cabal-store-gc --collect can't find package database

[noughtmare]

Running cabal-store-gc --collect yields:

[   0.00076] ghc.info: ghc
[   0.00483] process.0.start: cwd=/tmp ghc --info
[   0.08585] info: Reading global package db
[   0.08606] ghc.read-package-db: /home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/package.conf.d
[   0.12203] info: 34 packages in /home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/package.conf.d
[   0.12389] info: Reading store package db
[   0.12412] ghc.read-package-db: /home/jaro/.cabal/store/ghc-8.10.4/package.db
[   0.29674] info: 193 packages in /home/jaro/.cabal/store/ghc-8.10.4/package.db
[   0.30614] info: Reading installdir roots
[   0.32144] debug: Found 19 installdir roots from 3 executables
[   0.32233] info: Reading environment roots
[   0.32293] debug: Found 26 environment roots
[   0.32316] info: Reading indirect roots
[   0.33123] debug: Found 26 indirect roots
[   0.33154] info: Found 140 roots
[   0.33202] info: Finding dependencies
[   0.34100] info: 233 components are referenced from the roots
[   0.34497] info: 175 components are in the store
[   0.34521] info: 18 components will be removed from the store
[   0.34548] ghc.find-ghc-pkg: GhcInfo {ghcPath = "ghc", ghcVersion = mkVersion [8,10,4], ghcEnvDir = Path "/home/jaro/.ghc/x86_64-linux-8.10.4/environments", ghcGlobalDb = Path "/home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/package.conf.d", ghcLibDir = Path "/home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4"}
[   0.34651] process.1.start: cwd=/home/jaro/.ghc /home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/bin/ghc-pkg --version
[   0.36305] ghc.find-ghc-pkg.result: /home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/bin/ghc-pkg
[   0.36351] info: Removing async-2.2.3-236a4dc2f1b240551dae7a0b57a37c7de0b8dd5dcd25a2be0640dfd6e7afc562
[   0.36477] info: Removing attoparsec-0.13.2.5-d25a5dd2588894a14d2bae233a4fcb72e50147763f995af2de858d4af56a4616
[   0.36859] info: Removing case-insensitive-1.2.1.0-b2d0636a493060666e0f9b8b1150344d33f989b7db2023ae885cf27af0400c58
[   0.36988] info: Removing data-fix-0.3.1-08a094bb7b050df795bee7c81792f03ef71fbd8d967ae3a02ce9941882d9ba72
[   0.37083] info: Removing gentle-introduction-2021.1-2174da8667e1c277d3e7bef4326707ece8b0914e633e77ed14c522732b3fe68f
[   0.37184] info: Removing hashable-1.3.1.0-d6843a1c354b03ec345a56de12b120cc2558ac419378e59c75471c08f0c9e3bb
[   0.37330] info: Removing indexed-traversable-instances-0.1-3bd722fa5eb0aab1c992decd8138b22a52c07092075091c20e53561c61e7bfc6
[   0.37450] info: Removing lattices-2.0.2-5392f2233466144065aa296d4087703042d6c46abe97abee50d0b9f6cf4f8a01
[   0.37827] info: Removing optics-extra-0.3-aaba74d59681213761e63b57c695a6d2d4a823157254324f1d294bd1d025b3c7
[   0.38227] info: Removing scientific-0.3.6.2-e93e3f666210ea472bcfba3c150692c34101d365d8ab4de460bde5e83bd421e5
[   0.38406] info: Removing semialign-1.1.0.1-2dea8aa3a90a86fff8db0dbaf5245edc3e6950ae6141f046d88e2872e86de60f
[   0.38563] info: Removing semigroupoids-5.3.5-c5147d3a093fe9110baf508c76e32c407d6bbebd190c66441ffbd1127a0ffc83
[   0.38937] info: Removing serialise-0.2.3.0-45becdd1efe6d655411ea2481fce0bc672a5a22499f62b670cf5d992b0c9c3e2
[   0.39136] info: Removing strict-0.4.0.1-8e4ccb9dcf2e61791c3d3c7ffce9fa64d1460621894c4c6625009e401d5f4032
[   0.39307] info: Removing these-1.1.1.1-1b010073e9d9bbe2950bc05199efccc34e7352eb215c03cd84d116d1e69859c3
[   0.39432] info: Removing unordered-containers-0.2.13.0-25a25c80a274cafa04144e390819c8940e24acb3e26f2c4ae170825b997e9e77
[   0.39655] info: Removing uuid-types-1.0.4-5818046324226ec90721eea4b7822bb4e00d0c3db14e472f609185635b1ac3d1
[   0.39793] info: Removing witherable-0.4.1-7c0f8c80c8257681dd1b8254304a7600b6e462b781a890cddf823350329361c4
[   0.39922] process.2.start: cwd=/home/jaro/.cabal/store /home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/bin/ghc-pkg recache --package-db=/home/jaro/.cabal/store/ghc-8.10.4/package.db
[   0.41562] process.2.failed: Exitcode 1
========= stdout ================== stderr =========ghc-pkg: Can't find package database in /home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/lib
[   0.41628] peu.die: process check failed

Running the command manually gives the same error:

$ cwd=/home/jaro/.cabal/store /home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/bin/ghc-pkg recache --package-db=/home/jaro/.cabal/store/ghc-8.10.4/package.db
ghc-pkg: Can't find package database in /home/jaro/.ghcup/ghc/8.10.4/lib/ghc-8.10.4/lib

But running ghc-pkg manually does work:

$ which ghc-pkg
/home/jaro/.ghcup/bin/ghc-pkg
$ cwd=/home/jaro/.cabal/store ghc-pkg recache --package-db=/home/jaro/.cabal/store/ghc-8.10.4/package.db

So maybe cabal-store-gc does not work nicely in combination with ghcup?

[phadej]

Probably related to #31

[ulidtko]

Any idea why GHC ships 2 ghc-pkg executables that behave differently? 🤔

• $GHCDIST/bin/ghc-pkg-$GHCVER — symlinked from bin/ghc-pkg, this is the one that appears on PATH;
• $GHCDIST/lib/ghc-$GHCVER/bin/ghc-pkg — another one, that cabal-store-gc tries to call.

... Ah, Ben Gamari explained: the former is a wrapper for the latter, adds appropriate --global-package-db=...

It's weird though, why can't ghc-pkg recache just recache the given package-db and skip trying to load the global one?..

---

The patch from #99, applied locally, provides a workaround. (As well as manually running ghc-pkg recache).

@phadej #133 implements a fix for this, in the way that you wanted in #99. I'd tested, it does fix the issue. Merge?