Fix outer classname for javamicro/javanano.

- File class name is defined as the java_outer_classname option value
  or the file name ToCamelCase; never the single message's ClassName.
- File-scope enums are translated to constants in the file class,
  regardless of java_multiple_files.
- If java_multiple_files=true, and file's class name equals a message's
  class name, no error. This is done by detecting that the outer class
  is not needed and skipping the outer class codegen and clash checks.
  Note: there is a disparity between java[lite] and the previous
  java{micr|nan}o: when generating code for a single-message proto, the
  outer class is omitted by java{micr|nan}o if the file does not have
  java_outer_classname. This change makes java{micr|nan}o align with
  java[lite] codegen and create the outer class, but will print some
  info to warn of potential change of code.
- Also fixed the "is_own_file" detection and made all parseX() methods
  static. Previously, all messages in a java_multiple_files=true file
  are (incorrectly) considered to be in their own files, including
  nested messages, causing them to become inner classes (instance-
  bound) and forcing the parseX() methods to lose the static modifier.
- This change supersedes c/60164 and c/60086, which causes javanano to
  put enum values into enum shell classes if java_multiple_files=true.
  We now always use the parent class to host the enum values. A future
  change will add a command line option to provide more flexibility.
- Elaborated in java/README.txt.

Change-Id: I684932f90e0a028ef37c662b221def5ffa202439

2 files changed, 86 insertions, 5 deletions

diff --git a/java/src/test/java/com/google/protobuf/MicroTest.java b/java/src/test/java/com/google/protobuf/MicroTest.java
index 03005a7..1e43f07 100644
--- a/java/src/test/java/com/google/protobuf/MicroTest.java
+++ b/java/src/test/java/com/google/protobuf/MicroTest.java
@@ -32,14 +32,19 @@ package com.google.protobuf;
 
 import com.google.protobuf.micro.ByteStringMicro;
 import com.google.protobuf.micro.CodedInputStreamMicro;
+import com.google.protobuf.micro.FileScopeEnumRefMicro;
+import com.google.protobuf.micro.MessageScopeEnumRefMicro;
 import com.google.protobuf.micro.MicroOuterClass;
 import com.google.protobuf.micro.MicroOuterClass.TestAllTypesMicro;
 import com.google.protobuf.micro.MultipleImportingNonMultipleMicro1;
 import com.google.protobuf.micro.MultipleImportingNonMultipleMicro2;
-import com.google.protobuf.micro.RecursiveMessageMicro;
-import com.google.protobuf.micro.SimpleMessageMicro;
-import com.google.protobuf.micro.StringUtf8;
+import com.google.protobuf.micro.MultipleNameClashMicro;
 import com.google.protobuf.micro.UnittestImportMicro;
+import com.google.protobuf.micro.UnittestMultipleMicro;
+import com.google.protobuf.micro.UnittestRecursiveMicro.RecursiveMessageMicro;
+import com.google.protobuf.micro.UnittestSimpleMicro.SimpleMessageMicro;
+import com.google.protobuf.micro.UnittestSingleMicro.SingleMessageMicro;
+import com.google.protobuf.micro.UnittestStringutf8Micro.StringUtf8;
 
 import junit.framework.TestCase;
 
