mysql_connection.h causes "invalid covariant return type for..." during compile

[alex ekholm]

****EDIT: Nevermind for some reason I had put "mysql_connection.h" in my working directory. The problem we resolved when I removed it.






I am using Eclipse SDK 3.5.1 in Ubuntu 9.10 to invoke gcc 4.4.1 compile my code. I have compiled/installed boost 1.43.0 and mysql-connector-c++ 1.1.0~r791 (from source, not binary). I have linked to the mysqlcppconn library.

The error is coming from the "mysql_connection.h" file but here is the what I am trying to compile:

---code-------------------------------------------------
/*
* mtest.cpp
*
* Created on: Jun 4, 2010
* Author: aekholm
*/

#include <stdlib.h>
#include <iostream>
#include <sstream>
#include <stdexcept>

#include "mysql_connection.h"

#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>

#define EXAMPLE_HOST "localhost"
#define EXAMPLE_USER "root"
#define EXAMPLE_PASS "password"
#define EXAMPLE_DB "world"

using namespace std;

int main(int argc, const char **argv) {

string url(argc >= 2 ? argv[1] : EXAMPLE_HOST);
const string user(argc >= 3 ? argv[2] : EXAMPLE_USER);
const string pass(argc >= 4 ? argv[3] : EXAMPLE_PASS);
const string database(argc >= 5 ? argv[4] : EXAMPLE_DB);

cout << "Connector/C++ tutorial framework..." << endl;
cout << endl;

try {

sql::Driver* driver = get_driver_instance();
std::auto_ptr<sql::Connection> con(driver->connect(url, user, pass));
con->setSchema(database);
std::auto_ptr<sql::Statement> stmt(con->createStatement());

stmt->execute("CALL get_pop(\"Uganda\", @pop)");

std::auto_ptr<sql::ResultSet> res(stmt->executeQuery(
"SELECT @pop AS _reply"));
while (res->next())
cout << "Population of Uganda: " << res->getString("_reply")
<< endl;

stmt->execute("CALL get_pop_continent(\"Asia\", @pop)");

res.reset(stmt->executeQuery("SELECT @pop AS _reply"));
while (res->next())
cout << "Population of Asia: " << res->getString("_reply") << endl;

stmt->execute("CALL get_world_pop(@pop)");

res.reset(stmt->executeQuery("SELECT @pop AS _reply"));
while (res->next())
cout << "Population of World: " << res->getString("_reply") << endl;

} catch (sql::SQLException &e) {
/*
The MySQL Connector/C++ throws three different exceptions:

- sql::MethodNotImplementedException (derived from sql::SQLException)
- sql::InvalidArgumentException (derived from sql::SQLException)
- sql::SQLException (derived from std::runtime_error)
*/
cout << "# ERR: SQLException in " << __FILE__;
cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;
/* Use what() (derived from std::runtime_error) to fetch the error message */
cout << "# ERR: " << e.what();
cout << " (MySQL error code: " << e.getErrorCode();
cout << ", SQLState: " << e.getSQLState() << " )" << endl;

return EXIT_FAILURE;
}
}

--/code-------------------------------------------------





Here is the console output:

---console-----------------------------------------------

**** Build of configuration Debug for project mysql_test ****

make all
Building file: ../mtest.cpp
Invoking: GCC C++ Compiler
g++ -I/usr/include/mysql -I/usr/local/src/boost/ -I/usr/local/src/mysql-connector-c++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"mtest.d" -MT"mtest.d" -o"mtest.o" "../mtest.cpp"
In file included from ../mtest.cpp:13:
../mysql_connection.h:34: error: invalid covariant return type for ‘virtual std::string sql::mysql::MySQL_Savepoint::getSavepointName()’
/usr/local/src/mysql-connector-c++/cppconn/connection.h:53: error: overriding ‘virtual sql::SQLString sql::Savepoint::getSavepointName()’
../mysql_connection.h:67: error: invalid covariant return type for ‘virtual std::string sql::mysql::MySQL_Connection::getCatalog()’
/usr/local/src/mysql-connector-c++/cppconn/connection.h:78: error: overriding ‘virtual sql::SQLString sql::Connection::getCatalog()’
../mysql_connection.h:69: error: invalid covariant return type for ‘virtual std::string sql::mysql::MySQL_Connection::getSchema()’
/usr/local/src/mysql-connector-c++/cppconn/connection.h:80: error: overriding ‘virtual sql::SQLString sql::Connection::getSchema()’
../mysql_connection.h:71: error: invalid covariant return type for ‘virtual std::string sql::mysql::MySQL_Connection::getClientInfo()’
/usr/local/src/mysql-connector-c++/cppconn/connection.h:82: error: overriding ‘virtual sql::SQLString sql::Connection::getClientInfo()’
make: *** [mtest.o] Error 1

--/console-----------------------------------------------





I'm not really sure exactly what is going here. If anyone could shed some light on the problem it would be greatly appreciated. Thanks.



Edited 1 time(s). Last edit at 06/04/2010 02:15PM by alex ekholm.