Why is this an issue?

A case item has a known value that makes it impossible to ever match the case condition (or vice versa).

How to fix it

Code examples

Noncompliant code example

module m;
  logic [2:0] a;
  initial begin
    case (a)
      4'b1000: ; // Noncompliant
      3'b111: ; // Compliant
    endcase
end
endmodule

Compliant solution

module m;
  logic [2:0] a;
  initial begin
    case (a)
      3'b100: ; // Compliant
      3'b111: ; // Compliant
    endcase
end
endmodule