THRIFT-1394:Treatment of optional fields is not consistent between C++ and Java

Client: cpp
Patch: Diwaker Gupta

In CPP, all optional fields are guarded by the isset helper struct. On Java, however, the generated code takes advantage of nullable types: for containers, structs, exceptions, enums, and, notably, strings, the generator elides explicit use of an "isset" bit vector and instead emits checks of the form "field null". This leads to varying behavior between the two languages: an optional string field with a default value will have {{isset[fieldid]}} false on C, but the equivalent test in Java will be true.

git-svn-id: https://svn.apache.org/repos/asf/thrift/trunk@1236529 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/compiler/cpp/src/generate/t_cpp_generator.cc b/compiler/cpp/src/generate/t_cpp_generator.cc
index 27d6633..db19c90 100755 (executable)
--- a/compiler/cpp/src/generate/t_cpp_generator.cc
+++ b/compiler/cpp/src/generate/t_cpp_generator.cc
@@ -815,13 +815,14 @@ void t_cpp_generator::generate_struct_definition(ofstream& out,
       if ((*m_iter)->get_req() == t_field::T_REQUIRED) {
         continue;
       }
+      string isSet = ((*m_iter)->get_value() != NULL) ? "true" : "false";
       if (first) {
         first = false;
         out <<
-          ": " << (*m_iter)->get_name() << "(false)";
+          ": " << (*m_iter)->get_name() << "(" << isSet << ")";
       } else {
         out <<
-          ", " << (*m_iter)->get_name() << "(false)";
+          ", " << (*m_iter)->get_name() << "(" << isSet << ")";
       }
     }
     out << " {}" << endl;

diff --git a/lib/cpp/test/OptionalRequiredTest.cpp b/lib/cpp/test/OptionalRequiredTest.cpp
index 7472603..5d58f09 100644 (file)
--- a/lib/cpp/test/OptionalRequiredTest.cpp
+++ b/lib/cpp/test/OptionalRequiredTest.cpp
@@ -242,5 +242,21 @@ int main() {
     assert(t1 != t2);
   }
 
+  {
+    OptionalDefault t1, t2;
+    cout << ThriftDebugString(t1) << endl;
+    assert(t1.__isset.opt_int == true);
+    assert(t1.__isset.opt_str == true);
+    assert(t1.opt_int == t2.opt_int);
+    assert(t1.opt_str == t2.opt_str);
+
+    write_to_read(t1, t2);
+    cout << ThriftDebugString(t2) << endl;
+    assert(t2.__isset.opt_int == true);
+    assert(t2.__isset.opt_str == true);
+    assert(t1.opt_int == t2.opt_int);
+    assert(t1.opt_str == t2.opt_str);
+  }
+
   return 0;
 }

diff --git a/test/OptionalRequiredTest.thrift b/test/OptionalRequiredTest.thrift
index 8108a7f..dcdd0f2 100644 (file)
--- a/test/OptionalRequiredTest.thrift
+++ b/test/OptionalRequiredTest.thrift
@@ -49,6 +49,11 @@ struct Tricky3 {
   1: required i16 im_required;
 }
 
+struct OptionalDefault {
+  1: optional i16 opt_int = 1234;
+  2: optional string opt_str = "default";
+}
+
 struct Complex {
   1:          i16 cp_default;
   2: required i16 cp_required;