Require C++17

CMakeLists.txt

@@ -98,16 +98,28 @@ SET(COMPILER_FLAGS -pedantic -Wall -Wextra -Wcast-align -Wcast-qual -Wconversion
 
 INCLUDE("cmake/compiler-flag-checks.cmake")
 
-# Check for C++17 and require C++17 if available else fallback to C++14 (should currently be sufficient)
+# Use CCache if available
+FIND_PROGRAM(CCACHE_FOUND ccache)
+IF(CCACHE_FOUND)
+    MESSAGE(STATUS "Using Ccache: ${CCACHE_FOUND}")
+    SET(CMAKE_CXX_COMPILER_LAUNCHER
+        "${CCACHE_FOUND}"
+        CACHE PATH "CCache program" FORCE)
+ENDIF()
+
+# Require C++17
 CHECK_CXX_COMPILER_FLAG(-std=c++17 SUPPORT_STD_CXX17)
-IF(SUPPORT_STD_CXX17)
-    SET(CMAKE_CXX_STANDARD 17)
-ELSE()
-    SET(CMAKE_CXX_STANDARD 14)
+IF(NOT SUPPORT_STD_CXX17)
+    MESSAGE(FATAL_ERROR "Compiler does not support required standard C++17")
 ENDIF()
+
+SET(CMAKE_CXX_STANDARD 17)
 SET(CMAKE_CXX_STANDARD_REQUIRED ON)
 SET(CMAKE_CXX_EXTENSIONS OFF)
 
+# Check if compiler version supports all features:
+INCLUDE("cmake/compiler-version-checks.cmake")
+
 # Set some debug flags
 # FIXME: not using the flag checker now because it wrongly rejects a sanitizer flag..
 IF(CMAKE_BUILD_TYPE MATCHES Debug AND ((CMAKE_CXX_COMPILER_ID STREQUAL "Clang") OR (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")))

cmake/compiler-version-checks.cmake

+# General overview for compiler support of CXX language and library features:
+# https://en.cppreference.com/w/cpp/compiler_support
+#
+# TODO: at some point this should probably be replaced by a proper use of CMAKE_CXX_COMPILE_FEATURES
+# https://cmake.org/cmake/help/latest/manual/cmake-compile-features.7.html
+
+# Minimum GCC versions for C++14 and C++17 feature support.
+# based on
+# https://gcc.gnu.org/projects/cxx-status.html
+# https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.2017
+SET(GCC_CXX_14_VERSION_MIN "6.1")
+SET(GCC_CXX_17_VERSION_MIN "8.0")
+
+# Minimum Clang versions for C++14 and C++17 feature support.
+# based on
+# https://clang.llvm.org/cxx_status.html
+SET(CLANG_CXX_14_VERSION_MIN "3.4")
+SET(CLANG_CXX_17_VERSION_MIN "7.0")
+
+# Minimum Apple Clang versions for C++14 and C++17 feature support.
+# based on
+# https://trac.macports.org/wiki/XcodeVersionInfo
+SET(APPLECLANG_CXX_14_VERSION_MIN "6.1")
+SET(APPLECLANG_CXX_17_VERSION_MIN "10.0")
+
+IF(CMAKE_CXX_STANDARD EQUAL 17)
+    SET(GCC_VERSION_MIN ${GCC_CXX_17_VERSION_MIN})
+    SET(CLANG_VERSION_MIN ${CLANG_CXX_17_VERSION_MIN})
+    SET(APPLECLANG_VERSION_MIN ${APPLECLANG_CXX_17_VERSION_MIN})
+ELSE()
+    SET(GCC_VERSION_MIN ${GCC_CXX_14_VERSION_MIN})
+    SET(CLANG_VERSION_MIN ${CLANG_CXX_14_VERSION_MIN})
+    SET(APPLECLANG_VERSION_MIN ${APPLECLANG_CXX_14_VERSION_MIN})
+ENDIF()
+
+IF(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    IF(CMAKE_CXX_COMPILER_VERSION VERSION_LESS GCC_VERSION_MIN)
+        MESSAGE(FATAL_ERROR "Requiring at least GCC version ${GCC_VERSION_MIN}. Available version"
+                            " ${CMAKE_CXX_COMPILER_VERSION} does not fully support required C++ features")
+    ENDIF()
+ELSEIF(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    IF(CMAKE_CXX_COMPILER_VERSION VERSION_LESS CLANG_VERSION_MIN)
+        MESSAGE(FATAL_ERROR "Requiring at least Clang version ${CLANG_VERSION_MIN}. Available version"
+                            " ${CMAKE_CXX_COMPILER_VERSION} does not fully support required C++ features")
+    ENDIF()
+ELSEIF(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
+    IF(CMAKE_CXX_COMPILER_VERSION VERSION_LESS APPLECLANG_VERSION_MIN)
+        MESSAGE(FATAL_ERROR "Requiring at least AppleClang version ${APPLECLANG_VERSION_MIN}. Available version"
+                            " ${CMAKE_CXX_COMPILER_VERSION} does not fully support required C++ features")
+    ENDIF()
+ENDIF()