When building a very simple app which includes mongo headers and other boost headers, the app fails to build. The problem is that mongo headers have a #define for malloc which is forced upon your program silently.

This piece of code will fail to compile. The error will indicate that malloc is now mongo::ourmalloc which is most certainly NOT what the user wants. It also causes a conflict with the boost header which has a member function called malloc.

#include <mongo/client/dbclient.h>
#include <boost/pool/pool.hpp>

int main(int argc, char* argv[])
{
malloc();
return 0;
}

error when building:
In file included from /usr/include/boost/pool/pool.hpp:34,
from shit.c:2:
/usr/include/boost/pool/simple_segregated_storage.hpp:99: error: invalid use of '::'
In file included from shit.c:2:
/usr/include/boost/pool/pool.hpp:54: error: invalid use of '::'
/usr/include/boost/pool/pool.hpp:65: error: invalid use of '::'
/usr/include/boost/pool/pool.hpp:219: error: invalid use of '::'
/usr/include/mongo/client/../util/allocator.h: In function 'int main(int, char**)':
/usr/include/mongo/client/../util/allocator.h:22: error: too few arguments to function 'void* mongo::ourmalloc(size_t)'
shit.c:6: error: at this point in file

The expected error here is error: too few arguments to function 'void* malloc(size_t)' when the systems (proper) malloc is used