tbv2: support capture-thrift-isset

Support the capture-thrift-isset feature with TreeBuilder-v2. Fairly minor
changes here except the type of the Enum in a template parameter now matters.

We follow the previous behaviour of capturing a value for each field in a
struct that has an `isset_bitset`. This value is a VarInt captured before the
C++ contents of the member. It has 3 values: 0 (not set), 1 (set), and 2
(unavailable). These are handled by the processor and represented in the output
as `false`, `true`, and `std::nullopt_t` respectively.

Changes:
- Add a simple Thrift isset processor before any fields that have Thrift isset.
- Store the fully qualified names of enum types in DrgnParser - it already
  worked out this information anyway for naming the values and this is
  consistent with classes.
- Forward all enum template parameters under their input name under the
  assumption that they will all be policy type things like `IssetBitsetOption`.
  This could turn out to be wrong.

Test plan:
- CI (doesn't test thrift changes but covers other regressions)
- Updated Thrift enum tests for new format.
- `FILTER='OilIntegration.*' make test` - Thrift tests failed before, succeed
  after.

include/oi/exporters/Json.h

@@ -158,7 +158,7 @@ inline void Json::printFields(const result::Element& el,
     printUnsignedField("capacity", el.container_stats->capacity, indent);
   }
   if (el.is_set_stats.has_value())
-    printUnsignedField("is_set", el.is_set_stats->is_set, indent);
+    printBoolField("is_set", el.is_set_stats->is_set, indent);
   printBoolField("is_primitive", el.is_primitive, indent);
 }
 

oi/CodeGen.cpp

@@ -687,7 +687,9 @@ void CodeGen::genClassTraversalFunction(const Class& c, std::string& code) {
     }
 
     if (thriftIssetMember != nullptr && thriftIssetMember != &member) {
-      code += "\n  .write(getThriftIsset(t, " + std::to_string(i) + "))";
+      code += "\n      .write(getThriftIsset(t, ";
+      code += std::to_string(i);
+      code += "))";
     }
 
     code += "\n      .";
@@ -765,6 +767,12 @@ void CodeGen::genClassStaticType(const Class& c, std::string& code) {
 
 void CodeGen::genClassTreeBuilderInstructions(const Class& c,
                                               std::string& code) {
+  const Member* thriftIssetMember = nullptr;
+  if (const auto it = thriftIssetMembers_.find(&c);
+      it != thriftIssetMembers_.end()) {
+    thriftIssetMember = it->second;
+  }
+
   code += " private:\n";
   size_t index = 0;
   for (const auto& m : c.members) {
@@ -799,12 +807,32 @@ void CodeGen::genClassTreeBuilderInstructions(const Class& c,
       continue;
     std::string fullName = c.name() + "::" + m.name;
     bool isPrimitive = dynamic_cast<const Primitive*>(&m.type());
-    code += "      inst::Field{sizeof(" + fullName + "), " +
+    code += "      inst::Field{sizeof(";
-            std::to_string(calculateExclusiveSize(m.type())) + ",\"" +
+    code += fullName;
-            m.inputName + "\", member_" + std::to_string(index) +
+    code += "), ";
-            "_type_names, TypeHandler<Ctx, decltype(" + fullName +
+    code += std::to_string(calculateExclusiveSize(m.type()));
-            ")>::fields, TypeHandler<Ctx, decltype(" + fullName +
+    code += ",\"";
-            ")>::processors, ";
+    code += m.inputName;
+    code += "\", member_";
+    code += std::to_string(index);
+    code += "_type_names, TypeHandler<Ctx, decltype(";
+    code += fullName;
+    code += ")>::fields, ";
+
+    if (thriftIssetMember != nullptr && thriftIssetMember != &m) {
+      code += "ThriftIssetHandler<";
+      // code += "member_";
+      // code += std::to_string(index);
+      // code += "_processors";
+    }
+    code += "TypeHandler<Ctx, decltype(";
+    code += fullName;
+    code += ")>";
+    if (thriftIssetMember != nullptr && thriftIssetMember != &m) {
+      code += '>';
+    }
+    code += "::processors, ";
+
     code += isPrimitive ? "true" : "false";
     code += "},\n";
   }
@@ -825,10 +853,10 @@ void CodeGen::genClassTypeHandler(const Class& c, std::string& code) {
   static int getThriftIsset(const %1%& t, size_t i) {
     using thrift_data = apache::thrift::TStructDataStorage<%2%>;
 
