Feature request: synth* to call check after hierarchy

[Laksen]

The below test module is very obviously broken since the test2 instance is wired wrongly. Running a hierarchy, and then check gives good feedback, but just a hierarchy; flatten; will make all of the warnings disappear and subtle bugs sneak in.

module test(input x,
            output y);

  test2 instance(
    .y(x),
    .x(y)
  );

endmodule

module test2(input x,
             output y);

  assign x = y;

endmodule

Basically this is a request for having the inbuilt synth scripts use check after hierarchy to expose warnings that might otherwise be lost.