rspec/rules/S960/cfamily/rule.adoc

It is tempting to treat function-like macros as functions, but the two things work differently. For instance, the use of functions offers parameter type-checking, while the use of macros does not. Additionally, with macros, there is the potential for a macro to be evaluated multiple times. In general, functions offer a safer, more robust mechanism than function-like macros, and that safety usually outweighs the speed advantages offered by macros. Therefore functions should be used instead when possible.


== Noncompliant Code Example

----
#define CUBE (X) ((X) * (X) * (X)) // Noncompliant

void func(void) {
  int i = 2;
  int a = CUBE(++i); // Noncompliant. Expands to: int a = ((++i) * (++i) * (++i))
  // ...
}
----


== Compliant Solution

----
inline int cube(int i) { 
  return i * i * i;
}

void func(void) {
  int i = 2;
  int a = cube(++i); // yields 27
  // ...
}
----


== See

* MISRA C:2004, 19.7 - A function should be used in preference to a function-like macro.
* MISRA {cpp}:2008, 16-0-4 - Function-like macros shall not be defined.
* MISRA C:2012, Dir. 4.9 - A function should be used in preference to a function-like macro where they are interchangeable
* https://wiki.sei.cmu.edu/confluence/x/INcxBQ[CERT, PRE00-C.] - Prefer inline or static functions to function-like macros
* https://github.com/isocpp/CppCoreGuidelines/blob/036324/CppCoreGuidelines.md#es31-dont-use-macros-for-constants-or-functions[{cpp} Core Guidelines ES.31] - Don't use macros for constants or "functions"


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