Code Correctness: Macro Misuse

Families of functions that operate on shared resources and are implemented as macros on some platforms must be called in the same program scope.

Certain families of functions are implemented as functions on some platforms and macros on others. If the functions rely on a shared resource that is maintained internally rather than passed in when they are invoked, they must be used in the same program scope because the otherwise the shared resource will be inaccessible.

Example 1: The following code uses pthread_cleanup_push() to push the function routine onto the calling thread's cleanup stack and returns. Since pthread_cleanup_push() and its partner function pthread_cleanup_pop() are implemented as macros on platforms other than IBM AIX, the data structure created by pthread_cleanup_push() will not be accessible to subsequent calls to pthread_cleanup_pop(). The code will either fail to compile or behave incorrectly at runtime on all platforms where these functions are implemented as macros.

void helper() {
   ...
   pthread_cleanup_push (routine, arg);
}