Create a compile database for YouCompleteMe

[ff2000]

This is more of a little tip for hacking rather than an issue. But I could not find a "hacking" section or file, so I post it here - feel free to put it (modified) somewhere else everyone can find it:

First off the easiest solution is to use a compile_commands.json file. cmake could generate it itself, but astroid uses scons ;) So we need a handy little helper - called Bear.

cd ~/src
git clone https://github.com/rizsotto/Bear.git
cd Bear
mkdir build
cd build && cmake ..
make

You then can find a bear executable and a libear.so inside build/src. Furthermore there is an example config located at ~/src/Bear/src/bear.conf. You can copy them wherever you want, I simply left them where they are.

Now go over to your astroid src dir:

cd ~/src/astroid
scons --clean
~/src/Bear/build/src/bear -l ~/src/Bear/build/src/libear.so -c ~/src/Bear/src/bear.conf -- scons --verbose

and you have your compile_commands.json!

I put that long command into a small shell script - you might guess it, Bear is usable with ANY build script/system/... that actually can print the commands it runs.

$ cat ~/bin/run_bear 
#!/bin/sh

~/src/Bear/build/src/bear -l ~/src/Bear/build/src/libear.so -c ~/src/Bear/src/bear.conf "$@"

Now you need a .ycm_extra_conf.py inside /src/astroid. I tried the one shipped with neovim/contrib/YouCompleteMe, but that never worked.
The one that Valloric uses himself in YouCompleteMe works perfectly fine. It's located at YouCompleteMe/third_party/ycmd/cpp/ycm/.ycm_extra_conf.py
On line 105 set
compilation_database_folder = '/src/astroid'
and you are done! Completions everywhere :)

[gauteh]

Nice! I need to test this out. I guess this could go in the wiki? We need a HACKING file with links to this as well!

[gauteh]

I used the .ycm_extra_conf.py file as you described from https://github.com/Valloric/ycmd/blob/master/cpp/ycm/.ycm_extra_conf.py, but I moved the DirectoryOfThisScript() function up a bit and used it as the compilation_database_folder:

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

# 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 = DirectoryOfThisScript ()

I guess standard practice is to check this file into the repository?

also, Arch Linux, has bear available as an AUR package so all I had to do there (using yaourt) was:

yaourt -S bear
yaourt -S vim-youcompleteme-git
cd path/to/astorid
scons -c
bear -- scons --verbose

thanks for figuring this out!

[ff2000]

Yeah, having it packaged by the distro is the easiest way ;)
You can also use "make install" after passing an install prefix with

cmake -DCMAKE_INSTALL_PREFIX="/path/to/install/prefix

(or stick to the default - /usr/local)
and prepend "/path/to/install/prefix/bin" to your PATH.
(but I personally like to keep my env clean - already had trouble with crashing apps due to a leftover of an old "make install" - and bear can be run without "make install")

[gauteh]

I set up Hacking and Contributing pages (https://github.com/gauteh/astroid/wiki/Hacking), this kind of information should go in there once it gets cleaned up a bit.

[gauteh]

I've added the complete scripts to the repository, after we've added this information to the wiki we can close the issue.

[gauteh]

Included more complete instructions in the wiki, so closing here.