-    if (&thrift_data::isset_indexes == nullptr) return -1;
+    if (&thrift_data::isset_indexes == nullptr) return 2;
 
     auto idx = thrift_data::isset_indexes[i];
-    if (idx == -1) return -1;
+    if (idx == -1) return 2;
 
     return t.%3%.get(idx);
   }
@@ -900,7 +928,15 @@ void genContainerTypeHandler(std::unordered_set<const ContainerInfo*>& used,
   for (const auto& p : templateParams) {
     if (p.value) {
       code += ", ";
-      code += p.type().name();
+
+      // HACK: forward all enums directly. this might turn out to be a problem
+      // if there are enums we should be regenerating/use in the body.
+      if (const auto* e = dynamic_cast<const Enum*>(&p.type())) {
+        code += e->inputName();
+      } else {
+        code += p.type().name();
+      }
+
       code += " N" + std::to_string(values++);
     } else {
       code += ", typename T" + std::to_string(types++);
@@ -1048,11 +1084,32 @@ void addCaptureKeySupport(std::string& code) {
   )";
 }
 
+void addThriftIssetSupport(std::string& code) {
+  code += R"(
+void processThriftIsset(result::Element& el, std::function<void(inst::Inst)> stack_ins, ParsedData d) {
+  auto v = std::get<ParsedData::VarInt>(d.val).value;
+  if (v <= 1) {
+    el.is_set_stats.emplace(result::Element::IsSetStats { v == 1 });
+  }
+}
+static constexpr exporters::inst::ProcessorInst thriftIssetProcessor{
+  types::st::VarInt<int>::describe,
+  &processThriftIsset,
+};
+
+template <typename Handler>
+struct ThriftIssetHandler {
+  static constexpr auto processors = arrayPrepend(Handler::processors, thriftIssetProcessor);
+};
+)";
+}
+
 void addStandardTypeHandlers(TypeGraph& typeGraph,
                              FeatureSet features,
                              std::string& code) {
-  if (features[Feature::TreeBuilderV2])
+  addCaptureKeySupport(code);
-    addCaptureKeySupport(code);
+  if (features[Feature::CaptureThriftIsset])
+    addThriftIssetSupport(code);
 
   // Provide a wrapper function, getSizeType, to infer T instead of having to
   // explicitly specify it with TypeHandler<Ctx, T>::getSizeType every time.

oi/OITraceCode.cpp

@@ -40,6 +40,11 @@ constexpr int oidMagicId = 0x01DE8;
 
 namespace {
 
+template <typename T, size_t N>
+constexpr std::array<T, N + 1> arrayPrepend(std::array<T, N> a, T t);
+template <typename T, size_t N, size_t... I>
+constexpr std::array<T, N+1> arrayPrependHelper(std::array<T, N> a, T t, std::index_sequence<I...>);
+
 template <size_t Size = (1 << 20) / sizeof(uintptr_t)>
 class PointerHashSet {
  private:
@@ -182,6 +187,20 @@ bool isStorageInline(const auto& c) {
          (uintptr_t)std::data(c) >= (uintptr_t)&c;
 }
 
+namespace {
+
+template <typename T, size_t N, size_t... I>
+constexpr std::array<T, N+1> arrayPrependHelper(std::array<T, N> a, T t, std::index_sequence<I...>) {
+  return {t, a[I]...};
+}
+
+template <typename T, size_t N>
+constexpr std::array<T, N + 1> arrayPrepend(std::array<T, N> a, T t) {
+  return arrayPrependHelper(a, t, std::make_index_sequence<N>());
+}
+
+}
+
 namespace OIInternal {
 namespace {
 

oi/type_graph/ClangTypeParser.cpp

@@ -137,6 +137,8 @@ Typedef& ClangTypeParser::enumerateTypedef(const clang::TypedefType& ty) {
 }
 
 Enum& ClangTypeParser::enumerateEnum(const clang::EnumType& ty) {
+  std::string fqName = clang::TypeName::getFullyQualifiedName(
+      clang::QualType(&ty, 0), *ast, {ast->getLangOpts()});
   std::string name = ty.getDecl()->getNameAsString();
   auto size = ast->getTypeSize(clang::QualType(&ty, 0)) / 8;
 
@@ -148,7 +150,8 @@ Enum& ClangTypeParser::enumerateEnum(const clang::EnumType& ty) {
     }
   }
 
-  return makeType<Enum>(ty, std::move(name), size, std::move(enumeratorMap));
+  return makeType<Enum>(
+      ty, std::move(name), std::move(fqName), size, std::move(enumeratorMap));
 }
 
