Centralized caching workflow

[Anton-Latukha]

Discussed in: https://matrix.to/#/!oOjZFsoNYPAbTEgSOA:libera.chat/$ckv7h8SSMbimsa_5pCaCFn2uMm_nEVIy6gy0QyFgc8M?via=libera.chat&via=matrix.org&via=monoid.al

Short: Cabal builds deps from the source. Currently, cache gets saved only on the successful passing of the CI workflow pipeline (includes dependencies built, then all HLS projects built & then successful passing of all tests, core word is "successful" passing of all of that), while successful Cabal dependency build stage depends only on does Hackage snapshot state (success of Cabal dependency build stage).

Basic idea - is to run cabal v2-build --only-dependencies, which would ensure saving & sharing of the snapshot of successfully built dependencies into pull requests. To run on schedule & on push to master.

[Anton-Latukha]

Cache for *-build-* stores:

        with:
          path: |
            ${{ env.CABAL_PKGS_DIR }}
            ${{ env.CABAL_STORE_DIR }}

That is ~/.cabal/packages & ~/.cabal/store which are build dependency storage. That means that build is just a dependency cache & that is seen from that dist-newstyle build artifacts are not cached at all.

So introducing dependency caching already as is - uses *-build-* already properly.

[Anton-Latukha]

The first successful caching happened in: https://github.com/haskell/haskell-language-server/runs/4369337368?check_suite_focus=true. Further builds are cache reuse.

[jneira]

I am a little bit worried too by the duplication between this and the test workflow (to the already existing duplication with the build workflow). But well we can tackle it in next pr's
Will take a look to the link you provided to see how can we remove it
have you planned working on that?

[jneira]

lgtm, many thanks for helping to improve ci

[jneira]

Not related at all with this pr but the nix build in master has failed with

primitive-extras> Preprocessing library for primitive-extras-0.10.1..
primitive-extras> Building library for primitive-extras-0.10.1..
primitive-extras> [ 1 of 10] Compiling PrimitiveExtras.Prelude ( library/PrimitiveExtras/Prelude.hs, dist/build/PrimitiveExtras/Prelude.o, dist/build/PrimitiveExtras/Prelude.dyn_o )
primitive-extras> [ 2 of 10] Compiling PrimitiveExtras.Types ( library/PrimitiveExtras/Types.hs, dist/build/PrimitiveExtras/Types.o, dist/build/PrimitiveExtras/Types.dyn_o )
primitive-extras> [ 3 of 10] Compiling PrimitiveExtras.SmallArray ( library/PrimitiveExtras/SmallArray.hs, dist/build/PrimitiveExtras/SmallArray.o, dist/build/PrimitiveExtras/SmallArray.dyn_o )
primitive-extras> [ 4 of 10] Compiling PrimitiveExtras.Bitmap ( library/PrimitiveExtras/Bitmap.hs, dist/build/PrimitiveExtras/Bitmap.o, dist/build/PrimitiveExtras/Bitmap.dyn_o )
primitive-extras> library/PrimitiveExtras/Bitmap.hs:5:3: error:
primitive-extras>     Ambiguous occurrence ‘singleton’
primitive-extras>     It could refer to
primitive-extras>        either ‘PrimitiveExtras.Prelude.singleton’,
primitive-extras>               imported from ‘PrimitiveExtras.Prelude’ at library/PrimitiveExtras/Bitmap.hs:25:1-70
primitive-extras>               (and originally defined in ‘base-4.15.0.0:Data.OldList’)
primitive-extras>            or ‘PrimitiveExtras.Bitmap.singleton’,
primitive-extras>               defined at library/PrimitiveExtras/Bitmap.hs:53:1
primitive-extras>   |
primitive-extras> 5 |   singleton,
primitive-extras>   |   ^^^^^^^^^
primitive-extras> [ 6 of 10] Compiling PrimitiveExtras.UnliftedArray ( library/PrimitiveExtras/UnliftedArray.hs, dist/build/PrimitiveExtras/UnliftedArray.o, dist/build/PrimitiveExtras/UnliftedArray.dyn_o )

so i guess some hackage change has triggered it? the nix build soes not use the pinned hackage index from cabal.project?

//cc @maralorn @michaelpj

[jneira]

EDITED: we are building an older release 0.10.1 which seems to be not compatible with ghc-9.0.1

[Anton-Latukha]

lgtm, many thanks for helping to improve ci

Thank you also.

It is highly motivating to get work accepted & get maintainer notes on what can be made further.

Would take another round on CI code.