Gaps in enums

[delirium5223]

Can we have a new rule that says 

  if enum is used as an iterator type then there shall not be gaps in enum values.

Code:

typedef enum
{
  PIN_A = 1, 
    //missing 2
  PIN_B = 3,
  PIN_C = 4,
  PIN_MAX,
} tPin;
 
for(tPin i = PIN_A ; i < PIN_MAX; i++) 
{
// i reaching 2 is unintended/refactoring/human error
}

Surely we would want to know/acknowledge that enum has a gap if we plan to iterate over it.
(regardless where the 'for' loop starts/end)
   
It would make a good higher level/abstraction rule.
 
Or at least make it advisory.