From c956cdd79a3a41b0675cd410945ca6556a9900d9 Mon Sep 17 00:00:00 2001
From: Thomas Leonard <talex5@gmail.com>
Date: Thu, 5 Apr 2012 17:48:11 +0100
Subject: [PATCH] Fixed error solving with optional dependencies

If the dependency contained no implementations and we needed to choose the
next variable to try, the result was:

File ".../zeroinstall/injector/solver.py", line 571, in find_undecided
   group = group_clause_for[uri]
KeyError: u'...'

This could easily happen if the feed for the dependency wasn't cached yet.

Reported by Tim Cuthbertson.
---
 tests/OptionalMissing.xml      | 14 ++++++++++++++
 tests/testsolver.py            |  5 +++++
 zeroinstall/injector/solver.py |  8 +++++++-
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 tests/OptionalMissing.xml

diff --git a/tests/OptionalMissing.xml b/tests/OptionalMissing.xml
new file mode 100644
index 0000000..dabd03f
--- /dev/null
+++ b/tests/OptionalMissing.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" ?>
+<interface xmlns="http://zero-install.sourceforge.net/2004/injector/interface">
+  <name>OptionalMissing</name>
+  <summary>optional dependency on a missing interface</summary>
+
+  <group>
+    <requires interface="http://localhost/Missing.xml" importance='recommended'/>
+
+    <!-- a feed with multiple possibilities -->
+    <requires interface="./Binary.xml"/>
+
+    <implementation id="a" local-path='.' version="0.1" main='.'/>
+  </group>
+</interface>
diff --git a/tests/testsolver.py b/tests/testsolver.py
index fec0a81..3552b3c 100755
--- a/tests/testsolver.py
+++ b/tests/testsolver.py
@@ -225,5 +225,10 @@ class TestSolver(BaseTest):
 		watch_xml = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'watchdog.xml')
 		s.solve(watch_xml, arch.get_architecture(None, None), command_name = 'test')
 
+	def testRecommendBug(self):
+		s = solver.DefaultSolver(self.config)
+		optional_missing_xml = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'OptionalMissing.xml')
+		s.solve(optional_missing_xml, arch.get_architecture(None, None), command_name = None)
+
 if __name__ == '__main__':
 	unittest.main()
diff --git a/zeroinstall/injector/solver.py b/zeroinstall/injector/solver.py
index 0d5c4c7..3cae3c3 100644
--- a/zeroinstall/injector/solver.py
+++ b/zeroinstall/injector/solver.py
@@ -568,7 +568,13 @@ class SATSolver(Solver):
 					return	# Break cycles
 				seen.add(uri)
 
-				group = group_clause_for[uri]
+				group = group_clause_for.get(uri, None)
+
+				if group is None:
+					# (can be None if the selected impl has an optional dependency on 
+					# a feed with no implementations)
+					return
+
 				#print "Group for %s = %s" % (uri, group)
 				lit = group.current
 				if lit is None:
-- 
2.11.4.GIT