(gdb) bt
#0  0x00007ffff5a852fb in __cxxabiv1::__dynamic_cast(void const*, __cxxabiv1::__class_type_info const*, __cxxabiv1::__class_type_info const*, ptrdiff_t)
    (src_ptr=0x555556d90f60, src_type=0x5555557a3870 <typeinfo for WaveformBase>, dst_type=0x5555557a3858 <typeinfo for Waveform<EmptyConstructorWrapper<float> >>, src2dst=0) at ../../../../src/libstdc++-v3/libsupc++/dyncast.cc:68
#1  0x000055555562d578 in HistoryWindow::OnWaveformDataReady() (this=0x555555897bd0) at /ceph/fast/home/azonenberg/code/scopehal-apps/src/glscopeclient/HistoryWindow.cpp:227
#2  0x00005555556517cb in OscilloscopeWindow::LoadWaveformDataForScope(YAML::Node const&, Oscilloscope*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, IDTable&, FileProgressDialog&, float, float)
    (this=0x55555626cfe0, node=..., scope=0x555556374400, datadir="/ceph/fast/home/azonenberg/scopehal-tests/mdio_data", table=..., progress=..., base_progress=0, progress_range=1)
    at /ceph/fast/home/azonenberg/code/scopehal-apps/src/glscopeclient/OscilloscopeWindow.cpp:1588
#3  0x00005555556507fa in OscilloscopeWindow::LoadWaveformData(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, IDTable&)
    (this=0x55555626cfe0, filename="/ceph/fast/home/azonenberg/scopehal-tests/mdio.scopesession", table=...) at /ceph/fast/home/azonenberg/code/scopehal-apps/src/glscopeclient/OscilloscopeWindow.cpp:1410
#4  0x000055555564fddc in OscilloscopeWindow::DoFileOpen(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, bool, bool)
    (this=0x55555626cfe0, filename="/ceph/fast/home/azonenberg/scopehal-tests/mdio.scopesession", loadLayout=true, loadWaveform=true, reconnect=false)
    at /ceph/fast/home/azonenberg/code/scopehal-apps/src/glscopeclient/OscilloscopeWindow.cpp:1299