Fix for bug#49517: Inconsistent behavior while using

NULLable BIGINT and INT columns in comparison

Problem: a consequence of the fix for 43668.
Some Arg_comparator inner initialization missed,
that may lead to unpredictable (wrong) comparison
results.

Fix: always properly initialize Arg_comparator
before its usage.


mysql-test/r/select.result:
  Fix for bug#49517: Inconsistent behavior while using 
  NULLable BIGINT and INT columns in comparison
    -test result.
mysql-test/t/select.test:
  Fix for bug#49517: Inconsistent behavior while using 
  NULLable BIGINT and INT columns in comparison
    -test case.
sql/item_cmpfunc.cc:
  Fix for bug#49517: Inconsistent behavior while using 
  NULLable BIGINT and INT columns in comparison
    - now all Arg_comparator::set_cmp_func() set
  Arg_comparator::set_null to ensure its proper initialization
  in all cases (by default it's set to TRUE in constructors).
sql/item_cmpfunc.h:
  Fix for bug#49517: Inconsistent behavior while using 
  NULLable BIGINT and INT columns in comparison
    - now all Arg_comparator::set_cmp_func() set
  Arg_comparator::set_null to ensure its proper initialization
  in all cases (by default it's set to TRUE in constructors).

1 files changed, 2 insertions, 2 deletions

diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index d4542dac820..05c9fc96ff5 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -54,10 +54,10 @@ public:
   /* Allow owner function to use string buffers. */
   String value1, value2;
 
-  Arg_comparator(): thd(0), a_cache(0), b_cache(0), set_null(0),
+  Arg_comparator(): thd(0), a_cache(0), b_cache(0), set_null(TRUE),
     get_value_a_func(0), get_value_b_func(0) {};
   Arg_comparator(Item **a1, Item **a2): a(a1), b(a2), thd(0),
-    a_cache(0), b_cache(0), set_null(0),
+    a_cache(0), b_cache(0), set_null(TRUE),
     get_value_a_func(0), get_value_b_func(0) {};
 
   int set_compare_func(Item_result_field *owner, Item_result type);