Use C++20 (#6877)

.clang-tidy

@@ -54,6 +54,7 @@ Checks: >
     performance-*,
     -performance-noexcept-move-constructor,
     -performance-no-int-to-ptr,
+    -performance-type-promotion-in-math-fn,
     readability-*,
     -readability-avoid-const-params-in-decls,
     -readability-braces-around-statements,
@@ -82,6 +83,7 @@ Checks: >
     -readability-make-member-function-const,
     -readability-redundant-string-init,
     -readability-non-const-parameter,
+    -readability-container-contains,
     -readability-static-accessed-through-instance
     
 WarningsAsErrors: '*'

.github/workflows/osrm-backend.yml

@@ -396,7 +396,36 @@ jobs:
         elif [[ "${RUNNER_OS}" == "macOS" ]]; then
           echo "JOBS=$((`sysctl -n hw.ncpu` + 1))" >>  $GITHUB_ENV
         fi
+    # See: https://github.com/actions/toolkit/issues/946#issuecomment-1590016041
+    # We need it to be able to access system folders while restoring cached Boost below
+    - name: Give tar root ownership 
+      if: runner.os == 'Linux' && matrix.ENABLE_CONAN != 'ON'
+      run: sudo chown root /bin/tar && sudo chmod u+s /bin/tar
+    - name: Cache Boost
+      if: runner.os == 'Linux' && matrix.ENABLE_CONAN != 'ON'
+      id: cache-boost
+      uses: actions/cache@v4
+      with:
+        path: |
+          /usr/local/include/boost
+          /usr/local/lib/libboost*
+        key: v1-boost-${{ runner.os }}-${{ runner.arch }}-${{ matrix.runs-on }}
+        restore-keys: |
+          v1-boost-${{ runner.os }}-${{ runner.arch }}-${{ matrix.runs-on }}
 
+    - name: Install Boost
+      if: steps.cache-boost.outputs.cache-hit != 'true' && runner.os == 'Linux' && matrix.ENABLE_CONAN != 'ON'
+      run: |
+        BOOST_VERSION="1.85.0"
+        BOOST_VERSION_UNDERSCORE="${BOOST_VERSION//./_}"
+        wget -q https://boostorg.jfrog.io/artifactory/main/release/${BOOST_VERSION}/source/boost_${BOOST_VERSION_UNDERSCORE}.tar.gz
+        tar xzf boost_${BOOST_VERSION_UNDERSCORE}.tar.gz
+        cd boost_${BOOST_VERSION_UNDERSCORE}
+        sudo ./bootstrap.sh
+        sudo ./b2 install
+        cd ..
+        sudo rm -rf boost_${BOOST_VERSION_UNDERSCORE}*
+    
     - name: Install dev dependencies
       run: |
         python3 -m pip install "conan<2.0.0" || python3 -m pip install "conan<2.0.0" --break-system-packages
@@ -417,7 +446,7 @@ jobs:
         # Linux dev packages
         if [ "${ENABLE_CONAN}" != "ON" ]; then
           sudo apt-get update -y
-          sudo apt-get install -y libbz2-dev libxml2-dev libzip-dev liblua5.2-dev libboost-all-dev
+          sudo apt-get install -y libbz2-dev libxml2-dev libzip-dev liblua5.2-dev
           if [[ "${CCOMPILER}" != clang-* ]]; then
             sudo apt-get install -y ${CXXCOMPILER}
           fi

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.18)
 
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 

cmake/warnings.cmake

@@ -78,4 +78,9 @@ add_warning(switch-bool)
 add_warning(tautological-compare)
 add_warning(trampolines)
 # these warnings are not enabled by default
-# no_warning(name-of-warning)
+# no_warning(name-of-warning)
+no_warning(deprecated-comma-subscript)
+no_warning(comma-subscript)
+no_warning(ambiguous-reversed-operator)
+no_warning(restrict)
+no_warning(free-nonheap-object)

include/util/static_assert.hpp

@@ -1,6 +1,7 @@
 #ifndef OSRM_STATIC_ASSERT_HPP
 #define OSRM_STATIC_ASSERT_HPP
 
+#include <iterator>
 #include <type_traits>
 
 namespace osrm::util
@@ -8,14 +9,13 @@ namespace osrm::util
 
 template <typename It, typename Value> inline void static_assert_iter_value()
 {
-    using IterValueType = typename std::iterator_traits<It>::value_type;
-    static_assert(std::is_same<IterValueType, Value>::value, "");
+    static_assert(std::is_same_v<std::iter_value_t<It>, Value>, "");
 }
 
 template <typename It, typename Category> inline void static_assert_iter_category()
 {
     using IterCategoryType = typename std::iterator_traits<It>::iterator_category;
-    static_assert(std::is_base_of<Category, IterCategoryType>::value, "");
+    static_assert(std::is_base_of_v<Category, IterCategoryType>, "");
 }
 
 } // namespace osrm::util