QA Notice: Package has poor programming practices which may compile
               but will almost certainly crash on 64bit architectures.
   

A large portion of code in the open source world is developed on the 32bit x86 architecture. Unfortunately, this has led to many pieces of code not handling pointer types properly. When compiled and run on a 64bit architecture, the code in question will probably crash horribly. Some common examples are assuming that an integer type is large enough to hold pointers. This is true on 32bit architectures (an integer can hold 32bits and a pointer is 32bits big), but not true on 64bit architectures (an integer still holds just 32bits, but a pointer is 64bits big).

Since this issue can manifest itself in many ways (as there are many ways to improperly truncate a pointer), you will need to read the source code starting with the displayed warning. Make sure types are declared, used, and passed properly. Make sure that all function prototypes are found (see the Implicit Declarations section for more information). So on and so forth.