CMake, VTK8 and Embarcaderos Clang compiler

Question

The current Embarcadero version of C++ Builder (10.2.3) ships with Clang 32 and 64 bit C/C++ compilers. The Clang version is claimed to be 3.3, (http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Win32_Clang-enhanced_Compilers).

I'm looking into compiling VTK 8.0, and other libraries using these compilers and CMake.

However, the 'system' CMake file (Windows-Embarcadero.cmake) that ships with CMake is not configured for Clang, but the older bcc32 compiler.

Embarcadero suggest to copy their distributed "Windows-Embarcadero.cmake" file (http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Using_CMake_with_C%2B%2B_Builder), to CMakes Modules/Platform folder, and overwrite the Windows-Embarcadero.cmake file that is shipped with CMake. I'm using CMake 3.10.

However, following Embarcaderos suggestions don't allow much to be compiled. In addition to not working properly, the new .cmake file breaks support for the old bcc32 compiler(!).

The first error when trying to configure VTK8 sources using CMake and the bcc32x (clang32) compiler is:

CMake Error at CMake/vtkModuleMacros.cmake:586 (target_compile_features):
target_compile_features no known features for CXX compiler

"Embarcadero"

version 7.30.36015.
Call Stack (most recent call first):
CMake/vtkModuleMacros.cmake:660 (vtk_add_library)
Common/Core/CMakeLists.txt:399 (vtk_module_library)

Digging into the CMake/vtkModuleMacros at line 586 shows where the error occurs:

  function(vtk_add_library name)
  add_library(${name} ${ARGN} ${headers})
  # We use compile features to specify that VTK requires C++11.
  # We request a series of C++11 features that will conform to VTK's
  # desired minimum requirements.
  # - cxx_override enforces Intel 14+, and GCC 4.7+
  # - cxx_nullptr as this a hard requirement for all compiler
  # CMake 3.8+ introduces the concept of meta language compiler features, and
  # also introduces the first compilers that are only meta language feature
  # aware. So if we have CMake 3.8+ we will also set the meta feature as
  # a private flag ( private so we don't force consumers to also use 3.8+ )
  if(NOT VTK_IGNORE_CMAKE_CXX11_CHECKS)
    target_compile_features(${name} PUBLIC cxx_nullptr cxx_override) **This is line 586** 
    if(NOT CMAKE_VERSION VERSION_LESS 3.8)
      target_compile_features(${name} PRIVATE cxx_std_11)
    endif()
  endif()
  if(NOT ARGV1 STREQUAL OBJECT)
    vtk_target(${name})
  endif()
endfunction()

This does perhaps indicate that the CMake file that Embarcadero ships is not proper/complete. Embarcaderos CMake file looks like this:

# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

set(_EMBT_CPP_PREPROCESSOR "cpp32")
set(EMBT_TARGET Windows)

if(CMAKE_BASE_NAME STREQUAL "bcc32x")
  set(BCC32X TRUE)
  set(_EMBT_CPP_PREPROCESSOR "cpp32x")
  set(CLANG_BASED TRUE)
endif()

if(CMAKE_BASE_NAME STREQUAL "bcc64")
  set(BCC64 TRUE)
  set(_EMBT_CPP_PREPROCESSOR "cpp64")
  set(CLANG_BASED TRUE)
endif()

if(CMAKE_BASE_NAME STREQUAL "bcc32c")
  set(BCC32C TRUE)
  set(_EMBT_CPP_PREPROCESSOR "cpp32c")
endif()

# This module is shared by multiple languages; use include blocker.
if(__WINDOWS_EMBARCADERO)
  return()
endif()

set(__WINDOWS_EMBARCADERO 1)
set(BORLAND 1)

if("${CMAKE_${_lang}_COMPILER_VERSION}" VERSION_LESS 6.30)
  # Borland target type flags (bcc32 -h -t):
  set(_tW "-tW")       # -tW  GUI App         (implies -U__CONSOLE__)
  set(_tC "-tWC")      # -tWC Console App     (implies -D__CONSOLE__=1)
  set(_tD "-tWD")      # -tWD Build a DLL     (implies -D__DLL__=1 -D_DLL=1)
  set(_tM "-tWM")      # -tWM Enable threads  (implies -D__MT__=1 -D_MT=1)
  set(_tR "-tWR -tW-") # -tWR Use DLL runtime (implies -D_RTLDLL, and '-tW' too!!)
  # Notes:
  #  - The flags affect linking so we pass them to the linker.
  #  - The flags affect preprocessing so we pass them to the compiler.
  #  - Since '-tWR' implies '-tW' we use '-tWR -tW-' instead.
  #  - Since '-tW-' disables '-tWD' we use '-tWR -tW- -tWD' for DLLs.
else()
  set(EMBARCADERO 1)
  set(_tC "-tC") # Target is a console application
  set(_tD "-tD") # Target is a shared library
  set(_tM "-tM") # Target is multi-threaded
  set(_tR "-tR") # Target uses the dynamic RTL
  set(_tW "-tW") # Target is a Windows application
  set(_tV "-tV") # Target is a VCL application
  set(_tJ "-tJ") # Target uses the Delphi Runtime
  set(_tF "-tF") # Target is a FMX application
  set(_tP "-tP") # Target creates a Package
  set(_tU "-tU") # Target creates a Unicode
endif()

