Use completions from C header files in C++ projects

[jchnkl]

If I have C++ file, YCM works well for std:: etc. (in general cpp headers), but when I use a header which is basically a C header wrapped in extern "C" I don't get any completions.
Does this generally not work or am I just missing some configuration?

[Valloric]

Please provide a testcase.

[jchnkl]

Go to cpp/ycm/ClangCompleter. Open a file test.cpp and insert

#include <clang-c/CXCompilationDatabase.h>

int main( int argc, char ** argv )
{
   // try to complete e.g. clang_CompilationDatabase_fromDirectory
   return 0;
 }

Note that the above example already fails for the #include completion for me. Completing C functions, like the clang_* ones does not work either.

[Update]
I tried it with a vanilla vim setup, no other plugins, despite YCM. Same result. The only thing that works is file name completion when I type #include ".

[Another Update]
Ok, I figured out that I can trigger the completion anywhere using Ctrl-Space. However, I still do not have completion for standard header files, e.g. iostream or after std::. I've appended '-isystem', '/usr/include' to the flags but it doesn't seem to help.

[More Updates]
I observed this behaviour (this is not quite true, see below).
When '-isystem', '/usr/include/c++' is added to flags, I get completion for std::.
For '-isystem', '/usr/include/c++/4.7.2', file names like iostream get completed, but not std::.
If I put both paths in flags, it's the same as in the latter case.

Sometimes it works, sometimes not. I'm having std:: completion only with '-isystem', '/usr/include', but still lack file name completion for std headers. Sometimes means: when I'm starting a function which has no closing brace yet, completion does not work. After adding the closing brace, completion works.

Now I've tried adding #include <xcb/xcb.h>. No matter if I have /usr/include/xcb in flags or not or if I'm pressing Ctrl-Space, I do not get completions for xcb_*.

Also, if I start with a plain, empty file, there is no comletion for keywords like include, int, void, etc.
Any chance to get reasonable stdlib + keyword completion?

[pedrovanzella]

Look at #303 for std:: completion.

[jchnkl]

@pedrovanzella Thank you!

[Valloric]

The std:: completion part sounds like issue #303, so I'm closing this issue as a duplicate of that one.

There's no keyword completion in YCM. Issue #142 tracks that.

[akirayu101]

closed? how do you got that problem solved plz?