Enable VDT by default and use builtin if not found

cmake/modules/RootBuildOptions.cmake

@@ -171,7 +171,7 @@ ROOT_BUILD_OPTION(tmva-cpu ON "Build TMVA with CPU support for deep learning. Re
 ROOT_BUILD_OPTION(tmva-gpu ON "Build TMVA with GPU support for deep learning. Requries CUDA")
 ROOT_BUILD_OPTION(unuran OFF "UNURAN - package for generating non-uniform random numbers")
 ROOT_BUILD_OPTION(vc OFF "Vc adds a few new types for portable and intuitive SIMD programming")
-ROOT_BUILD_OPTION(vdt OFF "VDT adds a set of fast and vectorisable mathematical functions")
+ROOT_BUILD_OPTION(vdt ON "VDT adds a set of fast and vectorisable mathematical functions")
 ROOT_BUILD_OPTION(veccore OFF "VecCore SIMD abstraction library")
 ROOT_BUILD_OPTION(vecgeom OFF "VecGeom is a vectorized geometry library enhancing the performance of geometry navigation.")
 ROOT_BUILD_OPTION(winrtdebug OFF "Link against the Windows debug runtime library")

cmake/modules/SearchInstalledSoftware.cmake

@@ -1442,9 +1442,8 @@ if(vdt OR builtin_vdt)
         message(FATAL_ERROR "VDT not found. Ensure that the installation of VDT is in the CMAKE_PREFIX_PATH")
       else()
         message(STATUS "VDT not found. Ensure that the installation of VDT is in the CMAKE_PREFIX_PATH")
-        message(STATUS "               Alternatively, you can also enable the option 'builtin_vdt' to build the VDT libraries internally")
-        message(STATUS "               For the time being switching OFF 'vdt' option")
-        set(vdt OFF CACHE BOOL "Disabled because external vdt not found (${vdt_description})" FORCE)
+        message(STATUS "               Switching ON 'builtin_vdt' option")
+        set(builtin_vdt ON CACHE BOOL "Enabled because external vdt not found (${vdt_description})" FORCE)
       endif()
     endif()
   endif()