MDEV-28696 View created as "select b''; " references invalid table(s)…

… or column(s) or function(s) or definer/invoker of view lack rights to use them

mysql-test/main/varbinary.test

@@ -149,12 +149,9 @@ select N'', length(N'');
 select '', length('');
 --enable_view_protocol
 
-#enable after fix MDEV-28696
---disable_view_protocol
 select b'', 0+b'';
 
 select x'', 0+x'';
---enable_view_protocol
 
 --error ER_BAD_FIELD_ERROR
 select 0x;

mysql-test/main/view.result

@@ -6905,5 +6905,13 @@ deallocate prepare stmt;
 drop view v1;
 drop table t1;
 #
+# MDEV-28696 View created as "select b''; " references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
+#
+CREATE VIEW v1 as select b'';
+SELECT * FROM v1;
+b''
+
+DROP VIEW v1;
+#
 # End of 10.3 tests
 #

mysql-test/main/view.test

@@ -6644,6 +6644,15 @@ deallocate prepare stmt;
 drop view v1;
 drop table t1;
 
+--echo #
+--echo # MDEV-28696 View created as "select b''; " references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
+--echo #
+
+CREATE VIEW v1 as select b'';
+SELECT * FROM v1;
+DROP VIEW v1;
+
+
 --echo #
 --echo # End of 10.3 tests
 --echo #

sql/item.cc

@@ -7409,6 +7409,25 @@ Item_bin_string::Item_bin_string(THD *thd, const char *str, size_t str_length):
 }
 
 
+void Item_bin_string::print(String *str, enum_query_type query_type)
+{
+  if (!str_value.length())
+  {
+    /*
+      Historically a bit string such as b'01100001'
+      prints itself in the hex hybrid notation: 0x61
+      In case of an empty bit string b'', the hex hybrid
+      notation would result in a bad syntax: 0x
+      So let's print empty bit strings using bit string notation: b''
+    */
+    static const LEX_CSTRING empty_bit_string= {STRING_WITH_LEN("b''")};
+    str->append(empty_bit_string);
+  }
+  else
+    Item_hex_hybrid::print(str, query_type);
+}
+
+
 bool Item_temporal_literal::eq(const Item *item, bool binary_cmp) const
 {
   return

sql/item.h

@@ -4490,6 +4490,7 @@ class Item_bin_string: public Item_hex_hybrid
 {
 public:
   Item_bin_string(THD *thd, const char *str, size_t str_length);
+  void print(String *str, enum_query_type query_type);
 };