# if build type is not provided set it to debug mode
if(NOT CMAKE_BUILD_TYPE)
  set (CMAKE_BUILD_TYPE DEBUG CACHE STRING "Choose the type of build, options are: DEBUG RELEASE RELWITHDEBINFO MINSIZEREL.")
endif()


# to get the latest version of Rad Studio Installed by passing _EMBT_SDK_DIR path.
macro(_embt_getbdsversion result curdir)
  file(GLOB children RELATIVE ${curdir} ${curdir}/*)
  set(dirlist "")
  foreach(child ${children})
    if(IS_DIRECTORY ${curdir}/${child})
      list(APPEND dirlist ${child})
    endif()
  endforeach()
  list(LENGTH dirlist dirlength)
  set(latest_dir_index ${dirlength})
  math(EXPR latest_dir_index "${latest_dir_index}-1")
  list (GET dirlist ${latest_dir_index} latest_dir)
  set(${result} ${latest_dir})
endmacro()

set(_EMBT_SDK_DIR "")

if(NOT "$ENV{APPDATA}" STREQUAL "")
  set(_EMBT_SDK_DIR "$ENV{APPDATA}\\Embarcadero\\BDS") #have to pick up by path from %APPDATA%
  string(REGEX REPLACE "\\\\" "/" _EMBT_SDK_DIR "${_EMBT_SDK_DIR}")
  file(TO_CMAKE_PATH "${_EMBT_SDK_DIR}" _EMBT_SDK_DIR)
endif()

if(EXISTS ${_EMBT_SDK_DIR})
  _embt_getbdsversion(LATESTVER ${_EMBT_SDK_DIR})
  get_filename_component(ROOTDIR "[HKEY_LOCAL_MACHINE\\SOFTWARE\\Embarcadero\\BDS\\${LATESTVER};RootDir]" ABSOLUTE CACHE)
  string(REGEX REPLACE "\\\\" "/" ROOTDIR ${ROOTDIR})
else()
  #if RAD Studio is not installed,
  find_path(BIN_DIR_PATH NAMES ${CMAKE_BASE_NAME}.exe)
  get_filename_component(ROOTDIR ${BIN_DIR_PATH} PATH)
endif()

include_directories(SYSTEM "${ROOTDIR}/include/windows/crtl")
include_directories(SYSTEM "${ROOTDIR}/include/windows/sdk")
include_directories(SYSTEM "${ROOTDIR}/include/windows/rtl")
include_directories(SYSTEM "${ROOTDIR}/include/dinkumware64")

if(BCC32X OR BCC32C)
  if(CMAKE_BUILD_TYPE MATCHES ".*DEB.*")
    set(linker_Path1 "${ROOTDIR}/lib/win32c/debug")
    set(linker_Path2 "${ROOTDIR}/lib/win32/debug")
    set(linker_Path3 "${ROOTDIR}/lib/win32/debug/psdk")
    set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path1}\"")
    set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path2}\"")
    set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path3}\"")
  endif()
  set(linker_Path1 "${ROOTDIR}/lib/win32c/release")
  set(linker_Path2 "${ROOTDIR}/lib/win32/release")
  set(linker_Path3 "${ROOTDIR}/lib/win32/release/psdk")
  set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path1}\"")
  set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path2}\"")
  set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path3}\"")
endif()

if(CLANG_BASED)

  if(BCC32X)
    set(CMAKE_C_COMPILER ${ROOTDIR}/bin/bcc32x.exe)
    set(CMAKE_CXX_COMPILER ${ROOTDIR}/bin/bcc32x.exe)
  endif()

  if(BCC64)
    if(CMAKE_BUILD_TYPE MATCHES ".*DEB.*")
      set(linker_Path1 "${ROOTDIR}/lib/win64/debug")
      set(linker_Path2 "${ROOTDIR}/lib/win64/debug/psdk")
      set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path1}\"")
      set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path2}\"")
    endif()
    set(linker_Path1 "${ROOTDIR}/lib/win64/release")
    set(linker_Path2 "${ROOTDIR}/lib/win64/release/psdk")
    set(CMAKE_C_COMPILER ${ROOTDIR}/bin/bcc64.exe)
    set(CMAKE_CXX_COMPILER ${ROOTDIR}/bin/bcc64.exe)
    set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path1}\"")
    set(windows_LIBRARY "${windows_LIBRARY} -L \"${linker_Path2}\"")
  endif()

