Using default .ycm_extra_conf.py, the standard c++11 headers are not found.

[cebrusfs]

I set g:ycm_global_ycm_extra_conf in my vimrc.

let g:ycm_global_ycm_extra_conf = '~/.vim/bundle/YouCompleteMe/cpp/ycm/.ycm_extra_conf.py'

After including a c++11 header unordered_map, I got 'unordered_map' file not found reported by Syntastic plugin.

After adding

'-I',                                                                              
'/usr/include/c++/4.2.1/tr1/'

in flags in .ycm_extra_conf, now my problem is solved.

In default .ycm_extra_conf, the environment didn't include any c++11 headers, but the argument -std=c++11 still in flags?

I think it's strange. Something should be wrong.

I use the mac os 10.7.5 (Lion) and the following is report by :YcmDebugInfo command, hope it helps.

-- Flags for /Users/cebrusfs/test.cpp loaded from /Users/cebrusfs/.vim/bundle/YouCompleteMe/cpp/ycm/.ycm_extra_conf.py:
-- ['-Wall', '-Wextra', '-Werror', '-Wc++98-compat', '-Wno-long-long', '-Wno-variadic-macros', '-fex
ceptions', '-DNDEBUG', '-DUSE_CLANG_COMPLETER', '-std=c++11', '-x', 'c++', '-isystem', '/Users/cebru
sfs/.vim/bundle/YouCompleteMe/cpp/ycm/../BoostParts', '-isystem', '/System/Library/Frameworks/Python
.framework/Headers', '-isystem', '/Users/cebrusfs/.vim/bundle/YouCompleteMe/cpp/ycm/../llvm/include'
, '-isystem', '/Users/cebrusfs/.vim/bundle/YouCompleteMe/cpp/ycm/../llvm/tools/clang/include', '-I',
 '/Users/cebrusfs/.vim/bundle/YouCompleteMe/cpp/ycm/.', '-I', '/Users/cebrusfs/.vim/bundle/YouComple
teMe/cpp/ycm/./ClangCompleter', '-isystem', '/Users/cebrusfs/.vim/bundle/YouCompleteMe/cpp/ycm/./tes
ts/gmock/gtest', '-isystem', '/Users/cebrusfs/.vim/bundle/YouCompleteMe/cpp/ycm/./tests/gmock/gtest/
include', '-isystem', '/Users/cebrusfs/.vim/bundle/YouCompleteMe/cpp/ycm/./tests/gmock', '-isystem',
 '/Users/cebrusfs/.vim/bundle/YouCompleteMe/cpp/ycm/./tests/gmock/include', '-I', '/Users/cebrusfs/.
vim/bundle/YouCompleteMe/autoload/../python/clang_includes']
-- Has Clang support compiled in: True
-- clang version 3.2 (tags/RELEASE_32/final)

[pedrovanzella]

This didn't work for me.
It keeps saying that random doesn't exist.

Also, I get the same thing as #192.

[oblitum]

I've gone through this too and assumed that the current behavior won't try check clang default include directories from compiler flags as -std=libc++ and -std=c++11 for example. They can be verified with echo | clang -std=c++11 -stdlib=libc++ -v -E -x c++ -

[pedrovanzella]

I found out that YCM keeps adding '-I', '/Users/pedrovanzella /dotfiles/vim/bundle/YouCompleteMe/autoload/../python/clang_includes' to the flags, and this makes compilation fail.

This works fine:

clang++ hello.cpp -Wall -Wextra -Werror -Wno-long-long -Wno-variadic-macros -fexceptions -DNDEBUG -DUSE_CLANG_COMPLETER -std=c++11 -stdlib=libc++ -x c++ -c

This fails:

clang++ hello.cpp -Wall -Wextra -Werror -Wno-long-long -Wno-variadic-macros -fexceptions -DNDEBUG -DUSE_CLANG_COMPLETER -std=c++11 -stdlib=libc++ -x c++ -c -I /Users/pedrovanzella/dotfiles/vim/bundle/YouCompleteMe/autoload/../python/clang_includes

I stripped .ycm_extra_conf.py bare, but YCM keeps adding this to the flags.

[pedrovanzella]

I found this: https://gist.github.com/locojay/4950253

And it works wonders.

Basically, the only include flag you really need is '-isystem', '/usr/lib/c++/v1',.

This should also fix #305.

[Valloric]

The .ycm_extra_conf.py file linked to from the README is an example file, it's not supposed to cover everything for everyone. The flags that are there by default work for YCM; you're supposed to make an extra conf file yourself that best fits your project (usually by modifying the example file). The easiest way is often to just take the same flags you're passing to gcc/clang when you compile your source files.

YCM adds the path to clang_includes because without those clang-specific includes, semantic code completion would be slow. Clang needs to be able to see the files in that folder to operate correctly, no matter what source code you're compiling.

[oblitum]

@Valloric Does that answer whether it's assumed as issue or not for YCM not to be able to automatically include default included header files (which for flags -std=c++11 and -stdlib=libc++ for example, can be easily verified with echo | clang -std=c++11 -stdlib=libc++ -v -E -x c++ -)?.

Just passing the same flags you're passing to gcc/clang when you compile your source files won't lead to working completion, one must know which headers the compiler include by default for a given set of flags, and include those by hand (IIRC, I had to list even simple /usr/local/include).

[Valloric]

@oblitum Yes, that is troubling... I still can't understand why freaking libclang won't use its default header search paths for code completion like it would for normal compilation. I guess we need a way to pull out the default search paths and append them. Any ideas? We can't call the clang binary because it may not exist on the system. The solution would have to be based on pure libclang.

I know some Clang developers; I'll ask what they think about this.

[oblitum]

@Valloric Sadly, from libclang solely, I've no idea... But, should this issue just be kept closed? At last, this seems a good place for solutions to be brought and, this is indeed a thing newcomers may stumble upon recurrently.

[oblitum]

If not reopened, I think it's a good item for FAQ (I've not checked whether there's one such item already).

[Valloric]

Reopening until we figure this out fully.

[pedrovanzella]

Could we include a few example ycm_extra_conf.py in the README? This sounds like a sensible solution.

[xunfan]

I just have the similar problems and now I have solved them. If standard headers are not found, the good tool to debug is to use :YcmDiages in vim to see the bug information. You will see what errors are there, such as in xxx.h, yyy.h cannot find. Then you will find yyy.h and add the correct include path to the .ycm_extra_conf.py.

Another thing is sometimes the auto-completion cannot find members of a class I defined. The problem is there are errors in :YcmDiages. It seems sometimes if there are errors, ycm stop auto-competion for you...