Preprocessor macro expanding to a type attribute
#include <SYS/TYPES.H>
void * __MALLOC_ATTR__ function(args...);
This macro expands to a compiler-specific attribute telling that the function allocates memory — i.e. it advises the compiler that the returned pointer doesn't alias any other memory object.
It enables the compiler to do better optimizations.
When using the gcc compiler, this macro expands to __attribute__((__malloc__))
.