Fix #3497: Add support for compiling in g++ 4.4 and 4.5

- Removed uses of lambda expressions

- Added custom defines for constexpr and nullptr

- Removed trailing comma of last value from generated enums

include/flatbuffers/flatbuffers.h

@@ -33,11 +33,30 @@
 #if __cplusplus <= 199711L && \
     (!defined(_MSC_VER) || _MSC_VER < 1600) && \
     (!defined(__GNUC__) || \
-      (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__ < 40603))
-  #error A C++11 compatible compiler is required for FlatBuffers.
+      (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__ < 40400))
+  #error A C++11 compatible compiler with support for the auto typing is required for FlatBuffers.
   #error __cplusplus _MSC_VER __GNUC__  __GNUC_MINOR__  __GNUC_PATCHLEVEL__
 #endif
 
+#if !defined(__clang__) && \
+    defined(__GNUC__) && \
+    (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__ < 40600)
+  // Backwards compatability for g++ 4.4, and 4.5 which don't have the nullptr and constexpr
+  // keywords. Note the __clang__ check is needed, because clang presents itself as an older GNUC
+  // compiler.
+  #ifndef nullptr_t
+    const class nullptr_t {
+    public:
+      template<class T> inline operator T*() const { return 0; }
+    private:
+      void operator&() const;
+    } nullptr = {};
+  #endif
+  #ifndef constexpr
+    #define constexpr const
+  #endif
+#endif
+
 // The wire format uses a little endian encoding (since that's efficient for
 // the common platforms).
 #if !defined(FLATBUFFERS_LITTLEENDIAN)
@@ -154,7 +173,11 @@ template<typename T> size_t AlignOf() {
   #ifdef _MSC_VER
     return __alignof(T);
   #else
-    return alignof(T);
+    #ifndef alignof
+      return __alignof__(T);
+    #else
+      return alignof(T);
+    #endif
   #endif
 }
 
@@ -836,15 +859,20 @@ class FlatBufferBuilder FLATBUFFERS_FINAL_CLASS {
     return CreateVectorOfStructs(v.data(), v.size());
   }
 
+  template<typename T>
+  struct TableKeyComparator {
+  TableKeyComparator(vector_downward& buf) : buf_(buf) {}
+    bool operator()(const Offset<T> &a, const Offset<T> &b) const {
+      auto table_a = reinterpret_cast<T *>(buf_.data_at(a.o));
+      auto table_b = reinterpret_cast<T *>(buf_.data_at(b.o));
+      return table_a->KeyCompareLessThan(table_b);
+    }
+    vector_downward& buf_;
+  };
+
   template<typename T> Offset<Vector<Offset<T>>> CreateVectorOfSortedTables(
                                                      Offset<T> *v, size_t len) {
-    std::sort(v, v + len,
-      [this](const Offset<T> &a, const Offset<T> &b) -> bool {
-        auto table_a = reinterpret_cast<T *>(buf_.data_at(a.o));
-        auto table_b = reinterpret_cast<T *>(buf_.data_at(b.o));
-        return table_a->KeyCompareLessThan(table_b);
-      }
-    );
+    std::sort(v, v + len, TableKeyComparator<T>(buf_));
     return CreateVector(v, len);
   }
 

include/flatbuffers/hash.h

@@ -20,6 +20,8 @@
 #include <cstdint>
 #include <cstring>
 
+#include "flatbuffers/flatbuffers.h"
+
 namespace flatbuffers {
 
 template <typename T>
@@ -36,8 +38,8 @@ struct FnvTraits<uint32_t> {
 
 template <>
 struct FnvTraits<uint64_t> {
-  static const uint64_t kFnvPrime = 0x00000100000001b3;
-  static const uint64_t kOffsetBasis = 0xcbf29ce484222645;
+  static const uint64_t kFnvPrime = 0x00000100000001b3ULL;
+  static const uint64_t kOffsetBasis = 0xcbf29ce484222645ULL;
 };
 
 template <typename T>

include/flatbuffers/idl.h

@@ -491,6 +491,10 @@ private:
   FLATBUFFERS_CHECKED_ERROR DoParse(const char *_source,
                                     const char **include_paths,
                                     const char *source_filename);
+  FLATBUFFERS_CHECKED_ERROR CheckClash(std::vector<FieldDef*> &fields,
+                                       StructDef *struct_def,
+                                       const char *suffix,
+                                       BaseType baseType);
 
  public:
   SymbolTable<StructDef> structs_;

