depgraph: fix runtime package mask interaction with slot operator rebuilds (bug 612094)

In some cases the backtracking runtime package mask can interact badly
with slot operator rebuilds, preventing a solution from being found.
This patch fixes the problem, which is demonstrated by the included
unit test.

X-Gentoo-bug: 612094
X-Gentoo-bug-url: https://bugs.gentoo.org/show_bug.cgi?id=612094
Acked-by: Brian Dolbec <dolsen@gentoo.org>

2 files changed, 152 insertions, 12 deletions

diff --git a/pym/_emerge/depgraph.py b/pym/_emerge/depgraph.py
index bb3e307f0..1379b0563 100644
--- a/pym/_emerge/depgraph.py
+++ b/pym/_emerge/depgraph.py
@@ -1597,9 +1597,6 @@ class depgraph(object):
 				atom.package and atom.slot_operator_built):
 				continue
 
-			if pkg not in conflict_pkgs:
-				continue
-
 			for other_pkg in slot_nodes:
 				if other_pkg in conflict_pkgs:
 					continue
@@ -2569,18 +2566,25 @@ class depgraph(object):
 			# runtime_pkg_mask, since that would trigger an
 			# infinite backtracking loop.
 			if self._dynamic_config._allow_backtracking:
-				if dep.parent in self._dynamic_config._runtime_pkg_mask:
-					if debug:
-						writemsg(
-							"!!! backtracking loop detected: %s %s\n" % \
-							(dep.parent,
-							self._dynamic_config._runtime_pkg_mask[
-							dep.parent]), noiselevel=-1)
-				elif dep.atom.package and dep.atom.slot_operator_built and \
-					self._slot_operator_unsatisfied_probe(dep):
+				if (dep.parent not in self._dynamic_config._runtime_pkg_mask and
+					dep.atom.package and dep.atom.slot_operator_built and
+					self._slot_operator_unsatisfied_probe(dep)):
 					self._slot_operator_unsatisfied_backtrack(dep)
 					return 1
 				else:
+					# This is for backward-compatibility with previous
+					# behavior, so that installed packages with unsatisfied
+					# dependencies trigger an error message but do not
+					# cause the dependency calculation to fail. Only do
+					# this if the parent is already in the runtime package
+					# mask, since otherwise we need to backtrack.
+					if (dep.parent.installed and
+						dep.parent in self._dynamic_config._runtime_pkg_mask and
+						not any(self._iter_match_pkgs_any(
+						dep.parent.root_config, dep.atom))):
+						self._dynamic_config._initially_unsatisfied_deps.append(dep)
+						return 1
+
 					# Do not backtrack if only USE have to be changed in
 					# order to satisfy the dependency. Note that when
 					# want_restart_for_use_change sets the need_restart
diff --git a/pym/portage/tests/resolver/test_slot_operator_runtime_pkg_mask.py b/pym/portage/tests/resolver/test_slot_operator_runtime_pkg_mask.py
new file mode 100644
index 000000000..0a5a7fa78
--- /dev/null
+++ b/pym/portage/tests/resolver/test_slot_operator_runtime_pkg_mask.py
@@ -0,0 +1,136 @@
+# Copyright 2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+from portage.tests import TestCase
+from portage.tests.resolver.ResolverPlayground import (
+	ResolverPlayground,
+	ResolverPlaygroundTestCase,
+)
+
+class SlotOperatorRuntimePkgMaskTestCase(TestCase):
+
+	def testSlotOperatorRuntimePkgMask(self):
+
+		ebuilds = {
+			"app-misc/meta-pkg-2" : {
+				"EAPI": "6",
+				"DEPEND": "=app-misc/B-2 =app-misc/C-1  =app-misc/D-1 =dev-libs/foo-2",
+				"RDEPEND": "=app-misc/B-2 =app-misc/C-1 =app-misc/D-1 =dev-libs/foo-2",
+			},
+
+			"app-misc/meta-pkg-1" : {
+				"EAPI": "6",
+				"DEPEND": "=app-misc/B-1 =app-misc/C-1  =app-misc/D-1 =dev-libs/foo-1",
+				"RDEPEND": "=app-misc/B-1 =app-misc/C-1 =app-misc/D-1 =dev-libs/foo-1",
+			},
+
+			"app-misc/B-1" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:=",
+				"RDEPEND": "dev-libs/foo:=",
+			},
+
+			"app-misc/B-2" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:=",
+				"RDEPEND": "dev-libs/foo:=",
+			},
+
+			"app-misc/C-1" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:=",
+				"RDEPEND": "dev-libs/foo:=",
+			},
+
+			"app-misc/C-2" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:=",
+				"RDEPEND": "dev-libs/foo:=",
+			},
+
+			"app-misc/D-1" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:=",
+				"RDEPEND": "dev-libs/foo:=",
+			},
+
+			"app-misc/D-2" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:=",
+				"RDEPEND": "dev-libs/foo:=",
+			},
+
+			"dev-libs/foo-1" : {
+				"EAPI": "6",
+				"SLOT": "0/1",
+			},
+
+			"dev-libs/foo-2" : {
+				"EAPI": "6",
+				"SLOT": "0/2",
+			},
+		}
+
+		installed = {
+			"app-misc/meta-pkg-1" : {
+				"EAPI": "6",
+				"DEPEND": "=app-misc/B-1 =app-misc/C-1  =app-misc/D-1 =dev-libs/foo-1",
+				"RDEPEND": "=app-misc/B-1 =app-misc/C-1 =app-misc/D-1 =dev-libs/foo-1",
+			},
+
+			"app-misc/B-1" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:0/1=",
+				"RDEPEND": "dev-libs/foo:0/1=",
+			},
+
+			"app-misc/C-1" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:0/1=",
+				"RDEPEND": "dev-libs/foo:0/1=",
+			},
+
+			"app-misc/D-1" : {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/foo:0/1=",
+				"RDEPEND": "dev-libs/foo:0/1=",
+			},
+
+			"dev-libs/foo-1" : {
+				"EAPI": "6",
+				"SLOT": "0/1",
+			},
+		}
+
+		world = (
+			"app-misc/meta-pkg",
+		)
+
+		test_cases = (
+			ResolverPlaygroundTestCase(
+				["=app-misc/meta-pkg-2"],
+				options = {
+					"--backtrack": 5,
+				},
+				success = True,
+				ambiguous_merge_order = True,
+				mergelist = [
+					'dev-libs/foo-2',
+					('app-misc/D-1', 'app-misc/C-1', 'app-misc/B-2'),
+					'app-misc/meta-pkg-2',
+				]
+			),
+		)
+
+		playground = ResolverPlayground(debug=False,
+			ebuilds=ebuilds, installed=installed,
+			world=world)
+		try:
+			for test_case in test_cases:
+				playground.run_TestCase(test_case)
+				self.assertEqual(test_case.test_success, True,
+					test_case.fail_msg)
+		finally:
+			# Disable debug so that cleanup works.
+			playground.debug = False
+			playground.cleanup()