CI: add a build with GHC 9.0

The GHC 9.0 build doesn't do any test, as they are performed by the
main branch.

This commit also fixes a caching bug in the Github action. It's too
small for a separate commit.

Author: aspiwack

.github/workflows/ci.yaml

@@ -23,8 +23,8 @@ jobs:
           ~/.cabal/packages
           ~/.cabal/store
           dist-newstyle
-        key: cache-${{ runner.os }}-${{ hashFiles('nixpkgs.nix') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('linear-base.cabal') }}-${{ github.sha }}
-        restore-keys: cache-${{ runner.os }}-${{ hashFiles('nixpkgs.nix') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('linear-base.cabal') }}-
+        key: cache-${{ runner.os }}-${{ hashFiles('nixpkgs.nix') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('capability.cabal') }}-${{ github.sha }}
+        restore-keys: cache-${{ runner.os }}-${{ hashFiles('nixpkgs.nix') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('capability.cabal') }}-
     - name: Update Cabal's database
       run: $NIXSHELL --run "cabal update"
     - name: Build Cabal's dependencies
@@ -35,3 +35,18 @@ jobs:
       run: $NIXSHELL --run "cabal --flag=dev test"
     - name: Haddock
       run: $NIXSHELL --run "cabal haddock"
+
+  stack-ghc9:
+    name: Build on GHC 9.0
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/[email protected]
+    - name: Cache dependencies
+      uses: actions/[email protected]
+      with:
+        path: ~/.stack
+        key: stack-ghc9-${{ runner.os }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('stack-ghc9.yaml.lock', 'capability.cabal') }}
+    - name: Upgrade stack
+      run: stack upgrade
+    - name: Build
+      run: stack --stack-yaml=stack-ghc9.yaml build --pedantic --test --bench --no-run-tests --no-run-benchmarks

stack-ghc9.yaml.lock

@@ -0,0 +1,38 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages:
+- completed:
+    subdir: generic-lens-core
+    name: generic-lens-core
+    version: 2.1.0.0
+    git: https://github.com/kcsongor/generic-lens.git
+    pantry-tree:
+      size: 2283
+      sha256: 5a26b16c38ad8d8ebc81182e1d09858858f16dc117a0c7b084d8446d3a17d749
+    commit: 8e1fc7dcf444332c474fca17110d4bc554db08c8
+  original:
+    subdir: generic-lens-core
+    git: https://github.com/kcsongor/generic-lens.git
+    commit: 8e1fc7dcf444332c474fca17110d4bc554db08c8
+- completed:
+    subdir: generic-lens
+    name: generic-lens
+    version: 2.1.0.0
+    git: https://github.com/kcsongor/generic-lens.git
+    pantry-tree:
+      size: 2630
+      sha256: aba81557550537d4cfda2c1b07accff8589da44a1e418a3cde5639eb438d1c86
+    commit: 8e1fc7dcf444332c474fca17110d4bc554db08c8
+  original:
+    subdir: generic-lens
+    git: https://github.com/kcsongor/generic-lens.git
+    commit: 8e1fc7dcf444332c474fca17110d4bc554db08c8
+snapshots:
+- completed:
+    size: 540164
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/nightly/2021/7/4.yaml
+    sha256: 195e3e9394de03e724525e210f82e30c4488f7c8a09fc70850d75d8b79332993
+  original: nightly-2021-07-04