build lib-benchmark from source to avoid a linker error about incompatible LTO versions

Author: mnikander

.github/workflows/cpp_ci.yaml

@@ -15,7 +15,17 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install C++ dependencies
-        run: sudo apt-get update && sudo apt-get install -y build-essential cmake libgtest-dev libbenchmark-dev
+        run: sudo apt-get update && sudo apt-get install -y build-essential cmake libgtest-dev # libbenchmark-dev
+
+      # 2025-05-12: Added to resolve a linker error about the compiler and benchmark having different LTO versions.
+      #             Hopefully this can be removed in the future.
+      - name: Build Google Benchmark from source
+        run: |
+          git clone https://github.com/google/benchmark.git
+          cd benchmark
+          git clone https://github.com/google/googletest.git
+          cmake -B build -S . -DCMAKE_BUILD_TYPE=Release
+          cmake --build build --target install
 
       - name: Setup
         run: cmake -B out -S .