Editor's combobox does not update when leaving function context

1. Make sure that clangd is being used for indexing source files.
2. Create a new cmake-based Plain C++ Application project.
   main.cpp is being displayed in the source code editor. Above that, the right combobox displays "using namespace std".
3. Move the cursor down to the empty line before "int main()".
   The combobox still displays "using namespace std".
4. Move the cursor down into the main function.
   The combobox' content changes to "main() -> int".
5. Move the cursor up again, to the empty line before "int main()", just like in step 3.
   The combobox still displays "main() -> int".

Actual result: The combobox only updates when entering the function context, not when leaving it.

Expected result: The combobox also updates when leaving the function's context. This works when disabling clangd.

Found while working on Squish tests tst_CSUP01 and tst_memberoperator.