CMake: disable format validation if clang-format fails to run

Author: TheMostDiligent

BuildTools/CMakeLists.txt

@@ -6,6 +6,14 @@ if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
     set(CLANG_FORMAT_EXECUTABLE "${CMAKE_CURRENT_SOURCE_DIR}/FormatValidation/clang-format_10.0.0.exe" CACHE INTERNAL "clang-format executable path")
 elseif(CMAKE_HOST_SYSTEM_NAME STREQUAL "Linux")
     set(CLANG_FORMAT_EXECUTABLE "${CMAKE_CURRENT_SOURCE_DIR}/FormatValidation/clang-format_linux_10.0.0" CACHE INTERNAL "clang-format executable path")
+    execute_process(
+        COMMAND "${CLANG_FORMAT_EXECUTABLE}" --version
+        RESULT_VARIABLE CLANG_FORMAT_EXIT_CODE
+    )
+    if (NOT CLANG_FORMAT_EXIT_CODE EQUAL 0)
+        message(WARNING "${CLANG_FORMAT_EXECUTABLE} failed to run. Format validation will be disabled.")
+        unset(CLANG_FORMAT_EXECUTABLE CACHE)
+    endif()    
 elseif(CMAKE_HOST_SYSTEM_NAME STREQUAL "Darwin")
     set(CLANG_FORMAT_EXECUTABLE "${CMAKE_CURRENT_SOURCE_DIR}/FormatValidation/clang-format_mac_10.0.0" CACHE INTERNAL "clang-format executable path")
 endif()