use cmake with YouCompleteme

.ycm_extra_conf.py

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from distutils.sysconfig import get_python_inc
import platform
import os
import ycm_core

# These are the compilation flags that will be used in case there's no
# compilation database set (by default, one is not set).
# CHANGE THIS LIST OF FLAGS. YES, THIS IS THE DROID YOU HAVE BEEN LOOKING FOR.
flags = [
'-Wall',
# THIS IS IMPORTANT! Without the '-x' flag, Clang won't know which language to
# use when compiling headers. So it will guess. Badly. So C++ headers will be
# compiled as C headers. You don't want that so ALWAYS specify the '-x' flag.
# For a C project, you would set this to 'c' instead of 'c++'.
'-x',
'c++',
'-I',
'.',
'-I/usr/local/include',
'-I/usr/include',
'-I/usr/include/x86_64-linux-gnu',
#'-I/usr/include/c++/5',
'-I/usr/include/c++/7',
#'-I/usr/include/x86_64-linux-gnu/c++/5',
'-I/usr/include/x86_64-linux-gnu/c++/7',
]

# Clang automatically sets the '-std=' flag to 'c++14' for MSVC 2015 or later,
# which is required for compiling the standard library, and to 'c++11' for older
# versions.
if platform.system() != 'Windows':
  flags.append( '-std=c++14' )


# Set this to the absolute path to the folder (NOT the file!) containing the
# compile_commands.json file to use that instead of 'flags'. See here for
# more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html
#
# You can get CMake to generate this file for you by adding:
#   set( CMAKE_EXPORT_COMPILE_COMMANDS 1 )
# to your CMakeLists.txt file.
#
# Most projects will NOT need to set this to anything; you can just change the
# 'flags' list of compilation flags. Notice that YCM itself uses that approach.

def DirectoryOfThisScript():
  return os.path.dirname( os.path.abspath( __file__ ) )

def DirectoryOfBuild():
  return os.path.join(DirectoryOfThisScript(), 'build')

compilation_database_folder = DirectoryOfBuild()

if os.path.exists( compilation_database_folder ):
  database = ycm_core.CompilationDatabase( compilation_database_folder )
else:
  database = None

SOURCE_EXTENSIONS = [ '.cpp', '.cxx', '.cc', '.c', '.m', '.mm' ]



def IsHeaderFile( filename ):
  extension = os.path.splitext( filename )[ 1 ]
  return extension in [ '.h', '.hxx', '.hpp', '.hh' ]


def GetCompilationInfoForFile( filename ):
  # The compilation_commands.json file generated by CMake does not have entries
  # for header files. So we do our best by asking the db for flags for a
  # corresponding source file, if any. If one exists, the flags for that file
  # should be good enough.
  if IsHeaderFile( filename ):
    basename = os.path.splitext( filename )[ 0 ]
    for extension in SOURCE_EXTENSIONS:
      replacement_file = basename + extension
      if os.path.exists( replacement_file ):
        compilation_info = database.GetCompilationInfoForFile(
          replacement_file )
        if compilation_info.compiler_flags_:
          return compilation_info
    return None
  return database.GetCompilationInfoForFile( filename )


def FlagsForFile( filename, **kwargs ):
  if not database:
    return {
      'flags': flags,
      'include_paths_relative_to_dir': DirectoryOfThisScript()
    }

  compilation_info = GetCompilationInfoForFile( filename )
  if not compilation_info:
    return {
      'flags': flags,
      'include_paths_relative_to_dir': DirectoryOfThisScript()
    }

  # Bear in mind that compilation_info.compiler_flags_ does NOT return a
  # python list, but a "list-like" StringVec object.
  final_flags = list( compilation_info.compiler_flags_ )

  try:
      final_flags.append("-I/usr/local/include")
      final_flags.append("-I/usr/include")
      final_flags.append('-I/usr/include/x86_64-linux-gnu')
      final_flags.append('-I/usr/include/c++/7')
      final_flags.append('-I/usr/include/x86_64-linux-gnu/c++/7')
  except ValueError:
      pass

  return {
    'flags': final_flags,
    'include_paths_relative_to_dir': compilation_info.compiler_working_dir_
  }