install old g++

.github/workflows/build-and-test.yml

@@ -66,9 +66,12 @@ jobs:
     - uses: actions/checkout@v2
     - name: "apt-get install ${{ matrix.cmp }}"
       run: |
+        export GCC_NAME="${{ matrix.cmp }}"
+        sudo apt-get update
         sudo apt-get -y install software-properties-common
         sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-        sudo apt-get -y install ${{ matrix.cmp }}
+        sudo apt-get update
+        sudo apt-get -y install g++-${GCC_NAME#gcc-}
     - name: Prepare and compile dependencies
       run: python cue.py prepare
     - name: Build main module (example app)