Hi Simon, It looks like you've done a release flavour build (which produces packages tagged with hash) and a non-release flavour like perf or quick (packages with -inplace tag) in this tree. What happened is that stale package config files from an earlier build got registered into the package database. You can fix it for now by removing _stage1/lib/package.conf.d and running the build again. This should be much quicker than rebuilding everything. If you only run non-release builds, you don't end up in this situation, since the inplace package config files have the same filename every time. The underlying issue should really be fixed in hadrian: It should ensure that stale package configs from earlier builds never get into the package database. cheers, Luite On Tue, Dec 2, 2025 at 5:10 PM Simon Peyton Jones wrote:

Friends

I'm getting this from my newly-built in-tree compiler

~/code/HEAD-11/_build/ghc-stage1 -c T24984.hs -O T24984.hs:1:1: error: [ ]8;;https://errors.haskell.org/messages/GHC-45102 \GHC-45102 ]8;; \] Ambiguous module name ‘Prelude’. it was found in multiple packages: base-4.22.0.0 base-4.22.0.0

What a bonkers message. What is going wrong?

I do see this:

ls -d /home/simonpj/code/HEAD-11/_build/stage1/lib/x86_64-linux-ghc-9.15.20251119/base* /home/simonpj/code/HEAD-11/_build/stage1/lib/x86_64-linux-ghc-9.15.20251119/base-4.22.0.0-c7d2 /home/simonpj/code/HEAD-11/_build/stage1/lib/x86_64-linux-ghc-9.15.20251119/base-4.22.0.0-inplace simonpj@LHR-WD-22561:~/code/HEAD-11/testsuite/tests/perf/compiler$

So there are two base packages around somehow. I don't know if that's the reason.

I'd love a bit of help.. it's super annoying

Maybe it's some leftover not-clean stuff -- but how would I diagnose? How can I see what package directories it is looking in, which package files it is reading?

THanks

Simon _______________________________________________ ghc-devs mailing list -- ghc-devs@haskell.org To unsubscribe send an email to ghc-devs-leave@haskell.org