Do you think it would be worth also catching multiple variable declarations on the same line? There are times when I think it doesn't hurt readability:

integer :: i, j, k

And others where it's just confusing:

real :: pi, some_array(:, :) time

There's probably some useful variations like that that could be done as separate rules:

• Avoid mixing array and scalar variable declarations on the same line
• Avoid declaring multiple dummy arguments on the same line (maybe)

Potentially also "avoid declaring dummy arguments and local variables on the same line", but that would/should actually be fixed by "missing intent"