[uvm] 报错randomize() failed due to conflicts between the following constraints

如果变量前 没有rand 不能定义constriant 来约束这个变量

bit[15:0] roetype;
constraint c_type_c{roetype==16'hfc3d;}

# ../../uvc/seq_lib/r_sequence.sv(39): randomize() failed due to conflicts between the following constraints:
#       ../../uvc/seq_lib/r_item.sv(41): c_r_sub_type_c { 1'h0; }