Xcode 7.2 does not support thread_local => no way to build the MySQL connector for sqlpp11

[juandent]

Hi,

After much searching around, I have been stopped by the frustrating reality that Xcode 7.2 does not yet support thread_local variables and thus it is currently impossible to build "sqlpp11-connector-mysql-master". Connection.cpp uses this like so:

void execute_statement(detail::connection_handle_t& handle, const std::string& statement)
{
thread_local MySqlThreadInitializer threadInitializer;

    if (handle.config->debug)
      std::cerr << "MySQL debug: Executing: '" << statement << "'" << std::endl;

    if (mysql_query(handle.mysql.get(), statement.c_str()))
    {
      throw sqlpp::exception("MySQL error: Could not execute MySQL-statement: " +
                             std::string(mysql_error(handle.mysql.get())) + " (statement was >>" + statement +
                             "<<\n");
    }
  }

If someone knows a workaround, I would be deeply grateful! Such a shame for a great library...'

Thanks again,
Juan

[rbock]

Hi Juan,

I currently can't test with Xcode directly, but I will setup testing on travis.ci soon.

For the time being, please try to use boost.thread:

static boost::thread_specific_ptr<MySqlThreadInitializer> mysqlThreadInit;
if (!mysqlThreadInit.get()
{
     mysqlThreadInit.reset(new MysqlThreadInit);
}

Best,

Roland

[juandent]

Hi Roland!

Your idea worked!! Thank you so much!!

Juan

[rbock]

Glad it worked out :-)

[CapSel]

This solution is really bad.
C++ from Apple does not support thread_local but the "original" clang/libc++ support it. This is very old BUG or FEATURE of Apple's XCode environment - not clang/llvm/libc++.

[rbock]

So what would be a good solution?

[CapSel]

The "best" solution is for Apple to fix this issue.
Simplest solution is to test for __APPLE__.

[CapSel]

CMake solution: https://cmake.org/cmake/help/v3.0/variable/APPLE.html

[rbock]

Since I don't think I have that kind of pull at Apple, I like the __APPLE__ version best.

Care to write a pull request?

[CapSel]

#29
How can I fix issue from AppVeyor?