Bug#41465: confusing error message when comment is too long

The problem was that the server was trying to use the unknown
error format string (ER_UNKNOWN_ERROR) to print messages about
comments being too long, but the said format string does not
accept arguments and will always default to "Unknown error".

The solution is to introduce new error messages which are
specific to the error conditions so that server wants to
signal -- this also means that it's possible to translate
those messages.

mysql-test/r/strict.result:
  Update test case result.
mysql-test/t/strict.test:
  Update test case with new errors.
sql/share/errmsg.txt:
  Introduce new errors for long comments.
sql/unireg.cc:
  Use new errors.

mysql-test/r/strict.result

@@ -1305,7 +1305,7 @@ set @@sql_mode='traditional';
 create table t1 (i int)
 comment '123456789*123456789*123456789*123456789*123456789*
          123456789*123456789*123456789*123456789*123456789*';
-ERROR HY000: Too long comment for table 't1'
+ERROR HY000: Comment for table 't1' is too long (max = 60)
 create table t1 (
 i int comment
 '123456789*123456789*123456789*123456789*
@@ -1315,7 +1315,7 @@ i int comment
  123456789*123456789*123456789*123456789*
  123456789*123456789*123456789*123456789*
  123456789*123456789*123456789*123456789*');
-ERROR HY000: Too long comment for field 'i'
+ERROR HY000: Comment for field 'i' is too long (max = 255)
 set @@sql_mode= @org_mode;
 create table t1
 (i int comment
@@ -1327,7 +1327,7 @@ create table t1
   123456789*123456789*123456789*123456789*
   123456789*123456789*123456789*123456789*');
 Warnings:
-Warning	1105	Unknown error
+Warning	1629	Comment for field 'i' is too long (max = 255)
 select column_name, column_comment from information_schema.columns where
 table_schema = 'test' and table_name = 't1';
 column_name	column_comment

mysql-test/t/strict.test

@@ -1163,11 +1163,11 @@ set @@sql_mode= @org_mode;
 # Bug #13934 Silent truncation of table comments
 #
 set @@sql_mode='traditional';
---error 1105
+--error ER_TOO_LONG_TABLE_COMMENT
 create table t1 (i int)
 comment '123456789*123456789*123456789*123456789*123456789*
          123456789*123456789*123456789*123456789*123456789*';
---error 1105
+--error ER_TOO_LONG_FIELD_COMMENT
 create table t1 (
 i int comment
 '123456789*123456789*123456789*123456789*

sql/share/errmsg.txt

@@ -6169,3 +6169,11 @@ ER_CONFLICT_FN_PARSE_ERROR
         eng "Error in parsing conflict function. Message: %-.64s"
 ER_EXCEPTIONS_WRITE_ERROR
         eng "Write to exceptions table failed. Message: %-.128s""
+
+ER_TOO_LONG_TABLE_COMMENT
+  eng "Comment for table '%-.64s' is too long (max = %lu)"
+  por "Coment<6E>rio para a tabela '%-.64s' <20> longo demais (max = %lu)"
+
+ER_TOO_LONG_FIELD_COMMENT
+  eng "Comment for field '%-.64s' is too long (max = %lu)"
+  por "Coment<6E>rio para o campo '%-.64s' <20> longo demais (max = %lu)"

sql/unireg.cc

@@ -229,16 +229,16 @@ bool mysql_create_frm(THD *thd, const char *file_name,
                                               create_info->comment.length, 60);
   if (tmp_len < create_info->comment.length)
   {
-    (void) my_snprintf(buff, sizeof(buff), "Too long comment for table '%s'",
-                       table);
     if ((thd->variables.sql_mode &
          (MODE_STRICT_TRANS_TABLES | MODE_STRICT_ALL_TABLES)))
     {
-      my_message(ER_UNKNOWN_ERROR, buff, MYF(0));
+      my_error(ER_TOO_LONG_TABLE_COMMENT, MYF(0), table, tmp_len);
       goto err;
     }
     push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
-                        ER_UNKNOWN_ERROR, ER(ER_UNKNOWN_ERROR), buff);
+                        ER_TOO_LONG_TABLE_COMMENT,
+                        ER(ER_TOO_LONG_TABLE_COMMENT),
+                        table, tmp_len);
     create_info->comment.length= tmp_len;
   }
 
@@ -613,17 +613,16 @@ static bool pack_header(uchar *forminfo, enum legacy_db_type table_type,
                                                      255);
     if (tmp_len < field->comment.length)
     {
-      char buff[128];
-      (void) my_snprintf(buff,sizeof(buff), "Too long comment for field '%s'",
-                         field->field_name);
       if ((current_thd->variables.sql_mode &
 	   (MODE_STRICT_TRANS_TABLES | MODE_STRICT_ALL_TABLES)))
       {
-        my_message(ER_UNKNOWN_ERROR, buff, MYF(0));
+        my_error(ER_TOO_LONG_FIELD_COMMENT, MYF(0), field->field_name, tmp_len);
 	DBUG_RETURN(1);
       }
       push_warning_printf(current_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
-                          ER_UNKNOWN_ERROR, ER(ER_UNKNOWN_ERROR), buff);
+                          ER_TOO_LONG_FIELD_COMMENT,
+                          ER(ER_TOO_LONG_FIELD_COMMENT),
+                          field->field_name, tmp_len);
       field->comment.length= tmp_len;
     }