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This compliant solution follows the guidance of PRE00-C. Prefer inline or static functions to function-like macros by defining an inline function iabs() to replace the ABS() macro. Unlike the ABS() macro, which operates on operands of any type, the iabs() function will truncate arguments of types wider than int whose value is not in range of the latter type.

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#include <assert.h>
#include <stddef.h>
  
void process(size_t index) {
  assert(index > 0); /* No side effect */
  ++index;
  /* ... */
}

Exceptions

PRE31-C-EX1: An exception can be made for invoking an unsafe macro with a function call argument provided that the function has no side effects. However, it is easy to forget about obscure side effects that a function might have, especially library functions for which source code is not available; even changing errno is a side effect. Unless the function is user-written and does nothing but perform a computation and return its result without calling any other functions, it is likely that many developers will forget about some side effect. Consequently, this exception must be used with great care.

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