 Array& ClangTypeParser::enumerateArray(const clang::ConstantArrayType& ty) {

oi/type_graph/DrgnParser.cpp

@@ -73,6 +73,8 @@ void warnForDrgnError(struct drgn_type* type,
                       const std::string& msg,
                       struct drgn_error* err);
 
+std::string getDrgnFullyQualifiedName(struct drgn_type* type);
+
 }  // namespace
 
 Type& DrgnParser::parse(struct drgn_type* root) {
@@ -150,6 +152,8 @@ Class& DrgnParser::enumerateClass(struct drgn_type* type) {
   std::string fqName;
   char* nameStr = nullptr;
   size_t length = 0;
+  // HACK: Leak this error. Freeing it causes a SEGV which suggests our
+  // underlying implementation is bad.
   auto* err = drgn_type_fully_qualified_name(type, &nameStr, &length);
   if (err == nullptr && nameStr != nullptr) {
     fqName = nameStr;
@@ -307,14 +311,7 @@ void DrgnParser::enumerateTemplateParam(struct drgn_type* type,
     // This template parameter is a value
     std::string value;
 
-    if (drgn_type_kind(obj->type) == DRGN_TYPE_ENUM) {
+    if (dynamic_cast<const Enum*>(&ttype)) {
-      char* nameStr = nullptr;
-      size_t length = 0;
-      err = drgn_type_fully_qualified_name(obj->type, &nameStr, &length);
-      if (err != nullptr || nameStr == nullptr) {
-        throw DrgnParserError{"Failed to get enum's fully qualified name", err};
-      }
-
       uint64_t enumVal;
       switch (obj->encoding) {
         case DRGN_OBJECT_ENCODING_SIGNED:
@@ -333,7 +330,9 @@ void DrgnParser::enumerateTemplateParam(struct drgn_type* type,
       size_t numEnumerators = drgn_type_num_enumerators(obj->type);
       for (size_t j = 0; j < numEnumerators; j++) {
         if (enumerators[j].uvalue == enumVal) {
-          value = std::string{nameStr} + "::" + enumerators[j].name;
+          value = ttype.inputName();
+          value += "::";
+          value += enumerators[j].name;
           break;
         }
       }
@@ -416,6 +415,8 @@ void DrgnParser::enumerateClassFunctions(struct drgn_type* type,
 }
 
 Enum& DrgnParser::enumerateEnum(struct drgn_type* type) {
+  std::string fqName = getDrgnFullyQualifiedName(type);
+
   const char* typeTag = drgn_type_tag(type);
   std::string name = typeTag ? typeTag : "";
   uint64_t size = get_drgn_type_size(type);
@@ -432,7 +433,8 @@ Enum& DrgnParser::enumerateEnum(struct drgn_type* type) {
     }
   }
 
-  return makeType<Enum>(type, name, size, std::move(enumeratorMap));
+  return makeType<Enum>(
+      type, std::move(name), std::move(fqName), size, std::move(enumeratorMap));
 }
 
 Typedef& DrgnParser::enumerateTypedef(struct drgn_type* type) {
@@ -528,6 +530,18 @@ void warnForDrgnError(struct drgn_type* type,
                << ": " << err->code << " " << err->message;
   drgn_error_destroy(err);
 }
+
+std::string getDrgnFullyQualifiedName(drgn_type* type) {
+  char* nameStr = nullptr;
+  size_t length = 0;
+  auto* err = drgn_type_fully_qualified_name(type, &nameStr, &length);
+  if (err != nullptr)
+    throw DrgnParserError("failed to get fully qualified name!", err);
+  if (nameStr != nullptr)
+    return nameStr;
+  return {};
+}
+
 }  // namespace
 
 }  // namespace oi::detail::type_graph

oi/type_graph/Types.h

@@ -477,14 +477,20 @@ class Container : public Type {
 class Enum : public Type {
  public:
   explicit Enum(std::string name,
+                std::string inputName,
                 size_t size,
                 std::map<int64_t, std::string> enumerators = {})
-      : name_(name),
+      : name_(std::move(name)),
-        inputName_(std::move(name)),
+        inputName_(std::move(inputName)),
         size_(size),
         enumerators_(std::move(enumerators)) {
   }
 
+  explicit Enum(std::string name,
+                size_t size,
+                std::map<int64_t, std::string> enumerators = {})
+      : Enum{name, std::move(name), size, std::move(enumerators)} {};
+
   static inline constexpr bool has_node_id = false;
 
