Using a library in C - where can there be a mistake?

Question

Eclipse

Hello.
Let's use our own library in one project - let's call it bibl(libbibl.a). We write the library in a neighboring project, we work in the exlipse. The library is built without errors, there are no errors inside in general. Libka is used in other projects and works.
We make a new project that uses this library. Of course, it was added to the linker settings, everything was registered. There are no errors by calling any library functions. As soon as we call a function from this library, then look - there are no errors in the project itself, but in the library project errors suddenly appear that the variables cannot be found anywhere. Although before that the library was perfectly assembled, without any errors. Eclipse writes that the variables cannot be found, but you can safely click on them and go to the declaration, all the inclusions are also declared.
Tell me where to dig - because the glitch is rather strange, I connected a lot of libraries, and worked with them, but today I encountered such an oddity.
ps index rebuild, wedge & rebuild all did.

Answer 1

Judging by the description - an eclipse bug