For performance reasons, the solver works purely on the dependency information specified in packages. For most update operations, this information is sufficient to enable IPS to automatically install correct updated packages.
Packages whose dependencies indicate that they can be installed at the same time but whose content conflicts, cause conflict checking to fail in pre-installation. If conflict checking fails, the end user must try to fix the problem, perhaps by manually specifying different versions of some packages. An example of conflicting content is two packages that install the same file.
The package developer must ensure that conflicting packages cannot be installed due to constraining dependencies. Use the pkglint utility to help discover such conflicts. See Verify the Package and the pkglint (1) man page for more information about pkglint.