5.3.2 Cyclic Project Dependencies

Cyclic dependencies are mostly forbidden: if A imports B (directly or indirectly) then B is not allowed to import A. However, there are cases when cyclic dependencies would be beneficial. For these cases, another form of import between projects exists: the `limited with'. A project A that imports a project B with a straight `with' may also be imported, directly or indirectly, by B through a limited with.

The difference between straight `with' and limited with is that the name of a project imported with a limited with cannot be used in the project importing it. In particular, its packages cannot be renamed and its variables cannot be referred to.

    with "b.gpr";
    with "c.gpr";
    project A is
        for Exec_Dir use B'Exec_Dir; -- ok
    end A;
    
    limited with "a.gpr";   --  Cyclic dependency: A -> B -> A
    project B is
       for Exec_Dir use A'Exec_Dir; -- not ok
    end B;
    
    with "d.gpr";
    project C is
    end C;
    
    limited with "a.gpr";  --  Cyclic dependency: A -> C -> D -> A
    project D is
       for Exec_Dir use A'Exec_Dir; -- not ok
    end D;