For namespaces with multiple files keep 'Compiled from' information empty

compiler/backend/src/org/jetbrains/jet/codegen/NamespaceCodegen.java

@@ -62,7 +62,7 @@ public class NamespaceCodegen extends MemberCodegen {
         name = fqName;
         this.files = namespaceFiles;
 
-        final PsiFile sourceFile = namespaceFiles.iterator().next().getContainingFile();
+        final PsiFile sourceFile = namespaceFiles.size() == 1 ? namespaceFiles.iterator().next().getContainingFile() : null;
 
         v.addOptionalDeclaration(new ClassBuilderOnDemand.ClassBuilderCallback() {
             @Override
@@ -75,8 +75,10 @@ public class NamespaceCodegen extends MemberCodegen {
                               "java/lang/Object",
                               new String[0]
                 );
-                // TODO figure something out for a namespace that spans multiple files
+                //We don't generate any source information for namespace with multiple files
-                v.visitSource(sourceFile.getName(), null);
+                if (sourceFile != null) {
+                    v.visitSource(sourceFile.getName(), null);
+                }
             }
         });
     }

compiler/testData/codegen/sourceInfo/foo1.kt

@@ -0,0 +1,5 @@
+package foo;
+
+fun box() = {
+  1
+}

compiler/testData/codegen/sourceInfo/foo2.kt

@@ -0,0 +1,5 @@
+package foo;
+
+fun box2() = {
+  1
+}

compiler/testData/codegen/sourceInfo/singleClass.kt

@@ -0,0 +1,4 @@
+class SingleClass {
+
+
+}

compiler/tests/org/jetbrains/jet/codegen/SourceInfoGenTest.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2010-2013 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jetbrains.jet.codegen;
+
+import org.jetbrains.asm4.ClassReader;
+import org.jetbrains.asm4.ClassVisitor;
+import org.jetbrains.asm4.Opcodes;
+import org.jetbrains.jet.ConfigurationKind;
+
+public class SourceInfoGenTest extends CodegenTestCase {
+
+    protected void setUp() throws Exception {
+        super.setUp();
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+    }
+
+    public void testSingleFileNamespace() {
+        String producer = "sourceInfo/foo1.kt";
+        loadFiles(producer);
+        assertEquals(producer, getProducerInfo("foo/FooPackage.class"));
+    }
+
+    public void testMultiFileNamespace() {
+        loadFiles("sourceInfo/foo1.kt", "sourceInfo/foo2.kt");
+        assertEquals(null, getProducerInfo("foo/FooPackage.class"));
+    }
+
+    public void testSingleClass() {
+        String producer = "sourceInfo/singleClass.kt";
+        loadFiles(producer);
+        assertEquals(producer, getProducerInfo("SingleClass.class"));
+    }
+
+    private String getProducerInfo(String name) {
+        ClassReader classReader = new ClassReader(generateClassesInFile().asBytes(name));
+
+        final String [] producer = new String [1];
+        classReader.accept(new ClassVisitor(Opcodes.ASM4) {
+
+            @Override
+            public void visitSource(String source, String debug) {
+                producer[0] = source;
+            }
+
+        }, 0);
+        return producer[0];
+    }
+}