Bug#38338: REPLACE causes last_insert_id() to return an incorrect value

                  
Fix the write_record function to record auto increment
values in a consistent way.

mysql-test/r/auto_increment.result:
  Updated the test result file with the output of the
  new test case added to verify this bug.
mysql-test/t/auto_increment.test:
  Added a new test case to verify this bug.
sql/sql_insert.cc:
  The algorithm for the write_record function
  in sql_insert.cc is (more emphasis given to
  the parts that deal with the autogenerated values)
  
  1) If a write fails
  
     1.1) save the autogenerated value to avoid 
          thd->insert_id_for_cur_row to become 0.
  
     1.2) <logic to handle INSERT ON DUPLICATE KEY
          UPDATE and REPLACE>
  
  2) record the first successful insert id.
  
  explanation of the failure
  --------------------------
  
  As long as 1.1) was executed 2) worked fine.
  
  1.1) was always executed when REPLACE worked 
       with the last row update optimization, but
       in cases where 1.1) was not executed 2)
       would fail and would result in the autogenerated
       value not being saved.
  
  solution
  --------
  
  repeat a check for thd->insert_id_for_cur_row 
  being zero similar to 1.1) before 2) and ensure
  that the correct value is saved.

mysql-test/r/auto_increment.result

@@ -454,3 +454,11 @@ select last_insert_id();
 last_insert_id()
 3
 drop table t1;
+create table t1 (a int primary key auto_increment, b int, c int, e int, d timestamp default current_timestamp, unique(b),unique(c),unique(e));
+insert into t1 values(null,1,1,1,now());
+insert into t1 values(null,0,0,0,null);
+replace into t1 values(null,1,0,2,null);
+select last_insert_id();
+last_insert_id()
+3
+drop table t1;

mysql-test/t/auto_increment.test

@@ -314,5 +314,15 @@ insert into t1 values(null,0,0,null);
 # this will delete two rows
 replace into t1 values(null,1,0,null);
 select last_insert_id();
+drop table t1;
 
+# Test of REPLACE when it does a INSERT+DELETE for all the conflicting rows
+# (i.e.) when there are three rows conflicting in unique key columns with
+# a row that is being inserted, all the three rows will be deleted and then
+# the new rows will be inserted.
+create table t1 (a int primary key auto_increment, b int, c int, e int, d timestamp default current_timestamp, unique(b),unique(c),unique(e));
+insert into t1 values(null,1,1,1,now());
+insert into t1 values(null,0,0,0,null);
+replace into t1 values(null,1,0,2,null);
+select last_insert_id();
 drop table t1;

sql/sql_insert.cc

@@ -1545,6 +1545,17 @@ int write_record(THD *thd, TABLE *table,COPY_INFO *info)
         }
       }
     }
+    
+    /*
+        If more than one iteration of the above while loop is done, from the second 
+        one the row being inserted will have an explicit value in the autoinc field, 
+        which was set at the first call of handler::update_auto_increment(). This 
+        value is saved to avoid thd->insert_id_for_cur_row becoming 0. Use this saved
+        autoinc value.
+     */
+    if (table->file->insert_id_for_cur_row == 0)
+      table->file->insert_id_for_cur_row= insert_id_for_cur_row;
+      
     thd->record_first_successful_insert_id_in_cur_stmt(table->file->insert_id_for_cur_row);
     /*
       Restore column maps if they where replaced during an duplicate key