Heisenbug with stack build resetting git history

[parsonsmatt]

General summary/comments (optional)

Occasionally, a stack build command will reset my git history to some point in the past.

Steps to reproduce

All of the examples I have are proprietary. I have a repro that I can share privately.

Stack version

λ ~/ stack --version
Version 1.2.1, Git revision 2caa0524b7a37c57c465b4c6414c1089eb81f137 x86_64 hpack-0.14.1

Method of installation

I did a stack upgrade --git sometime ago

[mgsloan]

Thanks for the report! I bet what is happening is that there is an empty directory and it tries to do a git reset on that dir, and it finds your repo instead! Argh!

I think the solution is to use --git-dir or the GIT_DIR environment variable to fix this in all of our usages of git. Relying on the working directory of the git command is too fragile.

[mgsloan]

I've made a change which causes stack to invoke git in such a way that this shouldn't be possible. If you do another stack upgrade --git, it'll pull in the change.

This doesn't address the root problem - that somehow the directory doesn't have a repository - but should prevent it from affecting your repo.

[parsonsmatt]

Thanks! I'll run it through my reproduction tomorrow and report back.

[parsonsmatt]

I haven't been able to get it to happen again, so I'm happy saying this is solved. Thanks for the quick fix! 😄

[mgsloan]

Welcome!