True multi package support in "stack ghci"

[mgsloan]

This is just a stub issue to keep track of the goal of having "stack ghci" properly load packages, including switching cwd when loading modules (for TH file loading). I am removing the support for using intero's :cd-ghc command with multiple packages, because it doesn't always work, doesn't work on reload, and was generally a regression in behavior for multi-package projects - see #3309

A proper solution to this requires an implementation in ghci / intero. Some relevant issues:

https://ghc.haskell.org/trac/ghc/ticket/10827
https://github.com/commercialhaskell/intero/issues/41
https://github.com/commercialhaskell/intero/issues/39

[Ericson2314]

ghc-proposals/ghc-proposals#263 There's a proposal this (and WIP PR for the first step of this).

[qrilka]

I've removed intero from the title as I suppose there is no need to take it into account as the project has reached its end of life - https://github.com/chrisdone/intero/blob/master/README.md

From the other side there were 2 GSoC projects and some MRs to GHC aiming to resolve the problem of loading multiple packages into GHCi, the main entry point looks to be the wiki page Multi Session GHC API

[flip111]

This might be possible now as https://gitlab.haskell.org/ghc/ghc/-/issues/10827 got resolved through https://gitlab.haskell.org/ghc/ghc/-/merge_requests/6805?commit_id=fd42ab5fa1df847a6b595dfe4b63d9c7eecbf400

Commit fd42ab5fa1df847a6b595dfe4b63d9c7eecbf400 is available in the following git tags (as of this moment):

• ghc-9.4.1-alpha1
• ghc-9.4.1-alpha2
• ghc-9.4.1-alpha3
• ghc-9.4.1-rc1
• ghc-9.4.1-release
• ghc-9.4.2-release
• ghc-9.4.3-release
• ghc-9.4.4-release
• ghc-9.5-start
• ghc-9.6.1-alpha2
• ghc-9.6.1-alpha3
• ghc-9.7-start