rspec/rules/S903/rule.adoc

== Why is this an issue?

Unused function parameters are often due to design changes and can lead to mismatched parameter lists.


Exception: An unnamed parameter in the definition of a function that is used as a callback does not violate this rule.


Example:


----
typedef int (*CallbackFn)(int a, int b);

int Callback_1(int a, int b)                  // Compliant - "a" and "b" both used
{
  return a + b;
}

int Callback_2(int a, int b)                  // Non-Compliant - "b" is unused
{
  return a;
}

int Callback_3(int a, int)                    // Compliant - unnamed callback parameter exception
{
  return a;
}
----