MDEV-33971-cleanup.diff

diff -u '--exclude=.*' sql/item.cc sql/item.cc
--- sql/item.cc	2024-07-10 15:21:32.686440163 +0300
+++ sql/item.cc	2024-07-10 15:25:11.262066814 +0300
@@ -2176,6 +2176,16 @@
 
 bool Item_name_const::fix_fields(THD *thd, Item **ref)
 {
+
+  if (value_item->fix_fields_if_needed(thd, &value_item) ||
+      name_item->fix_fields_if_needed(thd, &name_item) ||
+      !value_item->const_item() ||
+      !name_item->const_item())
+  {
+    my_error(ER_RESERVED_SYNTAX, MYF(0), "NAME_CONST");
+    return TRUE;
+  }
+
   /*
     If we have either of the following:
       ... WHERE foo=NAME_CONST(...)
@@ -2183,14 +2193,20 @@
     then we have an opportunity to unwrap the NAME_CONST and
     use the enclosed value directly, replacing NAME_CONST in
     the parse tree with the value it encloses.
-   */
+  */
   if ((thd->where == THD_WHERE::WHERE_CLAUSE ||
        thd->where == THD_WHERE::ON_CLAUSE) &&
       (value_item->type() == FUNC_ITEM ||
-       value_item->type() == CONST_ITEM) &&
-    !value_item->fix_fields_if_needed(thd, &value_item))
+       value_item->type() == CONST_ITEM))
   {
     thd->change_item_tree(ref, value_item);
+    /*
+      We're replacing NAME_CONST('name', value_item) with value_item.
+      Only a few constants and functions are possible as value_item, see
+      Create_func_name_const::create_2_arg.
+      Set the value_item's coercibility to be the same as NAME_CONST(...)
+      would have (see how it's set a few lines below).
+    */
     if (value_item->collation.derivation != DERIVATION_NUMERIC)
       value_item->collation.set(value_item->collation.collation,
                                 DERIVATION_IMPLICIT);
@@ -2198,14 +2214,6 @@
   }
   // else, could not unwrap, fall back to default handling below.
 
-  if (value_item->fix_fields_if_needed(thd, &value_item) ||
-      name_item->fix_fields_if_needed(thd, &name_item) ||
-      !value_item->const_item() ||
-      !name_item->const_item())
-  {
-    my_error(ER_RESERVED_SYNTAX, MYF(0), "NAME_CONST");
-    return TRUE;
-  }
   if (value_item->collation.derivation == DERIVATION_NUMERIC)
     collation= DTCollation_numeric();
   else
diff -u '--exclude=.*' sql/sql_class.h sql/sql_class.h
--- sql/sql_class.h	2024-07-10 15:21:32.690440303 +0300
+++ sql/sql_class.h	2024-07-10 15:23:38.710836775 +0300
@@ -2902,6 +2902,7 @@
   const char *get_proc_info() const
   { return proc_info; }
 
+  // Used by thd_where() when where==USE_WHERE_STRING
   const char *where_str;
 
   /*