Print suggestions for circular dependencies

diff --git a/pym/_emerge/depgraph.py b/pym/_emerge/depgraph.py
index 2e2508baf8259b1fe907355f484b07d9a87b2022..686015bc542015bdc6d58132888ac11ea7da7bcc 100644 (file)
--- a/pym/_emerge/depgraph.py
+++ b/pym/_emerge/depgraph.py
@@ -4144,18 +4144,42 @@ class depgraph(object):
                        noiselevel=-1)
                portage.writemsg("\n", noiselevel=-1)
 
+               suggestions = []
                if shortest_cycle:
                        indent = ""
                        for id, pkg in enumerate(shortest_cycle):
-                               parent = None
                                if id > 0:
                                        parent = shortest_cycle[id-1]
+                               else:
+                                       parent = shortest_cycle[-1]
 
-                               if parent:
-                                       priorities = mygraph.nodes[parent][0][pkg]
+                               priorities = mygraph.nodes[parent][0][pkg]
+                               if id > 0:
                                        writemsg(indent + "%s (%s)\n" % (pkg, priorities[-1],), noiselevel=-1)
                                else:
                                        writemsg(indent + str(pkg) + " depends on\n", noiselevel=-1)
+
+                               if priorities[-1].buildtime:
+                                       dep = parent.metadata["DEPEND"]
+                               elif priorities[-1].runtime:
+                                       dep = parent.metadata["RDEPEND"]
+                               parent_atoms = self._dynamic_config._parent_atoms.get(pkg)
+                               for ppkg, atom in parent_atoms:
+                                       if ppkg == parent:
+                                               parent_atom = atom.unevaluated_atom
+                                               break
+                               use_enabled, use_disabled = portage.dep.extract_use_cond(dep, parent_atom)
+                               if use_enabled:
+                                       for flag in use_enabled:
+                                               if flag in parent.use.enabled:
+                                                       suggestions.append("- %s (Change USE: %s)\n" \
+                                                               % (parent.cpv, colorize("blue", "-" + flag)))
+                               if use_disabled:
+                                       for flag in use_enabled:
+                                               if flag not in parent.use.enabled:
+                                                       suggestions.append("- %s (Change USE: %s)\n" \
+                                                               % (parent.cpv, colorize("red", "+" + flag)))
+
                                indent += " "
 
                        pkg = shortest_cycle[0]
@@ -4165,11 +4189,23 @@ class depgraph(object):
                else:
                        mygraph.debug_print()
 
-               portage.writemsg("\n", noiselevel=-1)
-               portage.writemsg(prefix + "Note that circular dependencies " + \
-                       "can often be avoided by temporarily\n", noiselevel=-1)
-               portage.writemsg(prefix + "disabling USE flags that trigger " + \
-                       "optional dependencies.\n", noiselevel=-1)
+               if suggestions:
+                       writemsg("\n\nIt might be possible to break this cycle\n", noiselevel=-1)
+                       if len(suggestions) == 1:
+                               writemsg("by applying the following change:\n", noiselevel=-1)
+                       else:
+                               writemsg("by applying " + colorize("bold", "any of") + \
+                                       " the following changes:\n", noiselevel=-1)
+                       writemsg("".join(suggestions), noiselevel=-1)
+                       writemsg("\nNote that this change can be reverted, once the package has" + \
+                               " been installed.\n\n", noiselevel=-1)
+               else:
+                       writemsg("\n", noiselevel=-1)
+                       writemsg(prefix + "Note that circular dependencies " + \
+                               "can often be avoided by temporarily\n", noiselevel=-1)
+                       writemsg(prefix + "disabling USE flags that trigger " + \
+                               "optional dependencies.\n", noiselevel=-1)
+
 
        def _show_merge_list(self):
                if self._dynamic_config._serialized_tasks_cache is not None and \