The issue was that the user could open a C-family file and have it start
compiling in the background. While it is still compiling, he could trigger the
completion system with a member dot operator. Because the file was still
compiling for the very first time, the TranslationUnit object was yet not
created. Sadly, this meant that UpdatingTranslationUnit would return false, and
a new query request would be created, the GUI would hang until it was done
aaaaand terrible lag until the file was compiled.
This was a very rare edge case that could also only be triggered if it takes a
considerable amount of time to compile the file.
One more thing needs to be done though: the clang_completer.py file needs to not
trigger at all when YCM has been compiled without cpp support. FIX THAT!