@@ -2104,6 +2109,41 @@ public class MicroTest extends TestCase {
   }
 
   /**
+   * Tests that code generation correctly wraps a single message into its outer
+   * class. The class {@code SingleMessageMicro} is imported from the outer
+   * class {@code UnittestSingleMicro}, whose name is implicit. Any error would
+   * cause this method to fail compilation.
+   */
+  public void testMicroSingle() throws Exception {
+    SingleMessageMicro msg = new SingleMessageMicro();
+  }
+
+  /**
+   * Tests that code generation correctly skips generating the outer class if
+   * unnecessary, letting a file-scope entity have the same name. The class
+   * {@code MultipleNameClashMicro} shares the same name with the file's outer
+   * class defined explicitly, but the file contains no other entities and has
+   * java_multiple_files set. Any error would cause this method to fail
+   * compilation.
+   */
+  public void testMicroMultipleNameClash() throws Exception {
+    MultipleNameClashMicro msg = new MultipleNameClashMicro();
+    msg.setField(0);
+  }
+
+  /**
+   * Tests that code generation correctly handles enums in different scopes in
+   * a source file with the option java_multiple_files set to true. Any error
+   * would cause this method to fail compilation.
+   */
+  public void testMicroMultipleEnumScoping() throws Exception {
+    FileScopeEnumRefMicro msg1 = new FileScopeEnumRefMicro();
+    msg1.setEnumField(UnittestMultipleMicro.ONE);
+    MessageScopeEnumRefMicro msg2 = new MessageScopeEnumRefMicro();
+    msg2.setEnumField(MessageScopeEnumRefMicro.TWO);
+  }
+
+  /**
    * Tests that code generation with mixed values of the java_multiple_files
    * options between the main source file and the imported source files would
    * generate correct references. Any error would cause this method to fail
diff --git a/java/src/test/java/com/google/protobuf/NanoTest.java b/java/src/test/java/com/google/protobuf/NanoTest.java
index 80f091b..b1251f8 100644
--- a/java/src/test/java/com/google/protobuf/NanoTest.java
+++ b/java/src/test/java/com/google/protobuf/NanoTest.java
@@ -33,16 +33,22 @@ package com.google.protobuf;
 import com.google.protobuf.nano.CodedInputByteBufferNano;
 import com.google.protobuf.nano.Extensions;
 import com.google.protobuf.nano.Extensions.AnotherMessage;
+import com.google.protobuf.nano.FileScopeEnumRefNano;
 import com.google.protobuf.nano.InternalNano;
 import com.google.protobuf.nano.MessageNano;
+import com.google.protobuf.nano.MessageScopeEnumRefNano;
 import com.google.protobuf.nano.MultipleImportingNonMultipleNano1;
 import com.google.protobuf.nano.MultipleImportingNonMultipleNano2;
+import com.google.protobuf.nano.MultipleNameClashNano;
 import com.google.protobuf.nano.NanoHasOuterClass.TestAllTypesNanoHas;
 import com.google.protobuf.nano.NanoOuterClass;
 import com.google.protobuf.nano.NanoOuterClass.TestAllTypesNano;
-import com.google.protobuf.nano.RecursiveMessageNano;
-import com.google.protobuf.nano.SimpleMessageNano;
 import com.google.protobuf.nano.UnittestImportNano;
+import com.google.protobuf.nano.UnittestMultipleNano;
+import com.google.protobuf.nano.UnittestRecursiveNano.RecursiveMessageNano;
+import com.google.protobuf.nano.UnittestSimpleNano.SimpleMessageNano;
+import com.google.protobuf.nano.UnittestSingleNano.SingleMessageNano;
+import com.google.protobuf.nano.UnittestStringutf8Nano.StringUtf8;
 
 import junit.framework.TestCase;
 
@@ -2043,6 +2049,41 @@ public class NanoTest extends TestCase {
   }
 
   /**
+   * Tests that code generation correctly wraps a single message into its outer
+   * class. The class {@code SingleMessageNano} is imported from the outer
+   * class {@code UnittestSingleNano}, whose name is implicit. Any error would
+   * cause this method to fail compilation.
+   */
+  public void testNanoSingle() throws Exception {
+    SingleMessageNano msg = new SingleMessageNano();
+  }
+
+  /**
+   * Tests that code generation correctly skips generating the outer class if
+   * unnecessary, letting a file-scope entity have the same name. The class
+   * {@code MultipleNameClashNano} shares the same name with the file's outer
+   * class defined explicitly, but the file contains no other entities and has
+   * java_multiple_files set. Any error would cause this method to fail
+   * compilation.
+   */
+  public void testNanoMultipleNameClash() throws Exception {
+    MultipleNameClashNano msg = new MultipleNameClashNano();
+    msg.field = 0;
+  }
+
+  /**
+   * Tests that code generation correctly handles enums in different scopes in
+   * a source file with the option java_multiple_files set to true. Any error
+   * would cause this method to fail compilation.
+   */
+  public void testNanoMultipleEnumScoping() throws Exception {
+    FileScopeEnumRefNano msg1 = new FileScopeEnumRefNano();
+    msg1.enumField = UnittestMultipleNano.ONE;
+    MessageScopeEnumRefNano msg2 = new MessageScopeEnumRefNano();
+    msg2.enumField = MessageScopeEnumRefNano.TWO;
+  }
+
+  /**
    * Tests that code generation with mixed values of the java_multiple_files
    * options between the main source file and the imported source files would
    * generate correct references. Any error would cause this method to fail