Why is this an issue?

A function call is cast to void but it already returns void so the cast is pointless.

How to fix it

Code examples

Noncompliant code example

module fly;
  function void foo; endfunction
  initial begin
    void'(foo());
  end
endmodule

Compliant solution

module fly;
  function void foo; endfunction
  initial begin
    foo();
  end
endmodule