* `stack repl` now always warns about GHCi problems with loading multiple
packages. It also sets now proper working directory when invoked with
one package. See
[#5421](https://github.com/commercialhaskell/stack/issues/5421)
* `custom-setup` dependencies are now properly initialized for `stack dist`.
This makes `explicit-setup-deps` no longer required and that option was
removed. See
[#4006](https://github.com/commercialhaskell/stack/issues/4006)
Other enhancements:
* Nix integration now passes `ghcVersion` (in addition to existing `ghc`) to
`shell-file` as an identifier that can be looked up in a compiler attribute set.
* Nix integration now allows Nix integration if the user is ready in nix-shell.
This gets rid of "In Nix shell but reExecL is False" error.
* Consider GHC 9.0 a tested compiler and remove warnings.
* `custom-preprocessor-extensions` is a new configuration option for allowing
stack to be aware of any custom preprocessors you have added to `Setup.hs`.
See [#3491](https://github.com/commercialhaskell/stack/issues/3491)
* Added `--candidate` flag to `upload` command to upload a package candidate
rather than publishing the package.
* Error output using `--no-interleaved-output` no longer prepends indentating
whitespace. This allows emacs compilation-mode and vim quickfix to locate
and track errors. See
[#5523](https://github.com/commercialhaskell/stack/pull/5523)
**Thanks to all our contributors for this release:**
* Aaron Allen
* Alexey Kuleshevich
* Andreas Källberg
* Domen Kožar
* Emanuel Borsboom
* Felix Yan
* Jens Petersen
* Kirill Zaborsky
* Marcin Tolysz
* Matt Audesse
* Matthew Wraith
* Michael Snoyman
* Mike Pilgrem
* Simon Michael