  # Setting the Link Library Path in flag
  set(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS ${windows_LIBRARY})
  set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS ${windows_LIBRARY})
  # setting the link library flag
  set(link_flags ${windows_LIBRARY})
  set(CMAKE_EXE_LINKER_FLAGS ${link_flags} CACHE INTERNAL "exe link flags")
  set(CMAKE_MODULE_LINKER_FLAGS ${link_flags} CACHE INTERNAL "module link flags")
  set(CMAKE_SHARED_LINKER_FLAGS ${link_flags} CACHE INTERNAL "shared lnk flags")
endif()

set(_COMPILE_C "-c")
set(_COMPILE_CXX "-P -c")
set(CMAKE_LIBRARY_PATH_FLAG "-L")
set(CMAKE_LINK_LIBRARY_FLAG "")
set(CMAKE_FIND_LIBRARY_SUFFIXES "-bcc.lib" ".lib")

# uncomment these out to debug makefiles
#set(CMAKE_START_TEMP_FILE "")
#set(CMAKE_END_TEMP_FILE "")
#set(CMAKE_VERBOSE_MAKEFILE 1)

# Borland cannot handle + in the file name, so mangle object file name
set (CMAKE_MANGLE_OBJECT_FILE_NAMES "ON")

# extra flags for a win32 exe
set(CMAKE_CREATE_WIN32_EXE "${_tW}" )
# extra flags for a console app
set(CMAKE_CREATE_CONSOLE_EXE "${_tC}" )

foreach(t EXE SHARED MODULE)
  string(APPEND CMAKE_${t}_LINKER_FLAGS_INIT " ${_tM} -lS:1048576 -lSc:4098 -lH:1048576 -lHc:8192 ")
  string(APPEND CMAKE_${t}_LINKER_FLAGS_DEBUG_INIT " -v")
  string(APPEND CMAKE_${t}_LINKER_FLAGS_RELWITHDEBINFO_INIT " -v")
endforeach()

# The Borland link tool does not support multiple concurrent
# invocations within a single working directory.
if(NOT DEFINED CMAKE_JOB_POOL_LINK)
  set(CMAKE_JOB_POOL_LINK BCC32LinkPool)
  get_property(_bccjp GLOBAL PROPERTY JOB_POOLS)
  if(NOT _bccjp MATCHES "BCC32LinkPool=")
    set_property(GLOBAL APPEND PROPERTY JOB_POOLS BCC32LinkPool=1)
  endif()
  unset(_bccjp)
endif()

macro(__embarcadero_language lang)
  set(CMAKE_${lang}_COMPILE_OPTIONS_DLL "${_tD}" ) # Note: This variable is a ';' separated list
  set(CMAKE_SHARED_LIBRARY_${lang}_FLAGS "${_tD}") # ... while this is a space separated string.
  set(CMAKE_${lang}_USE_RESPONSE_FILE_FOR_INCLUDES 1)

  # compile a source file into an object file
  # place <DEFINES> outside the response file because Borland refuses
  # to parse quotes from the response file.
  set(CMAKE_${lang}_COMPILE_OBJECT
    "<CMAKE_${lang}_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -o<OBJECT> ${_COMPILE_${lang}} <SOURCE>"
    )

  set(CMAKE_${lang}_LINK_EXECUTABLE
    "<CMAKE_${lang}_COMPILER> -o<TARGET> <LINK_FLAGS> <FLAGS> ${CMAKE_START_TEMP_FILE} <LINK_LIBRARIES> <OBJECTS>${CMAKE_END_TEMP_FILE}"
    )

  # place <DEFINES> outside the response file because Borland refuses
  # to parse quotes from the response file.
  set(CMAKE_${lang}_CREATE_PREPROCESSED_SOURCE
    "${_EMBT_CPP_PREPROCESSOR} <DEFINES> <INCLUDES> <FLAGS> -o<PREPROCESSED_SOURCE> ${_COMPILE_${lang}} <SOURCE>"
    )

