Index: model/org/eclipse/jdt/internal/core/builder/JavaBuilder.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/builder/JavaBuilder.java,v
retrieving revision 1.131
diff -u -r1.131 JavaBuilder.java
--- model/org/eclipse/jdt/internal/core/builder/JavaBuilder.java	19 Apr 2007 17:11:31 -0000	1.131
+++ model/org/eclipse/jdt/internal/core/builder/JavaBuilder.java	8 May 2007 17:53:22 -0000
@@ -587,7 +587,7 @@
 	}
 
 	this.binaryLocationsPerProject = new SimpleLookupTable(3);
-	this.nameEnvironment = new NameEnvironment(workspaceRoot, javaProject, binaryLocationsPerProject);
+	this.nameEnvironment = new NameEnvironment(workspaceRoot, javaProject, binaryLocationsPerProject, notifier);
 
 	if (forBuild) {
 		String filterSequence = javaProject.getOption(JavaCore.CORE_JAVA_BUILD_RESOURCE_COPY_FILTER, true);
Index: model/org/eclipse/jdt/internal/core/builder/NameEnvironment.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/builder/NameEnvironment.java,v
retrieving revision 1.59
diff -u -r1.59 NameEnvironment.java
--- model/org/eclipse/jdt/internal/core/builder/NameEnvironment.java	8 May 2007 17:24:27 -0000	1.59
+++ model/org/eclipse/jdt/internal/core/builder/NameEnvironment.java	8 May 2007 17:53:22 -0000
@@ -30,12 +30,14 @@
 boolean isIncrementalBuild;
 ClasspathMultiDirectory[] sourceLocations;
 ClasspathLocation[] binaryLocations;
-	
+BuildNotifier notifier;
+
 SimpleSet initialTypeNames; // assumed that each name is of the form "a/b/ClassName"
 SimpleLookupTable additionalUnits;
 
-NameEnvironment(IWorkspaceRoot root, JavaProject javaProject, SimpleLookupTable binaryLocationsPerProject) throws CoreException {
+NameEnvironment(IWorkspaceRoot root, JavaProject javaProject, SimpleLookupTable binaryLocationsPerProject, BuildNotifier notifier) throws CoreException {
 	this.isIncrementalBuild = false;
+	this.notifier = notifier;
 	computeClasspathLocations(root, javaProject, binaryLocationsPerProject);
 	setNames(null, null);
 }
@@ -259,6 +261,9 @@
 }
 
 private NameEnvironmentAnswer findClass(String qualifiedTypeName, char[] typeName) {
+	if (this.notifier != null)
+		this.notifier.checkCancelWithinCompiler();
+
 	if (this.initialTypeNames != null && this.initialTypeNames.includes(qualifiedTypeName)) {
 		if (isIncrementalBuild)
 			// catch the case that a type inside a source file has been renamed but other class files are looking for it