THRIFT-2513 clean up enum value assignment
Patch: Dave Watson

This closes #88

Summary:
Clean up how enum values are handled if an integer value is not
explicitly specified in the thrift file.

For example, the following used to be a compile error, but
works now:

  enum MyEnum {
	SOMEVALUE
  }
  struct MyStruct {
	1: MyEnum e = SOMEVALUE
  }

This change also cleans up some of the error handling with out-of-range
values.  Previously thrift simply issued a warning for enum values that
didn't fit in an i32, but serialized them as i32 anyway.  Now
out-of-range enum values result in a compile failure.

Test Plan:
Included a new unit test to verify the assignment of enum values.  I
also verified that g++ makes the same enum value assignments when
compiling these enums as C++ code.
diff --git a/lib/cpp/test/EnumTest.cpp b/lib/cpp/test/EnumTest.cpp
new file mode 100644
index 0000000..21bf819
--- /dev/null
+++ b/lib/cpp/test/EnumTest.cpp
@@ -0,0 +1,59 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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.
+ */
+#define BOOST_TEST_MODULE EnumTest
+#include <boost/test/unit_test.hpp>
+#include "thrift/test/gen-cpp/EnumTest_types.h"
+
+BOOST_AUTO_TEST_SUITE( EnumTest )
+
+BOOST_AUTO_TEST_CASE( test_enum ) {
+  // Check that all the enum values match what we expect
+  BOOST_CHECK_EQUAL(ME1_0, 0);
+  BOOST_CHECK_EQUAL(ME1_1, 1);
+  BOOST_CHECK_EQUAL(ME1_2, 2);
+  BOOST_CHECK_EQUAL(ME1_3, 3);
+  BOOST_CHECK_EQUAL(ME1_5, 5);
+  BOOST_CHECK_EQUAL(ME1_6, 6);
+
+  BOOST_CHECK_EQUAL(ME2_0, 0);
+  BOOST_CHECK_EQUAL(ME2_1, 1);
+  BOOST_CHECK_EQUAL(ME2_2, 2);
+
+  BOOST_CHECK_EQUAL(ME3_0, 0);
+  BOOST_CHECK_EQUAL(ME3_1, 1);
+  BOOST_CHECK_EQUAL(ME3_N2, -2);
+  BOOST_CHECK_EQUAL(ME3_N1, -1);
+  BOOST_CHECK_EQUAL(ME3_D0, 0);
+  BOOST_CHECK_EQUAL(ME3_D1, 1);
+  BOOST_CHECK_EQUAL(ME3_9, 9);
+  BOOST_CHECK_EQUAL(ME3_10, 10);
+
+  BOOST_CHECK_EQUAL(ME4_A, 0x7ffffffd);
+  BOOST_CHECK_EQUAL(ME4_B, 0x7ffffffe);
+  BOOST_CHECK_EQUAL(ME4_C, 0x7fffffff);
+}
+
+BOOST_AUTO_TEST_CASE( test_enum_constant ) {
+  MyStruct ms;
+  BOOST_CHECK_EQUAL(ms.me2_2, 2);
+  BOOST_CHECK_EQUAL(ms.me3_n2, -2);
+  BOOST_CHECK_EQUAL(ms.me3_d1, 1);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
diff --git a/lib/cpp/test/Makefile.am b/lib/cpp/test/Makefile.am
index c1fad3e..e68e66b 100755
--- a/lib/cpp/test/Makefile.am
+++ b/lib/cpp/test/Makefile.am
@@ -20,6 +20,8 @@
 noinst_LTLIBRARIES = libtestgencpp.la libprocessortest.la
 nodist_libtestgencpp_la_SOURCES = \
 	gen-cpp/DebugProtoTest_types.cpp \
+	gen-cpp/EnumTest_types.cpp \
+	gen-cpp/EnumTest_types.h \
 	gen-cpp/OptionalRequiredTest_types.cpp \
 	gen-cpp/DebugProtoTest_types.cpp \
 	gen-cpp/ThriftTest_types.cpp \
@@ -65,7 +67,8 @@
 	TFileTransportTest \
 	UnitTests \
 	link_test \
-	OpenSSLManualInitTest
+	OpenSSLManualInitTest \
+	EnumTest
 # disable these test ... too strong
 #       processor_test
 #	concurrency_test
@@ -112,6 +115,13 @@
   -l:libboost_unit_test_framework.a \
   -lz
 
+EnumTest_SOURCES = \
+  EnumTest.cpp
+
+EnumTest_LDADD = \
+  libtestgencpp.la \
+  $(BOOST_ROOT_PATH)/lib/libboost_unit_test_framework.a
+
 TFileTransportTest_SOURCES = \
 	TFileTransportTest.cpp
 
@@ -233,6 +243,9 @@
 gen-cpp/DebugProtoTest_types.cpp gen-cpp/DebugProtoTest_types.h: $(top_srcdir)/test/DebugProtoTest.thrift
 	$(THRIFT) --gen cpp:dense $<
 
+gen-cpp/EnumTest_types.cpp gen-cpp/EnumTest_types.h: $(top_srcdir)/test/EnumTest.thrift
+	$(THRIFT) --gen cpp $<
+
 gen-cpp/OptionalRequiredTest_types.cpp gen-cpp/OptionalRequiredTest_types.h: $(top_srcdir)/test/OptionalRequiredTest.thrift
 	$(THRIFT) --gen cpp:dense $<