include/flatbuffers/util.h

@@ -38,6 +38,8 @@
 #include <limits.h>
 #endif
 
+#include "flatbuffers/flatbuffers.h"
+
 namespace flatbuffers {
 
 // Convert an integer or floating point value to a string.
@@ -68,7 +70,7 @@ template<> inline std::string NumToString<double>(double t) {
   auto p = s.find_last_not_of('0');
   if (p != std::string::npos) {
     s.resize(p + 1);  // Strip trailing zeroes.
-    if (s.back() == '.')
+    if (s[s.size() - 1] == '.')
       s.erase(s.size() - 1, 1);  // Strip '.' if a whole number.
   }
   return s;
@@ -197,8 +199,8 @@ inline std::string StripFileName(const std::string &filepath) {
 inline std::string ConCatPathFileName(const std::string &path,
                                       const std::string &filename) {
   std::string filepath = path;
-  if (path.length() && path.back() != kPathSeparator &&
-                       path.back() != kPosixPathSeparator)
+  if (path.length() && path[path.size() - 1] != kPathSeparator &&
+                       path[path.size() - 1] != kPosixPathSeparator)
     filepath += kPathSeparator;
   filepath += filename;
   return filepath;

samples/monster_generated.h

@@ -65,7 +65,7 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
     VT_HP = 8,
     VT_NAME = 10,
     VT_INVENTORY = 14,
-    VT_COLOR = 16,
+    VT_COLOR = 16
   };
   const Vec3 *pos() const { return GetStruct<const Vec3 *>(VT_POS); }
   Vec3 *mutable_pos() { return GetStruct<Vec3 *>(VT_POS); }

src/flatc.cpp

@@ -17,6 +17,7 @@
 #include "flatbuffers/flatbuffers.h"
 #include "flatbuffers/idl.h"
 #include "flatbuffers/util.h"
+#include <limits>
 
 static void Error(const std::string &err, bool usage = false,
                   bool show_exe_name = true);

src/idl_gen_cpp.cpp

@@ -267,16 +267,24 @@ static void GenTable(const Parser &parser, StructDef &struct_def,
   // Generate field id constants.
   if (struct_def.fields.vec.size() > 0) {
     code += "  enum {\n";
+    bool is_first_field = true; // track the first field that's not deprecated
     for (auto it = struct_def.fields.vec.begin();
          it != struct_def.fields.vec.end();
          ++it) {
       auto &field = **it;
       if (!field.deprecated) {  // Deprecated fields won't be accessible.
+        if (!is_first_field) {
+          // Add trailing comma and newline to previous element. Don't add trailing comma to 
+          // last element since older versions of gcc complain about this.
+          code += ",\n";
+        } else {
+          is_first_field = false;
+        }
         code += "    " + GenFieldOffsetName(field) + " = ";
-        code += NumToString(field.value.offset) + ",\n";
+        code += NumToString(field.value.offset);
       }
     }
-    code += "  };\n";
+    code += "\n  };\n";
   }
   // Generate the accessors.
   for (auto it = struct_def.fields.vec.begin();
@@ -513,15 +521,32 @@ static void GenTable(const Parser &parser, StructDef &struct_def,
 }
 
 static void GenPadding(const FieldDef &field,
-                       const std::function<void (int bits)> &f) {
+            std::string &code,
+            int &padding_id,
+            const std::function<void (int bits, std::string &code, int &padding_id)> &f) {
   if (field.padding) {
     for (int i = 0; i < 4; i++)
       if (static_cast<int>(field.padding) & (1 << i))
-        f((1 << i) * 8);
+        f((1 << i) * 8, code, padding_id);
     assert(!(field.padding & ~0xF));
   }
 }
 
+static void PaddingDefinition(int bits, std::string &code, int &padding_id) {
+  code += "  int" + NumToString(bits) +
+          "_t __padding" + NumToString(padding_id++) + ";\n";
+}
+
+static void PaddingDeclaration(int bits, std::string &code, int &padding_id) {
+  (void)bits;
+  code += " (void)__padding" + NumToString(padding_id++) + ";";
+}
+
+static void PaddingInitializer(int bits, std::string &code, int &padding_id) {
+  (void)bits;
+  code += ", __padding" + NumToString(padding_id++) + "(0)";
+}
+
 // Generate an accessor struct with constructor for a flatbuffers struct.
 static void GenStruct(const Parser &parser, StructDef &struct_def,
                       std::string *code_ptr) {
@@ -543,10 +568,7 @@ static void GenStruct(const Parser &parser, StructDef &struct_def,
     auto &field = **it;
     code += "  " + GenTypeGet(parser, field.value.type, " ", "", " ", false);
     code += field.name + "_;\n";
-    GenPadding(field, [&code, &padding_id](int bits) {
-      code += "  int" + NumToString(bits) +
-              "_t __padding" + NumToString(padding_id++) + ";\n";
-    });
+    GenPadding(field, code, padding_id, PaddingDefinition);
   }
 
