Fixed incremental compilation, when removing all callables from file.

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/kotlin/PackagePartClassUtils.java

@@ -94,13 +94,18 @@ public class PackagePartClassUtils {
         return ContainerUtil.filter(packageFiles, new Condition<JetFile>() {
             @Override
             public boolean value(JetFile packageFile) {
-                for (JetDeclaration declaration : packageFile.getDeclarations()) {
-                    if (declaration instanceof JetProperty || declaration instanceof JetNamedFunction) {
-                        return true;
-                    }
-                }
-                return false;
+                return fileHasCallables(packageFile);
             }
         });
     }
+
+    public static boolean fileHasCallables(@NotNull JetFile file) {
+        for (JetDeclaration declaration : file.getDeclarations()) {
+            if (declaration instanceof JetProperty || declaration instanceof JetNamedFunction) {
+                return true;
+            }
+        }
+        return false;
+    }
+
 }

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/kotlin/incremental/IncrementalCacheUtil.kt

@@ -22,15 +22,20 @@ import org.jetbrains.jet.lang.resolve.name.FqName
 import org.jetbrains.jet.lang.resolve.java.JvmClassName
 import java.util.HashMap
 import java.io.File
+import org.jetbrains.jet.lang.resolve.kotlin.PackagePartClassUtils
 
 public fun IncrementalCache.getPackagesWithRemovedFiles(sourceFilesToCompile: Collection<JetFile>): Collection<FqName> {
     return getRemovedPackageParts(sourceFilesToCompile).map { it.getPackageFqName() }
 }
 
 public fun IncrementalCache.getRemovedPackageParts(sourceFilesToCompile: Collection<JetFile>): Collection<JvmClassName> {
-    val sourceFilesToFqName = HashMap<File, String>()
+    val sourceFilesToFqName = HashMap<File, String?>()
     for (sourceFile in sourceFilesToCompile) {
-        sourceFilesToFqName[File(sourceFile.getVirtualFile()!!.getPath())] = sourceFile.getPackageFqName().asString()
+        sourceFilesToFqName[File(sourceFile.getVirtualFile()!!.getPath())] =
+                if (PackagePartClassUtils.fileHasCallables(sourceFile))
+                    sourceFile.getPackageFqName().asString()
+                else
+                    null
     }
 
     return getRemovedPackageParts(sourceFilesToFqName).map { JvmClassName.byInternalName(it) }

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/kotlin/incremental/cache/IncrementalCache.kt

@@ -23,7 +23,10 @@ import java.util.HashMap
 import java.io.File
 
 public trait IncrementalCache {
-    public fun getRemovedPackageParts(sourceFilesToCompileAndFqNames: Map<File, String>): Collection<String>
+    public fun getRemovedPackageParts(
+            // null value means source file has no top-level callables (won't produce package part)
+            sourceFilesToCompileAndFqNames: Map<File, String?>
+    ): Collection<String>
 
     public fun getPackageData(fqName: String): ByteArray?