Check post remove ci templates

.github/workflows/bootstrap.yml

@@ -1,5 +1,10 @@
 name: Bootstrap
 
+# See: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency.
+concurrency:
+  group: ${{ github.head_ref }}-${{ github.workflow }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:

.github/workflows/linux.yml

@@ -1,5 +1,10 @@
 name: Linux
 
+# See: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency.
+concurrency:
+  group: ${{ github.head_ref }}-${{ github.workflow }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:
@@ -11,7 +16,7 @@ on:
 
 jobs:
   validate:
-    name: Validate ghc-${{ matrix.ghc }}
+    name: Validate ubuntu-latest ghc-${{ matrix.ghc }}
 
     runs-on: ubuntu-latest
     continue-on-error: ${{ matrix.experimental }}
@@ -108,3 +113,59 @@ jobs:
         if: matrix.cli == true
         run: sh validate.sh -j 2 -w ghc-${{ matrix.ghc }} -v ${{ matrix.flags }} -s cli-suite
 
+  validate-old-ghcs:
+    name: Validate old ghcs
+    runs-on: ubuntu-18.04
+    needs: validate
+    container:
+      image: phadej/ghc:8.8.4-xenial
+
+    strategy:
+      matrix:
+        ghc: ["8.10.7"]
+        extra-ghc: ["7.10.3", "7.8.4", "7.6.3", "7.4.2", "7.2.2", "7.0.4"]
+
+    steps:
+
+      # We can't use actions/checkout with the docker container, see:
+      # https://github.com/actions/checkout/issues/170
+      # https://github.com/actions/checkout/issues/295
+      # - uses: actions/checkout@v2
+      - name: Checkout
+        run: |
+          echo $GITHUB_REF $GITHUB_SHA
+          git clone --depth 1 https://github.com/$GITHUB_REPOSITORY.git .
+          git fetch origin $GITHUB_SHA:temporary-ci-branch
+          git checkout $GITHUB_SHA || (git fetch && git checkout $GITHUB_SHA)
+
+      - name: Install extra compiler
+        run: |
+          apt-get update
+          apt-get install -y ghc-${{ matrix.extra-ghc }}-dyn
+
+      - uses: haskell/actions/setup@v1
+        id: setup-haskell
+        with:
+          ghc-version: ${{ matrix.ghc }}
+
+      #  See the following link for a breakdown of the following step
+      #  https://github.com/haskell/actions/issues/7#issuecomment-745697160
+      - uses: actions/cache@v2
+        with:
+          path: |
+            ${{ steps.setup-haskell.outputs.cabal-store }}
+            dist-newstyle
+          key: ${{ runner.os }}-${{ matrix.ghc }}-${{ github.sha }}
+          restore-keys: ${{ runner.os }}-${{ matrix.ghc }}-
+
+      - name: Install cabal-plan
+        run: |
+          cd $(mktemp -d)
+          cabal install cabal-plan --constraint='cabal-plan +exe'
+          echo "$HOME/.cabal/bin" >> $GITHUB_PATH
+
+      - name: Validate build
+        run: sh validate.sh -j 2 -w ghc-${{ matrix.ghc }} -v ${{ matrix.flags }} -s build
+
+      - name: "Validate lib-suite-extras --extra-hc ghc-${{ matrix.extra-ghc }}"
+        run: sh validate.sh -j 2 -w ghc-${{ matrix.ghc }} -v --lib-only -s lib-suite-extras --extra-hc /opt/ghc/${{ matrix.extra-ghc }}/bin/ghc-${{ matrix.extra-ghc }}

.github/workflows/macos.yml

@@ -1,5 +1,10 @@
 name: MacOS
 
+# See: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency.
+concurrency:
+  group: ${{ github.head_ref }}-${{ github.workflow }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:
@@ -11,7 +16,7 @@ on:
 
 jobs:
   validate:
-    name: Validate ghc-${{ matrix.ghc }}
+    name: Validate macos-lastest ghc-${{ matrix.ghc }}
 
     runs-on: macos-latest
     continue-on-error: ${{ matrix.experimental }}
@@ -111,4 +116,3 @@ jobs:
       - name: Validate cli-suite
         if: matrix.cli == true
         run: sh validate.sh -j 2 -w ghc-${{ matrix.ghc }} -v ${{ matrix.flags }} -s cli-suite
-

.github/workflows/quick-jobs.yml

@@ -1,5 +1,10 @@
 name: Quick jobs
 
+# See: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency.
+concurrency:
+  group: ${{ github.head_ref }}-${{ github.workflow }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:

.github/workflows/users-guide.yml

@@ -2,6 +2,11 @@
 
 name: Users guide
 
+# See: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency.
+concurrency:
+  group: ${{ github.head_ref }}-${{ github.workflow }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:

.github/workflows/windows.yml

@@ -1,5 +1,10 @@
 name: Windows
 
+# See: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency.
+concurrency:
+  group: ${{ github.head_ref }}-${{ github.workflow }}
+  cancel-in-progress: true
+
 on:
   push:
     branches: