Fix specs detection for Container Build feature

- sometimes specs detection will be for a non-active
  build configuration so the project cannot be used to
  determine eligibility for the command launcher
- change ICommandLauncherFactory to accept an object in its
  getCommandLauncher method which can either be an IProject or
  ICConfigurationDesription
- change ContainerCommandLauncherFactory to accept an Object
  instead of IProject in its getCommandLauncher() method
- cast the Object received either to be an IProject or
  ICConfigurationDescription to determine if the build should
  occur in a Container or not
- fix CommandLauncherManager.getCommandLauncher() to accept
  and pass on an Object to the list of ICommandLauncherFactory
  instances
- fix AbstractBuiltinSpecsDetector to pass in the current
  configuration description when getting the CommandLauncher
  since the current configuration may not be the active
  configuration

build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java

@@ -657,7 +657,7 @@ public abstract class AbstractBuiltinSpecsDetector extends AbstractLanguageSetti
 			}
 			console.start(currentProject);
 
-			ICommandLauncher launcher = CommandLauncherManager.getInstance().getCommandLauncher();
+			ICommandLauncher launcher = CommandLauncherManager.getInstance().getCommandLauncher(currentCfgDescription);
 			launcher.setProject(currentProject);
 
 			IPath program = new Path(""); //$NON-NLS-1$
@@ -766,7 +766,7 @@ public abstract class AbstractBuiltinSpecsDetector extends AbstractLanguageSetti
 		// so collect them to save later when output finishes
 		if (entries != null) {
 			for (ICLanguageSettingEntry entry : entries) {
-				if (!detectedSettingEntries.contains(entry)) {
+				if (detectedSettingEntries != null && !detectedSettingEntries.contains(entry)) {
 					detectedSettingEntries.add(entry);
 				}
 			}

core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/CommandLauncherManager.java

@@ -166,11 +166,11 @@ public class CommandLauncherManager {
 	 * @param project - optional input to determine launcher.
 	 * @return an ICommandLauncher for running commands
 	 */
-	public ICommandLauncher getCommandLauncher(IProject project) {
+	public ICommandLauncher getCommandLauncher(Object object) {
 		// loop through list of factories and return first launcher
 		// returned
 		for (ICommandLauncherFactory factory : factories) {
-			ICommandLauncher launcher = factory.getCommandLauncher(project);
+			ICommandLauncher launcher = factory.getCommandLauncher(object);
 			if (launcher != null) {
 				return launcher;
 			}

core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICommandLauncherFactory.java

@@ -21,11 +21,11 @@ import org.eclipse.core.resources.IProject;
 public interface ICommandLauncherFactory {
 	
 	/**
-	 * Get a Command Launcher for a project (optional)
-	 * @param project - optional parameter to help determine appropriate launcher
-	 * @return ICommandLauncher or null if not appropriate for project
+	 * Get a Command Launcher for an object (IProject or IConfiguration) (optional)
+	 * @param object - optional parameter to help determine appropriate launcher
+	 * @return ICommandLauncher or null if not appropriate for object
 	 */
-	public ICommandLauncher getCommandLauncher(IProject project);
+	public ICommandLauncher getCommandLauncher(Object object);
 
 	/**
 	 * Register language setting entries for a project

launch/org.eclipse.cdt.docker.launcher/src/org/eclipse/cdt/docker/launcher/ContainerCommandLauncherFactory.java

@@ -39,10 +39,24 @@ public class ContainerCommandLauncherFactory
 		implements ICommandLauncherFactory {
 
 	@Override
-	public ICommandLauncher getCommandLauncher(IProject project) {
+	public ICommandLauncher getCommandLauncher(Object object) {
 		// check if container build enablement has been checked
-		ICConfigurationDescription cfgd = CoreModel.getDefault()
-				.getProjectDescription(project).getActiveConfiguration();
+		ICConfigurationDescription cfgd = null;
+		// We use an object because it could be an IProject, implying the
+		// active configuration, but it could be an ICConfigurationDescription
+		// as is used when computing specs for non-active configurations. We
+		// don't want to force callers to have to declare
+		// ICConfigurationDescription
+		// which is part of Managed build.
+		if (object instanceof IProject) {
+			IProject project = (IProject) object;
+			cfgd = CoreModel.getDefault().getProjectDescription(project)
+					.getActiveConfiguration();
+		} else if (object instanceof ICConfigurationDescription) {
+			cfgd = (ICConfigurationDescription) object;
+		} else {
+			return null;
+		}
 		IConfiguration cfg = ManagedBuildManager
 				.getConfigurationForDescription(cfgd);
 		IOptionalBuildProperties props = cfg.getOptionalBuildProperties();