C part :

mongo_connection_options * make_mongo_connection_options( char host[255], int port ){
        mongo_connection_options *opts = malloc(sizeof(mongo_connection_options));
        strcpy( opts->host , host );
        opts->port = port;
        return opts;
}


Perl6 part:

use NativeCall;

sub mongo_connect( OpaquePointer $client, OpaquePointer $options)
    returns OpaquePointer
    is native('libmongoc')
  { ... }

sub make_mongo_connection_options( Str $host, Int $port )
    returns OpaquePointer
    is native('libmongoc')
  { ... }

my OpaquePointer $connection;
my $options = make_mongo_connection_options('localhost', 27017);
my $answer = mongo_connect($connection,$options);
'done'.say;


The problem is $options becomes a UnManagedStruct , and passing it to mongo_connect does not work ( no connection, silent fail )