No or unhelpful error message when cabal dependency resolution fails

[ramirez7]

(on haskell.nix at 7e06e14ae1b894445254fe41288bfa7dd4ccbc6f)

Ran into this attempting to upgrade to GHC 9, which bumped base and caused dependency issues:

trace: No index state specified for haskell-project, using the latest index state that we know about (2022-03-03T00:00:00Z)!
trace: ERROR: cabal configure failed with:
Cloning into '/build/tmp.98bf8coUXq/dist-newstyle/src/5iznfxhg3_-fcc2e6bf5e8d0a29'...
HEAD is now at ab961c7 Minimal Repo For Haskell.Nix
Your branch is up to date with 'origin/minimal'.
Cloning into '/build/tmp.98bf8coUXq/dist-newstyle/src/j8hf6vl6n_-dd62867bd959eb2d'...
HEAD is now at f9e1e64 Minimal Repo For Haskell.Nix
Your branch is up to date with 'origin/minimal'.
Cloning into '/build/tmp.98bf8coUXq/dist-newstyle/src/j8wl52ps3_-b093b9a032d673dd'...
HEAD is now at b690ec1 Minimal Repo For Haskell.Nix
Your branch is up to date with 'origin/minimal'.
Warning: The package list for 'hackage.haskell.org-at-2022-03-03T000000Z' is
19056 days old.
Run 'cabal update' to get the latest list of available packages.
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: cute-c2-0.1.0.0 (user goal)
[__1] trying: base-4.16.0.0/installed-4.16.0.0 (dependency of cute-c2)
[__2] trying: elided-0.1.0.0 (user goal)
[__3] next goal: ekg (dependency of elided)
[__3] rejecting: ekg-0.4.0.15 (conflict: base==4.16.0.0/installed-4.16.0.0,
ekg => base>=4.5 && <4.15)
[__3] skipping: ekg-0.4.0.14, ekg-0.4.0.13, ekg-0.4.0.12, ekg-0.4.0.11,
ekg-0.4.0.10, ekg-0.4.0.9, ekg-0.4.0.8, ekg-0.4.0.7, ekg-0.4.0.6, ekg-0.4.0.5,
ekg-0.4.0.4, ekg-0.4.0.3 (has the same characteristics that caused the
previous version to fail: excludes 'base' version 4.16.0.0)
[__3] trying: ekg-0.4.0.2
[__4] next goal: time (dependency of ekg)
[__4] rejecting: time-1.11.1.1/installed-1.11.1.1 (conflict: ekg => time<1.5)
[__4] skipping: time-1.12.1, time-1.12, time-1.11.1.2, time-1.11.1.1,
time-1.11.1, time-1.11, time-1.10, time-1.9.3, time-1.9.2, time-1.9.1,
time-1.9, time-1.8.0.4, time-1.8.0.3, time-1.8.0.2, time-1.8.0.1, time-1.8,
time-1.7.0.1, time-1.7, time-1.6.0.1, time-1.6, time-1.5.0.1, time-1.5 (has
the same characteristics that caused the previous version to fail: excluded by
constraint '<1.5' from 'ekg')
[__4] trying: time-1.4.2
[__5] next goal: deepseq (dependency of time)
[__5] rejecting: deepseq-1.4.6.1 (conflict: time => deepseq>=1.1 && <1.4)
[__5] skipping: deepseq-1.4.5.0, deepseq-1.4.4.0, deepseq-1.4.3.0,
deepseq-1.4.2.0, deepseq-1.4.1.2, deepseq-1.4.1.1, deepseq-1.4.1.0,
deepseq-1.4.0.0 (has the same characteristics that caused the previous version
to fail: excluded by constraint '>=1.1 && <1.4' from 'time')
[__5] rejecting: deepseq-1.3.0.2 (conflict: base==4.16.0.0/installed-4.16.0.0,
deepseq => base>=4.3 && <4.8)
[__5] trying: deepseq-1.3.0.1
[__6] next goal: snap-server (dependency of ekg)
[__6] rejecting: snap-server-1.1.2.0 (conflict: ekg => snap-server<0.10)
[__6] skipping: snap-server-1.1.1.2, snap-server-1.1.1.1, snap-server-1.1.1.0,
snap-server-1.1.0.0, snap-server-1.0.3.3, snap-server-1.0.3.2,
snap-server-1.0.3.1, snap-server-1.0.3.0, snap-server-1.0.2.2,
snap-server-1.0.2.1, snap-server-1.0.2.0, snap-server-1.0.1.1,
snap-server-1.0.1.0, snap-server-1.0.0.0 (has the same characteristics that
caused the previous version to fail: excluded by constraint '<0.10' from
'ekg')
[__6] trying: snap-server-0.9.5.1
[__7] trying: template-haskell-2.18.0.0/installed-2.18.0.0 (dependency of
elided)
[__8] next goal: pretty (dependency of template-haskell)
[__8] rejecting: pretty-1.1.3.6/installed-1.1.3.6 (conflict: deepseq==1.3.0.1,
pretty => deepseq==1.4.6.0/installed-1.4.6.0)
[__8] rejecting: pretty-1.1.3.6, pretty-1.1.3.5, pretty-1.1.3.4,
pretty-1.1.3.3, pretty-1.1.3.2, pretty-1.1.3.1, pretty-1.1.2.1,
pretty-1.1.2.0, pretty-1.1.1.3, pretty-1.1.1.2, pretty-1.1.1.1,
pretty-1.1.1.0, pretty-1.1.0.0, pretty-1.0.1.2, pretty-1.0.1.1,
pretty-1.0.1.0, pretty-1.0.0.0 (conflict: template-haskell =>
pretty==1.1.3.6/installed-1.1.3.6)
[__8] fail (backjumping, conflict set: deepseq, pretty, template-haskell)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: template-haskell, time, pretty,
deepseq, snap-server, base, ekg, elided, cute-c2
Try running with --minimize-conflict-set to improve the error message.

error: attribute 'shellFor' missing

       at /nix/store/vigmrh748qnywz175y3hsyyp98nfb3qg-haskellNix-src/overlays/haskell.nix:653:18:

          652|                   selectedCrossProjects;
          653|               in rawProject.hsPkgs.shellFor (args' // {
             |                  ^
          654|                   # Add inputs from the cross compilation shells
(use '--show-trace' to show detailed location information)

The real error is that cabal couldn't solve, but the error is that shellFor is missing. It would be nice if we got a nice bold useful error.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[jbgi]

This issue was the cause for merging a build regression in https://github.com/input-output-hk/plutus/pull/4871#issuecomment-1266613546

[peterbecich]

Should this be labeled "enhancement"? https://github.com/input-output-hk/haskell.nix/issues?q=is%3Aissue+is%3Aopen+label%3Aenhancement