diff --git a/.gitignore b/.gitignore
index 5d08542451279ce32183e15482f7af4586283862..3d8f66c132830ab61a84c4bbf2aec4513c1d7af3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -72,3 +72,6 @@ commit.msg
 # by product of generating a source distribution for pip
 *.egg-info
 dist
+
+# generated by YouCompleteMe Vim plugin with clangd engine support.
+.clangd
diff --git a/.ycm_extra_conf.py b/.ycm_extra_conf.py
deleted file mode 100644
index a61e461ac159eaeefa9debeb1790b91c436434ac..0000000000000000000000000000000000000000
--- a/.ycm_extra_conf.py
+++ /dev/null
@@ -1,154 +0,0 @@
-# This file is NOT licensed under the GPLv3, which is the license for the rest
-# of YouCompleteMe.
-#
-# Here's the license text for this file:
-#
-# This is free and unencumbered software released into the public domain.
-#
-# Anyone is free to copy, modify, publish, use, compile, sell, or
-# distribute this software, either in source code form or as a compiled
-# binary, for any purpose, commercial or non-commercial, and by any
-# means.
-#
-# In jurisdictions that recognize copyright laws, the author or authors
-# of this software dedicate any and all copyright interest in the
-# software to the public domain. We make this dedication for the benefit
-# of the public at large and to the detriment of our heirs and
-# successors. We intend this dedication to be an overt act of
-# relinquishment in perpetuity of all present and future rights to this
-# software under copyright law.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
-# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
-# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
-# OTHER DEALINGS IN THE SOFTWARE.
-#
-# For more information, please refer to <http://unlicense.org/>
-
-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 = [
-    '-DNDEBUG',
-    '-std=c++14',
-    '-x',
-    'c++',
-    '-I',
-    'modcc',
-    '-I',
-    'arbor',
-    '-I',
-    'arbor/include',
-    '-I',
-    'build/arbor/include',
-    '-I',
-    'ext/json/single_include',
-    '-I',
-    'python/pybind11/include',
-    '-I',
-    'sup/include',
-    '-I',
-    'test',
-    '-I',
-    '/usr/include/python3.8',
-    '-I',
-    'python',
-]
-
-# 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
-#
-# 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.
-compilation_database_folder = ''
-
-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 DirectoryOfThisScript():
-  return os.path.dirname( os.path.abspath( __file__ ) )
-
-
-def MakeRelativePathsInFlagsAbsolute( flags, working_directory ):
-  if not working_directory:
-    return list( flags )
-  new_flags = []
-  make_next_absolute = False
-  path_flags = [ '-isystem', '-I', '-iquote', '--sysroot=' ]
-  for flag in flags:
-    new_flag = flag
-
-    if make_next_absolute:
-      make_next_absolute = False
-      if not flag.startswith( '/' ):
-        new_flag = os.path.join( working_directory, flag )
-
-    for path_flag in path_flags:
-      if flag == path_flag:
-        make_next_absolute = True
-        break
-
-      if flag.startswith( path_flag ):
-        path = flag[ len( path_flag ): ]
-        new_flag = path_flag + os.path.join( working_directory, path )
-        break
-
-    if new_flag:
-      new_flags.append( new_flag )
-  return new_flags
-
-
-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 database:
-    # Bear in mind that compilation_info.compiler_flags_ does NOT return a
-    # python list, but a "list-like" StringVec object
-    compilation_info = GetCompilationInfoForFile( filename )
-    if not compilation_info:
-      return None
-
-    final_flags = MakeRelativePathsInFlagsAbsolute(
-      compilation_info.compiler_flags_,
-      compilation_info.compiler_working_dir_ )
-
-  else:
-    relative_to = DirectoryOfThisScript()
-    final_flags = MakeRelativePathsInFlagsAbsolute( flags, relative_to )
-
-  return {
-    'flags': final_flags,
-    'do_cache': True
-  }