On 4-5 June 2018, I attended a workshop on Debugging Numerical Software at University of Bath. The workshop featured a variety of debugging-themed talks from experienced developers of numerical software, as well as group discussion sessions and an innovative interactive “bug hunt” session.
I submitted a bug for discussion during the bug hunt session (slides and source code can be found at the public github repository created for the session). The bug was originally encountered as unexpected changes in the behaviour of Fortran code (ONETEP) when compiled with/without OpenMP support. See the slides I produced for the workshop for further information: slide 1, slide 2 (slide 2 contains some useful information about how compilers silently change how variables are allocated when OpenMP flags are used).
During the bug hunt session we were able to create a minimal working example (MWE) for my bug. This was a nice outcome, given that a MWE had proven elusive in my investigations prior to the workshop.