g++ compile error while adding --trace-fst to verilator options

[hukangha]

Hi,
Trying to get fst waveform instead of vcd waveform from verilator so that the execution time and waveform data size can be reduced. (currently runs hours and generates a 30GB vcd file)
Added --trace-fst to execute option array:

Driver.execute( Array("--generate-vcd-output","off","--backend-name",s"$backendName",
      "--more-vcs-flags","--trace-fst --trace-depth 5 --x-initial unique"),
      ()=>new DMANetworkWithMem(memAddrWidth,memDataWidth)(nocDataWidth)(nNodesX,nNodesY)(nVCs)){
      c => new DMANetworkRWTest(c)

It reports an make error:

/home/hukang/data/work/noc/test_run_dir/noc.DMANetworkRWTester1555730092/DMANetworkWithMem-harness.cpp: In function ‘int main(int, char**, char**)’:
/home/hukang/data/work/noc/test_run_dir/noc.DMANetworkRWTester1555730092/DMANetworkWithMem-harness.cpp:673:23: error: no matching function for call to ‘VDMANetworkWithMem::trace(VerilatedVcdC*&, int)’
top->trace(tfp, 99);
^
In file included from :0:0:
./VDMANetworkWithMem.h:651:10: note: candidate: void VDMANetworkWithMem::trace(VerilatedFstC*, int, int)
void trace(VerilatedFstC* tfp, int levels, int options = 0);
^~~~~
./VDMANetworkWithMem.h:651:10: note: no known conversion for argument 1 from ‘VerilatedVcdC*’ to ‘VerilatedFstC*’
At global scope:
cc1plus: warning: unrecognized command line option ‘-Wno-undefined-bool-conversion’
make: *** [DMANetworkWithMem-harness.o] Error 1
make: *** Waiting for unfinished jobs....

and the test crushes.
This seems an unsupported feature, do we need extra effert to generate fst waveform ?