Workaround for cabal trying to build dependencies in nix-shell #8
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Without this PR, after a And after a It seems to work right now, but earlier I also encountered a spurious cc error doing this, which I can't reproduce anymore: Anyways, with this PR, and again with clean caches, it's more reproducible and also a lot faster: |
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This workaround could also be used for cardano-node, which seems to have the same problem: https://github.com/input-output-hk/cardano-node/blob/master/shell.nix#L15-L17 |
picnoir
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Dec 16, 2020
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Nit:
diff --git a/cabal.project b/cabal.project
index 2b8295a..11e0d0a 100644
--- a/cabal.project
+++ b/cabal.project
@@ -72,6 +72,12 @@ constraints: secp256k1-haskell +recovery
tests: True
+-- =============================================================
+-- WARNING:
+-- Do not add any directive other than source-repository-package
+-- past that point.
+-- =============================================================
+
source-repository-package
type: git
location: https://github.com/input-output-hk/cardano-baseGood job, LGTM!
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Applied! Edit: |
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For source-repository-package's, cabal tries to build them on its own, even when all dependencies are already provided by Nix. Relevant issues: - haskell/cabal#6049 - IntersectMBO/ouroboros-network#645 - haskell/cabal#5586 (comment) This seems to be a problem even with a cabal that includes haskell/cabal#6917 (see input-output-hk/haskell.nix#720 (comment) for how to test a cabal-install 3.4) The only known workaround is to remove the source-repository-package sections from cabal.project, but this should only be done for cabal when used from a nix-shell, not from cabal without a nix-shell, and not outside the nix-shell. To make this work smoothly, the script `scripts/nix-setup` can be used, which splits the source-repository-package sections into cabal.project.srcs, which is then again included from here (to make the Nix setup still work). Running the script again undoes it.
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For source-repository-package's, cabal tries to build them on its own, even
when all dependencies are already provided by Nix. Relevant issues:
This seems to be a problem even with a cabal that includes
haskell/cabal#6917 (see
input-output-hk/haskell.nix#720 (comment)
for how to test a cabal-install 3.4)
The only known workaround is to remove the source-repository-package
sections from cabal.project, but this should only be done for cabal when
used from a nix-shell, not from cabal without a nix-shell, and not outside
the nix-shell.
To make this work smoothly, the script
scripts/nix-setupcan be used,which splits the source-repository-package sections into cabal.project.srcs,
which is then again included from here (to make the Nix setup still work).
Running the script again undoes it.
Note that once the script is ran,
cabal.projectis marked as read-only, and git won't track changes to it (since you wouldn't want to commit the removed source-repository-package sections). To make changes, run the script again first.This is a pretty heavy-handed workaround, but I believe this is the best solution possible without spending huge amounts of time on it. This seemed to work very well in my testing and shouldn't conflict with the non-Nix development workflow or with
nix-build's.