  # Create a module library.
  set(CMAKE_${lang}_CREATE_SHARED_MODULE
    "<CMAKE_${lang}_COMPILER> ${_tD} ${CMAKE_START_TEMP_FILE}-o<TARGET> <LINK_FLAGS> <LINK_LIBRARIES> <OBJECTS>${CMAKE_END_TEMP_FILE}"
    )

  # Create an import library for another target.
  set(CMAKE_${lang}_CREATE_IMPORT_LIBRARY
    "implib -c -w <TARGET_IMPLIB> <TARGET>"
    )

  # Create a shared library.
  # First create a module and then its import library.
  set(CMAKE_${lang}_CREATE_SHARED_LIBRARY
    ${CMAKE_${lang}_CREATE_SHARED_MODULE}
    ${CMAKE_${lang}_CREATE_IMPORT_LIBRARY}
    )

  # create a static library
  if(BCC64)
    set(CMAKE_${lang}_CREATE_STATIC_LIBRARY
      "tlib64 ${CMAKE_START_TEMP_FILE}/p2048 <LINK_FLAGS> /a <TARGET_QUOTED> <OBJECTS>${CMAKE_END_TEMP_FILE}"
      )
  else()
    set(CMAKE_${lang}_CREATE_STATIC_LIBRARY
      "tlib ${CMAKE_START_TEMP_FILE}/p512 <LINK_FLAGS> /a <TARGET_QUOTED> <OBJECTS>${CMAKE_END_TEMP_FILE}"
      )
  endif()


  # Initial configuration flags.
  string(APPEND CMAKE_${lang}_FLAGS_INIT " ${_tM}")

  if(CLANG_BASED)
    string(APPEND CMAKE_${lang}_FLAGS_DEBUG_INIT " -O0 -v")
    string(APPEND CMAKE_${lang}_FLAGS_MINSIZEREL_INIT " -O1 -DNDEBUG")
    string(APPEND CMAKE_${lang}_FLAGS_RELEASE_INIT " -O2 -DNDEBUG")
    string(APPEND CMAKE_${lang}_FLAGS_RELWITHDEBINFO_INIT " -O3")
  else()
    string(APPEND CMAKE_${lang}_FLAGS_DEBUG_INIT " -Od -v")
    string(APPEND CMAKE_${lang}_FLAGS_MINSIZEREL_INIT " -O1 -DNDEBUG")
    string(APPEND CMAKE_${lang}_FLAGS_RELEASE_INIT " -O2 -DNDEBUG")
    string(APPEND CMAKE_${lang}_FLAGS_RELWITHDEBINFO_INIT " -Od")
    set(CMAKE_${lang}_STANDARD_LIBRARIES_INIT "import32.lib")
  endif()
endmacro()

macro(set_embt_target)
  foreach(arg IN ITEMS ${ARGN})
    if(${arg} STREQUAL "FMX")
      set(CMAKE_${_lang}_FLAGS "${CMAKE_${_lang}_FLAGS} ${_tF}")
      include_directories(SYSTEM "${ROOTDIR}/include/windows/fmx")
    elseif(${arg} STREQUAL "VCL")
      set(CMAKE_${_lang}_FLAGS "${CMAKE_${_lang}_FLAGS} ${_tV}")
      include_directories(SYSTEM "${ROOTDIR}/include/windows/vcl")
    elseif(${arg} STREQUAL "DR")
      set(CMAKE_${_lang}_FLAGS "${CMAKE_${_lang}_FLAGS} ${_tJ}")
    elseif(${arg} STREQUAL "DynamicRuntime")
      set(CMAKE_${_lang}_FLAGS "${CMAKE_${_lang}_FLAGS} ${_tR}")
    elseif(${arg} STREQUAL "Package")
      set(CMAKE_${_lang}_FLAGS "${CMAKE_${_lang}_FLAGS} ${_tP}")
    elseif(${arg} STREQUAL "Unicode")
      set(CMAKE_${_lang}_FLAGS "${CMAKE_${_lang}_FLAGS} ${_tU}")
    else()
      message("Error in set_embt_target: unknown target specified \"${arg}\"")
    endif()
  endforeach()
endmacro()

Anyone knowing how to configure CMake in order to be able to use these Embarcadero modified Clang compilers? This should be relevant for anyone using these compilers.

Answer 1

The Cmake error shows that your compiler don't support some C++11 feature (nullptr or override).

I guess you can just comment the cmake code with "#". However you may encounter some compiler error when you ignore the C++11 feature's check.

Here list some method to Workaround for C++11 Attributes:

http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Workaround_for_C%2B%2B11_Attributes_(Clang-enhanced_C%2B%2B_Compilers)