   // Generate a constructor that takes all fields as arguments.
@@ -574,21 +596,16 @@ static void GenStruct(const Parser &parser, StructDef &struct_def,
     } else {
       code += "_" + field.name + ")";
     }
-    GenPadding(field, [&code, &padding_id](int bits) {
-      (void)bits;
-      code += ", __padding" + NumToString(padding_id++) + "(0)";
-    });
+    GenPadding(field, code, padding_id, PaddingInitializer);
   }
+
   code += " {";
   padding_id = 0;
   for (auto it = struct_def.fields.vec.begin();
        it != struct_def.fields.vec.end();
        ++it) {
     auto &field = **it;
-    GenPadding(field, [&code, &padding_id](int bits) {
-      (void)bits;
-      code += " (void)__padding" + NumToString(padding_id++) + ";";
-    });
+    GenPadding(field, code, padding_id, PaddingDeclaration);
   }
   code += " }\n\n";
 
@@ -642,6 +659,12 @@ void CloseNestedNameSpaces(Namespace *ns, std::string *code_ptr) {
 
 }  // namespace cpp
 
+struct IsAlnum {
+  bool operator()(char c) {
+    return !isalnum(c);
+  }
+};
+
 // Iterate through all definitions we haven't generate code for (enums, structs,
 // and tables) and output them to a single file.
 std::string GenerateCPP(const Parser &parser,
@@ -712,7 +735,7 @@ std::string GenerateCPP(const Parser &parser,
     include_guard_ident.erase(
       std::remove_if(include_guard_ident.begin(),
                      include_guard_ident.end(),
-                     [](char c) { return !isalnum(c); }),
+                     IsAlnum()),
       include_guard_ident.end());
     std::string include_guard = "FLATBUFFERS_GENERATED_" + include_guard_ident;
     include_guard += "_";

src/idl_parser.cpp

@@ -1109,6 +1109,33 @@ CheckedError Parser::StartStruct(const std::string &name, StructDef **dest) {
   return NoError();
 }
 
+CheckedError Parser::CheckClash(std::vector<FieldDef*> &fields,
+                                StructDef *struct_def,
+                                const char *suffix,
+                                BaseType basetype) {
+  auto len = strlen(suffix);
+  for (auto it = fields.begin(); it != fields.end(); ++it) {
+    auto &fname = (*it)->name;
+    if (fname.length() > len &&
+        fname.compare(fname.length() - len, len, suffix) == 0 &&
+        (*it)->value.type.base_type != BASE_TYPE_UTYPE) {
+      auto field = struct_def->fields.Lookup(
+                                             fname.substr(0, fname.length() - len));
+      if (field && field->value.type.base_type == basetype)
+        return Error("Field " + fname +
+                     " would clash with generated functions for field " +
+                     field->name);
+    }
+  }
+  return NoError();
+}
+    
+static bool compareFieldDefs(const FieldDef *a, const FieldDef *b) {
+  auto a_id = atoi(a->attributes.Lookup("id")->constant.c_str());
+  auto b_id = atoi(b->attributes.Lookup("id")->constant.c_str());
+  return a_id < b_id;
+}
+
 CheckedError Parser::ParseDecl() {
   std::vector<std::string> dc = doc_comment_;
   bool fixed = Is(kTokenStruct);
@@ -1151,12 +1178,7 @@ CheckedError Parser::ParseDecl() {
               "either all fields or no fields must have an 'id' attribute");
       // Simply sort by id, then the fields are the same as if no ids had
       // been specified.
-      std::sort(fields.begin(), fields.end(),
-        [](const FieldDef *a, const FieldDef *b) -> bool {
-          auto a_id = atoi(a->attributes.Lookup("id")->constant.c_str());
-          auto b_id = atoi(b->attributes.Lookup("id")->constant.c_str());
-          return a_id < b_id;
-      });
+      std::sort(fields.begin(), fields.end(), compareFieldDefs);
       // Verify we have a contiguous set, and reassign vtable offsets.
       for (int i = 0; i < static_cast<int>(fields.size()); i++) {
         if (i != atoi(fields[i]->attributes.Lookup("id")->constant.c_str()))
@@ -1166,34 +1188,13 @@ CheckedError Parser::ParseDecl() {
       }
     }
   }
-  // Check that no identifiers clash with auto generated fields.
-  // This is not an ideal situation, but should occur very infrequently,
-  // and allows us to keep using very readable names for type & length fields
-  // without inducing compile errors.
-  auto CheckClash = [&fields, &struct_def, this](const char *suffix,
-                                            BaseType basetype) -> CheckedError {
-    auto len = strlen(suffix);
-    for (auto it = fields.begin(); it != fields.end(); ++it) {
-      auto &fname = (*it)->name;
-      if (fname.length() > len &&
-          fname.compare(fname.length() - len, len, suffix) == 0 &&
-          (*it)->value.type.base_type != BASE_TYPE_UTYPE) {
-        auto field = struct_def->fields.Lookup(
-                       fname.substr(0, fname.length() - len));
-        if (field && field->value.type.base_type == basetype)
-          return Error("Field " + fname +
-                " would clash with generated functions for field " +
-                field->name);
-      }
-    }
-    return NoError();
-  };
-  ECHECK(CheckClash("_type", BASE_TYPE_UNION));
-  ECHECK(CheckClash("Type", BASE_TYPE_UNION));
-  ECHECK(CheckClash("_length", BASE_TYPE_VECTOR));
-  ECHECK(CheckClash("Length", BASE_TYPE_VECTOR));
-  ECHECK(CheckClash("_byte_vector", BASE_TYPE_STRING));
-  ECHECK(CheckClash("ByteVector", BASE_TYPE_STRING));
+
+  ECHECK(CheckClash(fields, struct_def, "_type", BASE_TYPE_UNION));
+  ECHECK(CheckClash(fields, struct_def, "Type", BASE_TYPE_UNION));
+  ECHECK(CheckClash(fields, struct_def, "_length", BASE_TYPE_VECTOR));
+  ECHECK(CheckClash(fields, struct_def, "Length", BASE_TYPE_VECTOR));
+  ECHECK(CheckClash(fields, struct_def, "_byte_vector", BASE_TYPE_STRING));
+  ECHECK(CheckClash(fields, struct_def, "ByteVector", BASE_TYPE_STRING));
   EXPECT('}');
   return NoError();
 }
@@ -1235,6 +1236,10 @@ CheckedError Parser::ParseNamespace() {
   return NoError();
 }
 
