Use Platform's findFiles as fallback, bug 260516.

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/rewrite/changegenerator/ChangeGenerator.java

@@ -43,8 +43,8 @@ import org.eclipse.cdt.internal.core.dom.rewrite.commenthandler.NodeCommentMap;
 import org.eclipse.cdt.internal.core.dom.rewrite.util.FileContentHelper;
 import org.eclipse.cdt.internal.core.dom.rewrite.util.FileHelper;
 import org.eclipse.cdt.internal.core.parser.scanner.ILocationResolver;
+import org.eclipse.cdt.internal.core.resources.ResourceLookup;
 import org.eclipse.core.resources.IFile;
-import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.Path;
 import org.eclipse.ltk.core.refactoring.Change;
@@ -230,13 +230,10 @@ public class ChangeGenerator extends CPPASTVisitor {
 			targetLocation = getFileLocationOfEmptyTranslationUnit(modification.getTargetNode());
 			String currentFile = targetLocation.getFileName();
 			IPath implPath = new Path(currentFile);
-			IFile[] relevantFiles = ResourcesPlugin.getWorkspace().getRoot().findFilesForLocation(implPath);
+			IFile relevantFile= ResourceLookup.selectFileForLocation(implPath, null);
-			if (relevantFiles.length == 0) { // if not in workspace or local file system
+			if (relevantFile == null) { // if not in workspace or local file system
 			    throw new UnhandledASTModificationException(modification);
 			}
-			// There may be multiple links to the same file, but since their contents are the
-			// same, just use the first one.
-			IFile relevantFile = relevantFiles[0];
 			MultiTextEdit edit;
 			if (changes.containsKey(relevantFile)) {
 				edit = changes.get(relevantFile);

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/rewrite/commenthandler/NodeCommenter.java

@@ -35,8 +35,8 @@ import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPASTTemplateDeclaration;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPASTWhileStatement;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.GPPASTExplicitTemplateInstantiation;
 import org.eclipse.cdt.internal.core.dom.rewrite.util.OffsetHelper;
+import org.eclipse.cdt.internal.core.resources.ResourceLookup;
 import org.eclipse.core.resources.IFile;
-import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.Path;
 
@@ -150,8 +150,7 @@ public class NodeCommenter {
 				return true;
 			}
 			IPath path = new Path(node.getContainingFilename());
-			IFile[] files = ResourcesPlugin.getWorkspace().getRoot().findFilesForLocation(path);
+			IFile file = ResourceLookup.selectFileForLocation(path, null); // NPE thrown below, like original behavior
-			IFile file = files.length > 0 ? files[0] : null; // NPE thrown below, like original behavior
 			
 			//XXX HSR Guido: Possible Performance Issue (File access)
 			try {

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/rewrite/util/FileHelper.java

@@ -18,6 +18,7 @@ import java.io.InputStream;
 
 import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
 import org.eclipse.cdt.core.dom.ast.IASTNode;
+import org.eclipse.cdt.internal.core.resources.ResourceLookup;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.ProjectScope;
@@ -36,8 +37,7 @@ public class FileHelper {
 
 	public static IFile getIFilefromIASTNode(IASTNode node) {
 		IPath implPath = new Path(node.getContainingFilename());
-		IFile[] files = ResourcesPlugin.getWorkspace().getRoot().findFilesForLocation(implPath);
+		return ResourceLookup.selectFileForLocation(implPath, null);
-		return files.length > 0 ? files[0] : null;
 	}
 	
 	public static boolean isFirstWithinSecondLocation(IASTFileLocation loc1, IASTFileLocation loc2){

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/resources/LocationAdapter.java

@@ -14,7 +14,9 @@ import java.io.File;
 import java.io.IOException;
 import java.net.URI;
 
+import org.eclipse.core.filesystem.URIUtil;
 import org.eclipse.core.resources.IFile;
+import org.eclipse.core.resources.IWorkspaceRoot;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.IPath;
 
@@ -36,7 +38,8 @@ abstract class LocationAdapter<T> {
 
 		@Override
 		public IFile[] platformsFindFilesForLocation(IPath location) {
-			return ResourcesPlugin.getWorkspace().getRoot().findFilesForLocation(location);
+			final IWorkspaceRoot root = ResourcesPlugin.getWorkspace().getRoot();
+			return root.findFilesForLocationURI(URIUtil.toURI(location.makeAbsolute()));
 		}
 
 		@Override

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/resources/ResourceLookup.java

@@ -79,11 +79,11 @@ public class ResourceLookup {
 
 	/**
 	 * Uses {@link #findFilesForLocation(IPath)} and selects the most relevant file
-	 * from the result. Files form the first project, from cdt-projects and those on source
+	 * from the result. Files form the preferred project, from cdt-projects and those on source
 	 * roots are preferred, see {@link FileRelevance}. 
 	 * @param location a path for the location of the files to search for.
 	 * @param preferredProject a project to be preferred over others, or <code>null</code>.
-	 * @return a file for the location in one of the given projects, or <code>null</code>.
+	 * @return a file for the location or <code>null</code>.
 	 */
 	public static IFile selectFileForLocation(IPath location, IProject preferredProject) {
 		return selectFile(findFilesForLocation(location), preferredProject);

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/resources/ResourceLookupTree.java

@@ -653,20 +653,16 @@ class ResourceLookupTree implements IResourceChangeListener, IResourceDeltaVisit
 		synchronized (fLock) {
 			initializeProjects(ResourcesPlugin.getWorkspace().getRoot().getProjects());
 			Object obj= fNodeMap.get(hashCode(name.toCharArray()));
-			if (obj == null) {
+			if (obj != null) {
-				if (fDefaultExtensions.isRelevant(name))
-					return NO_FILES;
-			} else {
 				candidates= convert(obj);
+				IFile[] result= extractMatchesForLocation(candidates, location, adapter);
+				if (result.length > 0)
+					return result;
 			}
 		}	
 		
 		// fall back to platform functionality
-		if (candidates == null) {
+		return adapter.platformsFindFilesForLocation(location);
-			return adapter.platformsFindFilesForLocation(location);
-		}
-		
-		return extractMatchesForLocation(candidates, location, adapter);
 	}
 
 	private Node[] convert(Object obj) {