Guard loading top-level classes with a check that they are not Kotlin binaries

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

@@ -16,6 +16,7 @@
 
 package org.jetbrains.jet.lang.resolve.kotlin;
 
+import com.intellij.ide.highlighter.JavaClassFileType;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.util.Ref;
@@ -80,6 +81,7 @@ public class VirtualFileKotlinClass implements KotlinJvmBinaryClass {
 
     @Nullable
     /* package */ static VirtualFileKotlinClass create(@NotNull VirtualFile file) {
+        assert file.getFileType() == JavaClassFileType.INSTANCE : "Trying to read binary data from a non-class file " + file;
         try {
             byte[] fileContents = file.contentsToByteArray();
             Pair<JvmClassName, KotlinClassHeader> nameAndHeader = readClassNameAndHeader(fileContents);

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

@@ -16,9 +16,12 @@
 
 package org.jetbrains.jet.lang.resolve.kotlin;
 
+import com.intellij.ide.highlighter.JavaClassFileType;
 import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.jet.lang.resolve.java.structure.JavaClass;
+import org.jetbrains.jet.lang.resolve.java.structure.impl.JavaClassImpl;
 import org.jetbrains.jet.lang.resolve.name.FqName;
 
 public abstract class VirtualFileKotlinClassFinder implements VirtualFileFinder {
@@ -28,4 +31,27 @@ public abstract class VirtualFileKotlinClassFinder implements VirtualFileFinder
         VirtualFile file = findVirtualFileWithHeader(fqName);
         return file == null ? null : KotlinBinaryClassCache.getKotlinBinaryClass(file);
     }
+
+    @Override
+    @Nullable
+    public KotlinJvmBinaryClass findKotlinClass(@NotNull JavaClass javaClass) {
+        VirtualFile file = ((JavaClassImpl) javaClass).getPsi().getContainingFile().getVirtualFile();
+        if (javaClass.getOuterClass() != null) {
+            // For nested classes we get a file of the containing class, to get the actual class file for A.B.C,
+            // we take the file for A, take its parent directory, then in this directory we look for A$B$C.class
+            file = file.getParent().findChild(classFileName(javaClass) + ".class");
+            assert file != null : "Virtual file not found for " + javaClass;
+        }
+
+        if (file.getFileType() != JavaClassFileType.INSTANCE) return null;
+
+        return KotlinBinaryClassCache.getKotlinBinaryClass(file);
+    }
+
+    @NotNull
+    private static String classFileName(@NotNull JavaClass jClass) {
+        JavaClass outerClass = jClass.getOuterClass();
+        if (outerClass == null) return jClass.getName().asString();
+        return classFileName(outerClass) + "$" + jClass.getName().asString();
+    }
 }