Set C++ standard to 20 if not defined (#3583)

Why? to be able to use a greater c++ when using conan.

Because conan reports: Warning: Standard CMAKE_CXX_STANDARD value defined in conan_toolchain.cmake to 23 has been modified to 20 by .conan2/p/b/spdlo815dcec129526/b/src/CMakeLists.txt

.github/workflows/coverity_scan.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Coverity Scan
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install dependencies
         run: |

.github/workflows/linux.yml

@@ -28,7 +28,7 @@ jobs:
       image: ${{ matrix.config.compiler == 'clang' && 'teeks99/clang-ubuntu' || matrix.config.compiler }}:${{ matrix.config.version }}
     name: "${{ matrix.config.compiler}} ${{ matrix.config.version }} (C++${{ matrix.config.cppstd }} ${{ matrix.config.build_type }} ${{ matrix.config.asan == 'ON' && 'ASAN' || '' }}${{ matrix.config.tsan == 'ON' && 'TSAN' || '' }})"
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Setup
         run: |
           apt-get update
@@ -68,7 +68,7 @@ jobs:
     runs-on: macOS-latest
     name: "OS X Clang (C++11, Release)"
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Build
         run: |
           mkdir -p build && cd build

.github/workflows/macos.yml

@@ -19,7 +19,7 @@ jobs:
               BUILD_EXAMPLE: 'ON'
               
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Build
         run: |
           mkdir -p build && cd build

.github/workflows/windows.yml

@@ -42,7 +42,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: CMake ${{ matrix.config.GENERATOR }} CXX=${{matrix.config.CXX_STANDARD}} WCHAR=${{matrix.config.WCHAR_FILES}} STD_FORMAT=${{matrix.config.USE_STD_FORMAT}}
         shell: pwsh

CMakeLists.txt

@@ -30,7 +30,9 @@ endif()
 # Compiler config
 # ---------------------------------------------------------------------------------------
 if(SPDLOG_USE_STD_FORMAT)
+if(NOT DEFINED CMAKE_CXX_STANDARD)
     set(CMAKE_CXX_STANDARD 20)
+endif()
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
 elseif(NOT CMAKE_CXX_STANDARD)
     set(CMAKE_CXX_STANDARD 11)

bench/CMakeLists.txt

@@ -19,7 +19,7 @@ if(NOT benchmark_FOUND)
     # disable tests
     set(BENCHMARK_ENABLE_TESTING OFF CACHE INTERNAL "")
     # Do not build and run googlebenchmark tests
-    FetchContent_Declare(googlebenchmark GIT_REPOSITORY https://github.com/google/benchmark.git GIT_TAG v1.6.0)
+    FetchContent_Declare(googlebenchmark GIT_REPOSITORY https://github.com/google/benchmark.git GIT_TAG v1.8.4)
     FetchContent_MakeAvailable(googlebenchmark)
 endif()