   DECLARE_ACCEPT

test/integration/enums.toml

@@ -36,12 +36,12 @@ definitions = '''
     param_types = ["ScopedEnum"]
     setup = "return {};"
     expect_json = '[{"staticSize":4, "dynamicSize":0}]'
-    expect_json_v2 = '[{"typeNames": ["ScopedEnum"], "staticSize":4, "exclusiveSize":4, "size":4}]'
+    expect_json_v2 = '[{"typeNames": ["ns_enums::ScopedEnum"], "staticSize":4, "exclusiveSize":4, "size":4}]'
   [cases.scoped_uint8]
     param_types = ["ScopedEnumUint8"]
     setup = "return {};"
     expect_json = '[{"staticSize":1, "dynamicSize":0}]'
-    expect_json_v2 = '[{"typeNames": ["ScopedEnumUint8"], "staticSize":1, "exclusiveSize":1, "size":1}]'
+    expect_json_v2 = '[{"typeNames": ["ns_enums::ScopedEnumUint8"], "staticSize":1, "exclusiveSize":1, "size":1}]'
   [cases.unscoped]
     param_types = ["UNSCOPED_ENUM"]
     setup = "return {};"
@@ -60,7 +60,7 @@ definitions = '''
     expect_json = '[{"staticSize":2, "dynamicSize":0}]'
     expect_json_v2 = '''[
       {"staticSize": 2, "exclusiveSize": 0, "size":2, "members": [
-        {"typeNames": ["ScopedEnumUint8"], "staticSize":1, "exclusiveSize":1, "size":1},
+        {"typeNames": ["ns_enums::ScopedEnumUint8"], "staticSize":1, "exclusiveSize":1, "size":1},
         {"typeNames": ["uint8_t"], "staticSize":1, "exclusiveSize":1, "size":1}
       ]}
     ]'''

test/integration/thrift_isset.toml

@@ -77,7 +77,6 @@ namespace cpp2 {
 
 [cases]
   [cases.unpacked]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const cpp2::MyThriftStructUnpacked&"]
     setup = '''
       cpp2::MyThriftStructUnpacked ret;
@@ -95,9 +94,19 @@ namespace cpp2 {
         {"name":"__fbthrift_field_c", "staticSize":4, "isset":true},
         {"name":"__isset", "staticSize":3}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":16,
+      "exclusiveSize":1,
+      "size":16,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_b", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_c", "staticSize":4, "is_set":true},
+        {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+      ]
+    }]'''
 
   [cases.packed]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const cpp2::MyThriftStructPacked&"]
     setup = '''
       cpp2::MyThriftStructPacked ret;
@@ -126,9 +135,25 @@ namespace cpp2 {
         {"name":"__fbthrift_field_j", "staticSize":4, "isset":true},
         {"name":"__isset", "staticSize":2}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":44,
+      "exclusiveSize":2,
+      "size":44,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_b", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_c", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_d", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_e", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_f", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_g", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_h", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_i", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_j", "staticSize":4, "is_set":true},
+        {"name":"__isset", "staticSize":2, "NOT":"is_set"}
+      ]}]'''
 
   [cases.packed_non_atomic]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const cpp2::MyThriftStructPackedNonAtomic&"]
     setup = '''
       cpp2::MyThriftStructPackedNonAtomic ret;
@@ -147,9 +172,19 @@ namespace cpp2 {
         {"name":"__fbthrift_field_d", "staticSize":4, "isset":false},
         {"name":"__isset", "staticSize":1}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":20,
+      "exclusiveSize":3,
+      "size":20,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_b", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_c", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_d", "staticSize":4, "is_set":false},
+        {"name":"__isset", "staticSize":1, "NOT":"is_set"}
+      ]}]'''
 
   [cases.out_of_order]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const cpp2::MyThriftStructOutOfOrder&"]
     setup = '''
       cpp2::MyThriftStructOutOfOrder ret;
@@ -166,9 +201,18 @@ namespace cpp2 {
         {"name":"__fbthrift_field_c", "staticSize":4, "isset":false},
         {"name":"__isset", "staticSize":3}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":16,
+      "exclusiveSize":1,
+      "size":16,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_b", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_c", "staticSize":4, "is_set":false},
+        {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+      ]}]'''
 
   [cases.required]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const cpp2::MyThriftStructRequired&"]
     setup = '''
       cpp2::MyThriftStructRequired ret;
@@ -189,9 +233,21 @@ namespace cpp2 {
         {"name":"__fbthrift_field_f", "staticSize":4, "isset":true},
         {"name":"__isset", "staticSize":3}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":28,
+      "exclusiveSize":1,
+      "size":28,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":4, "NOT":"is_set"},
+        {"name":"__fbthrift_field_b", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_c", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_d", "staticSize":4, "NOT":"is_set"},
+        {"name":"__fbthrift_field_e", "staticSize":4, "NOT":"is_set"},
+        {"name":"__fbthrift_field_f", "staticSize":4, "is_set":true},
+        {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+      ]}]'''
 
