggers a rollback of previously completed
renames to preserve atomicity.

However, when an error occurs, `my_error()` is invoked immediately, which
sets the `thd->is_error()` flag. This premature flag setting causes
the rollback logic to misinterpret the thread state, leading to incorrect
reversion behavior and assertion failures.

To address this, the error is now captured and deferred — stored during
the failure and only passed to `my_error()` after the DDL reversion
is complete. This ensures the error state is not prematurely set, allowing
the rollback logic to execute safely and correctly.

Author: Olernov

include/my_sys.h

@@ -502,6 +502,13 @@ typedef struct st_io_cache		/* Used when caching files */
   size_t alloced_buffer;
 } IO_CACHE;
 
+typedef struct Prepared_error
+{
+  uint code;
+  char message[MYSYS_ERRMSG_SIZE];
+  myf flags;
+} MY_PREPARED_ERROR;
+
 typedef void (*my_error_reporter)(enum loglevel level, const char *format, ...)
   ATTRIBUTE_FORMAT_FPTR(printf, 2, 3);
 
@@ -743,6 +750,8 @@ extern int my_error_register(const char** (*get_errmsgs) (int nr),
 extern my_bool my_error_unregister(uint first, uint last);
 extern void my_message(uint my_err, const char *str,myf MyFlags);
 extern void my_message_stderr(uint my_err, const char *str, myf MyFlags);
+extern struct Prepared_error my_error_prepare(uint nr, myf MyFlags, ...);
+extern void my_error_issue(struct Prepared_error* error);
 extern my_bool my_init(void);
 extern void my_end(int infoflag);
 extern int my_redel(const char *from, const char *to, time_t backup_time_stamp,

mysql-test/main/rename.result

@@ -175,3 +175,19 @@ drop table t2;
 rename table if exists t1 to t2;
 alter table if exists t2 rename to t1;
 drop table t1;
+#
+# MDEV-36484 Atomic DDL: Assertion `!param->got_error' failed upon
+#             unsuccessful multi-RENAME TABLE
+#
+CREATE TABLE t1 (a INT);
+CREATE TRIGGER t1 AFTER INSERT ON t1 FOR EACH ROW INSERT INTO t1 VALUES (0);
+RENAME TABLE t1 TO t2, t3 TO t4;
+ERROR 42S02: Table 'test.t3' doesn't exist
+SHOW CREATE TRIGGER t1;
+Trigger	sql_mode	SQL Original Statement	character_set_client	collation_connection	Database Collation	Created
+t1	STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	CREATE DEFINER=`root`@`localhost` TRIGGER t1 AFTER INSERT ON `t1` FOR EACH ROW INSERT INTO t1 VALUES (0)	latin1	latin1_swedish_ci	utf8mb4_uca1400_ai_ci	#
+RENAME TABLE t1 TO t2;
+SHOW CREATE TRIGGER t1;
+Trigger	sql_mode	SQL Original Statement	character_set_client	collation_connection	Database Collation	Created
+t1	STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	CREATE DEFINER=`root`@`localhost` TRIGGER t1 AFTER INSERT ON `t2` FOR EACH ROW INSERT INTO t1 VALUES (0)	latin1	latin1_swedish_ci	utf8mb4_uca1400_ai_ci	#
+DROP TABLE t2;

mysql-test/main/rename.test

@@ -166,3 +166,21 @@ drop table t2;
 rename table if exists t1 to t2;
 alter table if exists t2 rename to t1;
 drop table t1;
+
+
+--echo #
+--echo # MDEV-36484 Atomic DDL: Assertion `!param->got_error' failed upon
+--echo #             unsuccessful multi-RENAME TABLE
+--echo #
+CREATE TABLE t1 (a INT);
+CREATE TRIGGER t1 AFTER INSERT ON t1 FOR EACH ROW INSERT INTO t1 VALUES (0);
+--error ER_NO_SUCH_TABLE
+RENAME TABLE t1 TO t2, t3 TO t4;
+
+--replace_column 7 #
+SHOW CREATE TRIGGER t1;
+RENAME TABLE t1 TO t2;
+
+--replace_column 7 #
+SHOW CREATE TRIGGER t1;
+DROP TABLE t2;

mysys/my_error.c

@@ -18,6 +18,7 @@
 #include <m_string.h>
 #include <stdarg.h>
 #include <m_ctype.h>
+#include <my_sys.h>
 
 /* Max length of a error message. Should be kept in sync with MYSQL_ERRMSG_SIZE. */
 #define ERRMSGSIZE      (512)
@@ -93,6 +94,62 @@ const char *my_get_err_msg(uint nr)
   return format;
 }
 
+/**
+   Internal method used to format and prepare the error structure.
+   Called by my_error_prepare() and my_error().
+ */
+static struct Prepared_error my_error_format(uint nr, myf MyFlags, va_list args)
+{
+  const char *format;
+  struct Prepared_error error;
+  error.code= nr;
+  error.flags= MyFlags;
+
+  if (!(format = my_get_err_msg(nr)))
+    (void) my_snprintf(error.message, sizeof(error.message),
+                       "Unknown error %d", nr);
+  else
+  {
+    (void) my_vsnprintf_ex(&my_charset_utf8mb3_general_ci,
+                           error.message, sizeof(error.message), format, args);
+  }
+  return error;
+}
+
+/**
+  Prepare the error message for deferred printing with my_error_issue()
+
+  @param nr        error number
+  @param MyFlags   Flags
+  @param ...       variable list matching that error format string
+
+  @retval error    prepared structure containg error code, formatted message
+                   and flags
+*/
+
+struct Prepared_error my_error_prepare(uint nr, myf MyFlags, ...)
+{
+  struct Prepared_error error;
+  va_list args;
+
+  va_start(args,MyFlags);
+  error= my_error_format(nr, MyFlags, args);
+  va_end(args);
+
+  return error;
+}
+
+
+/**
+   Print a previously prepared error (see my_error_prepare())
+
+ * @param error        error structure prepared for deferred printing@retval
+ */
+void my_error_issue(struct Prepared_error* error)
+{
+  (*error_handler_hook)(error->code, error->message, error->flags);
+}
+
 
 /**
   Fill in and print a previously registered error message.
@@ -107,21 +164,14 @@ const char *my_get_err_msg(uint nr)
 
 void my_error(uint nr, myf MyFlags, ...)
 {
-  const char *format;
+  struct Prepared_error error;
   va_list args;
-  char ebuff[ERRMSGSIZE];
   DBUG_ENTER("my_error");
   DBUG_PRINT("my", ("nr: %d  MyFlags: %lu  errno: %d", nr, MyFlags, errno));
-  if (!(format = my_get_err_msg(nr)))
-    (void) my_snprintf(ebuff, sizeof(ebuff), "Unknown error %d", nr);
-  else
-  {
-    va_start(args,MyFlags);
-    (void) my_vsnprintf_ex(&my_charset_utf8mb3_general_ci, ebuff,
-                           sizeof(ebuff), format, args);
-    va_end(args);
-  }
-  (*error_handler_hook)(nr, ebuff, MyFlags);
+  va_start(args,MyFlags);
+  error= my_error_format(nr, MyFlags, args);
+  my_error_issue(&error);
+  va_end(args);
   DBUG_VOID_RETURN;
 }