Only show Language Setting property on old build system projects.

Change-Id: I21e71af0f5e701939d133707353e5bde7e4ab0e1

core/org.eclipse.cdt.core/plugin.xml

@@ -880,5 +880,15 @@
          </run>
       </builder>
    </extension>
+   <extension
+         point="org.eclipse.core.expressions.propertyTesters">
+      <propertyTester
+            class="org.eclipse.cdt.internal.core.build.CBuildPropertyTester"
+            id="buildPropertyTester"
+            namespace="org.eclipse.cdt.core.build"
+            properties="isSupported"
+            type="org.eclipse.core.resources.IResource">
+      </propertyTester>
+   </extension>
 
 </plugin>

core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/build/ICBuildConfigurationManager.java

@@ -17,6 +17,7 @@ import org.eclipse.core.runtime.IProgressMonitor;
  * to CDT build configuration.
  * 
  * @since 6.0
+ * @noimplement This interface is not intended to be implemented by clients.
  */
 public interface ICBuildConfigurationManager {
 
@@ -60,4 +61,16 @@ public interface ICBuildConfigurationManager {
 	 */
 	ICBuildConfiguration getBuildConfiguration(IBuildConfiguration buildConfig) throws CoreException;
 
+	/**
+	 * Does this build system support this project. This is determined by
+	 * searching the build configuration providers looking to see if any of them
+	 * support this project.
+	 * 
+	 * @param project
+	 * @return is this project supported by this build system
+	 * @throws CoreException
+	 * @since 6.1
+	 */
+	boolean supports(IProject project) throws CoreException;
+
 }

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/build/CBuildConfigurationManager.java

@@ -281,4 +281,25 @@ public class CBuildConfigurationManager implements ICBuildConfigurationManager,
 		}
 	}
 
+	@Override
+	public boolean supports(IProject project) throws CoreException {
+		initProviders();
+
+		// First see if we have a build config registered
+		for (IBuildConfiguration config : project.getBuildConfigs()) {
+			if (configs.containsKey(config)) {
+				return true;
+			}
+		}
+
+		// See if one of the providers supports this project
+		for (Provider provider : providers.values()) {
+			if (provider.supports(project)) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 }

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/build/CBuildPropertyTester.java

@@ -0,0 +1,38 @@
+/*******************************************************************************
+ * Copyright (c) 2016, QNX Software Systems and others
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *******************************************************************************/
+package org.eclipse.cdt.internal.core.build;
+
+import org.eclipse.cdt.core.CCorePlugin;
+import org.eclipse.cdt.core.build.ICBuildConfigurationManager;
+import org.eclipse.core.expressions.PropertyTester;
+import org.eclipse.core.resources.IProject;
+import org.eclipse.core.resources.IResource;
+import org.eclipse.core.runtime.CoreException;
+
+public class CBuildPropertyTester extends PropertyTester {
+
+	@Override
+	public boolean test(Object receiver, String property, Object[] args, Object expectedValue) {
+		switch (property) {
+		case "isSupported": //$NON-NLS-1$
+			if (receiver instanceof IResource) {
+				IProject project = ((IResource) receiver).getProject();
+				try {
+					return CCorePlugin.getService(ICBuildConfigurationManager.class).supports(project);
+				} catch (CoreException e) {
+					CCorePlugin.log(e.getStatus());
+					return false;
+				}
+			}
+			return false;
+		default:
+			return false;
+		}
+	}
+
+}

core/org.eclipse.cdt.ui/plugin.xml

@@ -3502,6 +3502,11 @@
                <and>
                   <test property="org.eclipse.core.resources.projectNature"
                         value="org.eclipse.cdt.core.cnature"/>
+                  <not>
+                     <test
+                           property="org.eclipse.cdt.core.build.isSupported">
+                     </test>
+                  </not>
                   <test property="org.eclipse.cdt.ui.checkPreference"
                         value="org.eclipse.cdt.core/language.settings.providers.disabled=false"/>
                </and>