synthesis warning of undriven signal

 If there are some undriven signals in my design,can RTL-Compiler find that?

 Is there any synthesis "warning", "Info" or "Error about this issue?

Should I set any attribure to find this problem?

Here are some sample code:

module mydesign (A, B) ;

input [3:0] A;

output [3:0] B;

wire [1:0] undriven_signal;

reg [5:0] reg_A;

always@(*) begin

     case(A)

     4'd0: XXXXXX

     4'd1: XXXXXX

     4'd2: XXXXXX

     4'd3: XXXXXX

     4'd4: XXXXXX

     4'd5: XXXXXX

     4'd6: XXXXXX

     4'd7: XXXXXX

     4'd8: XXXXXX

     4'd9: XXXXXX

     4'd10: XXXXXX

     4'd11: XXXXXX

     4'd12: XXXXXX

     4'd13: XXXXXX

     4'd14: XXXXXX

     4'd15:  reg_A = {undriven_signal, A};

end

endmodule

Warning : Undriven signal detected. [ELABUTL-125]

This warning only tell me that reg_A has some undriven signals, but I want the tool tells me more about undriven_signal.

The tool tells me that the warning location at line "case(A)". Can the tool find the line at "4'd15:  reg_A = {undriven_signal, A};"?