circular_dependency: fix REQUIRED_USE test

1 files changed, 17 insertions, 0 deletions

diff --git a/pym/_emerge/resolver/circular_dependency.py b/pym/_emerge/resolver/circular_dependency.py
index cb64962f2..e4d679f0f 100644
--- a/pym/_emerge/resolver/circular_dependency.py
+++ b/pym/_emerge/resolver/circular_dependency.py
@@ -138,7 +138,24 @@ class circular_dependency_handler(object):
 			usemask, useforce = self._get_use_mask_and_force(parent)
 			autounmask_changes = self._get_autounmask_changes(parent)
 			untouchable_flags = frozenset(chain(usemask, useforce, autounmask_changes))
+
 			affecting_use.difference_update(untouchable_flags)
+
+			#If any of the flags we're going to touch is in REQUIRED_USE, add all
+			#other flags in REQUIRED_USE to affecting_use, to not lose any solution.
+			required_use_flags = get_required_use_flags(parent.metadata["REQUIRED_USE"])
+
+			if affecting_use.intersection(required_use_flags):
+				# TODO: Find out exactly which REQUIRED_USE flags are
+				# entangled with affecting_use. We have to limit the
+				# number of flags since the number of loops is
+				# exponentially related (see bug #374397).
+				total_flags = set()
+				total_flags.update(affecting_use, required_use_flags)
+				if len(total_flags) <= 10:
+					affecting_use.update(required_use_flags)
+					affecting_use.difference_update(untouchable_flags)
+
 			affecting_use = tuple(affecting_use)
 
 			if not affecting_use: