How to proceeed with bug investigation?

I’m trying to see if there’s anything I can do about this bug. But I am completely unfamiliar with LLDB/clang integration… Any advice, where to start looking?

I think the best way to start here is to try creating a minimal reproducer (which is unfortunately a bit tricky when multiple files are involved).

Having said that, this might just be a duplicate of lldb crashes with relatively simple gcc debug info · Issue #51160 · llvm/llvm-project · GitHub

A way to check if it’s a duplicate is to see if you can fix the bug in LLDB by adding names to all template arguments in the faulty class hierarchy in the eigen source. All explicit template specializations of DenseCoeffsBase and the template itself should be enough.

If it’s a duplicate you might be able to workaround it by adding dummy template names to the source. And the proper fix is described in the linked bug report.

If it’s not a dupe then someone has to reduce the test case first I fear :frowning:

I’ve updated the bug with a reduced repro.
As far as I understand, clang crashes because in lldb constructed AST Class is derived from itself. But why would it do that? Class<0> and Class<1> are clearly represented as distinct types in the debug info…

I commented on the bug (I think it makes sense to keep the discussion there as more of the involved folks get emails etc.)