emerge: Show package USE in conflict messages

Bug: https://bugs.gentoo.org/310009
Signed-off-by: Zac Medico <zmedico@gentoo.org>

lib/_emerge/depgraph.py

@@ -1302,8 +1302,15 @@ def _show_missed_update_slot_conflicts(self, missed_updates):
 					atom, marker = format_unmatched_atom(
 						pkg, atom, self._pkg_use_enabled)
 
+					if isinstance(parent, Package):
+						use_display = pkg_use_display(parent,
+							self._frozen_config.myopts,
+							modified_use=self._pkg_use_enabled(parent))
+					else:
+						use_display = ""
+
 					msg.append(2*indent)
-					msg.append("%s required by %s\n" % (atom, parent))
+					msg.append("%s required by %s %s\n" % (atom, parent, use_display))
 					msg.append(2*indent)
 					msg.append(marker)
 					msg.append("\n")
@@ -8472,14 +8479,20 @@ def _show_unsatisfied_blockers(self, blockers):
 					else:
 						# Display the specific atom from SetArg or
 						# Package types.
+						if isinstance(parent, Package):
+							use_display = pkg_use_display(parent,
+								self._frozen_config.myopts,
+								modified_use=self._pkg_use_enabled(parent))
+						else:
+							use_display = ""
 						if atom.package and atom != atom.unevaluated_atom:
 							# Show the unevaluated atom, since it can reveal
 							# issues with conditional use-flags missing
 							# from IUSE.
-							msg.append("%s (%s) required by %s" %
-								(atom.unevaluated_atom, atom, parent))
+							msg.append("%s (%s) required by %s %s" %
+								(atom.unevaluated_atom, atom, parent, use_display))
 						else:
-							msg.append("%s required by %s" % (atom, parent))
+							msg.append("%s required by %s %s" % (atom, parent, use_display))
 					msg.append("\n")
 
 				msg.append("\n")

lib/_emerge/resolver/slot_collision.py

@@ -9,6 +9,7 @@
 from _emerge.AtomArg import AtomArg
 from _emerge.Package import Package
 from _emerge.PackageArg import PackageArg
+from _emerge.UseFlagDisplay import pkg_use_display
 from portage.dep import check_required_use
 from portage.output import colorize
 from portage._sets.base import InternalPackageSet
@@ -260,7 +261,9 @@ def _prepare_conflict_msg_and_check_for_specificity(self):
 
 			for pkg in pkgs:
 				msg.append(indent)
-				msg.append("%s" % (pkg,))
+				msg.append("%s %s" % (pkg, pkg_use_display(pkg,
+					self.depgraph._frozen_config.myopts,
+					modified_use=self.depgraph._pkg_use_enabled(pkg))))
 				parent_atoms = self.all_parents.get(pkg)
 				if parent_atoms:
 					#Create a list of collision reasons and map them to sets
@@ -569,9 +572,15 @@ def highlight_violations(atom, version, use, slot_violated):
 								ordered_list.append(parent_atom)
 					for parent_atom in ordered_list:
 						parent, atom = parent_atom
+						if isinstance(parent, Package):
+							use_display = pkg_use_display(parent,
+								self.depgraph._frozen_config.myopts,
+								modified_use=self.depgraph._pkg_use_enabled(parent))
+						else:
+							use_display = ""
 						if atom.soname:
-							msg.append("%s required by %s\n" %
-								(atom, parent))
+							msg.append("%s required by %s %s\n" %
+								(atom, parent, use_display))
 						elif isinstance(parent, PackageArg):
 							# For PackageArg it's
 							# redundant to display the atom attribute.
@@ -602,7 +611,7 @@ def highlight_violations(atom, version, use, slot_violated):
 							if version_violated or slot_violated:
 								self.is_a_version_conflict = True
 
-							cur_line = "%s required by %s\n" % (atom_str, parent)
+							cur_line = "%s required by %s %s\n" % (atom_str, parent, use_display)
 							marker_line = ""
 							for ii in range(len(cur_line)):
 								if ii in colored_idx: