vim youcompleteme can't find cstdint - vim

Question

I've encountered a problem trying to set up a C++ project on my Mac (Yosemite with Xcode 6) using CMake with Unix style Makefiles and vim with the youcompleteme plugin (I'm a Linux veteran and Mac newbie so I prefer this setup to Xcode). The code builds and runs but youcompleteme throws some bogus errors which I think boil down to it not being able to find the <cstdint> header.
I've just tried it on Linux too, and had the same problem.
I've configured .ycm_extra_conf.py to use a compile_commands.json generated by cake. The "command" lines in compile_commands.json use these flags:
"command": "/usr/bin/c++ -std=c++11 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -F/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk/System/Library/Frameworks -I/usr/local/include -I/Users/tony/Dev/cow/jni -I/Users/tony/Library/Frameworks/SDL2.framework/Headers -Wall -Wextra -Wunused -F/Users/tony/Library/Frameworks -o ...
There doesn't seem to be an explicit reference there to any directory containing stdint as a direct parent.
Is there a way I can get youcompleteme to do its stuff with libclang in such a way that it can find the directory implicitly, which seems to work when running c++ on the command line? Or what's the best way to get cmake to add an appropriate system header path without hardwiring it? I want my CMakeLists.txt to be portable and to be able to cope with toolchain upgrades.
My .ycm_extra_conf.py was pretty much a copy of the supplied example modified slightly to find compile_commands.json where I put it.

Answer 1

As #ladislas said, YCM needs to be explicitly pointed to all relevant include directories as libclang won't use the same implicit location a normal compiler driver invocation (i.e. clang++ from the command line) would use.
What I usually do, on OSX, is to let YCM know about Xcode's libc++ headers with something like (in .ycm_extra_conf.py):
import os
import ycm_core
import subprocess
xcode_cpp11headers = subprocess.Popen("xcode-select -p", stdout = subprocess.PIPE, shell=True).communicate()[0].rstrip('\n') + '/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1'
.
.
flags = [
.
.
'-isystem',
xcode_cpp11headers,
.
.
]
The "xcode_cpp11headers" variable is populated with the proper path depending on the location of your current Xcode's installation, and you can change it accordingly if you want to use say the commandline-tools version of libc++ (i.e. the includes are in /Library/Developer/CommandLineTools/usr/include/c++/v1) or a source distribution of libc++ if you have compiled your own.
Of course this is platform dependant and either you provide a platform specific .ycm_extra_conf.py alongside your project, or you can populate that variable differently with some extra python code accordingly to the current platform.

Answer 2

You must add all the paths where YCM needs to look for your sources, libraries, and so on.
It does not work recursively, so it's a little bit cumbersome at first but is should not change once set for your project.
As an example, here is mine for an Arduino project :
https://github.com/ladislas/Bare-Arduino-Project/blob/master/.ycm_extra_conf.py#L21
Hope this helps!
EDIT - 2015/01/08
The solution of #abigagli is very elegant! I too use something like this to parse my lib directory and look for .h files to add their path to flags.
Here it is if it can be useful :) http://git.io/IiR1JA

Answer 3

As I found out from the above answers, YCM needs to be told the compiler's system include paths which are usually implicit in other ways of using the compiler. I added a function GetSystemIncludePaths() to .ycm_extra_conf.py to discover and cache these paths portably. Here's the full file with comments and irrelevant content of flags list snipped. The original is Copyright (C) 2014 Google Inc with a GPL2+ licence:
import subprocess, os
import ycm_core
flags = []
def DirectoryOfThisScript():
return os.path.dirname( os.path.abspath( __file__ ) )
compilation_database_folder = os.path.abspath(
os.path.join(DirectoryOfThisScript(), 'build-make'))
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 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 ):
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 GetSystemIncludePaths():
cache = os.path.join(DirectoryOfThisScript(), ".ycm_sys_incs")
if os.path.exists(cache):
fp = open(cache, 'r')
flags = fp.readlines()
fp.close()
flags = [s.strip() for s in flags]
else:
devnull = open(os.devnull, 'r')
child = subprocess.Popen(["/usr/bin/cpp", "-xc++", "-v"],
stdin = devnull, stderr = subprocess.PIPE)
output = child.communicate()[1].split('\n')
devnull.close()
flags = []
status = 0
for l in output:
l = l.strip()
if l == '#include "..." search starts here:':
status = 1
elif l == '#include <...> search starts here:':
status = 2
elif status:
if l == 'End of search list.':
break
elif l.endswith('(framework directory)'):
continue
elif status == 1:
flags.append('-I')
elif status == 2:
flags.append('-isystem')
flags.append(os.path.normpath(l))
fp = open(cache, 'w')
fp.write('\n'.join(flags))
fp.close()
return flags
def FlagsForFile( filename, **kwargs ):
if database:
compilation_info = GetCompilationInfoForFile( filename )
if not compilation_info:
return None
final_flags = MakeRelativePathsInFlagsAbsolute(
compilation_info.compiler_flags_,
compilation_info.compiler_working_dir_ )
sys_incs = GetSystemIncludePaths()
if sys_incs:
final_flags += sys_incs
else:
relative_to = DirectoryOfThisScript()
final_flags = MakeRelativePathsInFlagsAbsolute( flags, relative_to )
return {
'flags': final_flags,
'do_cache': True
}