+static bool compareEnumVals(const EnumVal *a, const EnumVal* b) {
+  return a->value < b->value;
+}
+
 // Best effort parsing of .proto declarations, with the aim to turn them
 // in the closest corresponding FlatBuffer equivalent.
 // We parse everything as identifiers instead of keywords, since we don't
@@ -1285,9 +1290,8 @@ CheckedError Parser::ParseProtoDecl() {
     if (Is(';')) NEXT();
     // Protobuf allows them to be specified in any order, so sort afterwards.
     auto &v = enum_def->vals.vec;
-    std::sort(v.begin(), v.end(), [](const EnumVal *a, const EnumVal *b) {
-      return a->value < b->value;
-    });
+    std::sort(v.begin(), v.end(), compareEnumVals);    
+
     // Temp: remove any duplicates, as .fbs files can't handle them.
     for (auto it = v.begin(); it != v.end(); ) {
       if (it != v.begin() && it[0]->value == it[-1]->value) it = v.erase(it);
@@ -1735,11 +1739,14 @@ std::set<std::string> Parser::GetIncludedFilesRecursive(
 
 // Schema serialization functionality:
 
+template<typename T> bool compareName(const T* a, const T* b) {
+    return a->name < b->name;
+}
+
 template<typename T> void AssignIndices(const std::vector<T *> &defvec) {
   // Pre-sort these vectors, such that we can set the correct indices for them.
   auto vec = defvec;
-  std::sort(vec.begin(), vec.end(),
-            [](const T *a, const T *b) { return a->name < b->name; });
+  std::sort(vec.begin(), vec.end(), compareName<T>);
   for (int i = 0; i < static_cast<int>(vec.size()); i++) vec[i]->index = i;
 }
 

tests/monster_test_generated.h

@@ -98,7 +98,7 @@ STRUCT_END(Vec3, 32);
 
