Why is this an issue?

System timing check parameters should always be positive.

How to fix it

Code examples

Noncompliant code example

module fly(input a, b);
  specify
    $setup(posedge a, b, -1);
  endspecify
endmodule

Compliant solution

module fly(input a, b);
  specify
    $setup(posedge a, b, 1);
  endspecify
endmodule