try to test with g++11

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

@@ -13,18 +13,31 @@ jobs:
   build:
     name: ${{ matrix.compilers }}
     strategy:
-          fail-fast: false
-          matrix:
-            compilers: [g++-7, g++-8, g++-9, g++-10, g++-11]
+      fail-fast: false
+      matrix:
+        compilers: [g++-7, g++-8, g++-9, g++-10, g++-11]
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v1
-      - run: sudo apt-get update || true;
-             sudo apt-get install ${{ matrix.compilers }};
-             sudo apt-get install build-essential libglu1-mesa-dev mesa-common-dev libxrandr-dev libxinerama-dev libxcursor-dev libxi-dev libboost-all-dev libcgal-dev qt5-default;
-             rm -rf Release;
-             mkdir Release;
-             cd Release;
-             cmake -DCMAKE_CXX_COMPILER=${{ matrix.compilers }} -DCMAKE_BUILD_TYPE=Release ..;
-             make;
-
+      - name: Install GCC
+        run: |
+          sudo apt-get update || true
+          if [ "${{ matrix.compilers }}" == "g++-11" ]; then
+            sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
+            sudo apt-get update
+          fi
+          sudo apt-get install ${{ matrix.compilers }}
+      - name: Install Dependencies
+        run: |
+          sudo apt-get install build-essential libglu1-mesa-dev mesa-common-dev libxrandr-dev libxinerama-dev libxcursor-dev libxi-dev libboost-all-dev libcgal-dev qt5-default
+      - name: Build Project
+        run: |
+          rm -rf Release
+          mkdir Release
+          cd Release
+          if [ "${{ matrix.compilers }}" == "g++-11" ]; then
+            cmake -DCMAKE_CXX_COMPILER=/usr/bin/g++-11 -DCMAKE_BUILD_TYPE=Release ..
+          else
+            cmake -DCMAKE_CXX_COMPILER=${{ matrix.compilers }} -DCMAKE_BUILD_TYPE=Release ..
+          fi
+          make