message: Test that creating root signatures identical to internal sigs works OK
diff: @@ -63,6 +63,13 @@ float4 main() : SV_Target0
  psoCreator.GraphicsDesc.StreamOutput.NumStrides = 0xcccccccc;
  psoCreator.GraphicsDesc.StreamOutput.pBufferStrides = (UINT *)0x1234;
  + ID3D12RootSignaturePtr duplicateSig = MakeSig(
  + {
  + cbvParam(D3D12_SHADER_VISIBILITY_PIXEL, 0, 0),
  + constParam(D3D12_SHADER_VISIBILITY_PIXEL, 0, 1, 1),
  + },
  + D3D12_ROOT_SIGNATURE_FLAG_NONE);
  +
  ID3D12PipelineStatePtr pso = psoCreator;
  // if D3D12.4 (??) is available, use different interfaces
  @@ -124,6 +131,9 @@ float4 main() : SV_Target0
  ID3D12ResourcePtr bb = StartUsingBackbuffer(cmd, D3D12_RESOURCE_STATE_RENDER_TARGET);
  + // force duplicate signature to be used
  + cmd->SetGraphicsRootSignature(duplicateSig);
  +
  if(debug)
  debug->AssertResourceState(bb, D3D12_RESOURCE_STATE_RENDER_TARGET, 0);
  