 struct TestSimpleTableWithEnum FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
   enum {
-    VT_COLOR = 4,
+    VT_COLOR = 4
   };
   Color color() const { return static_cast<Color>(GetField<int8_t>(VT_COLOR, 2)); }
   bool mutate_color(Color _color) { return SetField(VT_COLOR, static_cast<int8_t>(_color)); }
@@ -132,7 +132,7 @@ struct Stat FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
   enum {
     VT_ID = 4,
     VT_VAL = 6,
-    VT_COUNT = 8,
+    VT_COUNT = 8
   };
   const flatbuffers::String *id() const { return GetPointer<const flatbuffers::String *>(VT_ID); }
   flatbuffers::String *mutable_id() { return GetPointer<flatbuffers::String *>(VT_ID); }
@@ -201,7 +201,7 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
     VT_TESTHASHU32_FNV1A = 46,
     VT_TESTHASHS64_FNV1A = 48,
     VT_TESTHASHU64_FNV1A = 50,
-    VT_TESTARRAYOFBOOLS = 52,
+    VT_TESTARRAYOFBOOLS = 52
   };
   const Vec3 *pos() const { return GetStruct<const Vec3 *>(VT_POS); }
   Vec3 *mutable_pos() { return GetStruct<Vec3 *>(VT_POS); }

tests/namespace_test/namespace_test1_generated.h

@@ -43,7 +43,7 @@ STRUCT_END(StructInNestedNS, 8);
 
 struct TableInNestedNS FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
   enum {
-    VT_FOO = 4,
+    VT_FOO = 4
   };
   int32_t foo() const { return GetField<int32_t>(VT_FOO, 0); }
   bool mutate_foo(int32_t _foo) { return SetField(VT_FOO, _foo); }

tests/namespace_test/namespace_test2_generated.h

@@ -22,7 +22,7 @@ struct TableInFirstNS FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
   enum {
     VT_FOO_TABLE = 4,
     VT_FOO_ENUM = 6,
-    VT_FOO_STRUCT = 8,
+    VT_FOO_STRUCT = 8
   };
   const NamespaceA::NamespaceB::TableInNestedNS *foo_table() const { return GetPointer<const NamespaceA::NamespaceB::TableInNestedNS *>(VT_FOO_TABLE); }
   NamespaceA::NamespaceB::TableInNestedNS *mutable_foo_table() { return GetPointer<NamespaceA::NamespaceB::TableInNestedNS *>(VT_FOO_TABLE); }

tests/test.cpp

@@ -478,8 +478,8 @@ void FuzzTest1() {
   const uint16_t ushort_val = 0xFEEE;
   const int32_t  int_val    = 0x83333333;
   const uint32_t uint_val   = 0xFDDDDDDD;
-  const int64_t  long_val   = 0x8444444444444444;
-  const uint64_t ulong_val  = 0xFCCCCCCCCCCCCCCC;
+  const int64_t  long_val   = 0x8444444444444444LL;
+  const uint64_t ulong_val  = 0xFCCCCCCCCCCCCCCCULL;
   const float    float_val  = 3.14159f;
   const double   double_val = 3.14159265359;
 
@@ -564,8 +564,28 @@ void FuzzTest2() {
 
   struct RndDef {
     std::string instances[instances_per_definition];
+
+    // Since we're generating schema and corresponding data in tandem,
+    // this convenience function adds strings to both at once.
+    static void Add(RndDef (&definitions_l)[num_definitions],
+                    std::string &schema_l,
+                    const int instances_per_definition_l,
+                    const char *schema_add, const char *instance_add,
+                    int definition) {
+      schema_l += schema_add;
+      for (int i = 0; i < instances_per_definition_l; i++)
+        definitions_l[definition].instances[i] += instance_add;
+    }
   };
 
+  #define AddToSchemaAndInstances(schema_add, instance_add) \
+    RndDef::Add(definitions, schema, instances_per_definition, \
+                schema_add, instance_add, definition)
+
+  #define Dummy() \
+    RndDef::Add(definitions, schema, instances_per_definition, \
+                "byte", "1", definition)
+
   RndDef definitions[num_definitions];
 
   // We are going to generate num_definitions, the first
@@ -577,17 +597,6 @@ void FuzzTest2() {
   // being generated. We generate multiple instances such that when creating
   // hierarchy, we get some variety by picking one randomly.
   for (int definition = 0; definition < num_definitions; definition++) {
-    // Since we're generating schema & and corresponding data in tandem,
-    // this convenience function adds strings to both at once.
-    auto AddToSchemaAndInstances = [&](const char *schema_add,
-                                       const char *instance_add) {
-      schema += schema_add;
-      for (int i = 0; i < instances_per_definition; i++)
-        definitions[definition].instances[i] += instance_add;
-    };
-    // Generate a default type if we can't generate something else.
-    auto Dummy = [&]() { AddToSchemaAndInstances("byte", "1"); };
-
     std::string definition_name = "D" + flatbuffers::NumToString(definition);
 
     bool is_struct = definition < num_struct_definitions;