Fixed bug in LEFT JOIN ... WHERE not_null_key_column=NULL;

Docs/manual.texi:
  ChangeLog
sql/field.h:
  New virtual function to set a field to null or signal an error
sql/field_conv.cc:
  New function to set a field to null or signal an error
sql/item.cc:
  When setting a field to null internally (for WHERE testing) don't autoconvert NULL -> now() or last_insert_id()
sql/item.h:
  New virtual function to set a field to null or signal an error

Docs/manual.texi

@@ -46942,6 +46942,8 @@ temporary tables used for some (unlikely) @code{GROUP BY} queries.
 Fixed a bug in key optimizing handling where the expression
 @code{WHERE column_name = key_column_name} was calculated as true
 for @code{NULL} values.
+@item
+Fixed core dump bug when doing @code{LEFT JOIN ... WHERE key_column=NULL}.
 @end itemize
 
 @node News-3.23.53, News-3.23.52, News-3.23.54, News-3.23.x

sql/field.h

@@ -1043,6 +1043,7 @@ Field *make_field(char *ptr, uint32 field_length,
 uint pack_length_to_packflag(uint type);
 uint32 calc_pack_length(enum_field_types type,uint32 length);
 bool set_field_to_null(Field *field);
+bool set_field_to_null_with_conversions(Field *field);
 uint find_enum(TYPELIB *typelib,const char *x, uint length);
 ulonglong find_set(TYPELIB *typelib,const char *x, uint length);
 bool test_if_int(const char *str,int length);

sql/field_conv.cc

@@ -112,35 +112,52 @@ static void do_outer_field_to_null_str(Copy_field *copy)
 bool
 set_field_to_null(Field *field)
 {
-  if (field->maybe_null())
+  if (field->real_maybe_null())
   {
     field->set_null();
     field->reset();
+    return 0;
   }
-  else
+  return 1;
+}
+
+
+bool
+set_field_to_null_with_conversions(Field *field)
+{
+  if (field->real_maybe_null())
   {
-    if (field->type() == FIELD_TYPE_TIMESTAMP)
-    {
-      ((Field_timestamp*) field)->set_time();
-      return 0;					// Ok to set time to NULL
-    }
+    field->set_null();
     field->reset();
-    if (field == field->table->next_number_field)
-      return 0;					// field is set in handler.cc
-    if (current_thd->count_cuted_fields)
-    {
-      current_thd->cuted_fields++;		// Increment error counter
-      return 0;
-    }
-    if (!current_thd->no_errors)
-      my_printf_error(ER_BAD_NULL_ERROR,ER(ER_BAD_NULL_ERROR),MYF(0),
-		      field->field_name);
-    return 1;
+    return 0;
+  }
+
+  /*
+    Check if this is a special type, which will get a special walue
+    when set to NULL
+  */
+  if (field->type() == FIELD_TYPE_TIMESTAMP)
+  {
+    ((Field_timestamp*) field)->set_time();
+    return 0;					// Ok to set time to NULL
+  }
+  field->reset();
+  if (field == field->table->next_number_field)
+    return 0;					// field is set in handler.cc
+  if (current_thd->count_cuted_fields)
+  {
+    current_thd->cuted_fields++;		// Increment error counter
+    return 0;
   }
-  return 0;
+  if (!current_thd->no_errors)
+    my_printf_error(ER_BAD_NULL_ERROR,ER(ER_BAD_NULL_ERROR),MYF(0),
+		    field->field_name);
+  return 1;
 }
 
 
+
+
 static void do_skip(Copy_field *copy __attribute__((unused)))
 {
 }

sql/item.cc

@@ -383,7 +383,7 @@ void Item_field::save_org_in_field(Field *to)
   if (field->is_null())
   {
     null_value=1;
-    set_field_to_null(to);
+    set_field_to_null_with_conversions(to);
   }
   else
   {
@@ -398,7 +398,7 @@ bool Item_field::save_in_field(Field *to)
   if (result_field->is_null())
   {
     null_value=1;
-    return set_field_to_null(to);
+    return set_field_to_null_with_conversions(to);
   }
   else
   {
@@ -409,8 +409,41 @@ bool Item_field::save_in_field(Field *to)
   return 0;
 }
 
+/*
+  Store null in field
+
+  SYNOPSIS
+    save_in_field()
+    field		Field where we want to store NULL
+
+  DESCRIPTION
+    This is used on INSERT.
+    Allow NULL to be inserted in timestamp and auto_increment values
+
+  RETURN VALUES
+    0	 ok
+    1	 Field doesn't support NULL values and can't handle 'field = NULL'
+*/   
 
 bool Item_null::save_in_field(Field *field)
+{
+  return set_field_to_null_with_conversions(field);
+}
+
+
+/*
+  Store null in field
+
+  SYNOPSIS
+    save_safe_in_field()
+    field		Field where we want to store NULL
+
+  RETURN VALUES
+    0	 ok
+    1	 Field doesn't support NULL values
+*/   
+
+bool Item_null::save_safe_in_field(Field *field)
 {
   return set_field_to_null(field);
 }
@@ -427,7 +460,7 @@ bool Item::save_in_field(Field *field)
     str_value.set_quick(buff,sizeof(buff));
     result=val_str(&str_value);
     if (null_value)
-      return set_field_to_null(field);
+      return set_field_to_null_with_conversions(field);
     field->set_notnull();
     field->store(result->ptr(),result->length());
     str_value.set_quick(0, 0);
@@ -444,13 +477,14 @@ bool Item::save_in_field(Field *field)
   {
     longlong nr=val_int();
     if (null_value)
-      return set_field_to_null(field);
+      return set_field_to_null_with_conversions(field);
     field->set_notnull();
     field->store(nr);
   }
   return 0;
 }
 
+
 bool Item_string::save_in_field(Field *field)
 {
   String *result;

sql/item.h

@@ -55,6 +55,8 @@ public:
   virtual bool save_in_field(Field *field);
   virtual void save_org_in_field(Field *field)
     { (void) save_in_field(field); }
+  virtual bool save_safe_in_field(Field *field)
+    { return save_in_field(field); }
   virtual bool send(String *str);
   virtual bool eq(const Item *, bool binary_cmp) const;
   virtual Item_result result_type () const { return REAL_RESULT; }
@@ -144,6 +146,7 @@ public:
   String *val_str(String *str);
   void make_field(Send_field *field);
   bool save_in_field(Field *field);
+  bool save_safe_in_field(Field *field);
   enum Item_result result_type () const
   { return STRING_RESULT; }
   bool send(String *str);