   [cases.box]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const cpp2::MyThriftStructBoxed&"]
     setup = '''
       cpp2::MyThriftStructBoxed ret;
@@ -211,6 +267,18 @@ namespace cpp2 {
         {"name":"__fbthrift_field_e", "staticSize":4, "isset":true},
         {"name":"__isset", "staticSize":3}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":32,
+      "exclusiveSize":1,
+      "size":32,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":8, "NOT":"is_set"},
+        {"name":"__fbthrift_field_b", "staticSize":8, "NOT":"is_set"},
+        {"name":"__fbthrift_field_c", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_d", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_e", "staticSize":4, "is_set":true},
+        {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+      ]}]'''
 
   [cases.no_capture]
     param_types = ["const cpp2::MyThriftStructBoxed&"]
@@ -231,3 +299,15 @@ namespace cpp2 {
         {"name":"__fbthrift_field_e", "staticSize":4, "NOT":"isset"},
         {"name":"__isset", "staticSize":3}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":32,
+      "exclusiveSize":1,
+      "size":32,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":8, "NOT":"is_set"},
+        {"name":"__fbthrift_field_b", "staticSize":8, "NOT":"is_set"},
+        {"name":"__fbthrift_field_c", "staticSize":4, "NOT":"is_set"},
+        {"name":"__fbthrift_field_d", "staticSize":4, "NOT":"is_set"},
+        {"name":"__fbthrift_field_e", "staticSize":4, "NOT":"is_set"},
+        {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+      ]}]'''

test/integration/thrift_isset_missing.toml

@@ -58,7 +58,6 @@ raw_definitions = '''
 '''
 [cases]
   [cases.present]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const FakeThriftWithData&"]
     setup = '''
       FakeThriftWithData ret;
@@ -78,8 +77,17 @@ raw_definitions = '''
         {"name":"__fbthrift_field_c", "staticSize":4, "isset":true},
         {"name":"__isset", "staticSize":3}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":16,
+      "exclusiveSize":1,
+      "size":16,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":4, "is_set":true},
+        {"name":"__fbthrift_field_b", "staticSize":4, "is_set":false},
+        {"name":"__fbthrift_field_c", "staticSize":4, "is_set":true},
+        {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+      ]}]'''
   [cases.missing]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const FakeThriftWithoutData&"]
     setup = '''
       FakeThriftWithoutData ret;
@@ -99,8 +107,17 @@ raw_definitions = '''
         {"name":"__fbthrift_field_c", "staticSize":4, "NOT":"isset"},
         {"name":"__isset", "staticSize":3}
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":16,
+      "exclusiveSize":1,
+      "size":16,
+      "members":[
+        {"name":"__fbthrift_field_a", "staticSize":4, "NOT":"is_set"},
+        {"name":"__fbthrift_field_b", "staticSize":4, "NOT":"is_set"},
+        {"name":"__fbthrift_field_c", "staticSize":4, "NOT":"is_set"},
+        {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+      ]}]'''
   [cases.mixed]
-    oil_skip = 'oil does not support thrift isset yet' # https://github.com/facebookexperimental/object-introspection/issues/296
     param_types = ["const Mixed&"]
     setup = '''
       Mixed ret;
@@ -143,3 +160,31 @@ raw_definitions = '''
           ]
         }
       ]}]'''
+    expect_json_v2 = '''[{
+      "staticSize":32,
+      "exclusiveSize":0,
+      "size":32,
+      "members":[
+        {
+          "staticSize":16,
+          "exclusiveSize":1,
+          "size":16,
+          "members":[
+            {"name":"__fbthrift_field_a", "staticSize":4, "is_set":true},
+            {"name":"__fbthrift_field_b", "staticSize":4, "is_set":false},
+            {"name":"__fbthrift_field_c", "staticSize":4, "is_set":true},
+            {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+          ]
+        },
+        {
+          "staticSize":16,
+          "exclusiveSize":1,
+          "size":16,
+          "members":[
+            {"name":"__fbthrift_field_a", "staticSize":4, "NOT":"is_set"},
+            {"name":"__fbthrift_field_b", "staticSize":4, "NOT":"is_set"},
+            {"name":"__fbthrift_field_c", "staticSize":4, "NOT":"is_set"},
+            {"name":"__isset", "staticSize":3, "NOT":"is_set"}
+          ]
+        }
+      ]}]'''