Consider dependencies of transitively included fragments

Fixes #1727

Author: HannesWell

ui/org.eclipse.pde.core/src/org/eclipse/pde/internal/core/DependencyManager.java

@@ -35,6 +35,7 @@
 import org.eclipse.pde.core.target.NameVersionDescriptor;
 import org.osgi.framework.Constants;
 import org.osgi.framework.Version;
+import org.osgi.framework.namespace.HostNamespace;
 import org.osgi.framework.wiring.BundleRequirement;
 import org.osgi.framework.wiring.BundleRevision;
 import org.osgi.framework.wiring.BundleWire;
@@ -196,6 +197,19 @@ public static Set<BundleDescription> findRequirementsClosure(Collection<BundleDe
 				}
 			}
 
+			if (isFragment(wiring.getRevision())) {
+				// Requirements of a fragment are hosted at the host, which
+				// therefore requires the corresponding wires: OSGi Core spec,
+				// chapter 6.4.1 - Hosted Requirements and Capabilities
+				for (BundleWire hostWire : wiring.getRequiredWires(HostNamespace.HOST_NAMESPACE)) {
+					// Temporarily remove this fragment's host from the closure
+					// to ensure it's added again below. In the subsequent
+					// processing this fragment's requirements will then also be
+					// considered (before it was discarded).
+					closure.remove(hostWire.getProvider());
+				}
+			}
+
 			List<BundleWire> requiredWires = wiring.getRequiredWires(null);
 			for (BundleWire wire : requiredWires) {
 				BundleRevision declaringBundle = wire.getRequirement().getRevision();
@@ -222,6 +236,10 @@ private static void addNewRequiredBundle(BundleDescription bundle, Set<BundleDes
 		}
 	}
 
+	private static boolean isFragment(BundleRevision bundle) {
+		return (bundle.getTypes() & BundleRevision.TYPE_FRAGMENT) != 0;
+	}
+
 	private static boolean isOptional(BundleRequirement requirement) {
 		return Constants.RESOLUTION_OPTIONAL.equals(requirement.getDirectives().get(Constants.RESOLUTION_DIRECTIVE));
 	}

ui/org.eclipse.pde.ui.tests/src/org/eclipse/pde/core/tests/internal/DependencyManagerTest.java

@@ -308,6 +308,34 @@ public void testFindRequirementsClosure_includeFragmentsProvidingPackages() thro
 		assertThat(wClosure).isEqualTo(Set.of(bundleW, bundleB, fragmentB));
 	}
 
+	@Test
+	public void testFindRequirementsClosure_requirementsOfTransitivlyRequiredFragment() throws Exception {
+		setTargetPlatform( //
+				bundle("bundle.host", "1.0.0"),
+
+				bundle("bundle.a", "1.0.0", //
+						entry(REQUIRE_BUNDLE, "bundle.host"), //
+						entry(REQUIRE_CAPABILITY, "some.test.capability")),
+
+				bundle("bundle.fragment", "1.0.0", //
+						entry(FRAGMENT_HOST, "bundle.host"), //
+						entry(REQUIRE_BUNDLE, "bundle.b"), //
+						entry(PROVIDE_CAPABILITY, "some.test.capability")),
+
+				bundle("bundle.b", "1.0.0"));
+
+		BundleDescription bundleHost = bundleDescription("bundle.host", "1.0.0");
+		BundleDescription bundleFragment = bundleDescription("bundle.fragment", "1.0.0");
+		BundleDescription bundleA = bundleDescription("bundle.a", "1.0.0");
+		BundleDescription bundleB = bundleDescription("bundle.b", "1.0.0");
+
+		List<BundleDescription> bundles = List.of(bundleHost, bundleA);
+		// It's important that the host is first
+
+		Set<BundleDescription> noFragmentsClosure = findRequirementsClosure(bundles);
+		assertThat(noFragmentsClosure).isEqualTo(Set.of(bundleHost, bundleFragment, bundleA, bundleB));
+	}
+
 	@Test
 	public void testFindRequirementsClosure_includeOptional() throws Exception {