UBSAN detects division by zero in impurity_trace.cpp:417

[Wentzell]

During Warmup of the Py_histograms test UBSAN reports a division by zero in c++/triqs_cthyb/impurity_trace.cpp:417 with backtrace

cthyb/c++/triqs_cthyb/impurity_trace.cpp:417:66: runtime error: division by zero
    #0 0x7fc53ea88567 in triqs_cthyb::impurity_trace::compute(double, double) /mnt/home/wentzell/Dropbox/Coding/cthyb/c++/triqs_cthyb/impurity_trace.cpp:417:66
    #1 0x7fc53ed0330a in triqs_cthyb::move_insert_c_cdag::attempt() /mnt/home/wentzell/Dropbox/Coding/cthyb/c++/triqs_cthyb/moves/insert.cpp:108:74
    #2 0x7fc53e97f9e7 in triqs::mc_tools::move_set<double>::attempt() /mnt/home/wentzell/opt/triqs_2.2.x_san/include/triqs/mc_tools/./mc_move_set.hpp:201:42
    #3 0x7fc53e97f9e7 in triqs::mc_tools::move_set<double>::attempt() /mnt/home/wentzell/opt/triqs_2.2.x_san/include/triqs/mc_tools/./mc_move_set.hpp:201:42
    #4 0x7fc53ea6faa0 in triqs::mc_tools::mc_generic<double>::run(unsigned long, unsigned long, std::__1::function<bool ()>, bool) /mnt/home/wentzell/opt/triqs_2.2.x_san/include/triqs/mc_tools/mc_generic.hpp:227:31
    #5 0x7fc53ea6f09c in triqs::mc_tools::mc_generic<double>::warmup(unsigned long, long, std::__1::function<bool ()>) /mnt/home/wentzell/opt/triqs_2.2.x_san/include/triqs/mc_tools/mc_generic.hpp:131:14
    #6 0x7fc53e82831d in triqs::mc_tools::mc_generic<double>::warmup_and_accumulate(unsigned long, unsigned long, unsigned long, std::__1::function<bool ()>) /mnt/home/wentzell/opt/triqs_2.2.x_san/include/triqs/mc_tools/mc_generic.hpp:180:20
    #7 0x7fc53e80d9fc in triqs_cthyb::solver_core::solve(triqs_cthyb::solve_parameters_t const&) /mnt/home/wentzell/Dropbox/Coding/cthyb/c++/triqs_cthyb/solver_core.cpp:403:12
    #8 0x7fc53e570129 in SolverCore_solve(_object*, _object*, _object*) /mnt/home/wentzell/Dropbox/Coding/cthyb/build/python/triqs_cthyb/solver_core_wrap.cxx:839:17

@parcollet This is your line of code, please review.

[Wentzell]

Cf.

cthyb/c++/triqs_cthyb/impurity_trace.cpp

Line 417 in 4fc601e

histo->trace_first_over_sec_term << real(trace_partial / first_term);