Fixed usage of not initialized memory in LIKE ... ESCAPE

This was noticed wben running "mtr --valgrind main.precedence"

The problem was that Item_func_like::escape could be left unitialized
when used with views combined with UNIONS like in:

create or replace view v1 as select 2 LIKE 1 ESCAPE 3 IN (SELECT 0 UNION SELECT 1), 2 LIKE 1 ESCAPE (3 IN (SELECT 0 UNION SELECT 1)), (2 LIKE 1 ESCAPE 3) IN (SELECT 0 UNION SELECT 1);

The above query causes in fix_escape_item()
escape_item->const_during_execution() to be true
and
escape_item->const_item() to be false

in which case 'escape' is never calculated.

The fix is to make the main logic of fix_escape_item() out to a
separate function and call that function once in Item.

Other things:
- Reorganized fields in Item_func_like class to make it more compact

1 files changed, 20 insertions, 17 deletions

diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index fa715badfc7..1808884647e 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -2672,14 +2672,24 @@ public:
 
 class Item_func_like :public Item_bool_func2
 {
-  // Turbo Boyer-Moore data
-  bool        canDoTurboBM;	// pattern is '%abcd%' case
   const char* pattern;
-  int         pattern_len;
+  Item *escape_item;
+  DTCollation cmp_collation;
+  String cmp_value1, cmp_value2;
 
+  // Turbo Boyer-Moore data
   // TurboBM buffers, *this is owner
-  int* bmGs; //   good suffix shift table, size is pattern_len + 1
-  int* bmBc; // bad character shift table, size is alphabet_size
+  int *bmGs; //   good suffix shift table, size is pattern_len + 1
+  int *bmBc; // bad character shift table, size is alphabet_size
+  int  pattern_len;
+public:
+  int escape;
+  bool negated;
+private:
+  bool canDoTurboBM;	// pattern is '%abcd%' case
+  bool escape_item_evaluated;
+  bool escape_used_in_parsing;
+  bool use_sampling;
 
   void turboBM_compute_suffixes(int* suff);
   void turboBM_compute_good_suffix_shifts(int* suff);
@@ -2687,13 +2697,6 @@ class Item_func_like :public Item_bool_func2
   bool turboBM_matches(const char* text, int text_len) const;
   enum { alphabet_size = 256 };
 
-  Item *escape_item;
-
-  bool escape_used_in_parsing;
-  bool use_sampling;
-
-  DTCollation cmp_collation;
-  String cmp_value1, cmp_value2;
   bool with_sargable_pattern() const;
 protected:
   SEL_TREE *get_func_mm_tree(RANGE_OPT_PARAM *param,
@@ -2706,13 +2709,13 @@ protected:
                        KEY_PART *key_part,
                        Item_func::Functype type, Item *value);
 public:
-  int escape;
-  bool negated;
 
   Item_func_like(THD *thd, Item *a, Item *b, Item *escape_arg, bool escape_used):
-    Item_bool_func2(thd, a, b), canDoTurboBM(FALSE), pattern(0), pattern_len(0),
-    bmGs(0), bmBc(0), escape_item(escape_arg),
-    escape_used_in_parsing(escape_used), use_sampling(0), negated(0) {}
+    Item_bool_func2(thd, a, b), pattern(0), escape_item(escape_arg),
+      bmGs(0), bmBc(0), pattern_len(0),  negated(0), canDoTurboBM(FALSE),
+      escape_item_evaluated(0), escape_used_in_parsing(escape_used),
+      use_sampling(0)
+  {}
 
   bool get_negated() const { return negated; } // Used by ColumnStore