How can I investigate possible alignment issues when there is a segfault?
Once I know, I can add that to our debug_tips.md.
Do you have a concrete example or error?
Yeah, this is the one I want to solve. We've had alignment issues before so I really wanted to write down a general procedure to investigate and fix them if that is possible.
I'm not sure of a good generic guide for those type of issues. They tend to be low level and finicky. Aside from saying run with valgrind/gdb/lldb and look at both llvm ir generation. I don't think I have any sort of generic advise.
Probably this needs some pretty specific compiler internal errors to figure out. In this case, it is almost certainly a very specific llvm ir issue.
Sightly offtopic, but you fuzzed the stdlib a fair bit didn't you? This issue looks like it's in List builtin. Or is this more codegen on the roc side?
Nvm, you already gave an idea
I guess the issue is somehow with lambda closure capture inputs. I wonder if they are aligned correctly.
Somehow this is caused by a combination of:
I can confidently say I don't know what any of those mean... :sweat_smile:
Hopefully someday I'll get there. :smiley:
Last updated: Jul 06 2025 at 12:14 UTC