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I am currently learning OpenGL and C++ and I would like to have gl* completion ready on my C++ projects.

YCM is not scanning the <GL/glew.h> header when I include it - isn't it supposed to do it by default? That's how I understood it to work in the first place - maybe I'm wrong here.

I am using following default global YCM config file:

# Generated by YCM Generator at 2016-03-06 01:49:19.854235

# 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

flags = [
    '-x',
    'c++',
    '-std=c++11',
    '-isystem', '/usr/include',
    '-isystem', '/usr/local/include',
    '-I', 'src',
    '-I', 'include'
]


# 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.
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
  }

I'm not very good at Python, though, and have not enough knowledge of compiler settings to configure this.

How can I make YCM to give me OpenGL completions in my case?

Edit: I think this option https://github.com/Valloric/YouCompleteMe#the-gycm_semantic_triggers-option may have something to do with it, but I haven't managed to find the solution yet.

  • Perhaps try -I instead of -isystem. – VanLaser Mar 8 '16 at 22:09
  • @VanLaser that makes sense. But now it still has some problems. When I start to type glcle (while looking for glClearBuffer function), it popups a list of matching IDs from the local file (it seems). Only when I press ctrl-space the list gets populated with all the stuff from glew.h. Any ideas on how to make it load it by default? – Paweł Pela Mar 8 '16 at 22:57
  • I don't use YCM. From what I see in the docs, you'd probably have to play with adjusting the various g:ycm_ prefixed options, which enable/disable or make kick in sooner, or later, various completions types. But I may be wrong. – VanLaser Mar 8 '16 at 23:23
  • @VanLaser you are right - I am currently looking at github.com/Valloric/… and I think this may be it, but I still haven't got it right. – Paweł Pela Mar 8 '16 at 23:25
2

So, after some iterations and tests, the answer to this is by using the g:ycm_semantic_triggers option as described here: https://github.com/Valloric/YouCompleteMe#the-gycm_semantic_triggers-option This has to be done via the regex mode.

Here's the relevant config line from my .vimrc:

let g:ycm_semantic_triggers =  { 'cpp,objcpp' : ['->', '.', '::', 're!gl'] }

It adds the 're!gl' item to the list of default semantic triggers in C++ and Obj-C++. This will trigger semantic completion on anything starting with gl.

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