Can't depend on ghc-lib-parser-9.8.4.20241130 and ghc-9.8.4 at the same time

[fendor]

Hi! Trying to build HLS with ghc 9.8.4, I encountered this solver error:

> cabal repl -w ghc-9.8.4 -b ghc,ghc-lib-parser --constraint="ghc-lib-parser==9.8.4.20241130"
Resolving dependencies...
Error: [Cabal-7107]
Could not resolve dependencies:
[__0] trying: fake-package-0 (user goal)
[__1] next goal: ghc-lib-parser (dependency of fake-package)
[__1] rejecting: ghc-lib-parser; 9.10.1.20241103, 9.10.1.20240511 (constraint from command line flag requires ==9.8.4.20241130)
[__1] trying: ghc-lib-parser-9.8.4.20241130
[__2] next goal: filepath (dependency of ghc-lib-parser)
[__2] rejecting: filepath-1.4.301.0/installed-211c (conflict: ghc-lib-parser => filepath>=1.5 && <1.6)
[__2] trying: filepath-1.5.4.0
[__3] next goal: directory (dependency of ghc-lib-parser)
[__3] rejecting: directory-1.3.8.5/installed-b24b (conflict: filepath==1.5.4.0, directory => filepath==1.4.301.0/installed-211c)
[__3] trying: directory-1.3.9.0
[__4] next goal: ghc (dependency of fake-package)
[__4] rejecting: ghc-9.8.4/installed-c895 (conflict: directory==1.3.9.0, ghc => directory==1.3.8.5/installed-b24b)
[__4] rejecting: ghc; 9.10.1, 9.8.2, 9.8.1, 9.6.6, 9.6.5, 9.6.4, 9.6.3, 9.6.1, 9.4.8, 9.4.7, 9.4.6, 9.4.5, 9.4.4, 9.4.3, 9.4.2, 9.4.1, 9.2.8, 9.2.7, 9.2.6, 9.2.5, 9.2.4, 9.2.3, 9.2.2, 9.2.1, 9.0.2, 8.10.7, 8.10.2, 8.10.1, 8.8.3, 8.8.1, 8.6.5, 8.6.4, 8.6.1, 8.4.4, 8.4.3, 8.4.1, 8.2.2, 8.2.1, 9.2.3.20220620 (constraint from non-reinstallable package requires installed instance)
[__4] fail (backjumping, conflict set: directory, fake-package, ghc)
After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: ghc, ghc-lib-parser, base, directory, filepath, fake-package
Try running with --minimize-conflict-set to improve the error message.

One can relax the filepath constraint (>= 1.5 && <1.6), and then it successfully compiles.

I don't know how this constraint is derived, maybe it is implied by some flag?

[juhp]

Yes I just hit this too for Stackage Nightly

Revision also needed for ghc-lib-9.8.4.20241130 of course

[juhp]

I could make a Hackage revision?
to help expedite moving Stackage Nightly to 9.8.4

[shayne-fletcher]

i tightened the lower bounds on filepath in #571 for the 9.8 and 9.10 cases. apparently, that was not a good thing to do. i'll put them back to filepath >= 1 as it was in the code and in the 9.8.4 hackage distributions.

[shayne-fletcher]

I don't know how this constraint is derived, maybe it is implied by some flag?

they are chosen by examining the GHC .cabal files on the branch of the ghc-lib sources (e.g. ghc-9.8.4-release).

hackage has been fixed up for ghc-lib-parser-9.8.4.20241130 and ghc-lib-9.8.4.20241130

[fendor]

Thank you for the quick response and fix! Closing as fixed :)