IDE inspection seems to ignore or miss headers

Update: boost-less, minified example.

I have four files now. "external.hpp" is outside the project (one directory up from the project directory). "internal.hpp", "main.cpp", and "CMakeLists.txt" are in the project. external.hpp and internal.hpp essentially do the same thing. When using internal.hpp there is no warning, when using external.hpp then there is a warning.

CMakeLists.txt:

cmake_minimum_required(VERSION 3.12)
project(externalHeaderWarning)
add_executable(externalHeaderWarning main.cpp)

main.cpp:

#define TRIGGER
//#include "internal.hpp" // all good
#include "../external.hpp" // warning about unused macro in #define above

#include <iostream>
int main() {
    std::cout << string << std::endl;
    return 0;
}

internal.hpp:

#if defined TRIGGER
const char *string = "This is in the CLion project.";
#endif // TRIGGER

external.hpp:

#if defined TRIGGER
const char *string = "This is not in the CLion project.";
#endif // TRIGGER

Update 2: This also works with a global variable instead of a preprocessor macro.

I find it interesting that in all examples things declared in the project-external header (be it macros or other identifiers) are no problem for the inspections.

main.cpp:

bool flag = true;
//#include "internal.h" // all good
#include "../external.h" // warning about unused global variable

#include <iostream>
int main() {
    std::cout << text << std::endl;
    return 0;
}

internal.h:

char const *text = flag ? "inside CLion project" : "";

external.h:

char const *text = flag ? "outside CLion project" : "";

More notes on this:

I created a symlink to the external header location via 'ln -s .. additional-includes' and marked that as "Project Sources and Headers" in the project view. After updating the #include directive for external.h I still got the warning.

Funnily, the warning went away when I created an actual new directory in the project ("more-includes") and moved external.h there. Didn't even need to mark the directory in any way.

Why does this workaround work with a real directory but not with a symlink?!

Side note: Playing around with include_directories() in CMakeLists.txt does not seem to change anything, here.

Edit: The warning also goes away when the additional-includes symlink does not point to a parent of the project directory. I moved the external.h to an unrelated directory and let additional-includes point there and that did the trick.

Open question: How can I do this without symlinking stuff into my project directory?

Hello!

Before CLion 2018.2, if header files were not added explicitly to CMake, CLion wasn't able to understand that they belonged to the project and therefore wasn't able to provide any code insight features for such files.

Now, if you include the header or source file into any project file, CLion will automatically treat it as a project file as well, which means full code insight will work in there! That's why everything works fine for internal.h. But this works only if the file is located under the project root, so it won’t affect standard or 3rd party libraries located outside of the project. That's why it doesn't work for external.h.

More info: https://intellij-support.jetbrains.com/hc/en-us/articles/207253145-Project-can-be-compiled-correctly-but-highlighting-completion-refactorings-etc-in-CLion-are-not-working-CLion-fails-to-find-some-of-my-classes-What-to-do-, https://blog.jetbrains.com/clion/2018/06/clion-2018-2-eap-automatically-treats-included-files-as-project-files/.

Hi,

thanks for the clarification and background. I‘ll make up my mind then whether to stick with symlinks or ignore the warning for the boost.test use case.

Kind regards

Leo