CI: while we can't test on Windows, we still can build on it

Author: ulysses4ever

.github/workflows/validate.yml

@@ -30,6 +30,71 @@ env:
   COMMON_FLAGS: '-j 2 -v'
 
 jobs:
+  windows-build:
+    name: Windows, ghc-${{ matrix.ghc }}
+    runs-on: "windows-latest"
+    outputs:
+      GHC_FOR_RELEASE: ${{ format('["{0}"]', env.GHC_FOR_RELEASE) }}
+    strategy:
+      matrix:
+        ghc: ["9.6.1", "9.4.2", "9.2.3", "9.0.2"]
+    steps:
+
+      - uses: actions/checkout@v3
+
+      - uses: haskell/actions/setup@v2
+        id: setup-haskell
+        with:
+          ghc-version: ${{ matrix.ghc }}
+          cabal-version: '3.8.1.0' # can't use 3.10, see
+          # https://github.com/haskell/actions/issues/202#issuecomment-1465856373
+          # this will force us to not configure/run tests
+
+      # The '+exe' constraint below is important, otherwise cabal-install
+      # might decide to build the library but not the executable which is
+      # what we need.
+      - name: Install cabal-plan
+        run: |
+          cd $(mktemp -d)
+          cabal install cabal-plan --allow-newer="base" --constraint='cabal-plan +exe'
+          echo "$HOME/.cabal/bin:$HOME/.local/bin" >> $GITHUB_PATH
+
+      - name: Allow newer dependencies when built with latest GHC
+        if: ${{ matrix.ghc }} == '9.6.1'
+        run: |
+          echo "allow-newer: *:base" >> cabal.project.release
+
+      - name: Validate print-config
+        run: sh validate.sh $FLAGS -s print-config
+
+      - name: Validate print-tool-versions
+        run: sh validate.sh $FLAGS -s print-tool-versions
+
+      - name: Release build
+        run: cabal build all --project-file=cabal.project.release
+
+      - name: Tar cabal head executable
+        if: matrix.ghc == env.GHC_FOR_RELEASE
+        run: |
+          CABAL_EXEC=$(cabal-plan list-bin cabal-install:exe:cabal)
+          # We have to tar the executable to preserve executable permissions
+          # see https://github.com/actions/upload-artifact/issues/38
+          #
+          # `cabal-plan` gives us a windows path but tar needs the posix one
+          CABAL_EXEC=$(cygpath $CABAL_EXEC)
+          tar -cvf cabal-head.tar -C $(dirname "$CABAL_EXEC") $(basename "$CABAL_EXEC")
+          echo "CABAL_EXEC_TAR=cabal-head.tar" >> $GITHUB_ENV
+
+      # We upload the cabal executable built with the ghc used in the release for:
+      # - Reuse it in the dogfooding job (although we could use the cached build dir)
+      # - Make it available in the workflow to make easier testing it locally
+      - name: Upload cabal-install executable to workflow artifacts
+        if: matrix.ghc == env.GHC_FOR_RELEASE
+        uses: actions/upload-artifact@v3
+        with:
+          name: cabal-${{ runner.os }}-${{ matrix.ghc }}
+          path: ${{ env.CABAL_EXEC_TAR }}
+
   validate:
     name: Validate ${{ matrix.os }} ghc-${{ matrix.ghc }}
     runs-on: ${{ matrix.os }}
@@ -57,12 +122,12 @@ jobs:
           # lot of segfaults caused by ghc bugs
           - os: "windows-latest"
             ghc: "8.8.4"
-          # it also throws segfaults randomly
-          - os: "windows-latest"
-            ghc: "8.4.4"
           # it often randomly does "C:\Users\RUNNER~1\AppData\Local\Temp\ghcFEDE.c: DeleteFile "\\\\?\\C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\ghcFEDE.c": permission denied (Access is denied.)"
           - os: "windows-latest"
             ghc: "8.6.5"
+          # it also throws segfaults randomly
+          - os: "windows-latest"
+            ghc: "8.4.4"
 
     steps:
 
@@ -101,6 +166,7 @@ jobs:
           restore-keys: ${{ runner.os }}-${{ matrix.ghc }}-20231920-
 
       - name: Did we get a cache hit
+        if: ${{ runner.os != 'Windows' }}
         continue-on-error: true
         run: echo "GHA cache hit:" ${{ steps.cache-haskell.outputs.cache-hit }}
 
@@ -166,7 +232,7 @@ jobs:
         run: sh validate.sh $FLAGS -s build
 
       - name: Tar cabal head executable
-        if: matrix.cmoewmoewli != 'false' && matrix.ghc == env.GHC_FOR_RELEASE
+        if: matrix.cli != 'false' && matrix.ghc == env.GHC_FOR_RELEASE
         run: |
           CABAL_EXEC=$(cabal-plan list-bin --builddir=dist-newstyle-validate-ghc-${{ matrix.ghc }} cabal-install:exe:cabal)
           # We have to tar the executable to preserve executable permissions
@@ -246,10 +312,10 @@ jobs:
         with:
           # validate.sh uses a special build dir
           path: |
-            ${{ steps.setup-haskell.outputs.cabal-store }}
+            # TODO: need cabal store path; where does ghcup put it?
             dist-*
-          key: ${{ runner.os }}-${{ matrix.ghc }}-20231920-${{ github.sha }}
-          restore-keys: ${{ runner.os }}-${{ matrix.ghc }}-20231920-
+          key: ${{ runner.os }}-prerelease-20231920-${{ github.sha }}
+          restore-keys: ${{ runner.os }}-prerelease-20231920-
 
       # See https://github.com/haskell/cabal/pull/8739
       - name: Sudo chmod to permit ghcup to update its cache
@@ -327,7 +393,8 @@ jobs:
         env:
           # `rawSystemStdInOut reports text decoding errors`
           # test does not find ghc without the full path in windows
-          GHCPATH: ${{ steps.setup-haskell.outputs.ghc-exe }}
+          GHCPATH: ${{ steps.setup-haskell.outputs.ghc-exe }} # TODO: we don't
+                              # use setup-haskell here, so above variable is not set
         run: sh validate.sh $FLAGS -s lib-tests
 
       - name: Validate lib-suite
@@ -385,7 +452,6 @@ jobs:
       - uses: actions/cache@v3
         with:
           path: |
-            ${{ steps.setup-haskell.outputs.cabal-store }}
             dist-*
           key: ${{ runner.os }}-${{ matrix.ghc }}-20231920-${{ github.sha }}
           restore-keys: ${{ runner.os }}-${{ matrix.ghc }}-20231920-
@@ -421,7 +487,7 @@ jobs:
   dogfooding:
     name: Dogfooding ${{ matrix.os }} ghc-${{ matrix.ghc }}
     runs-on: ${{ matrix.os }}
-    needs: validate
+    needs: [validate, windows-build]
     strategy:
       matrix:
         os: ["ubuntu-20.04", "macos-latest", "windows-latest"]
@@ -481,7 +547,7 @@ jobs:
     name: Validate post job
     runs-on: ubuntu-20.04
     # IMPORTANT! Any job added to the workflow should be added here too
-    needs: [validate, validate-old-ghcs, dogfooding]
+    needs: [validate, windows-build, validate-old-ghcs, dogfooding]
 
     steps:
       - run: |