MDEV-25069: Assertion `root->weight >= ...' failed in SEL_ARG::tree_delete #2

Note they key_or() may call tree_delete(), which will cause the weight
asserts to be checked. In order to avoid them from firing, update key1
tree's weight after we've changed key1->some_local_child->next_key_part.

Having done that, do we still need this at the function end:

  /* Re-compute the result tree's weight. */
  key1->update_weight_locally();
?

Author: spetrunia

mysql-test/main/range_notembedded.result

@@ -239,3 +239,12 @@ insert into t1 values (1,1,1,1), (2,2,2,2), (3,3,3,3);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	PRIMARY	PRIMARY	2	NULL	3	Using where
 drop table t1;
+#
+# MDEV-25069: Assertion `root->weight >= ...' failed in SEL_ARG::tree_delete #2
+#
+SELECT *
+FROM mysql.help_relation
+WHERE
+(help_topic_id < '2' OR help_topic_id != 8 OR help_topic_id < 1) AND
+help_keyword_id = help_topic_id;
+help_topic_id	help_keyword_id

mysql-test/main/range_notembedded.test

@@ -140,3 +140,13 @@ WHERE
 --enable_query_log
 
 drop table t1;
+
+--echo #
+--echo # MDEV-25069: Assertion `root->weight >= ...' failed in SEL_ARG::tree_delete #2
+--echo #
+
+SELECT *
+FROM mysql.help_relation
+WHERE
+  (help_topic_id < '2' OR help_topic_id != 8 OR help_topic_id < 1) AND
+  help_keyword_id = help_topic_id;

sql/opt_range.cc

@@ -10642,9 +10642,15 @@ key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2)
          */
         tmp->maybe_flag|= key2_cpy.maybe_flag;
         key2_cpy.increment_use_count(key1->use_count+1);
+
+        uint old_weight= tmp->next_key_part? tmp->next_key_part->weight: 0;
+
         tmp->next_key_part= key_or(param, tmp->next_key_part,
                                    key2_cpy.next_key_part);
 
+        uint new_weight= tmp->next_key_part? tmp->next_key_part->weight: 0;
+        key1->weight += (new_weight - old_weight);
+
         if (!cmp)
           break;                     // case b: done with this key2 range